Split internal/imgcache into the image proxy and the cache (closes #317)

The new package internal/imageproxy holds Proxy, which was imgcache.Service,
with its Config, ImageResponse, CacheStatus and errors. imageproxy.New makes
and registers the counters of upstream fetches and transforms.
internal/imgcache holds the cache only, with its hit and miss counters, and
imgcache.CacheConfig is imgcache.Config. The cache reads and writes each kind
it keeps with one pair of methods: Variant and PutVariant, Source and
PutSource, Failure and PutFailure. Source replaces LookupSource followed by
GetSourceContent. imgcache.go and module.go are gone. The proxy's tests moved
with it. The cache's tests check that the reconciliation pass removes an empty
or cut file and its row. The proxy's tests remove them by hand, then check
that Get fetches or converts again.

Model: opus-5-5

internal/imgcache/cache.go

@@ -1,3 +1,10 @@
+// Package imgcache is the image cache. It keeps:
+//   - the source images fetched from upstream
+//   - the variants made from them
+//   - the negative cache: the source URLs whose fetch failed recently
+//
+// Each image is a file with a row in the database. Eviction removes the
+// least recently used images to keep the cache under its size limit.
 package imgcache
 
 import (
@@ -26,8 +33,12 @@ const maxPendingAccessTimes = 10000
 // have expired.
 const cleanExpiredBatchSize = 1000
 
-// CacheConfig holds cache configuration.
-type CacheConfig struct {
+// DefaultNegativeTTL is how long pixad keeps a failed fetch in the negative
+// cache.
+const DefaultNegativeTTL = 5 * time.Minute
+
+// Config holds cache configuration.
+type Config struct {
 	StateDir    string
 	NegativeTTL time.Duration
 
@@ -48,7 +59,7 @@ type Cache struct {
 	db         *sql.DB
 	srcContent *ContentStorage // source images by source key
 	variants   *VariantStorage // processed variants by cache key
-	config     CacheConfig
+	config     Config
 	log        *slog.Logger
 
 	// Eviction machinery. The channels are created in NewCache so
@@ -73,13 +84,10 @@ type Cache struct {
 	pendingAccessTimesDone    chan struct{}
 	pendingAccessTimesCancel  context.CancelFunc
 
-	// The counts of what the cache does, made and registered by
+	// The counts of cache hits and misses, made and registered by
 	// registerCounters (see counters.go)
-	cacheHits          prometheus.Counter
-	cacheMisses        prometheus.Counter
-	upstreamFetches    prometheus.Counter
-	upstreamFetchBytes prometheus.Counter
-	transforms         prometheus.Counter
+	cacheHits   prometheus.Counter
+	cacheMisses prometheus.Counter
 
 	// reconciliationPageSize is the most rows one read of a content table
 	// returns in the reconciliation pass. NewCache sets it to
@@ -97,7 +105,7 @@ type Cache struct {
 // metricsRegistry. pixad passes Prometheus' default registry, the one
 // /metrics serves. It makes no database call.
 func NewCache(
-	db *sql.DB, config CacheConfig, metricsRegistry prometheus.Registerer,
+	db *sql.DB, config Config, metricsRegistry prometheus.Registerer,
 ) (*Cache, error) {
 	log := config.Logger
 	if log == nil {
@@ -147,75 +155,35 @@ func NewCache(
 	return c, nil
 }
 
-// GetVariant opens a cached variant and returns a reader, its size and its
+// Variant opens a cached variant and returns a reader, its size and its
 // content type, read from the variant file's first bytes. It opens that one
-// file and makes no database call. A variant not in the cache, or any
-// variant of a disabled cache, is ErrNotFound; a variant file whose first
-// bytes are not those of an output format is another error.
-func (c *Cache) GetVariant(
+// file and makes no database call. A variant it opens has its access time
+// handed to the background writer without waiting (see touchVariant). A
+// variant not in the cache, or any variant of a disabled cache, is
+// ErrNotFound; a variant file whose first bytes are not those of an output
+// format is another error.
+func (c *Cache) Variant(
 	cacheKey imagerequest.VariantKey,
 ) (io.ReadCloser, int64, string, error) {
 	if c.config.MaxBytes == 0 {
 		return nil, 0, "", ErrNotFound
 	}
 
-	return c.variants.LoadWithContentType(cacheKey)
+	reader, size, contentType, err := c.variants.LoadWithContentType(cacheKey)
+	if err != nil {
+		return nil, 0, "", err
+	}
+
+	c.touchVariant(cacheKey)
+
+	return reader, size, contentType, nil
 }
 
-// StoreSource stores fetched source content: it writes the file named by
-// the source's key, then the source's row. When the row cannot be written
-// the file is removed and the store fails, as a file with no row is never
-// served or evicted; if that removal fails too, the next reconciliation
-// pass removes the file. On a disabled cache it is a no-op returning an
-// empty key.
-func (c *Cache) StoreSource(
-	ctx context.Context,
-	req *imagerequest.Request,
-	content io.Reader,
-) (imagerequest.SourceKey, error) {
-	if c.config.MaxBytes == 0 {
-		return "", nil
-	}
-
-	data, err := io.ReadAll(content)
-	if err != nil {
-		return "", fmt.Errorf("failed to read source content: %w", err)
-	}
-
-	key := req.Source.Key()
-
-	size, err := c.srcContent.Store(key, data)
-	if err != nil {
-		return "", fmt.Errorf("failed to store source content: %w", err)
-	}
-
-	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO source_content (source_key, size_bytes)
-		VALUES (?, ?)
-		ON CONFLICT(source_key) DO UPDATE SET
-			size_bytes = excluded.size_bytes,
-			last_accessed_at = CURRENT_TIMESTAMP
-	`, string(key), size)
-	if err != nil {
-		deleteErr := c.srcContent.Delete(key)
-		if deleteErr != nil {
-			c.log.Warn("failed to remove source file whose row was not written",
-				"source_key", key, "error", deleteErr)
-		}
-
-		return "", fmt.Errorf("failed to insert source content: %w", err)
-	}
-
-	c.notifyWritePressure()
-
-	return key, nil
-}
-
-// StoreVariant stores a processed variant by its cache key and records
+// PutVariant stores a processed variant by its cache key and records
 // it in the size accounting. On a disabled cache it is a no-op. The
 // accounting insert is best-effort (the startup reconciliation pass
 // adopts any variant file that misses its accounting row).
-func (c *Cache) StoreVariant(
+func (c *Cache) PutVariant(
 	ctx context.Context, cacheKey imagerequest.VariantKey, content io.Reader,
 ) error {
 	if c.config.MaxBytes == 0 {
@@ -244,19 +212,18 @@ func (c *Cache) StoreVariant(
 	return nil
 }
 
-// LookupSource checks if we have cached source content for a request.
-// Returns the source key if found, or an empty key if not; a row whose
-// file is missing is not found. A source found has its access time
-// handed to the background writer without waiting (see
-// touchSourceContent); a disabled cache always reports no cached source.
-func (c *Cache) LookupSource(
-	ctx context.Context, req *imagerequest.Request,
-) (imagerequest.SourceKey, error) {
+// Source opens the cached source of src and returns a reader and its size
+// in bytes. A source whose row or file is missing is ErrNotFound, as is any
+// source of a disabled cache. A source it opens has its access time handed
+// to the background writer without waiting (see touchSourceContent).
+func (c *Cache) Source(
+	ctx context.Context, src imagerequest.Source,
+) (io.ReadCloser, int64, error) {
 	if c.config.MaxBytes == 0 {
-		return "", nil
+		return nil, 0, ErrNotFound
 	}
 
-	key := req.Source.Key()
+	key := src.Key()
 
 	var rowExists bool
 
@@ -264,25 +231,100 @@ func (c *Cache) LookupSource(
 		SELECT EXISTS(SELECT 1 FROM source_content WHERE source_key = ?)
 	`, string(key)).Scan(&rowExists)
 	if err != nil {
-		return "", fmt.Errorf("failed to lookup source: %w", err)
+		return nil, 0, fmt.Errorf("failed to lookup source: %w", err)
 	}
 
 	if !rowExists {
-		return "", nil
+		return nil, 0, ErrNotFound
 	}
 
-	// Verify the content file exists
-	if !c.srcContent.Exists(key) {
-		return "", nil
+	reader, size, err := c.srcContent.LoadWithSize(key)
+	if err != nil {
+		return nil, 0, err
 	}
 
 	c.touchSourceContent(key)
 
+	return reader, size, nil
+}
+
+// PutSource stores fetched source content: it writes the file named by
+// the source's key, then the source's row. When the row cannot be written
+// the file is removed and the store fails, as a file with no row is never
+// served or evicted; if that removal fails too, the next reconciliation
+// pass removes the file. On a disabled cache it is a no-op returning an
+// empty key.
+func (c *Cache) PutSource(
+	ctx context.Context,
+	src imagerequest.Source,
+	content io.Reader,
+) (imagerequest.SourceKey, error) {
+	if c.config.MaxBytes == 0 {
+		return "", nil
+	}
+
+	data, err := io.ReadAll(content)
+	if err != nil {
+		return "", fmt.Errorf("failed to read source content: %w", err)
+	}
+
+	key := src.Key()
+
+	size, err := c.srcContent.Store(key, data)
+	if err != nil {
+		return "", fmt.Errorf("failed to store source content: %w", err)
+	}
+
+	_, err = c.db.ExecContext(ctx, `
+		INSERT INTO source_content (source_key, size_bytes)
+		VALUES (?, ?)
+		ON CONFLICT(source_key) DO UPDATE SET
+			size_bytes = excluded.size_bytes,
+			last_accessed_at = CURRENT_TIMESTAMP
+	`, string(key), size)
+	if err != nil {
+		deleteErr := c.srcContent.Delete(key)
+		if deleteErr != nil {
+			c.log.Warn("failed to remove source file whose row was not written",
+				"source_key", key, "error", deleteErr)
+		}
+
+		return "", fmt.Errorf("failed to insert source content: %w", err)
+	}
+
+	c.notifyWritePressure()
+
 	return key, nil
 }
 
-// StoreNegative stores a negative cache entry for a failed fetch.
-func (c *Cache) StoreNegative(ctx context.Context, req *imagerequest.Request) error {
+// Failure reports whether src is in the negative cache. It only reads: a
+// row past its expiry is not a hit, and the eviction goroutine deletes it
+// with the other expired rows (see CleanExpired).
+func (c *Cache) Failure(
+	ctx context.Context, src imagerequest.Source,
+) (bool, error) {
+	var expiresAt time.Time
+
+	err := c.db.QueryRowContext(ctx, `
+		SELECT expires_at FROM negative_cache
+		WHERE source_host = ? AND source_path = ? AND source_query = ?
+	`, src.Host, src.Path, src.Query).Scan(&expiresAt)
+
+	if errors.Is(err, sql.ErrNoRows) {
+		return false, nil
+	}
+
+	if err != nil {
+		return false, fmt.Errorf("failed to check negative cache: %w", err)
+	}
+
+	expired := time.Now().After(expiresAt)
+
+	return !expired, nil
+}
+
+// PutFailure stores a negative cache entry for src, whose fetch failed.
+func (c *Cache) PutFailure(ctx context.Context, src imagerequest.Source) error {
 	expiresAt := time.Now().UTC().Add(c.config.NegativeTTL)
 
 	_, err := c.db.ExecContext(ctx, `
@@ -291,7 +333,7 @@ func (c *Cache) StoreNegative(ctx context.Context, req *imagerequest.Request) er
 		VALUES (?, ?, ?, ?)
 		ON CONFLICT(source_host, source_path, source_query) DO UPDATE SET
 			expires_at = excluded.expires_at
-	`, req.Source.Host, req.Source.Path, req.Source.Query, expiresAt)
+	`, src.Host, src.Path, src.Query, expiresAt)
 	if err != nil {
 		return fmt.Errorf("failed to insert negative cache: %w", err)
 	}
@@ -299,18 +341,6 @@ func (c *Cache) StoreNegative(ctx context.Context, req *imagerequest.Request) er
 	return nil
 }
 
-// GetSourceContent returns a reader for cached source content by its key,
-// and the content's size in bytes.
-func (c *Cache) GetSourceContent(
-	key imagerequest.SourceKey,
-) (io.ReadCloser, int64, error) {
-	if c.config.MaxBytes == 0 {
-		return nil, 0, ErrNotFound
-	}
-
-	return c.srcContent.LoadWithSize(key)
-}
-
 // CleanExpired removes the negative cache rows past their expiry, one
 // batch per statement, until none is left. Once ctx ends it starts no
 // further batch and returns ctx's error. The eviction goroutine calls it
@@ -334,34 +364,15 @@ func (c *Cache) CleanExpired(ctx context.Context) error {
 	}
 }
 
-// IncrementStats counts a cache hit or miss, and an upstream fetch that read
-// fetchBytes bytes, as IncrementUpstreamFetch does. Like the other Increment
-// methods, it only adds to the cache's Prometheus counters in memory (see
-// counters.go), so it never waits for the database or fails.
-func (c *Cache) IncrementStats(hit bool, fetchBytes int64) {
+// IncrementStats counts a cache hit or miss. It only adds to the cache's
+// Prometheus counters in memory (see counters.go), so it never waits for the
+// database or fails.
+func (c *Cache) IncrementStats(hit bool) {
 	if hit {
 		c.cacheHits.Inc()
 	} else {
 		c.cacheMisses.Inc()
 	}
-
-	c.IncrementUpstreamFetch(fetchBytes)
-}
-
-// IncrementUpstreamFetch counts one upstream fetch that read fetchBytes bytes.
-// A fetch that read no bytes is not counted.
-func (c *Cache) IncrementUpstreamFetch(fetchBytes int64) {
-	if fetchBytes <= 0 {
-		return
-	}
-
-	c.upstreamFetches.Inc()
-	c.upstreamFetchBytes.Add(float64(fetchBytes))
-}
-
-// IncrementTransformCount counts one image transcoded by the image processor.
-func (c *Cache) IncrementTransformCount() {
-	c.transforms.Inc()
 }
 
 // touchVariant hands the access time of a variant served from the cache to
@@ -388,32 +399,6 @@ func (c *Cache) touchSourceContent(key imagerequest.SourceKey) {
 	}
 }
 
-// checkNegativeCache checks if a request is in the negative cache. It only
-// reads: a row past its expiry is not a hit, and the eviction goroutine
-// deletes it with the other expired rows (see CleanExpired).
-func (c *Cache) checkNegativeCache(
-	ctx context.Context, req *imagerequest.Request,
-) (bool, error) {
-	var expiresAt time.Time
-
-	err := c.db.QueryRowContext(ctx, `
-		SELECT expires_at FROM negative_cache
-		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&expiresAt)
-
-	if errors.Is(err, sql.ErrNoRows) {
-		return false, nil
-	}
-
-	if err != nil {
-		return false, fmt.Errorf("failed to check negative cache: %w", err)
-	}
-
-	expired := time.Now().After(expiresAt)
-
-	return !expired, nil
-}
-
 // cleanExpiredBatch deletes up to cleanExpiredBatchSize negative cache
 // rows past their expiry in one statement, and returns how many it
 // deleted. DELETE ... LIMIT needs a SQLite build option, so the subquery

internal/imgcache/cache_hit_internal_test.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"image/color"
 	"io"
-	"os"
 	"testing"
 	"time"
 
@@ -15,10 +14,10 @@ import (
 	"sneak.berlin/go/pixa/internal/magic"
 )
 
-// TestGetVariant_ContentTypeFromFirstBytes stores an image in each output
-// format as a variant and checks that GetVariant serves it whole with the
+// TestVariant_ContentTypeFromFirstBytes stores an image in each output
+// format as a variant and checks that Variant serves it whole with the
 // content type of its format, read from the file.
-func TestGetVariant_ContentTypeFromFirstBytes(t *testing.T) {
+func TestVariant_ContentTypeFromFirstBytes(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -50,14 +49,14 @@ func TestGetVariant_ContentTypeFromFirstBytes(t *testing.T) {
 
 		key := imagerequest.VariantKey("aabbccdd10" + string(format))
 
-		err = cache.StoreVariant(t.Context(), key, bytes.NewReader(image))
+		err = cache.PutVariant(t.Context(), key, bytes.NewReader(image))
 		if err != nil {
-			t.Fatalf("StoreVariant(%s) error = %v", format, err)
+			t.Fatalf("PutVariant(%s) error = %v", format, err)
 		}
 
-		reader, size, contentType, err := cache.GetVariant(key)
+		reader, size, contentType, err := cache.Variant(key)
 		if err != nil {
-			t.Fatalf("GetVariant(%s) error = %v", format, err)
+			t.Fatalf("Variant(%s) error = %v", format, err)
 		}
 
 		served, err := io.ReadAll(reader)
@@ -80,11 +79,11 @@ func TestGetVariant_ContentTypeFromFirstBytes(t *testing.T) {
 	}
 }
 
-// TestGetVariant_RefusesFileOfNoOutputFormat checks that GetVariant refuses
+// TestVariant_RefusesFileOfNoOutputFormat checks that Variant refuses
 // a variant file whose first bytes are not those of an output format, with
 // an error other than ErrNotFound, and that a variant with no file, or any
 // variant of a disabled cache, is ErrNotFound.
-func TestGetVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
+func TestVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -110,118 +109,30 @@ func TestGetVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
 			t.Fatalf("%s: storing the variant file: %v", tt.name, err)
 		}
 
-		reader, _, contentType, err := cache.GetVariant(key)
-		t.Logf("%s: GetVariant() error = %v", tt.name, err)
+		reader, _, contentType, err := cache.Variant(key)
+		t.Logf("%s: Variant() error = %v", tt.name, err)
 
 		if reader != nil || contentType != "" || !errors.Is(err, tt.wantErr) {
-			t.Errorf("%s: GetVariant() = reader %v, content type %q, error %v; "+
+			t.Errorf("%s: Variant() = reader %v, content type %q, error %v; "+
 				"want no reader and %v", tt.name, reader, contentType, err, tt.wantErr)
 		}
 	}
 
-	reader, _, _, err := cache.GetVariant(testVariantKeyFour)
+	reader, _, _, err := cache.Variant(testVariantKeyFour)
 	if reader != nil || !errors.Is(err, ErrNotFound) {
-		t.Errorf("GetVariant() of a variant with no file = reader %v, error %v; "+
+		t.Errorf("Variant() of a variant with no file = reader %v, error %v; "+
 			"want no reader and %v", reader, err, ErrNotFound)
 	}
 
 	disabled, _ := newEvictionTestCache(t, 0)
 
-	reader, _, _, err = disabled.GetVariant(testVariantKeyOne)
+	reader, _, _, err = disabled.Variant(testVariantKeyOne)
 	if reader != nil || !errors.Is(err, ErrNotFound) {
-		t.Errorf("GetVariant() on a disabled cache = reader %v, error %v; "+
+		t.Errorf("Variant() on a disabled cache = reader %v, error %v; "+
 			"want no reader and %v", reader, err, ErrNotFound)
 	}
 }
 
-// TestService_Get_MakesAgainVariantOfNoOutputFormat replaces a cached
-// variant's file with text, and checks that the next request is a miss
-// answered with the variant made again, and the one after a hit.
-func TestService_Get_MakesAgainVariantOfNoOutputFormat(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	want, _ := getImage(t, svc, req)
-
-	path := svc.cache.variants.keyToPath(imagerequest.CacheKey(req))
-
-	err := os.WriteFile(path, []byte("this is text, not an image"), StorageFilePerm)
-	if err != nil {
-		t.Fatalf("replacing the variant file: %v", err)
-	}
-
-	got, status := getImage(t, svc, req)
-	t.Logf("after the replacement: %d bytes, %s", len(got), status)
-
-	if status != CacheMiss || !bytes.Equal(got, want) {
-		t.Errorf("after the replacement: Get() = %d bytes, %s; want the %d bytes "+
-			"made again, %s", len(got), status, len(want), CacheMiss)
-	}
-
-	got, status = getImage(t, svc, req)
-
-	if status != CacheHit || !bytes.Equal(got, want) {
-		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
-			len(got), status, len(want), CacheHit)
-	}
-}
-
-// TestService_Get_HitWaitsForNoDatabaseWrite holds the database's one
-// connection while a cached variant is requested. The hit must be answered
-// while the connection is still held, and its access time must reach the
-// database once it is free.
-func TestService_Get_HitWaitsForNoDatabaseWrite(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	key := imagerequest.CacheKey(req)
-
-	getImage(t, svc, req)
-
-	// Each connection to an in-memory SQLite database opens a new, empty one,
-	// so the goroutine that writes the access times must share the
-	// connection that holds the schema.
-	svc.cache.db.SetMaxOpenConns(1)
-	svc.cache.StartPendingAccessTimeWrites()
-
-	defer func() { _ = svc.cache.StopPendingAccessTimeWrites(t.Context()) }()
-
-	anHourAgo := time.Now().Add(-time.Hour)
-	setVariantLastAccessed(t, svc.cache, key, anHourAgo)
-
-	releaseDatabase := holdDatabase(t, svc.cache)
-	defer releaseDatabase()
-
-	results := startGet(t.Context(), svc, req)
-
-	select {
-	case got := <-results:
-		if got.err != nil {
-			t.Fatalf("Get() of the cached variant error = %v", got.err)
-		}
-	case <-time.After(pendingAccessTimesWait):
-		t.Fatal("the cache hit waited for the database")
-	}
-
-	releaseDatabase()
-
-	deadline := time.Now().Add(pendingAccessTimesWait)
-
-	for countRows(t, svc.cache, `
-		SELECT COUNT(*) FROM variant_content
-		WHERE cache_key = ? AND last_accessed_at > ?
-	`, string(key), anHourAgo.UTC().Format(sqliteTimestampFormat)) == 0 {
-		if time.Now().After(deadline) {
-			t.Fatal("the hit's access time was not written")
-		}
-
-		time.Sleep(10 * time.Millisecond)
-	}
-}
-
 // TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit hands one
 // more access time of a variant, and one more of a source, than may wait to
 // be written. touchVariant and touchSourceContent must return each time

internal/imgcache/cache_internal_test.go

@@ -50,7 +50,7 @@ func TestCache_CleanExpired(t *testing.T) {
 	tmpDir := t.TempDir()
 	db := setupTestDB(t)
 
-	cache, _ := NewCache(db, CacheConfig{
+	cache, _ := NewCache(db, Config{
 		StateDir:    tmpDir,
 		NegativeTTL: 1 * time.Millisecond,
 		MaxBytes:    1 << 30,
@@ -103,7 +103,7 @@ func TestCache_StorageDirectoriesCreated(t *testing.T) {
 	tmpDir := t.TempDir()
 	db := setupTestDB(t)
 
-	_, err := NewCache(db, CacheConfig{
+	_, err := NewCache(db, Config{
 		StateDir: tmpDir,
 		MaxBytes: 1 << 30,
 	}, prometheus.NewRegistry())

internal/imgcache/concurrent_misses_internal_test.go

@@ -1,559 +0,0 @@
-package imgcache
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"image/jpeg"
-	"io"
-	"io/fs"
-	"strings"
-	"sync"
-	"sync/atomic"
-	"testing"
-	"time"
-
-	"github.com/getsentry/sentry-go"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/magic"
-)
-
-// arrivalWait is how long a test gives requests it has started to reach the
-// point where they wait for a held fetch.
-const arrivalWait = 100 * time.Millisecond
-
-// heldFetcher counts the fetches it is asked for and holds each one until
-// releaseFetches is called, so that a test can have requests arrive while a
-// fetch is in progress. started receives once for every fetch.
-type heldFetcher struct {
-	upstream    httpfetcher.Fetcher
-	fetches     atomic.Int32
-	started     chan struct{}
-	release     chan struct{}
-	releaseOnce sync.Once
-}
-
-func (f *heldFetcher) Fetch(
-	ctx context.Context, source imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	f.fetches.Add(1)
-
-	f.started <- struct{}{}
-
-	select {
-	case <-f.release:
-	case <-ctx.Done():
-		return nil, ctx.Err()
-	}
-
-	return f.upstream.Fetch(ctx, source)
-}
-
-// releaseFetches lets every held fetch, and every later one, go on.
-func (f *heldFetcher) releaseFetches() {
-	f.releaseOnce.Do(func() { close(f.release) })
-}
-
-// setupHeldFetchService returns a test service whose fetches go through a
-// heldFetcher. Its database is limited to one connection: each connection to
-// an in-memory SQLite database opens a new, empty one, so requests running at
-// once must share the connection that holds the schema.
-func setupHeldFetchService(t *testing.T) (*Service, *TestFixtures, *heldFetcher) {
-	t.Helper()
-
-	svc, fixtures := SetupTestService(t)
-	svc.cache.db.SetMaxOpenConns(1)
-
-	fetcher := &heldFetcher{
-		upstream: svc.fetcher,
-		started:  make(chan struct{}, 100),
-		release:  make(chan struct{}),
-	}
-	svc.fetcher = fetcher
-
-	t.Cleanup(fetcher.releaseFetches)
-
-	return svc, fixtures, fetcher
-}
-
-// photoVariant asks for the test photo, 100x100, at 50x25 as a JPEG of the
-// given quality and fit mode. Each call returns a new request, which a test
-// may change.
-func photoVariant(
-	fixtures *TestFixtures, quality int, fit imagerequest.Fit,
-) *imagerequest.Request {
-	return &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 25},
-			Format:  imagerequest.FormatJPEG,
-			Quality: quality,
-			FitMode: fit,
-		},
-	}
-}
-
-// getResult is what one Get call returned, with the image read out.
-type getResult struct {
-	image []byte
-	err   error
-}
-
-// startGet calls Get in a goroutine of its own and delivers what it returned
-// on the channel.
-func startGet(
-	ctx context.Context, svc *Service, req *imagerequest.Request,
-) <-chan getResult {
-	results := make(chan getResult, 1)
-
-	go func() {
-		resp, err := svc.Get(ctx, req)
-		if err != nil {
-			results <- getResult{err: err}
-
-			return
-		}
-
-		defer func() { _ = resp.Content.Close() }()
-
-		image, err := io.ReadAll(resp.Content)
-		results <- getResult{image: image, err: err}
-	}()
-
-	return results
-}
-
-// jpegSize returns the width and height of the JPEG image in data, or 0 and 0
-// if data is not one.
-func jpegSize(data []byte) (int, int) {
-	config, err := jpeg.DecodeConfig(bytes.NewReader(data))
-	if err != nil {
-		return 0, 0
-	}
-
-	return config.Width, config.Height
-}
-
-// TestService_Get_ConcurrentMissesShareOneFetch starts several requests for
-// one uncached variant while the first one's fetch is held. Between them they
-// must fetch the source once and transcode it once, every one must be answered
-// with the same 50x25 JPEG, and each must count one miss.
-func TestService_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	const requests = 8
-
-	pending := make([]<-chan getResult, 0, requests)
-	for range requests {
-		pending = append(pending,
-			startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover)))
-	}
-
-	<-fetcher.started
-	time.Sleep(arrivalWait)
-	fetcher.releaseFetches()
-
-	var first []byte
-
-	for i, results := range pending {
-		got := <-results
-		if got.err != nil {
-			t.Fatalf("request %d: Get() error = %v", i, got.err)
-		}
-
-		if width, height := jpegSize(got.image); width != 50 || height != 25 {
-			t.Errorf("request %d: image is %dx%d, want a 50x25 JPEG", i, width, height)
-		}
-
-		if first == nil {
-			first = got.image
-		} else if !bytes.Equal(got.image, first) {
-			t.Errorf("request %d: image differs from request 0's", i)
-		}
-	}
-
-	if fetches := fetcher.fetches.Load(); fetches != 1 {
-		t.Errorf("%d requests made %d upstream fetches, want 1", requests, fetches)
-	}
-
-	// NewTestFS builds the same files the test service's fetcher serves.
-	testFS, _ := NewTestFS(t)
-
-	photo, err := fs.ReadFile(testFS, fixtures.GoodHostJPEG)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	want := counterValues{0, requests, 1, int64(len(photo)), 1}
-
-	if got := readCounters(svc.cache); got != want {
-		t.Errorf("counters = %+v, want %+v", got, want)
-	}
-}
-
-// TestService_Get_ConcurrentVariantsStayApart requests three variants of the
-// test photo at once that differ only in quality or fit. Each must be made by
-// a fetch and a transcode of its own, and each answer must be its own variant.
-func TestService_Get_ConcurrentVariantsStayApart(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	cover := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-	lowQuality := startGet(t.Context(), svc,
-		photoVariant(fixtures, 40, imagerequest.FitCover))
-	contain := startGet(t.Context(), svc,
-		photoVariant(fixtures, 85, imagerequest.FitContain))
-
-	for range 3 {
-		select {
-		case <-fetcher.started:
-		case <-time.After(5 * time.Second):
-			t.Fatal("fewer fetches started than variants requested: " +
-				"variants differing in quality or fit were merged")
-		}
-	}
-
-	fetcher.releaseFetches()
-
-	images := make(map[string][]byte)
-
-	for _, variant := range []struct {
-		name          string
-		results       <-chan getResult
-		width, height int
-	}{
-		{"q=85 fit=cover", cover, 50, 25},
-		{"q=40 fit=cover", lowQuality, 50, 25},
-		{"q=85 fit=contain", contain, 25, 25},
-	} {
-		got := <-variant.results
-		if got.err != nil {
-			t.Fatalf("%s: Get() error = %v", variant.name, got.err)
-		}
-
-		width, height := jpegSize(got.image)
-		if width != variant.width || height != variant.height {
-			t.Errorf("%s: image is %dx%d, want a %dx%d JPEG", variant.name,
-				width, height, variant.width, variant.height)
-		}
-
-		images[variant.name] = got.image
-	}
-
-	if bytes.Equal(images["q=85 fit=cover"], images["q=40 fit=cover"]) {
-		t.Error("q=40 was answered with the q=85 image")
-	}
-}
-
-// TestService_Get_WaiterStopsWhenItsContextEnds has a second request for a
-// variant join the first one's held fetch, then ends the second request's
-// context. The second request must return at once with the context's error,
-// while the fetch is still held, and the first must still be answered.
-func TestService_Get_WaiterStopsWhenItsContextEnds(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	first := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	<-fetcher.started
-
-	waiterCtx, cancelWaiter := context.WithCancel(t.Context())
-	waiter := startGet(waiterCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	time.Sleep(arrivalWait)
-	cancelWaiter()
-
-	select {
-	case got := <-waiter:
-		if !errors.Is(got.err, context.Canceled) {
-			t.Errorf("waiting request: Get() error = %v, want %v",
-				got.err, context.Canceled)
-		}
-	case <-time.After(time.Second):
-		t.Fatal("waiting request did not return when its context ended")
-	}
-
-	fetcher.releaseFetches()
-
-	got := <-first
-	if got.err != nil {
-		t.Fatalf("first request: Get() error = %v", got.err)
-	}
-
-	if width, height := jpegSize(got.image); width != 50 || height != 25 {
-		t.Errorf("first request: image is %dx%d, want a 50x25 JPEG", width, height)
-	}
-
-	if fetches := fetcher.fetches.Load(); fetches != 1 {
-		t.Errorf("upstream fetches = %d, want 1", fetches)
-	}
-}
-
-// TestService_Get_FirstRequestLeavingKeepsTheWork ends the context of the
-// request whose fetch is held, after a second request has joined it. The fetch
-// and transcode must go on and answer the second request. The first request
-// waits for its own work, as every request did before misses were shared, and
-// is answered too.
-func TestService_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	firstCtx, cancelFirst := context.WithCancel(t.Context())
-	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	<-fetcher.started
-
-	second := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	time.Sleep(arrivalWait)
-	cancelFirst()
-	fetcher.releaseFetches()
-
-	for name, results := range map[string]<-chan getResult{
-		"first request": first, "second request": second,
-	} {
-		got := <-results
-		if got.err != nil {
-			t.Fatalf("%s: Get() error = %v", name, got.err)
-		}
-
-		if width, height := jpegSize(got.image); width != 50 || height != 25 {
-			t.Errorf("%s: image is %dx%d, want a 50x25 JPEG", name, width, height)
-		}
-	}
-
-	if fetches := fetcher.fetches.Load(); fetches != 1 {
-		t.Errorf("upstream fetches = %d, want 1", fetches)
-	}
-}
-
-// TestService_Get_ConcurrentMissesShareAFailure has several requests for an
-// image that cannot be served arrive while its fetch is held: the one fetch
-// answers all of them with its error. The request after them is answered from
-// the negative cache, where the failure is kept.
-func TestService_Get_ConcurrentMissesShareAFailure(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name        string
-		path        string
-		wantErr     error // what every request at once gets
-		wantNextErr error // what the request after them gets
-		wantFetches int32 // fetches once the request after them is answered
-	}{
-		{"upstream answers 404, kept in the negative cache",
-			"/images/missing.jpg", httpfetcher.ErrUpstreamError,
-			ErrNegativeCached, 1},
-		{"source fails the magic byte check, kept in the negative cache",
-			"/images/text.png", magic.ErrUnknownFormat, ErrNegativeCached, 1},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			svc, fixtures, fetcher := setupHeldFetchService(t)
-
-			request := func() *imagerequest.Request {
-				req := photoVariant(fixtures, 85, imagerequest.FitCover)
-				req.Source.Path = tc.path
-
-				return req
-			}
-
-			pending := make([]<-chan getResult, 0, 4)
-			for range 4 {
-				pending = append(pending, startGet(t.Context(), svc, request()))
-			}
-
-			<-fetcher.started
-			time.Sleep(arrivalWait)
-			fetcher.releaseFetches()
-
-			for i, results := range pending {
-				if got := <-results; !errors.Is(got.err, tc.wantErr) {
-					t.Errorf("request %d: Get() error = %v, want %v", i, got.err, tc.wantErr)
-				}
-			}
-
-			_, err := svc.Get(t.Context(), request())
-			if !errors.Is(err, tc.wantNextErr) {
-				t.Errorf("next request: Get() error = %v, want %v", err, tc.wantNextErr)
-			}
-
-			if fetches := fetcher.fetches.Load(); fetches != tc.wantFetches {
-				t.Errorf("upstream fetches = %d, want %d", fetches, tc.wantFetches)
-			}
-		})
-	}
-}
-
-// TestService_Get_EndedRequestFetchesNothing checks that a request whose
-// context has already ended when it misses the cache starts no fetch.
-func TestService_Get_EndedRequestFetchesNothing(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	ctx, cancel := context.WithCancel(t.Context())
-	cancel()
-
-	_, err := svc.Get(ctx, photoVariant(fixtures, 85, imagerequest.FitCover))
-	if !errors.Is(err, context.Canceled) {
-		t.Errorf("Get() error = %v, want %v", err, context.Canceled)
-	}
-
-	if fetches := fetcher.fetches.Load(); fetches != 0 {
-		t.Errorf("upstream fetches = %d, want 0", fetches)
-	}
-}
-
-// TestService_Get_ReturnsByItsDeadline gives a request a deadline and holds
-// its fetch until the fetch's context ends, as the fetcher does while it waits
-// for a free connection to the host. The request must return by its deadline
-// with the deadline's error.
-func TestService_Get_ReturnsByItsDeadline(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, _ := setupHeldFetchService(t)
-
-	const timeout = 200 * time.Millisecond
-
-	ctx, cancel := context.WithTimeout(t.Context(), timeout)
-	defer cancel()
-
-	results := startGet(ctx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	select {
-	case got := <-results:
-		if !errors.Is(got.err, context.DeadlineExceeded) {
-			t.Errorf("Get() error = %v, want %v", got.err, context.DeadlineExceeded)
-		}
-	case <-time.After(timeout + time.Second):
-		t.Fatal("request did not return by its deadline")
-	}
-}
-
-// TestService_Get_WaiterGetsProcessingTimedOut has a request with no deadline
-// join the held fetch of a first request with a short one. With the only
-// processing slot held, the first request's transcode waits for it until the
-// first request's deadline ends, and stops then. The waiting request, whose
-// own context has not ended, must get ErrProcessingTimedOut, which the image
-// routes answer 503 as when pixa is busy.
-func TestService_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
-	)
-
-	holdProcessingSlot(t, svc.processor)
-
-	const firstTimeout = 500 * time.Millisecond
-
-	firstCtx, cancelFirst := context.WithTimeout(t.Context(), firstTimeout)
-	defer cancelFirst()
-
-	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	<-fetcher.started
-
-	waiter := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	time.Sleep(arrivalWait)
-	fetcher.releaseFetches()
-
-	t.Logf("first request: Get() error = %v", (<-first).err)
-
-	got := <-waiter
-	t.Logf("waiting request: Get() error = %v", got.err)
-
-	if !errors.Is(got.err, ErrProcessingTimedOut) {
-		t.Errorf("waiting request: Get() error = %v, want %v",
-			got.err, ErrProcessingTimedOut)
-	}
-}
-
-// panickingFetcher panics on every fetch.
-type panickingFetcher struct{}
-
-func (panickingFetcher) Fetch(
-	context.Context, imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	panic("upstream fetcher panicked")
-}
-
-// TestService_Get_PanicBecomesAnError checks that a panic while a variant is
-// being made reaches its request as an error naming the panic, instead of
-// being raised again.
-func TestService_Get_PanicBecomesAnError(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	svc.fetcher = panickingFetcher{}
-
-	var err error
-
-	func() {
-		defer func() {
-			if recovered := recover(); recovered != nil {
-				t.Fatalf("Get() panicked: %v", recovered)
-			}
-		}()
-
-		_, err = svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
-	}()
-
-	if err == nil || !strings.Contains(err.Error(), "upstream fetcher panicked") {
-		t.Errorf("Get() error = %v, want one naming the panic", err)
-	}
-}
-
-// TestService_Get_PanicIsReportedToSentry checks that a panic while a variant
-// is being made is reported through the Sentry hub on the request's context,
-// where the Sentry middleware puts one when sentry_dsn is set.
-func TestService_Get_PanicIsReportedToSentry(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	svc.fetcher = panickingFetcher{}
-
-	transport := &sentry.MockTransport{}
-
-	client, err := sentry.NewClient(sentry.ClientOptions{
-		Dsn:       "https://abc123@sentry.example.com/42",
-		Transport: transport,
-	})
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	ctx := sentry.SetHubOnContext(t.Context(),
-		sentry.NewHub(client, sentry.NewScope()))
-
-	func() {
-		defer func() {
-			if recovered := recover(); recovered != nil {
-				t.Fatalf("Get() panicked: %v", recovered)
-			}
-		}()
-
-		_, _ = svc.Get(ctx, photoVariant(fixtures, 85, imagerequest.FitCover))
-	}()
-
-	events := transport.Events()
-	if len(events) != 1 || events[0].Message != "upstream fetcher panicked" {
-		t.Errorf("Sentry events = %+v, want one for the panic", events)
-	}
-}

internal/imgcache/counters.go

@@ -19,22 +19,8 @@ func (c *Cache) registerCounters(metricsRegistry prometheus.Registerer) error {
 		Name: "pixa_cache_misses_total",
 		Help: "Image requests not served from the cache.",
 	})
-	c.upstreamFetches = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "pixa_upstream_fetches_total",
-		Help: "Fetches of a source image from upstream that read any bytes.",
-	})
-	c.upstreamFetchBytes = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "pixa_upstream_fetch_bytes_total",
-		Help: "Bytes read from upstream by fetches of source images.",
-	})
-	c.transforms = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "pixa_transforms_total",
-		Help: "Images the image processor transformed.",
-	})
 
-	for _, counter := range []prometheus.Counter{
-		c.cacheHits, c.cacheMisses, c.upstreamFetches, c.upstreamFetchBytes, c.transforms,
-	} {
+	for _, counter := range []prometheus.Counter{c.cacheHits, c.cacheMisses} {
 		err := metricsRegistry.Register(counter)
 		if err != nil {
 			return fmt.Errorf("failed to register the cache's counters: %w", err)

internal/imgcache/counters_internal_test.go

@@ -8,26 +8,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus/testutil"
 )
 
-// counterValues holds the values of a cache's counters.
-type counterValues struct {
-	hitCount           int64
-	missCount          int64
-	upstreamFetchCount int64
-	upstreamFetchBytes int64
-	transformCount     int64
-}
-
-// readCounters reads cache's counters.
-func readCounters(cache *Cache) counterValues {
-	return counterValues{
-		hitCount:           int64(testutil.ToFloat64(cache.cacheHits)),
-		missCount:          int64(testutil.ToFloat64(cache.cacheMisses)),
-		upstreamFetchCount: int64(testutil.ToFloat64(cache.upstreamFetches)),
-		upstreamFetchBytes: int64(testutil.ToFloat64(cache.upstreamFetchBytes)),
-		transformCount:     int64(testutil.ToFloat64(cache.transforms)),
-	}
-}
-
 // TestNewCache_RegistersItsCountersOnItsRegistry checks that NewCache
 // registers the cache's counters on the registry it is given, under the
 // names README.md gives them.
@@ -37,7 +17,7 @@ func TestNewCache_RegistersItsCountersOnItsRegistry(t *testing.T) {
 	registry := prometheus.NewRegistry()
 
 	_, err := NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
 	if err != nil {
 		t.Fatalf("NewCache() error = %v", err)
 	}
@@ -45,9 +25,6 @@ func TestNewCache_RegistersItsCountersOnItsRegistry(t *testing.T) {
 	names := []string{
 		"pixa_cache_hits_total",
 		"pixa_cache_misses_total",
-		"pixa_upstream_fetches_total",
-		"pixa_upstream_fetch_bytes_total",
-		"pixa_transforms_total",
 	}
 
 	count, err := testutil.GatherAndCount(registry, names...)
@@ -70,13 +47,13 @@ func TestNewCache_FailsWhenItsCountersCannotBeRegistered(t *testing.T) {
 	registry := prometheus.NewRegistry()
 
 	_, err := NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
 	if err != nil {
 		t.Fatalf("NewCache() of the first cache error = %v", err)
 	}
 
 	_, err = NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
 	t.Logf("NewCache() of the second cache error = %v", err)
 
 	var alreadyRegistered prometheus.AlreadyRegisteredError

internal/imgcache/divzero_internal_test.go

@@ -1,47 +0,0 @@
-package imgcache
-
-import (
-	"fmt"
-	"math"
-	"testing"
-)
-
-func TestSizePercentSafeWithZeroFetchBytes(t *testing.T) {
-	t.Parallel()
-
-	// Simulate the calculation from processAndStore
-	fetchBytes := int64(0)
-	outputSize := int64(100)
-
-	var sizePercent float64
-	if fetchBytes > 0 {
-		sizePercent = float64(outputSize) / float64(fetchBytes) * 100.0
-	}
-
-	// sizePercent should be 0, not Inf or NaN
-	if math.IsInf(sizePercent, 0) || math.IsNaN(sizePercent) {
-		t.Errorf("sizePercent = %f, should not be Inf/NaN", sizePercent)
-	}
-
-	// Should produce valid log output
-	result := fmt.Sprintf("%.1f%%", sizePercent)
-	if result != "0.0%" {
-		t.Errorf("formatted size ratio = %q, want %q", result, "0.0%")
-	}
-}
-
-func TestSizePercentNormalCase(t *testing.T) {
-	t.Parallel()
-
-	fetchBytes := int64(1000)
-	outputSize := int64(500)
-
-	var sizePercent float64
-	if fetchBytes > 0 {
-		sizePercent = float64(outputSize) / float64(fetchBytes) * 100.0
-	}
-
-	if math.Abs(sizePercent-50.0) > 0.001 {
-		t.Errorf("sizePercent = %f, want 50.0", sizePercent)
-	}
-}

internal/imgcache/eviction.go

@@ -317,7 +317,7 @@ func (c *Cache) evictVariant(
 // evictSourceBlob removes one source: its row first, then its file, as
 // evictVariant does for a variant. It holds no lock: a store of the same
 // source in between can leave the source's row with no file, which
-// LookupSource treats as a miss.
+// Source treats as a miss.
 func (c *Cache) evictSourceBlob(ctx context.Context, key imagerequest.SourceKey) error {
 	_, err := c.db.ExecContext(ctx,
 		`DELETE FROM source_content WHERE source_key = ?`, string(key))
@@ -479,7 +479,7 @@ func (c *Cache) runCleanExpired(ctx context.Context) {
 // then on the first periodic eviction tick that comes at least ten times
 // as long after the last pass ended as that pass took, off the request
 // hot path: it adopts variant files that predate the accounting table
-// (or whose accounting insert failed, e.g. StoreVariant's best-effort
+// (or whose accounting insert failed, e.g. PutVariant's best-effort
 // insert under transient DB contention), drops variant accounting rows
 // whose files are missing, removes source blob files the database does
 // not know, removes source and variant files that are empty or not the

internal/imgcache/eviction_internal_test.go

@@ -67,7 +67,7 @@ func newEvictionTestCache(t *testing.T, maxBytes int64) (*Cache, string) {
 	db := evictionTestDB(t)
 
 	// maxBytes zero turns the disk cache off, as cache_max_bytes: 0 does.
-	cache, err := NewCache(db, CacheConfig{
+	cache, err := NewCache(db, Config{
 		StateDir:    tmpDir,
 		NegativeTTL: 5 * time.Minute,
 		MaxBytes:    maxBytes,
@@ -98,11 +98,11 @@ func storeEvictionTestSource(
 		},
 	}
 
-	key, err := cache.StoreSource(
-		context.Background(), req, bytes.NewReader(content),
+	key, err := cache.PutSource(
+		context.Background(), req.Source, bytes.NewReader(content),
 	)
 	if err != nil {
-		t.Fatalf("StoreSource(%s%s) failed: %v", host, path, err)
+		t.Fatalf("PutSource(%s%s) failed: %v", host, path, err)
 	}
 
 	return key
@@ -115,9 +115,9 @@ func storeEvictionTestVariant(
 ) {
 	t.Helper()
 
-	err := cache.StoreVariant(t.Context(), key, bytes.NewReader(content))
+	err := cache.PutVariant(t.Context(), key, bytes.NewReader(content))
 	if err != nil {
-		t.Fatalf("StoreVariant(%s) failed: %v", key, err)
+		t.Fatalf("PutVariant(%s) failed: %v", key, err)
 	}
 }
 
@@ -423,20 +423,20 @@ func assertDisabledCacheWritesAreNoOps(
 
 	ctx := t.Context()
 
-	err := cache.StoreVariant(
+	err := cache.PutVariant(
 		ctx, imagerequest.CacheKey(req), bytes.NewReader([]byte("data")),
 	)
 	if err != nil {
-		t.Fatalf("StoreVariant on disabled cache must be a no-op, got error: %v", err)
+		t.Fatalf("PutVariant on disabled cache must be a no-op, got error: %v", err)
 	}
 
-	key, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")))
+	key, err := cache.PutSource(ctx, req.Source, bytes.NewReader([]byte("data")))
 	if err != nil {
-		t.Fatalf("StoreSource on disabled cache must be a no-op, got error: %v", err)
+		t.Fatalf("PutSource on disabled cache must be a no-op, got error: %v", err)
 	}
 
 	if key != "" {
-		t.Errorf("StoreSource on disabled cache returned key %q, want empty", key)
+		t.Errorf("PutSource on disabled cache returned key %q, want empty", key)
 	}
 }
 
@@ -449,13 +449,13 @@ func assertDisabledCacheReadsAlwaysMiss(
 
 	ctx := t.Context()
 
-	key, err := cache.LookupSource(ctx, req)
-	if err != nil {
-		t.Fatalf("LookupSource on disabled cache failed: %v", err)
+	reader, _, err := cache.Source(ctx, req.Source)
+	if !errors.Is(err, ErrNotFound) {
+		t.Fatalf("Source on disabled cache error = %v, want %v", err, ErrNotFound)
 	}
 
-	if key != "" {
-		t.Errorf("LookupSource on disabled cache = %q, want empty", key)
+	if reader != nil {
+		t.Errorf("Source on disabled cache = reader %v, want none", reader)
 	}
 }
 
@@ -544,7 +544,7 @@ func TestEvictionRunsUnderWritePressure(t *testing.T) {
 }
 
 // TestEvictionRunsOnPeriodicSchedule writes three variant files straight
-// to disk, bypassing StoreVariant, so they have no accounting rows and no
+// to disk, bypassing PutVariant, so they have no accounting rows and no
 // write-pressure notification fires. Only a periodic reconciliation pass
 // can then adopt them, and only the eviction pass that follows it can
 // evict them.
@@ -697,7 +697,7 @@ func TestStartEvictionReconcilesAccountingWithDisk(t *testing.T) {
 // TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup proves
 // reconciliation is not a one-shot startup-only pass: it must also run
 // on the periodic ticker, so a variant file that lands on disk with no
-// accounting row well after startup (e.g. because StoreVariant's
+// accounting row well after startup (e.g. because PutVariant's
 // best-effort accounting insert failed under transient contention, or
 // any other cause of an untracked file appearing during steady-state
 // operation) is still adopted into accounting eventually, rather than
@@ -733,7 +733,7 @@ func TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup(t *testing.T) {
 
 	// Simulate a variant whose accounting insert failed after the
 	// process was already running and serving requests: the content
-	// file is written directly, bypassing StoreVariant's (and thus its
+	// file is written directly, bypassing PutVariant's (and thus its
 	// accounting insert) entirely, exactly as would happen if that
 	// insert had failed and only the file write had succeeded.
 	untracked := bytes.Repeat([]byte{0x41}, 900)

internal/imgcache/imgcache.go

@@ -1,29 +0,0 @@
-// Package imgcache provides types for the image caching proxy.
-package imgcache
-
-import "io"
-
-// ImageResponse represents a processed image ready to serve
-type ImageResponse struct {
-	// Content is the image data reader
-	Content io.ReadCloser
-	// ContentLength is the size in bytes (-1 if unknown)
-	ContentLength int64
-	// ContentType is the MIME type of the response
-	ContentType string
-	// ETag is the entity tag for caching
-	ETag string
-	// CacheStatus indicates HIT or MISS
-	CacheStatus CacheStatus
-	// FetchedBytes is the number of bytes fetched from upstream (0 if cache hit)
-	FetchedBytes int64
-}
-
-// CacheStatus indicates whether the response was served from cache.
-type CacheStatus string
-
-// Cache status values for response headers.
-const (
-	CacheHit  CacheStatus = "HIT"
-	CacheMiss CacheStatus = "MISS"
-)

internal/imgcache/max_concurrent_processing_internal_test.go

@@ -1,130 +0,0 @@
-package imgcache
-
-import (
-	"image/color"
-	"image/jpeg"
-	"io"
-	"os"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// widthOnlyRequest asks for the test photo at width, its height scaled to
-// keep the photo's aspect ratio.
-func widthOnlyRequest(fixtures *TestFixtures, width int) *imagerequest.Request {
-	return &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: width},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-}
-
-// holdProcessingSlot takes one of proc's processing slots and returns the
-// func that gives it back. Process takes its slot before it reads its input,
-// so once it has read a byte from the pipe it holds the slot, until the pipe
-// is closed.
-func holdProcessingSlot(
-	t *testing.T, proc *imageprocessor.ImageProcessor,
-) func() {
-	t.Helper()
-
-	input, feed := io.Pipe()
-
-	go func() {
-		_, _ = proc.Process(t.Context(), input, &imagerequest.Transform{})
-	}()
-
-	_, err := feed.Write([]byte{0})
-	if err != nil {
-		t.Fatalf("Process call to hold the slot did not start: %v", err)
-	}
-
-	release := func() { _ = feed.Close() }
-	t.Cleanup(release)
-
-	return release
-}
-
-// TestService_Get_WaitsForSlotBeforeReadingCachedSource checks that a
-// request whose source is cached holds none of it while it waits for a
-// processing slot: it reads the cached file only once it has a slot. With
-// the only slot held, a request for a new width of the cached 100x100 photo
-// waits; the cached file is then rewritten as a 100x50 image before the slot
-// is freed, so the request must answer with that image scaled to 40x20.
-func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
-	)
-
-	// A first request caches the photo as a source.
-	resp, err := svc.Get(t.Context(), widthOnlyRequest(fixtures, 50))
-	if err != nil {
-		t.Fatalf("first Get() error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	sourceKey, err := svc.cache.LookupSource(t.Context(),
-		widthOnlyRequest(fixtures, 50))
-	if err != nil || sourceKey == "" {
-		t.Fatalf("LookupSource() = %q, %v; want the cached source",
-			sourceKey, err)
-	}
-
-	release := holdProcessingSlot(t, svc.processor)
-
-	var (
-		waited    *ImageResponse
-		waitedErr error
-	)
-
-	done := make(chan struct{})
-
-	go func() {
-		defer close(done)
-
-		waited, waitedErr = svc.Get(t.Context(), widthOnlyRequest(fixtures, 40))
-	}()
-
-	// Give the request time to reach the slot: had it read the cached source
-	// before waiting, it would have read it by now.
-	time.Sleep(100 * time.Millisecond)
-
-	err = os.WriteFile(svc.cache.srcContent.keyToPath(sourceKey),
-		generateTestJPEG(t, 100, 50, color.RGBA{0, 0, 255, 255}), 0o600)
-	if err != nil {
-		t.Fatalf("failed to rewrite the cached source: %v", err)
-	}
-
-	release()
-	<-done
-
-	if waitedErr != nil {
-		t.Fatalf("Get() error = %v", waitedErr)
-	}
-
-	defer func() { _ = waited.Content.Close() }()
-
-	output, err := jpeg.DecodeConfig(waited.Content)
-	if err != nil {
-		t.Fatalf("failed to decode the response: %v", err)
-	}
-
-	if output.Width != 40 || output.Height != 20 {
-		t.Errorf("response is %dx%d, want 40x20: the request read the cached "+
-			"source before it had a processing slot", output.Width, output.Height)
-	}
-}

internal/imgcache/module.go

@@ -1,8 +0,0 @@
-package imgcache
-
-import "time"
-
-// CacheConfig defaults.
-const (
-	DefaultNegativeTTL = 5 * time.Minute
-)

internal/imgcache/negative_cache_internal_test.go

@@ -17,7 +17,7 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	db := setupTestDB(t)
 	dir := t.TempDir()
 
-	cache, err := NewCache(db, CacheConfig{
+	cache, err := NewCache(db, Config{
 		StateDir:    dir,
 		NegativeTTL: 5 * time.Minute,
 		MaxBytes:    1 << 30,
@@ -35,7 +35,7 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	}
 
 	// Initially should not be in negative cache
-	hit, err := cache.checkNegativeCache(ctx, req)
+	hit, err := cache.Failure(ctx, req.Source)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -45,13 +45,13 @@ func TestNegativeCache_StoreAndCheck(t *testing.T) {
 	}
 
 	// Store a negative entry
-	err = cache.StoreNegative(ctx, req)
+	err = cache.PutFailure(ctx, req.Source)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	// Now should be in negative cache
-	hit, err = cache.checkNegativeCache(ctx, req)
+	hit, err = cache.Failure(ctx, req.Source)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -67,7 +67,7 @@ func TestNegativeCache_Expired(t *testing.T) {
 	db := setupTestDB(t)
 	dir := t.TempDir()
 
-	cache, err := NewCache(db, CacheConfig{
+	cache, err := NewCache(db, Config{
 		StateDir:    dir,
 		NegativeTTL: 1 * time.Millisecond, // very short TTL
 		MaxBytes:    1 << 30,
@@ -85,7 +85,7 @@ func TestNegativeCache_Expired(t *testing.T) {
 	}
 
 	// Store a negative entry with very short TTL
-	err = cache.StoreNegative(ctx, req)
+	err = cache.PutFailure(ctx, req.Source)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -94,7 +94,7 @@ func TestNegativeCache_Expired(t *testing.T) {
 	time.Sleep(10 * time.Millisecond)
 
 	// Should no longer be in negative cache
-	hit, err := cache.checkNegativeCache(ctx, req)
+	hit, err := cache.Failure(ctx, req.Source)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -104,71 +104,6 @@ func TestNegativeCache_Expired(t *testing.T) {
 	}
 }
 
-// TestService_Get_ServesCachedVariantOfNegativeCachedURL caches a variant of
-// the test photo, then keeps a failed fetch of the photo's URL in the negative
-// cache, as a failed fetch for another variant does once the source has been
-// evicted. The cached variant is still served, and a variant not in the cache
-// is made from the cached source. Once the source is evicted, a variant not in
-// the cache needs a fetch and is refused.
-func TestService_Get_ServesCachedVariantOfNegativeCachedURL(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	resp, err := svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	err = svc.cache.StoreNegative(t.Context(),
-		photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("StoreNegative() error = %v", err)
-	}
-
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() of the cached variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Errorf("cached variant CacheStatus = %q, want %q",
-			resp.CacheStatus, CacheHit)
-	}
-
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 40, imagerequest.FitCover))
-	t.Logf("Get() of a variant made from the cached source: error = %v", err)
-
-	if err != nil {
-		t.Fatalf("Get() of a variant made from the cached source error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	sourceKey, err := svc.cache.LookupSource(t.Context(),
-		photoVariant(fixtures, 85, imagerequest.FitCover))
-	if err != nil || sourceKey == "" {
-		t.Fatalf("LookupSource() = %q, %v, want the cached source", sourceKey, err)
-	}
-
-	err = svc.cache.evictSourceBlob(t.Context(), sourceKey)
-	if err != nil {
-		t.Fatalf("evictSourceBlob() error = %v", err)
-	}
-
-	_, err = svc.Get(t.Context(), photoVariant(fixtures, 60, imagerequest.FitCover))
-	t.Logf("Get() of a variant whose source was evicted: error = %v", err)
-
-	if !errors.Is(err, ErrNegativeCached) {
-		t.Errorf("Get() of a variant whose source was evicted error = %v, want %v",
-			err, ErrNegativeCached)
-	}
-}
-
 // TestEvictionLoopRemovesExpiredNegativeCacheRows stores a failed fetch
 // that expires a second later and starts the eviction loop with a short
 // interval: a later tick must remove its row although its URL is never
@@ -190,7 +125,7 @@ func TestEvictionLoopRemovesExpiredNegativeCacheRows(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			cache, err := NewCache(evictionTestDB(t), CacheConfig{
+			cache, err := NewCache(evictionTestDB(t), Config{
 				StateDir:    t.TempDir(),
 				NegativeTTL: time.Second,
 				MaxBytes:    tt.maxBytes,
@@ -203,9 +138,9 @@ func TestEvictionLoopRemovesExpiredNegativeCacheRows(t *testing.T) {
 				Source: imagerequest.Source{Host: testHostExample, Path: "/gone.jpg"},
 			}
 
-			err = cache.StoreNegative(t.Context(), expired)
+			err = cache.PutFailure(t.Context(), expired.Source)
 			if err != nil {
-				t.Fatalf("StoreNegative failed: %v", err)
+				t.Fatalf("PutFailure failed: %v", err)
 			}
 
 			const notExpiredPath = "/later.jpg"
@@ -269,7 +204,7 @@ func TestCleanExpiredDeletesInBatches(t *testing.T) {
 	t.Parallel()
 
 	cache, err := NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30},
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
 		prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
@@ -325,7 +260,7 @@ func TestCleanExpiredRemovesMoreThanOneBatch(t *testing.T) {
 	t.Parallel()
 
 	cache, err := NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30},
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
 		prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
@@ -357,7 +292,7 @@ func TestCleanExpiredStopsOnceContextEnds(t *testing.T) {
 	t.Parallel()
 
 	cache, err := NewCache(evictionTestDB(t),
-		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30},
+		Config{StateDir: t.TempDir(), MaxBytes: 1 << 30},
 		prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
@@ -410,15 +345,3 @@ func negativeCacheTableRowCount(tb testing.TB, cache *Cache) int {
 
 	return count
 }
-
-func TestService_Get_ReturnsErrorForNegativeCachedURL(t *testing.T) {
-	t.Parallel()
-
-	// This test verifies that Service.Get() checks the negative cache
-	// We can't easily test the full pipeline without vips, but we can
-	// verify the error type
-	err := ErrNegativeCached
-	if !errors.Is(err, ErrNegativeCached) {
-		t.Error("ErrNegativeCached should be identifiable with errors.Is")
-	}
-}

internal/imgcache/partial_cache_files_internal_test.go

@@ -12,67 +12,6 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// getImage calls Get for req and returns the image it answered with and
-// its cache status.
-func getImage(
-	t *testing.T, svc *Service, req *imagerequest.Request,
-) ([]byte, CacheStatus) {
-	t.Helper()
-
-	resp, err := svc.Get(t.Context(), req)
-	if err != nil {
-		t.Fatalf("Get() of quality %d error = %v", req.Transform.Quality, err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	body, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("reading the image of quality %d: %v", req.Transform.Quality, err)
-	}
-
-	return body, resp.CacheStatus
-}
-
-// fileSize returns the size of the file at path.
-func fileSize(t *testing.T, path string) int64 {
-	t.Helper()
-
-	info, err := os.Stat(path)
-	if err != nil {
-		t.Fatalf("stat %s: %v", path, err)
-	}
-
-	return info.Size()
-}
-
-// truncateFile cuts the file at path down to size bytes.
-func truncateFile(t *testing.T, path string, size int64) {
-	t.Helper()
-
-	t.Logf("cutting %s from %d to %d bytes",
-		filepath.Base(path), fileSize(t, path), size)
-
-	err := os.Truncate(path, size)
-	if err != nil {
-		t.Fatalf("truncating %s: %v", path, err)
-	}
-}
-
-// cachedSourcePath returns the path of the cached source file req uses.
-func cachedSourcePath(
-	t *testing.T, svc *Service, req *imagerequest.Request,
-) string {
-	t.Helper()
-
-	sourceKey, err := svc.cache.LookupSource(t.Context(), req)
-	if err != nil || sourceKey == "" {
-		t.Fatalf("LookupSource() = %q, %v; want the cached source", sourceKey, err)
-	}
-
-	return svc.cache.srcContent.keyToPath(sourceKey)
-}
-
 // reconcileAsAtStartup runs the cache's reconciliation pass, as pixa does
 // when it starts, and returns what the pass logged.
 func reconcileAsAtStartup(t *testing.T, cache *Cache) string {
@@ -107,127 +46,65 @@ func assertWarningNames(t *testing.T, logs, path string) {
 	t.Errorf("reconciliation logged no warning naming %s", path)
 }
 
-// TestService_Get_FetchesAgainForEmptyCachedSource empties the cached source
-// file, as a crash or a restored snapshot could, and runs the reconciliation
-// pass, which must remove it with a warning naming it. It then asks for two
-// new sizes of the source: the first must fetch it again and cache it whole,
-// so that the second is made from the cache without a third fetch.
-func TestService_Get_FetchesAgainForEmptyCachedSource(t *testing.T) {
+// TestReconciliationRemovesDamagedFiles empties a cached source file and a
+// cached variant file, or cuts them to half their size, as a crash or a
+// restored snapshot could. It checks that the reconciliation pass removes
+// each file and its row, with a warning naming the file.
+func TestReconciliationRemovesDamagedFiles(t *testing.T) {
 	t.Parallel()
 
-	svc, fixtures := SetupTestService(t)
+	content := []byte("the whole cached image")
 
-	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
+	for name, size := range map[string]int64{
+		"empty":   0,
+		"partial": int64(len(content) / 2),
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
 
-	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-	wholeSize := fileSize(t, path)
+			cache, _ := newEvictionTestCache(t, 1<<30)
 
-	truncateFile(t, path, 0)
-	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
+			sourceKey := storeEvictionTestSource(t, cache, testHostCDN, testPathCat, content)
+			storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
 
-	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
-	getImage(t, svc, photoVariant(fixtures, 30, imagerequest.FitCover))
+			sourcePath := cache.srcContent.keyToPath(sourceKey)
+			variantPath := cache.variants.keyToPath(testVariantKeyOne)
 
-	fetches := readCounters(svc.cache).upstreamFetchCount
-	t.Logf("upstream fetches = %d", fetches)
+			for _, path := range []string{sourcePath, variantPath} {
+				err := os.Truncate(path, size)
+				if err != nil {
+					t.Fatalf("cutting %s to %d bytes: %v", path, size, err)
+				}
+			}
 
-	if fetches != 2 {
-		t.Errorf("upstream fetches = %d, want 2: the empty cached source "+
-			"was kept and fetched again on every new size", fetches)
+			logs := reconcileAsAtStartup(t, cache)
+
+			assertWarningNames(t, logs, sourcePath)
+			assertWarningNames(t, logs, variantPath)
+
+			if cache.srcContent.Exists(sourceKey) {
+				t.Error("the damaged source file is still on disk")
+			}
+
+			if cache.variants.Exists(testVariantKeyOne) {
+				t.Error("the damaged variant file is still on disk")
+			}
+
+			rows := countRows(t, cache,
+				`SELECT COUNT(*) FROM source_content WHERE source_key = ?`,
+				string(sourceKey))
+			if rows != 0 {
+				t.Errorf("the damaged source file kept %d rows, want 0", rows)
+			}
+
+			rows = countRows(t, cache,
+				`SELECT COUNT(*) FROM variant_content WHERE cache_key = ?`,
+				string(testVariantKeyOne))
+			if rows != 0 {
+				t.Errorf("the damaged variant file kept %d rows, want 0", rows)
+			}
+		})
 	}
-
-	size := fileSize(t, path)
-	if size != wholeSize {
-		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
-	}
-}
-
-// TestService_Get_FetchesAgainForPartialCachedSource cuts the cached source
-// file to half its size, as a crash or a restored snapshot could, and runs
-// the reconciliation pass, which must remove it with a warning naming it.
-// It then asks for two new sizes of the source: the first must fetch it
-// again rather than fail to decode the partial file, and the second is
-// made from the cache.
-func TestService_Get_FetchesAgainForPartialCachedSource(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	getImage(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	path := cachedSourcePath(t, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-	wholeSize := fileSize(t, path)
-
-	truncateFile(t, path, wholeSize/2)
-	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
-
-	getImage(t, svc, photoVariant(fixtures, 40, imagerequest.FitCover))
-	getImage(t, svc, photoVariant(fixtures, 30, imagerequest.FitCover))
-
-	fetches := readCounters(svc.cache).upstreamFetchCount
-	t.Logf("upstream fetches = %d", fetches)
-
-	if fetches != 2 {
-		t.Errorf("upstream fetches = %d, want 2", fetches)
-	}
-
-	size := fileSize(t, path)
-	if size != wholeSize {
-		t.Errorf("cached source is %d bytes, want %d", size, wholeSize)
-	}
-}
-
-// assertConvertedAgain caches a variant of the photo, cuts its file to size
-// bytes and runs the reconciliation pass, which must remove it with a
-// warning naming it. It then checks that Get converts the image again
-// instead of serving the file, and that the next Get serves the whole
-// variant from the cache.
-func assertConvertedAgain(t *testing.T, size int64) {
-	t.Helper()
-
-	svc, fixtures := SetupTestService(t)
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	want, _ := getImage(t, svc, req)
-
-	path := svc.cache.variants.keyToPath(imagerequest.CacheKey(req))
-
-	truncateFile(t, path, size)
-	assertWarningNames(t, reconcileAsAtStartup(t, svc.cache), path)
-
-	got, status := getImage(t, svc, req)
-	t.Logf("after the cut: %d bytes, %s", len(got), status)
-
-	if status != CacheMiss || !bytes.Equal(got, want) {
-		t.Errorf("after the cut: Get() = %d bytes, %s; want the %d bytes "+
-			"converted again, %s", len(got), status, len(want), CacheMiss)
-	}
-
-	got, status = getImage(t, svc, req)
-	t.Logf("next request: %d bytes, %s", len(got), status)
-
-	if status != CacheHit || !bytes.Equal(got, want) {
-		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
-			len(got), status, len(want), CacheHit)
-	}
-}
-
-// TestService_Get_ConvertsAgainForEmptyCachedVariant empties a cached
-// variant file, as a crash or a restored snapshot could, and checks that it
-// is converted again rather than served empty.
-func TestService_Get_ConvertsAgainForEmptyCachedVariant(t *testing.T) {
-	t.Parallel()
-
-	assertConvertedAgain(t, 0)
-}
-
-// TestService_Get_ConvertsAgainForPartialCachedVariant cuts a cached
-// variant file to ten bytes, as a crash or a restored snapshot could, and
-// checks that it is converted again rather than served cut short.
-func TestService_Get_ConvertsAgainForPartialCachedVariant(t *testing.T) {
-	t.Parallel()
-
-	assertConvertedAgain(t, 10)
 }
 
 // TestReconciliationRemovesEmptyVariantFileWithoutRow checks that the

internal/imgcache/pendingaccesstimes_internal_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"io"
 	"log/slog"
 	"strings"
 	"testing"
@@ -15,8 +16,7 @@ import (
 
 // pendingAccessTimesWait is how long a test waits for the database's
 // connection, for an access time to reach the database, for a write to start
-// waiting for the connection, for a request to return past its deadline, or
-// for StopPendingAccessTimeWrites to return.
+// waiting for the connection, or for StopPendingAccessTimeWrites to return.
 const pendingAccessTimesWait = 5 * time.Second
 
 // otherWritesWait is how long a test gives other writes, once one write waits
@@ -56,52 +56,6 @@ func waitForConnectionWaits(t *testing.T, db *sql.DB, waits int64) {
 	}
 }
 
-// TestService_Get_ReturnsByItsDeadlineWhileTheDatabaseIsBusy holds the
-// database's one connection while a request whose fetch is held reaches its
-// deadline. The request must return with the deadline's error while the
-// connection is still held, as it waits for no database write past its
-// deadline.
-func TestService_Get_ReturnsByItsDeadlineWhileTheDatabaseIsBusy(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures, fetcher := setupHeldFetchService(t)
-
-	svc.cache.StartPendingAccessTimeWrites()
-	defer func() { _ = svc.cache.StopPendingAccessTimeWrites(t.Context()) }()
-
-	// Room for the request to reach its fetch on a busy host
-	const timeout = 2 * time.Second
-
-	ctx, cancel := context.WithTimeout(t.Context(), timeout)
-	defer cancel()
-
-	deadline, _ := ctx.Deadline()
-
-	results := startGet(ctx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
-
-	// The request has made its database reads by the time it fetches.
-	select {
-	case <-fetcher.started:
-	case <-time.After(timeout):
-		t.Fatal("request did not reach its fetch by its deadline")
-	}
-
-	releaseDatabase := holdDatabase(t, svc.cache)
-	defer releaseDatabase()
-
-	select {
-	case got := <-results:
-		t.Logf("Get() returned %v after its deadline, error = %v",
-			time.Since(deadline), got.err)
-
-		if !errors.Is(got.err, context.DeadlineExceeded) {
-			t.Errorf("Get() error = %v, want %v", got.err, context.DeadlineExceeded)
-		}
-	case <-time.After(time.Until(deadline) + pendingAccessTimesWait):
-		t.Fatal("request did not return while the database was busy")
-	}
-}
-
 // TestStopPendingAccessTimeWrites_LetsTheWriteUnderWayFinish holds the
 // database's one connection while the goroutine that writes the pending
 // access times waits for it, hands over another access time, then stops that
@@ -242,11 +196,11 @@ func TestStopPendingAccessTimeWrites_ReturnsWhenItsContextEnds(t *testing.T) {
 	}
 }
 
-// TestLookupSource_HandsAccessTimeToTheBackgroundWriter finds a cached source
-// whose access time is an hour old. LookupSource must not write the access
+// TestSource_HandsAccessTimeToTheBackgroundWriter finds a cached source
+// whose access time is an hour old. Source must not write the access
 // time itself but hand it over to be written, and StopPendingAccessTimeWrites
 // must then write it.
-func TestLookupSource_HandsAccessTimeToTheBackgroundWriter(t *testing.T) {
+func TestSource_HandsAccessTimeToTheBackgroundWriter(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -261,15 +215,21 @@ func TestLookupSource_HandsAccessTimeToTheBackgroundWriter(t *testing.T) {
 	`
 	anHourAgoInDatabase := anHourAgo.UTC().Format(sqliteTimestampFormat)
 
-	found, err := cache.LookupSource(t.Context(), &imagerequest.Request{
-		Source: imagerequest.Source{Host: "example.com", Path: "/photo.jpg"},
-	})
-	if err != nil || found != key {
-		t.Fatalf("LookupSource() = %q, %v; want %q", found, err, key)
+	reader, _, err := cache.Source(t.Context(),
+		imagerequest.Source{Host: "example.com", Path: "/photo.jpg"})
+	if err != nil {
+		t.Fatalf("Source() error = %v; want the source of %q", err, key)
+	}
+
+	found, err := io.ReadAll(reader)
+	_ = reader.Close()
+
+	if err != nil || string(found) != "source bytes" {
+		t.Fatalf("Source() reads %q, %v; want the source of %q", found, err, key)
 	}
 
 	if countRows(t, cache, touchedQuery, string(key), anHourAgoInDatabase) != 0 {
-		t.Error("LookupSource wrote the source's access time itself")
+		t.Error("Source wrote the source's access time itself")
 	}
 
 	if waiting := len(cache.pendingSourceAccessTimes); waiting != 1 {

internal/imgcache/service.go

@@ -1,528 +0,0 @@
-package imgcache
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"fmt"
-	"io"
-	"log/slog"
-	"runtime/debug"
-	"time"
-
-	"github.com/dustin/go-humanize"
-	"github.com/getsentry/sentry-go"
-	"github.com/go-chi/chi/v5/middleware"
-	"golang.org/x/sync/singleflight"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/magic"
-)
-
-// Service orchestrates the cache, fetcher, and processor.
-type Service struct {
-	cache           *Cache
-	fetcher         httpfetcher.Fetcher
-	processor       *imageprocessor.ImageProcessor
-	log             *slog.Logger
-	maxResponseSize int64
-	// variantsInProgress lets the requests that miss the same variant at the
-	// same time share one fetch and one transcode.
-	variantsInProgress singleflight.Group
-}
-
-// ServiceConfig holds configuration for the image service.
-type ServiceConfig struct {
-	// Cache is the cache instance
-	Cache *Cache
-	// Fetcher fetches source images from upstream hosts
-	Fetcher httpfetcher.Fetcher
-	// Processor converts and resizes the images
-	Processor *imageprocessor.ImageProcessor
-	// MaxResponseSize is the largest source accepted, in bytes; a cached
-	// source larger than this is fetched again
-	MaxResponseSize int64
-	// Logger for logging
-	Logger *slog.Logger
-}
-
-// errCacheRequired is returned when the service is built without a cache.
-var errCacheRequired = errors.New("cache is required")
-
-// NewService creates a new image service.
-func NewService(cfg *ServiceConfig) (*Service, error) {
-	if cfg.Cache == nil {
-		return nil, errCacheRequired
-	}
-
-	log := cfg.Logger
-	if log == nil {
-		log = slog.Default()
-	}
-
-	// JPEG XL is the default output format, so pixad does not start
-	// without it.
-	err := imageprocessor.CheckJPEGXLSupport()
-	if err != nil {
-		return nil, err
-	}
-
-	return &Service{
-		cache:           cfg.Cache,
-		fetcher:         cfg.Fetcher,
-		processor:       cfg.Processor,
-		log:             log,
-		maxResponseSize: cfg.MaxResponseSize,
-	}, nil
-}
-
-// ErrNegativeCached is returned when a URL is in the negative cache (recently failed).
-var ErrNegativeCached = errors.New("request is in negative cache (recently failed)")
-
-// ErrProcessingTimedOut is returned when processing an image stopped because
-// the downstream_timeout of the request doing it ended, to that request and to
-// every request that waited for its image.
-var ErrProcessingTimedOut = errors.New(
-	"image processing stopped at the deadline of the request doing it")
-
-// Get retrieves a processed image, fetching and processing if necessary.
-// While its source URL is in the negative cache, a cached variant is still
-// served and a variant not in the cache is still made from a cached source;
-// only a request that needs the source fetched is refused.
-//
-// A cache hit opens the variant file and makes no database call: its access
-// time is handed to the goroutine that StartPendingAccessTimeWrites starts,
-// without waiting for it, and its hit is counted in memory. A variant file
-// that cannot be served, such as one whose first bytes are not those of an
-// output format, is a miss, and the variant is made again.
-func (s *Service) Get(
-	ctx context.Context, req *imagerequest.Request,
-) (*ImageResponse, error) {
-	cacheKey := imagerequest.CacheKey(req)
-
-	reader, size, contentType, err := s.cache.GetVariant(cacheKey)
-	if err == nil {
-		s.cache.touchVariant(cacheKey)
-		s.cache.IncrementStats(true, 0)
-
-		return &ImageResponse{
-			Content:       reader,
-			ContentLength: size,
-			ContentType:   contentType,
-			CacheStatus:   CacheHit,
-			ETag:          formatETag(cacheKey),
-		}, nil
-	}
-
-	if !errors.Is(err, ErrNotFound) {
-		s.log.Warn("cached variant not served, making it again",
-			"cache_key", cacheKey, "error", err)
-	}
-
-	// Cache miss - get the variant, processed once for all the requests that
-	// miss it at the same time, then count this request's miss, also when it
-	// failed or the request context has ended meanwhile
-	response, err := s.processOrWait(ctx, req)
-
-	s.cache.IncrementStats(false, 0)
-
-	if err != nil {
-		return nil, err
-	}
-
-	response.CacheStatus = CacheMiss
-
-	return response, nil
-}
-
-// WaitForProcessing waits until no image is being processed, or until ctx
-// ends, and returns how many images were still being processed then.
-func (s *Service) WaitForProcessing(ctx context.Context) int {
-	return s.processor.WaitForProcessing(ctx)
-}
-
-// errPanicked is returned when processing a variant panicked.
-var errPanicked = errors.New("panic while processing image")
-
-// processOrWait returns the variant req asks for. The first of the requests
-// that miss a variant at the same time processes it, and singleflight hands
-// its result, or its error, to the others: they fetch nothing, read no source
-// and take no upstream connection or processing slot. The processing ignores
-// the first request's cancellation, so the others are still served if that
-// client goes away, but keeps its deadline.
-func (s *Service) processOrWait(
-	ctx context.Context, req *imagerequest.Request,
-) (*ImageResponse, error) {
-	// A request that has already ended starts no processing
-	if ctx.Err() != nil {
-		return nil, ctx.Err()
-	}
-
-	cacheKey := imagerequest.CacheKey(req)
-
-	// Closed when this request's own function runs, which singleflight does
-	// only when no other request is processing the variant
-	processing := make(chan struct{})
-
-	results := s.variantsInProgress.DoChan(string(cacheKey),
-		func() (_ any, err error) {
-			close(processing)
-
-			// singleflight would raise a panic again in a goroutine of its
-			// own, where no handler recovers it, and stop pixad. It is
-			// reported through the Sentry hub that the Sentry middleware puts
-			// on the request's context when sentry_dsn is set.
-			defer func() {
-				recovered := recover()
-				if recovered != nil {
-					s.log.Error("panic while processing image",
-						"host", req.Source.Host, "path", req.Source.Path,
-						"panic", recovered, "stack", string(debug.Stack()))
-
-					if hub := sentry.GetHubFromContext(ctx); hub != nil {
-						hub.RecoverWithContext(ctx, recovered)
-					}
-
-					err = fmt.Errorf("%w: %v", errPanicked, recovered)
-				}
-			}()
-
-			processingCtx, cancel := withoutCancelKeepingDeadline(ctx)
-			defer cancel()
-
-			return s.processFromSourceOrFetch(processingCtx, req, cacheKey)
-		})
-
-	var result singleflight.Result
-
-	select {
-	case result = <-results:
-	case <-ctx.Done():
-		select {
-		case <-processing:
-			// This request is processing the variant: it waits for the
-			// result, as every request did before misses were shared
-			result = <-results
-		default:
-			// Another request is processing the variant, or this request's
-			// function has not started yet; the processing goes on without it
-			return nil, ctx.Err()
-		}
-	}
-
-	if result.Err != nil {
-		return nil, result.Err
-	}
-
-	variant, _ := result.Val.(*processedVariant)
-
-	return &ImageResponse{
-		Content:       io.NopCloser(bytes.NewReader(variant.data)),
-		ContentLength: int64(len(variant.data)),
-		ContentType:   variant.contentType,
-		FetchedBytes:  variant.fetchedBytes,
-		ETag:          formatETag(cacheKey),
-	}, nil
-}
-
-// withoutCancelKeepingDeadline returns ctx without its cancellation but with
-// its deadline, if it has one, and the func that releases the returned
-// context.
-func withoutCancelKeepingDeadline(
-	ctx context.Context,
-) (context.Context, context.CancelFunc) {
-	deadline, hasDeadline := ctx.Deadline()
-	if !hasDeadline {
-		return context.WithoutCancel(ctx), func() {}
-	}
-
-	return context.WithDeadline(context.WithoutCancel(ctx), deadline)
-}
-
-// loadCachedSource opens source content from cache, without reading it, and
-// returns it with its size; nil if the cached data is unavailable, empty or
-// exceeds maxResponseSize.
-func (s *Service) loadCachedSource(
-	sourceKey imagerequest.SourceKey,
-) (io.ReadCloser, int64) {
-	reader, size, err := s.cache.GetSourceContent(sourceKey)
-	if err != nil {
-		s.log.Warn("failed to load cached source, fetching", "error", err)
-
-		return nil, 0
-	}
-
-	if size > s.maxResponseSize {
-		_ = reader.Close()
-
-		s.log.Warn("cached source exceeds max response size, discarding",
-			"source_key", sourceKey,
-			"max_bytes", s.maxResponseSize,
-		)
-
-		return nil, 0
-	}
-
-	if size == 0 {
-		_ = reader.Close()
-
-		return nil, 0
-	}
-
-	return reader, size
-}
-
-// processFromSourceOrFetch processes an image, using cached source content
-// if available.
-func (s *Service) processFromSourceOrFetch(
-	ctx context.Context,
-	req *imagerequest.Request,
-	cacheKey imagerequest.VariantKey,
-) (*processedVariant, error) {
-	// Check if we have cached source content
-	sourceKey, err := s.cache.LookupSource(ctx, req)
-	if err != nil {
-		s.log.Warn("source lookup failed", "error", err)
-	}
-
-	var (
-		source     io.ReadCloser
-		sourceSize int64
-	)
-
-	if sourceKey != "" {
-		s.log.Debug("using cached source", "source_key", sourceKey)
-		source, sourceSize = s.loadCachedSource(sourceKey)
-	}
-
-	// Fetch from upstream if we don't have source data or it's empty
-	if source == nil {
-		return s.fetchAndProcess(ctx, req, cacheKey)
-	}
-
-	defer func() { _ = source.Close() }()
-
-	// Process using cached source; nothing was fetched from upstream. The
-	// image processor reads the source only once it has a processing slot,
-	// so a request waiting for one holds none of it in memory.
-	return s.processAndStore(ctx, req, cacheKey, source, sourceSize)
-}
-
-// fetchAndProcess fetches from upstream, processes, and caches the result.
-// It counts the fetch with the bytes read from upstream, including when
-// reading the response or a later step fails. It fetches nothing while the
-// source URL is in the negative cache.
-func (s *Service) fetchAndProcess(
-	ctx context.Context,
-	req *imagerequest.Request,
-	cacheKey imagerequest.VariantKey,
-) (*processedVariant, error) {
-	// Check negative cache - skip fetching for recently-failed URLs
-	negHit, err := s.cache.checkNegativeCache(ctx, req)
-	if err != nil {
-		s.log.Warn("negative cache check failed", "error", err)
-	}
-
-	if negHit {
-		s.log.Debug("negative cache hit",
-			"host", req.Source.Host,
-			"path", req.Source.Path,
-		)
-
-		return nil, fmt.Errorf("%w: %w", httpfetcher.ErrUpstreamError, ErrNegativeCached)
-	}
-
-	// Fetch from upstream
-	s.log.Debug("fetching from upstream", "host", req.Source.Host,
-		"path", req.Source.Path, "query", req.Source.Query)
-
-	fetchResult, err := s.fetcher.Fetch(ctx, req.Source)
-	if err != nil {
-		// Store negative cache for certain errors
-		if isNegativeCacheable(err) {
-			s.storeNegative(ctx, req)
-		}
-
-		return nil, fmt.Errorf("upstream fetch failed: %w", err)
-	}
-
-	// Closing the body frees the upstream connection. It is closed only
-	// after processing, so the fetcher's connection limit also bounds the
-	// fetched sources held in memory while their requests wait for a
-	// processing slot.
-	defer func() { _ = fetchResult.Content.Close() }()
-
-	// Read and validate the source content
-	sourceData, err := io.ReadAll(fetchResult.Content)
-	fetchBytes := int64(len(sourceData))
-
-	// Counted also when the request context has ended meanwhile
-	s.cache.IncrementUpstreamFetch(fetchBytes)
-
-	if err != nil {
-		return nil, fmt.Errorf("failed to read upstream response: %w", err)
-	}
-
-	// Calculate download bitrate
-	var downloadRate string
-
-	if fetchResult.FetchDurationMs > 0 {
-		seconds := float64(fetchResult.FetchDurationMs) / 1000.0 //nolint:mnd // ms to seconds
-		bitsPerSecond := float64(fetchBytes*8) / seconds         //nolint:mnd // bytes to bits
-		downloadRate = humanize.SI(bitsPerSecond, "bps")
-	}
-
-	// Log upstream fetch details
-	s.log.Info("upstream fetched",
-		"request_id", middleware.GetReqID(ctx),
-		"host", req.Source.Host,
-		"path", req.Source.Path,
-		"bytes", fetchBytes,
-		"fetch_ms", fetchResult.FetchDurationMs,
-		"rate", downloadRate,
-		"remote_addr", fetchResult.RemoteAddr,
-		"http", fetchResult.HTTPVersion,
-		"tls", fetchResult.TLSVersion,
-		"cipher", fetchResult.TLSCipherSuite,
-	)
-
-	// Validate magic bytes match content type. A body that does not is the
-	// upstream's error, so it gets a negative cache entry, as an upstream
-	// error status does.
-	err = magic.ValidateMagicBytes(sourceData, fetchResult.ContentType)
-	if err != nil {
-		s.log.Warn("source refused", "request_id", middleware.GetReqID(ctx),
-			"host", req.Source.Host, "path", req.Source.Path,
-			"content_type", fetchResult.ContentType, "error", err)
-		s.storeNegative(ctx, req)
-
-		return nil, fmt.Errorf("content validation failed: %w", err)
-	}
-
-	// Store source content
-	_, err = s.cache.StoreSource(ctx, req, bytes.NewReader(sourceData))
-	if err != nil {
-		s.log.Warn("failed to store source content", "error", err)
-		// Continue even if caching fails
-	}
-
-	return s.processAndStore(
-		ctx, req, cacheKey, bytes.NewReader(sourceData), fetchBytes,
-	)
-}
-
-// storeNegative stores a negative cache entry for req's source, whose fetch
-// failed, so the source is not fetched again until the entry expires. A
-// failure to store the entry is only logged.
-func (s *Service) storeNegative(ctx context.Context, req *imagerequest.Request) {
-	err := s.cache.StoreNegative(ctx, req)
-	if err != nil {
-		s.log.Warn("failed to store negative cache entry",
-			"host", req.Source.Host, "path", req.Source.Path, "error", err)
-	}
-}
-
-// processedVariant is a variant as processAndStore made it. Each request that
-// shared its processing serves it through a reader of its own.
-type processedVariant struct {
-	data         []byte
-	contentType  string
-	fetchedBytes int64
-}
-
-// processAndStore processes the image read from source and stores the
-// result.
-func (s *Service) processAndStore(
-	ctx context.Context,
-	req *imagerequest.Request,
-	cacheKey imagerequest.VariantKey,
-	source io.Reader,
-	fetchBytes int64,
-) (*processedVariant, error) {
-	// Process the image
-	processStart := time.Now()
-
-	// ctx has the deadline of the request doing the processing, which can
-	// end while a request waiting for its image has time left
-	processResult, err := s.processor.Process(ctx, source, &req.Transform)
-	if errors.Is(err, context.DeadlineExceeded) {
-		return nil, fmt.Errorf("%w: %w", ErrProcessingTimedOut, err)
-	}
-
-	if err != nil {
-		return nil, fmt.Errorf("image processing failed: %w", err)
-	}
-
-	processDuration := time.Since(processStart)
-
-	// Counted also when the request context has ended meanwhile
-	s.cache.IncrementTransformCount()
-
-	// Read processed content
-	processedData, err := io.ReadAll(processResult.Content)
-	_ = processResult.Content.Close()
-
-	if err != nil {
-		return nil, fmt.Errorf("failed to read processed content: %w", err)
-	}
-
-	// Log conversion details
-	outputSize := int64(len(processedData))
-
-	var sizePercent float64
-	if fetchBytes > 0 {
-		//nolint:mnd // percentage calculation
-		sizePercent = float64(outputSize) / float64(fetchBytes) * 100.0
-	}
-
-	s.log.Info("image converted",
-		"request_id", middleware.GetReqID(ctx),
-		"host", req.Source.Host,
-		"path", req.Source.Path,
-		"src_format", processResult.InputFormat,
-		"dst_format", req.Transform.Format,
-		"src_bytes", fetchBytes,
-		"dst_bytes", outputSize,
-		"src_dimensions", fmt.Sprintf("%dx%d",
-			processResult.InputWidth, processResult.InputHeight),
-		"dst_dimensions", fmt.Sprintf("%dx%d",
-			processResult.Width, processResult.Height),
-		"size_ratio", fmt.Sprintf("%.1f%%", sizePercent),
-		"convert_ms", processDuration.Milliseconds(),
-		"quality", req.Transform.Quality,
-		"fit", req.Transform.FitMode,
-	)
-
-	// Store variant to cache
-	err = s.cache.StoreVariant(ctx, cacheKey, bytes.NewReader(processedData))
-	if err != nil {
-		s.log.Warn("failed to store variant", "error", err)
-		// Continue even if caching fails
-	}
-
-	return &processedVariant{
-		data:         processedData,
-		contentType:  processResult.ContentType,
-		fetchedBytes: fetchBytes,
-	}, nil
-}
-
-// isNegativeCacheable returns true if the error should be cached.
-func isNegativeCacheable(err error) bool {
-	return errors.Is(err, httpfetcher.ErrUpstreamError)
-}
-
-// etagHashLength is the number of hash characters to use for ETags.
-const etagHashLength = 16
-
-// formatETag formats a VariantKey as a quoted ETag value.
-func formatETag(key imagerequest.VariantKey) string {
-	hash := string(key)
-	// Use first 16 characters of hash for a shorter but still unique ETag
-	if len(hash) > etagHashLength {
-		hash = hash[:etagHashLength]
-	}
-
-	return `"` + hash + `"`
-}

internal/imgcache/service_internal_test.go

@@ -1,584 +0,0 @@
-package imgcache
-
-import (
-	"context"
-	"io"
-	"os"
-	"testing"
-	"time"
-
-	"sneak.berlin/go/pixa/internal/imagerequest"
-	"sneak.berlin/go/pixa/internal/magic"
-)
-
-// Test data literals used repeatedly in this file (goconst).
-const (
-	testPathPhoto  = "/images/photo.jpg"
-	testPathUpload = "/uploads/image.jpg"
-)
-
-func TestService_Get_GoodHost(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	// Verify we got content
-	data, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("failed to read response: %v", err)
-	}
-
-	if len(data) == 0 {
-		t.Error("expected non-empty response")
-	}
-
-	if resp.ContentType != testContentTypeJPEG {
-		t.Errorf("ContentType = %q, want %q", resp.ContentType, testContentTypeJPEG)
-	}
-}
-
-// TestService_Get_OtherHost checks that the image service serves a second host
-// as it serves GoodHost.
-func TestService_Get_OtherHost(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.OtherHost,
-			Path: testPathUpload,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// Should fetch successfully
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	data, err := io.ReadAll(resp.Content)
-	if err != nil {
-		t.Fatalf("failed to read response: %v", err)
-	}
-
-	if len(data) == 0 {
-		t.Error("expected non-empty response")
-	}
-}
-
-func TestService_Get_InvalidFile(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	req.Source.Path = "/images/fake.jpg"
-	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
-
-	// Should fail because magic bytes don't match
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for invalid file")
-	}
-}
-
-func TestService_Get_NotFound(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := photoVariant(fixtures, 85, imagerequest.FitCover)
-	req.Source.Path = "/images/nonexistent.jpg"
-	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
-
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for nonexistent file")
-	}
-}
-
-func TestService_Get_FormatConversion(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	tests := []struct {
-		name       string
-		sourcePath string
-		outFormat  imagerequest.Format
-		wantMIME   string
-	}{
-		{
-			name:       "JPEG to PNG",
-			sourcePath: testPathPhoto,
-			outFormat:  imagerequest.FormatPNG,
-			wantMIME:   "image/png",
-		},
-		{
-			name:       "PNG to JPEG",
-			sourcePath: "/images/logo.png",
-			outFormat:  imagerequest.FormatJPEG,
-			wantMIME:   testContentTypeJPEG,
-		},
-		{
-			name:       "GIF to PNG",
-			sourcePath: "/images/animation.gif",
-			outFormat:  imagerequest.FormatPNG,
-			wantMIME:   "image/png",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			req := &imagerequest.Request{
-				Source: imagerequest.Source{Host: fixtures.GoodHost, Path: tt.sourcePath},
-				Transform: imagerequest.Transform{
-					Size:   imagerequest.Size{Width: 50, Height: 50},
-					Format: tt.outFormat, Quality: 85, FitMode: imagerequest.FitCover,
-				},
-			}
-
-			resp, err := svc.Get(ctx, req)
-			if err != nil {
-				t.Fatalf("Get() error = %v", err)
-			}
-
-			defer func() { _ = resp.Content.Close() }()
-
-			if resp.ContentType != tt.wantMIME {
-				t.Errorf("ContentType = %q, want %q", resp.ContentType, tt.wantMIME)
-			}
-
-			// Verify magic bytes match the expected format
-			data, err := io.ReadAll(resp.Content)
-			if err != nil {
-				t.Fatalf("failed to read response: %v", err)
-			}
-
-			detectedMIME, err := magic.DetectFormat(data)
-			if err != nil {
-				t.Fatalf("failed to detect format: %v", err)
-			}
-
-			expectedFormat, ok := magic.MIMEToImageFormat(tt.wantMIME)
-			if !ok {
-				t.Fatalf("unknown format for MIME type: %s", tt.wantMIME)
-			}
-
-			detectedFormat, ok := magic.MIMEToImageFormat(string(detectedMIME))
-			if !ok {
-				t.Fatalf("unknown format for detected MIME type: %s", detectedMIME)
-			}
-
-			if detectedFormat != expectedFormat {
-				t.Errorf("detected format = %q, want %q", detectedFormat, expectedFormat)
-			}
-		})
-	}
-}
-
-func TestService_Get_Caching(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// First request - should be a cache miss
-	resp1, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	if resp1.CacheStatus != CacheMiss {
-		t.Errorf("first request CacheStatus = %q, want %q", resp1.CacheStatus, CacheMiss)
-	}
-
-	data1, err := io.ReadAll(resp1.Content)
-	if err != nil {
-		t.Fatalf("failed to read first response: %v", err)
-	}
-
-	_ = resp1.Content.Close()
-
-	// Second request - should be a cache hit
-	resp2, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	if resp2.CacheStatus != CacheHit {
-		t.Errorf("second request CacheStatus = %q, want %q", resp2.CacheStatus, CacheHit)
-	}
-
-	data2, err := io.ReadAll(resp2.Content)
-	if err != nil {
-		t.Fatalf("failed to read second response: %v", err)
-	}
-
-	_ = resp2.Content.Close()
-
-	// Content should be identical
-	if len(data1) != len(data2) {
-		t.Errorf("response sizes differ: %d vs %d", len(data1), len(data2))
-	}
-}
-
-// TestService_Get_ServesSourceAndVariantCachedTwoDaysAgo caches a source and
-// a variant of it and sets back two days every time pixa stored for them.
-// For the source: last_accessed_at in source_content, and the access and
-// modification times of its file. For the variant: last_accessed_at in
-// variant_content, and the access and modification times of its file. It
-// then checks that the variant is still served from the cache and that a new
-// variant is made from the cached source without fetching it again.
-//
-// Left at the present: the files' status change and birth times, which a
-// program cannot set, and the times of the directories holding the files,
-// which other entries share.
-func TestService_Get_ServesSourceAndVariantCachedTwoDaysAgo(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	variant := photoVariant(fixtures, 85, imagerequest.FitCover)
-
-	resp, err := svc.Get(t.Context(), variant)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	twoDaysAgo := time.Now().AddDate(0, 0, -2)
-	backdateSource(t, svc.cache, variant, twoDaysAgo)
-	backdateVariant(t, svc.cache, variant, twoDaysAgo)
-
-	resp, err = svc.Get(t.Context(), variant)
-	if err != nil {
-		t.Fatalf("Get() of the cached variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Errorf("cached variant CacheStatus = %q, want %q",
-			resp.CacheStatus, CacheHit)
-	}
-
-	// Another quality is a new variant, made from the cached source
-	resp, err = svc.Get(t.Context(), photoVariant(fixtures, 40, imagerequest.FitCover))
-	if err != nil {
-		t.Fatalf("Get() of a new variant error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	fetches := readCounters(svc.cache).upstreamFetchCount
-	if fetches != 1 {
-		t.Errorf("upstream fetches = %d, want 1", fetches)
-	}
-}
-
-// backdateSource sets every time pixa stored for req's cached source to when,
-// as listed on TestService_Get_ServesSourceAndVariantCachedTwoDaysAgo.
-func backdateSource(
-	t *testing.T, cache *Cache, req *imagerequest.Request, when time.Time,
-) {
-	t.Helper()
-
-	key := req.Source.Key()
-	setSourceLastAccessed(t, cache, key, when)
-
-	path := cache.srcContent.keyToPath(key)
-
-	err := os.Chtimes(path, when, when)
-	if err != nil {
-		t.Fatalf("setting back the times of %s: %v", path, err)
-	}
-}
-
-// backdateVariant sets every time pixa stored for the cached variant req asks
-// for to when, as listed on
-// TestService_Get_ServesSourceAndVariantCachedTwoDaysAgo.
-func backdateVariant(
-	t *testing.T, cache *Cache, req *imagerequest.Request, when time.Time,
-) {
-	t.Helper()
-
-	key := imagerequest.CacheKey(req)
-	path := cache.variants.keyToPath(key)
-
-	setVariantLastAccessed(t, cache, key, when)
-
-	err := os.Chtimes(path, when, when)
-	if err != nil {
-		t.Fatalf("setting back the times of %s: %v", path, err)
-	}
-}
-
-func TestService_Get_DifferentSizes(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	// Request same image at different sizes
-	sizes := []imagerequest.Size{
-		{Width: 25, Height: 25},
-		{Width: 50, Height: 50},
-		{Width: 75, Height: 75},
-	}
-
-	responses := make([][]byte, 0, len(sizes))
-
-	for _, size := range sizes {
-		req := &imagerequest.Request{
-			Source: imagerequest.Source{
-				Host: fixtures.GoodHost,
-				Path: testPathPhoto,
-			},
-			Transform: imagerequest.Transform{
-				Size:    size,
-				Format:  imagerequest.FormatJPEG,
-				Quality: 85,
-				FitMode: imagerequest.FitCover,
-			},
-		}
-
-		resp, err := svc.Get(ctx, req)
-		if err != nil {
-			t.Fatalf("Get() error for size %v = %v", size, err)
-		}
-
-		data, err := io.ReadAll(resp.Content)
-		if err != nil {
-			t.Fatalf("failed to read response: %v", err)
-		}
-
-		_ = resp.Content.Close()
-
-		responses = append(responses, data)
-	}
-
-	// All responses should be different sizes (different cache entries)
-	for i := range len(responses) - 1 {
-		if len(responses[i]) == len(responses[i+1]) {
-			// Not necessarily an error, but worth noting
-			t.Logf("responses %d and %d have same size: %d bytes",
-				i, i+1, len(responses[i]))
-		}
-	}
-}
-
-func TestService_Get_ContextCancellation(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel() // Cancel immediately
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	_, err := svc.Get(ctx, req)
-	if err == nil {
-		t.Error("Get() expected error for cancelled context")
-	}
-}
-
-func TestService_Get_ReturnsETag(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() error = %v", err)
-	}
-
-	defer func() { _ = resp.Content.Close() }()
-
-	// ETag should be set
-	if resp.ETag == "" {
-		t.Error("ETag should be set in response")
-	}
-
-	// ETag should be properly quoted
-	if len(resp.ETag) < 2 || resp.ETag[0] != '"' || resp.ETag[len(resp.ETag)-1] != '"' {
-		t.Errorf("ETag should be quoted, got %q", resp.ETag)
-	}
-}
-
-func TestService_Get_ETagConsistency(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// First request
-	resp1, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	etag1 := resp1.ETag
-
-	_ = resp1.Content.Close()
-
-	// Second request (from cache)
-	resp2, err := svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	etag2 := resp2.ETag
-
-	_ = resp2.Content.Close()
-
-	// ETags should be identical for the same content
-	if etag1 != etag2 {
-		t.Errorf("ETags should match: %q != %q", etag1, etag2)
-	}
-}
-
-func TestService_Get_DifferentETagsForDifferentContent(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-	ctx := context.Background()
-
-	// Request same image at different sizes - should get different ETags
-	req1 := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 25, Height: 25},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	req2 := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	resp1, err := svc.Get(ctx, req1)
-	if err != nil {
-		t.Fatalf("Get() first request error = %v", err)
-	}
-
-	etag1 := resp1.ETag
-
-	_ = resp1.Content.Close()
-
-	resp2, err := svc.Get(ctx, req2)
-	if err != nil {
-		t.Fatalf("Get() second request error = %v", err)
-	}
-
-	etag2 := resp2.ETag
-
-	_ = resp2.Content.Close()
-
-	// ETags should be different for different content
-	if etag1 == etag2 {
-		t.Error("ETags should differ for different sizes")
-	}
-}

internal/imgcache/source_content_internal_test.go

@@ -10,11 +10,11 @@ import (
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// TestStoreSource_StoresIdenticalBytesOfTwoURLsTwice stores the same bytes
+// TestPutSource_StoresIdenticalBytesOfTwoURLsTwice stores the same bytes
 // for two source URLs and checks that each URL has a source_content row of
 // its own and a file of its own, named by its source key under
 // cache/sources/<ab>/<cd>/.
-func TestStoreSource_StoresIdenticalBytesOfTwoURLsTwice(t *testing.T) {
+func TestPutSource_StoresIdenticalBytesOfTwoURLsTwice(t *testing.T) {
 	t.Parallel()
 
 	cache, stateDir := newEvictionTestCache(t, 1<<30)
@@ -84,18 +84,12 @@ func TestEvictSourceBlob_LeavesSourceWithIdenticalBytesServed(t *testing.T) {
 		t.Errorf("the evicted source still has %d source_content rows", n)
 	}
 
-	kept, err := cache.LookupSource(t.Context(), &imagerequest.Request{
-		Source: imagerequest.Source{Host: testHostCDN, Path: "/kept.jpg"},
-	})
-	t.Logf("LookupSource() of the kept source = %q, error %v", kept, err)
+	reader, _, err := cache.Source(t.Context(),
+		imagerequest.Source{Host: testHostCDN, Path: "/kept.jpg"})
+	t.Logf("Source() of the kept source: error %v", err)
 
-	if err != nil || kept == "" {
-		t.Fatalf("LookupSource() of the kept source = %q, %v; want it cached", kept, err)
-	}
-
-	reader, _, err := cache.GetSourceContent(kept)
 	if err != nil {
-		t.Fatalf("GetSourceContent() of the kept source error = %v", err)
+		t.Fatalf("Source() of the kept source error = %v; want it cached", err)
 	}
 
 	defer func() { _ = reader.Close() }()
@@ -111,10 +105,10 @@ func TestEvictSourceBlob_LeavesSourceWithIdenticalBytesServed(t *testing.T) {
 	}
 }
 
-// TestStoreSource_FailedRowWriteLeavesNoFile drops source_content, so that
-// StoreSource cannot write the source's row, and checks that the store fails
+// TestPutSource_FailedRowWriteLeavesNoFile drops source_content, so that
+// PutSource cannot write the source's row, and checks that the store fails
 // and leaves no file under the source's key.
-func TestStoreSource_FailedRowWriteLeavesNoFile(t *testing.T) {
+func TestPutSource_FailedRowWriteLeavesNoFile(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
@@ -127,12 +121,12 @@ func TestStoreSource_FailedRowWriteLeavesNoFile(t *testing.T) {
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{Host: testHostCDN, Path: testPathCat},
 	}
-	key, err := cache.StoreSource(t.Context(), req,
+	key, err := cache.PutSource(t.Context(), req.Source,
 		bytes.NewReader([]byte("source bytes")))
-	t.Logf("StoreSource() = %q, error = %v", key, err)
+	t.Logf("PutSource() = %q, error = %v", key, err)
 
 	if err == nil {
-		t.Error("StoreSource() error = nil, want the failed row write")
+		t.Error("PutSource() error = nil, want the failed row write")
 	}
 
 	if cache.srcContent.Exists(req.Source.Key()) {

internal/imgcache/stats_internal_test.go

@@ -1,243 +0,0 @@
-package imgcache
-
-import (
-	"bytes"
-	"context"
-	"image/color"
-	"io"
-	"io/fs"
-	"testing"
-
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imagerequest"
-)
-
-// TestService_Get_CountsStats walks Get through a miss that fetches the
-// source, a hit, a miss that reuses the cached source, and two misses whose
-// source cannot be used, checking every counter of the cache after each.
-func TestService_Get_CountsStats(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	// NewTestFS builds the same files the test service's fetcher serves.
-	testFS, _ := NewTestFS(t)
-
-	photo, err := fs.ReadFile(testFS, fixtures.GoodHostJPEG)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	fake, err := fs.ReadFile(testFS, fixtures.InvalidFile)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	photoBytes, fakeBytes := int64(len(photo)), int64(len(fake))
-
-	// want is hits, misses, upstream fetches, upstream bytes, transforms.
-	steps := []struct {
-		name    string
-		path    string
-		size    int
-		wantErr bool
-		want    counterValues
-	}{
-		{"miss that fetches the source", testPathPhoto, 50, false,
-			counterValues{0, 1, 1, photoBytes, 1}},
-		{"hit", testPathPhoto, 50, false,
-			counterValues{1, 1, 1, photoBytes, 1}},
-		{"miss that reuses the cached source", testPathPhoto, 25, false,
-			counterValues{1, 2, 1, photoBytes, 2}},
-		{"miss whose source fails the magic byte check", "/images/fake.jpg", 50, true,
-			counterValues{1, 3, 2, photoBytes + fakeBytes, 2}},
-		{"miss whose source is not found", "/images/nonexistent.jpg", 50, true,
-			counterValues{1, 4, 2, photoBytes + fakeBytes, 2}},
-	}
-
-	for _, step := range steps {
-		resp, err := svc.Get(t.Context(), &imagerequest.Request{
-			Source: imagerequest.Source{
-				Host: fixtures.GoodHost,
-				Path: step.path,
-			},
-			Transform: imagerequest.Transform{
-				Size:    imagerequest.Size{Width: step.size, Height: step.size},
-				Format:  imagerequest.FormatJPEG,
-				Quality: 85,
-				FitMode: imagerequest.FitCover,
-			},
-		})
-		if (err != nil) != step.wantErr {
-			t.Fatalf("%s: Get() error = %v, want error %t", step.name, err, step.wantErr)
-		}
-
-		if err == nil {
-			_ = resp.Content.Close()
-		}
-
-		got := readCounters(svc.cache)
-		if got != step.want {
-			t.Fatalf("after the %s: counters = %+v, want %+v", step.name, got, step.want)
-		}
-	}
-}
-
-// fakeUpstream answers every fetch with itself as a JPEG body. The body
-// serves data, then calls cancel, when set, and returns err; io.EOF ends
-// the body normally.
-type fakeUpstream struct {
-	data   *bytes.Reader
-	cancel context.CancelFunc
-	err    error
-}
-
-func (u *fakeUpstream) Fetch(
-	context.Context, imagerequest.Source,
-) (*httpfetcher.FetchResult, error) {
-	return &httpfetcher.FetchResult{
-		Content:       io.NopCloser(u),
-		ContentLength: -1,
-		ContentType:   testContentTypeJPEG,
-	}, nil
-}
-
-func (u *fakeUpstream) Read(p []byte) (int, error) {
-	if u.data.Len() > 0 {
-		return u.data.Read(p)
-	}
-
-	if u.cancel != nil {
-		u.cancel()
-	}
-
-	return 0, u.err
-}
-
-// TestService_Get_CountsInterruptedMisses checks every counter of the cache
-// after a miss whose request context ends during or after the upstream
-// fetch, and after a miss whose upstream body is over the size limit.
-func TestService_Get_CountsInterruptedMisses(t *testing.T) {
-	t.Parallel()
-
-	photo := generateTestJPEG(t, 100, 100, color.RGBA{255, 0, 0, 255})
-	half := len(photo) / 2
-
-	// want is hits, misses, upstream fetches, upstream bytes, transforms.
-	tests := []struct {
-		name    string
-		served  int   // bytes of the photo the upstream body serves
-		cancel  bool  // whether the body then ends the request context
-		readErr error // what the body then returns
-		wantErr bool
-		want    counterValues
-	}{
-		{"request context ends during the fetch", half, true, context.Canceled, true,
-			counterValues{0, 1, 1, int64(half), 0}},
-		{"request context ends after the fetch", len(photo), true, io.EOF, false,
-			counterValues{0, 1, 1, int64(len(photo)), 1}},
-		{"upstream body over the size limit", half, false,
-			httpfetcher.ErrResponseTooLarge, true,
-			counterValues{0, 1, 1, int64(half), 0}},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			svc, fixtures := SetupTestService(t)
-
-			ctx, cancel := context.WithCancel(t.Context())
-			defer cancel()
-
-			upstream := &fakeUpstream{
-				data: bytes.NewReader(photo[:tc.served]),
-				err:  tc.readErr,
-			}
-			if tc.cancel {
-				upstream.cancel = cancel
-			}
-
-			svc.fetcher = upstream
-
-			resp, err := svc.Get(ctx, &imagerequest.Request{
-				Source: imagerequest.Source{
-					Host: fixtures.GoodHost,
-					Path: testPathPhoto,
-				},
-				Transform: imagerequest.Transform{
-					Size:    imagerequest.Size{Width: 50, Height: 50},
-					Format:  imagerequest.FormatJPEG,
-					Quality: 85,
-					FitMode: imagerequest.FitCover,
-				},
-			})
-			t.Logf("Get() error = %v", err)
-
-			if (err != nil) != tc.wantErr {
-				t.Fatalf("Get() error = %v, want error %t", err, tc.wantErr)
-			}
-
-			if err == nil {
-				_ = resp.Content.Close()
-			}
-
-			got := readCounters(svc.cache)
-			if got != tc.want {
-				t.Errorf("counters = %+v, want %+v", got, tc.want)
-			}
-		})
-	}
-}
-
-// TestService_Get_CountsHitAfterRequestEnds checks every counter of the
-// cache after a hit served with a request context that has already ended:
-// only the hit count moves.
-func TestService_Get_CountsHitAfterRequestEnds(t *testing.T) {
-	t.Parallel()
-
-	svc, fixtures := SetupTestService(t)
-
-	req := &imagerequest.Request{
-		Source: imagerequest.Source{
-			Host: fixtures.GoodHost,
-			Path: testPathPhoto,
-		},
-		Transform: imagerequest.Transform{
-			Size:    imagerequest.Size{Width: 50, Height: 50},
-			Format:  imagerequest.FormatJPEG,
-			Quality: 85,
-			FitMode: imagerequest.FitCover,
-		},
-	}
-
-	// A first request caches the variant.
-	resp, err := svc.Get(t.Context(), req)
-	if err != nil {
-		t.Fatalf("first Get() error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	want := readCounters(svc.cache)
-	want.hitCount++
-
-	ctx, cancel := context.WithCancel(t.Context())
-	cancel()
-
-	resp, err = svc.Get(ctx, req)
-	if err != nil {
-		t.Fatalf("Get() with an ended request context: error = %v", err)
-	}
-
-	_ = resp.Content.Close()
-
-	if resp.CacheStatus != CacheHit {
-		t.Fatalf("CacheStatus = %v, want %v", resp.CacheStatus, CacheHit)
-	}
-
-	got := readCounters(svc.cache)
-	if got != want {
-		t.Errorf("counters = %+v, want %+v", got, want)
-	}
-}

internal/imgcache/testutil_internal_test.go

@@ -2,98 +2,19 @@ package imgcache
 
 import (
 	"bytes"
-	"context"
-	"database/sql"
 	"image"
 	"image/color"
-	"image/gif"
 	"image/jpeg"
-	"image/png"
-	"io/fs"
 	"testing"
-	"testing/fstest"
-	"time"
-
-	"github.com/prometheus/client_golang/prometheus"
-	"sneak.berlin/go/pixa/internal/database"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
 )
 
 // Shared test data literals, extracted as constants for goconst.
 const (
-	testHostCDN         = "cdn.example.com"
-	testHostExample     = "example.com"
-	testPathCat         = "/photos/cat.jpg"
-	testContentTypeJPEG = "image/jpeg"
+	testHostCDN     = "cdn.example.com"
+	testHostExample = "example.com"
+	testPathCat     = "/photos/cat.jpg"
 )
 
-// TestFixtures contains paths to test files in the mock filesystem.
-type TestFixtures struct {
-	// Valid image files
-	GoodHostJPEG  string // valid JPEG on GoodHost
-	GoodHostPNG   string // valid PNG on GoodHost
-	GoodHostGIF   string // valid GIF on GoodHost
-	OtherHostJPEG string // valid JPEG on OtherHost
-	OtherHostPNG  string // valid PNG on OtherHost
-
-	// Invalid/edge case files
-	InvalidFile string // file with wrong magic bytes
-	EmptyFile   string // zero-byte file
-	TextFile    string // text file masquerading as image
-
-	// Hostnames
-	GoodHost  string // a host the mock fetcher serves
-	OtherHost string // a second host the mock fetcher serves
-}
-
-// DefaultFixtures returns the standard test fixture paths.
-func DefaultFixtures() *TestFixtures {
-	return &TestFixtures{
-		GoodHostJPEG:  "goodhost.example.com/images/photo.jpg",
-		GoodHostPNG:   "goodhost.example.com/images/logo.png",
-		GoodHostGIF:   "goodhost.example.com/images/animation.gif",
-		OtherHostJPEG: "otherhost.example.com/uploads/image.jpg",
-		OtherHostPNG:  "otherhost.example.com/uploads/icon.png",
-		InvalidFile:   "goodhost.example.com/images/fake.jpg",
-		EmptyFile:     "goodhost.example.com/images/empty.jpg",
-		TextFile:      "goodhost.example.com/images/text.png",
-		GoodHost:      "goodhost.example.com",
-		OtherHost:     "otherhost.example.com",
-	}
-}
-
-// NewTestFS creates a mock filesystem with test images.
-func NewTestFS(t *testing.T) (fs.FS, *TestFixtures) {
-	t.Helper()
-
-	fixtures := DefaultFixtures()
-
-	// Generate test images
-	jpegData := generateTestJPEG(t, 100, 100, color.RGBA{255, 0, 0, 255})
-	pngData := generateTestPNG(t, 100, 100, color.RGBA{0, 255, 0, 255})
-	gifData := generateTestGIF(t, 100, 100, color.RGBA{0, 0, 255, 255})
-
-	// Create the mock filesystem
-	mockFS := fstest.MapFS{
-		// Good host files
-		fixtures.GoodHostJPEG: &fstest.MapFile{Data: jpegData},
-		fixtures.GoodHostPNG:  &fstest.MapFile{Data: pngData},
-		fixtures.GoodHostGIF:  &fstest.MapFile{Data: gifData},
-
-		// Other host files
-		fixtures.OtherHostJPEG: &fstest.MapFile{Data: jpegData},
-		fixtures.OtherHostPNG:  &fstest.MapFile{Data: pngData},
-
-		// Invalid files
-		fixtures.InvalidFile: &fstest.MapFile{Data: []byte("not a real image file content")},
-		fixtures.EmptyFile:   &fstest.MapFile{Data: []byte{}},
-		fixtures.TextFile:    &fstest.MapFile{Data: []byte("This is just text, not a PNG")},
-	}
-
-	return mockFS, fixtures
-}
-
 // generateTestJPEG creates a minimal valid JPEG image.
 func generateTestJPEG(t *testing.T, width, height int, c color.Color) []byte {
 	t.Helper()
@@ -114,104 +35,3 @@ func generateTestJPEG(t *testing.T, width, height int, c color.Color) []byte {
 
 	return buf.Bytes()
 }
-
-// generateTestPNG creates a minimal valid PNG image.
-func generateTestPNG(t *testing.T, width, height int, c color.Color) []byte {
-	t.Helper()
-
-	img := image.NewRGBA(image.Rect(0, 0, width, height))
-	for y := range height {
-		for x := range width {
-			img.Set(x, y, c)
-		}
-	}
-
-	var buf bytes.Buffer
-
-	err := png.Encode(&buf, img)
-	if err != nil {
-		t.Fatalf("failed to encode test PNG: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// generateTestGIF creates a minimal valid GIF image.
-func generateTestGIF(t *testing.T, width, height int, c color.Color) []byte {
-	t.Helper()
-
-	img := image.NewPaletted(
-		image.Rect(0, 0, width, height),
-		[]color.Color{c, color.White},
-	)
-	for y := range height {
-		for x := range width {
-			img.SetColorIndex(x, y, 0)
-		}
-	}
-
-	var buf bytes.Buffer
-
-	err := gif.Encode(&buf, img, nil)
-	if err != nil {
-		t.Fatalf("failed to encode test GIF: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// SetupTestService creates a Service with mock fetcher for testing.
-func SetupTestService(t *testing.T) (*Service, *TestFixtures) {
-	t.Helper()
-
-	mockFS, fixtures := NewTestFS(t)
-
-	// Create temp directory for cache
-	tmpDir := t.TempDir()
-
-	// Create in-memory database
-	db := setupServiceTestDB(t)
-
-	cache, err := NewCache(db, CacheConfig{
-		StateDir:    tmpDir,
-		NegativeTTL: 5 * time.Minute,
-		MaxBytes:    1 << 30,
-	}, prometheus.NewRegistry())
-	if err != nil {
-		t.Fatalf("failed to create cache: %v", err)
-	}
-
-	svc, err := NewService(&ServiceConfig{
-		Cache:   cache,
-		Fetcher: httpfetcher.NewMock(mockFS),
-		Processor: imageprocessor.New(imageprocessor.Params{
-			MaxInputBytes:           50 << 20,
-			MaxConcurrentProcessing: 2,
-		}),
-		MaxResponseSize: 50 << 20,
-	})
-	if err != nil {
-		t.Fatalf("failed to create service: %v", err)
-	}
-
-	return svc, fixtures
-}
-
-// setupServiceTestDB creates an in-memory SQLite database for testing
-// using the production schema.
-func setupServiceTestDB(t *testing.T) *sql.DB {
-	t.Helper()
-
-	db, err := sql.Open("sqlite", ":memory:")
-	if err != nil {
-		t.Fatalf("failed to open test db: %v", err)
-	}
-
-	// Use the real production schema via migrations
-	err = database.ApplyMigrations(context.Background(), db, nil)
-	if err != nil {
-		t.Fatalf("failed to apply migrations: %v", err)
-	}
-
-	return db
-}