test: add failing tests for cache_max_bytes config and cache eviction
Red phase for #51: covers strict cache_max_bytes parsing (invalid explicit values abort naming key and value), the computed default of max(75% of free space, 500 MiB) via an injectable free-space probe, explicit-value-no-floor, zero-disables-cache, size accounting over source blobs and variants, LRU eviction under the limit, the multi-referenced blob case, write-pressure and periodic eviction triggers, and startup reconciliation. Minimal API skeletons keep the tree compiling and lint-clean; only the new tests fail.
This commit is contained in:
271
internal/config/cache_max_bytes_test.go
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271
internal/config/cache_max_bytes_test.go
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@@ -0,0 +1,271 @@
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package config
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import (
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"errors"
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"io"
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"log/slog"
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"os"
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"path/filepath"
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"strings"
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"testing"
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)
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// discardLogger returns a logger that swallows all output, for tests
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// that exercise code paths which log.
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func discardLogger() *slog.Logger {
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return slog.New(slog.NewTextHandler(io.Discard, nil))
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}
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// TestCacheMaxBytesExplicitValueUsedWithoutFloor verifies that an
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// explicitly configured cache_max_bytes value is used exactly as
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// given: the 500 MiB floor applies only to the computed default, never
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// to explicit values.
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func TestCacheMaxBytesExplicitValueUsedWithoutFloor(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 1024\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("explicit cache_max_bytes must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 1024 {
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t.Errorf("CacheMaxBytes = %d, want 1024 (no floor for explicit values)",
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c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesZeroIsValidAndDisablesCache verifies that an
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// explicit zero is a valid value (it disables the disk cache), not an
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// error.
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func TestCacheMaxBytesZeroIsValidAndDisablesCache(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 0\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("cache_max_bytes: 0 must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 0 {
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t.Errorf("CacheMaxBytes = %d, want 0", c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesLargeExplicitValueParses verifies that values above
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// 32-bit range parse correctly (the field is an int64 byte count).
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func TestCacheMaxBytesLargeExplicitValueParses(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 10737418240\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("large cache_max_bytes must be accepted, got error: %v", err)
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}
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if c.CacheMaxBytes != 10737418240 {
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t.Errorf("CacheMaxBytes = %d, want 10737418240", c.CacheMaxBytes)
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}
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}
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// TestCacheMaxBytesInvalidValuesAbortStartup verifies that a SET but
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// invalid cache_max_bytes value aborts startup naming the key and the
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// offending value, per the no-silent-fallback rule: defaults apply
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// only to omitted keys.
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func TestCacheMaxBytesInvalidValuesAbortStartup(t *testing.T) {
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signingKeyLine := "signing_key: " + validTestSigningKey + "\n"
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cases := []struct {
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name string
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yaml string
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// wantErrSubstrings must all appear in the error message.
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wantErrSubstrings []string
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}{
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{
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name: "negative",
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yaml: signingKeyLine + "cache_max_bytes: -1024\n",
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wantErrSubstrings: []string{"cache_max_bytes", "-1024"},
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},
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{
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name: "float",
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yaml: signingKeyLine + "cache_max_bytes: 3.5\n",
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wantErrSubstrings: []string{"cache_max_bytes", "3.5"},
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},
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{
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name: "non-numeric string",
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yaml: signingKeyLine + "cache_max_bytes: banana\n",
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wantErrSubstrings: []string{"cache_max_bytes", "banana"},
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},
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{
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name: "explicit null",
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yaml: signingKeyLine + "cache_max_bytes: null\n",
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wantErrSubstrings: []string{"cache_max_bytes", "null"},
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},
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{
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name: "bare key no value",
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yaml: signingKeyLine + "cache_max_bytes:\n",
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wantErrSubstrings: []string{"cache_max_bytes", "null"},
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},
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{
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name: "boolean",
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yaml: signingKeyLine + "cache_max_bytes: true\n",
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wantErrSubstrings: []string{"cache_max_bytes", "true"},
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},
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{
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name: "list",
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yaml: signingKeyLine + "cache_max_bytes:\n - 1\n",
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wantErrSubstrings: []string{"cache_max_bytes"},
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},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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c, err := configFromYAML(t, tc.yaml)
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if err == nil {
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t.Fatalf("config with %s cache_max_bytes must abort startup, got config: %+v",
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tc.name, c)
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}
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t.Logf("got expected error: %v", err)
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for _, want := range tc.wantErrSubstrings {
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if !strings.Contains(err.Error(), want) {
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t.Errorf("error %q does not mention %q", err.Error(), want)
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}
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}
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})
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}
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}
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// TestComputeDefaultCacheMaxBytesUses75PercentOfFreeSpace verifies the
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// computed default is 75% of the probed free space when that exceeds
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// the floor.
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func TestComputeDefaultCacheMaxBytesUses75PercentOfFreeSpace(t *testing.T) {
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// 4 GiB free -> 3 GiB default.
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probe := func(string) (uint64, error) { return 4294967296, nil }
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got, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err != nil {
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t.Fatalf("ComputeDefaultCacheMaxBytes returned error: %v", err)
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}
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if got != 3221225472 {
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t.Errorf("ComputeDefaultCacheMaxBytes = %d, want 3221225472 (75%% of 4 GiB)", got)
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}
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}
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// TestComputeDefaultCacheMaxBytesAppliesFloorToComputedDefault
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// verifies that when 75% of free space is below 500 MiB, the computed
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// default is floored at DefaultCacheMaxBytesFloor.
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func TestComputeDefaultCacheMaxBytesAppliesFloorToComputedDefault(t *testing.T) {
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cases := []struct {
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name string
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freeBytes uint64
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}{
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{name: "100 MiB free", freeBytes: 104857600},
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{name: "zero free", freeBytes: 0},
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{name: "just below floor threshold", freeBytes: 699050665},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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probe := func(string) (uint64, error) { return tc.freeBytes, nil }
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got, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err != nil {
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t.Fatalf("ComputeDefaultCacheMaxBytes returned error: %v", err)
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}
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if got != DefaultCacheMaxBytesFloor {
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t.Errorf("ComputeDefaultCacheMaxBytes = %d, want floor %d",
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got, DefaultCacheMaxBytesFloor)
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}
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})
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}
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}
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// TestComputeDefaultCacheMaxBytesPropagatesProbeError verifies that a
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// failing free-space probe produces an error naming the config key,
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// instead of a silently wrong default.
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func TestComputeDefaultCacheMaxBytesPropagatesProbeError(t *testing.T) {
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probe := func(string) (uint64, error) { return 0, errors.New("statfs failed") }
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_, err := ComputeDefaultCacheMaxBytes(t.TempDir(), probe)
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if err == nil {
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t.Fatal("probe failure must produce an error, got nil")
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}
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t.Logf("got expected error: %v", err)
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if !strings.Contains(err.Error(), "cache_max_bytes") {
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t.Errorf("error %q does not name the config key cache_max_bytes", err.Error())
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}
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}
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// TestResolveCacheMaxBytesComputesDefaultWhenOmitted verifies that an
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// omitted cache_max_bytes key resolves to the computed default, that
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// the probe is pointed at <state_dir>/cache/ (which must be created
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// first so statfs measures the right filesystem), and that the result
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// lands on the Config.
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func TestResolveCacheMaxBytesComputesDefaultWhenOmitted(t *testing.T) {
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c, err := configFromYAML(t, "signing_key: "+validTestSigningKey+"\n")
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if err != nil {
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t.Fatalf("minimal config should be valid, got error: %v", err)
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}
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c.StateDir = t.TempDir()
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wantCacheDir := filepath.Join(c.StateDir, "cache")
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var probedPath string
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// 4 GiB free -> 3 GiB default.
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probe := func(path string) (uint64, error) {
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probedPath = path
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return 4294967296, nil
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}
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if err := c.resolveCacheMaxBytes(discardLogger(), probe); err != nil {
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t.Fatalf("resolveCacheMaxBytes returned error: %v", err)
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}
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if c.CacheMaxBytes != 3221225472 {
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t.Errorf("CacheMaxBytes = %d, want computed default 3221225472", c.CacheMaxBytes)
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}
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if probedPath != wantCacheDir {
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t.Errorf("free space probed at %q, want cache directory %q", probedPath, wantCacheDir)
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}
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info, err := os.Stat(wantCacheDir)
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if err != nil || !info.IsDir() {
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t.Errorf("cache directory %q was not created before probing: info=%v err=%v",
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wantCacheDir, info, err)
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}
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}
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// TestResolveCacheMaxBytesDoesNotOverrideExplicitValue verifies that
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// an explicitly configured value survives resolution untouched and
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// that the free-space probe is never consulted for it.
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func TestResolveCacheMaxBytesDoesNotOverrideExplicitValue(t *testing.T) {
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yamlContent := "signing_key: " + validTestSigningKey + "\ncache_max_bytes: 1024\n"
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c, err := configFromYAML(t, yamlContent)
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if err != nil {
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t.Fatalf("explicit cache_max_bytes must be accepted, got error: %v", err)
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}
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c.StateDir = t.TempDir()
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probe := func(string) (uint64, error) {
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t.Error("free-space probe must not be consulted for explicit values")
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return 0, errors.New("probe must not be called")
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}
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if err := c.resolveCacheMaxBytes(discardLogger(), probe); err != nil {
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t.Fatalf("resolveCacheMaxBytes returned error: %v", err)
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}
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if c.CacheMaxBytes != 1024 {
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t.Errorf("CacheMaxBytes = %d, want explicit 1024 (no floor, no recompute)",
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c.CacheMaxBytes)
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}
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}
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60
internal/config/cachesize.go
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60
internal/config/cachesize.go
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@@ -0,0 +1,60 @@
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package config
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import (
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"fmt"
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"log/slog"
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"path/filepath"
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"syscall"
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)
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// DefaultCacheMaxBytesFloor is the minimum computed default for the
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// cache_max_bytes setting: 500 MiB. The floor applies only to the
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// computed default (when the key is omitted from the configuration),
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// never to explicitly configured values.
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const DefaultCacheMaxBytesFloor int64 = 524288000
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// FreeSpaceProbeFunc reports the number of free bytes available on the
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// filesystem containing path. It is a function type so tests can
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// inject a fake probe instead of depending on the host disk.
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type FreeSpaceProbeFunc func(path string) (uint64, error)
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// defaultFreeSpaceProbe reports free filesystem bytes via statfs on
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// the given path, as available to unprivileged processes.
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func defaultFreeSpaceProbe(path string) (uint64, error) {
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var stat syscall.Statfs_t
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if err := syscall.Statfs(path, &stat); err != nil {
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return 0, err
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}
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if stat.Bsize < 0 {
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return 0, fmt.Errorf("statfs reported negative block size %d for %q", stat.Bsize, path)
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}
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blockSize := uint64(stat.Bsize) //nolint:gosec // G115: negative Bsize rejected above
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return stat.Bavail * blockSize, nil
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}
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// ComputeDefaultCacheMaxBytes returns the default cache size limit for
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// the filesystem containing cacheDir: 75% of the free bytes reported
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// by probe, with a floor of DefaultCacheMaxBytesFloor.
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func ComputeDefaultCacheMaxBytes(_ string, _ FreeSpaceProbeFunc) (int64, error) {
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// Red phase: implementation follows the failing tests.
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return 0, nil
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}
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// resolveCacheMaxBytes finalizes CacheMaxBytes after state_dir
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// validation: an explicitly configured value is kept as-is (no floor
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// applies), while an omitted key receives the computed default based
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// on free space in <state_dir>/cache/. The effective limit is logged.
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func (c *Config) resolveCacheMaxBytes(log *slog.Logger, probe FreeSpaceProbeFunc) error {
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// Red phase: implementation follows the failing tests.
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limit, err := ComputeDefaultCacheMaxBytes(filepath.Join(c.StateDir, "cache"), probe)
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if err != nil {
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return err
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}
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log.Debug("cache size limit resolution not implemented", "computed", limit)
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return nil
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}
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@@ -48,6 +48,13 @@ type Config struct {
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AllowlistHosts []string // Hosts that don't require signatures
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AllowHTTP bool // Allow non-TLS upstream (testing only)
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UpstreamConnectionsPerHost int // Max concurrent connections per upstream host
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// CacheMaxBytes is the disk cache size limit in bytes. Zero
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// disables the disk cache entirely. When cache_max_bytes is
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// omitted from the configuration, this holds the computed default
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// (75% of free space on the filesystem containing
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// <state_dir>/cache/, floored at DefaultCacheMaxBytesFloor).
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CacheMaxBytes int64
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}
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// New creates a new Config instance by loading configuration from file.
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@@ -73,6 +80,10 @@ func New(_ fx.Lifecycle, params Params) (*Config, error) {
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return nil, err
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}
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if err := c.resolveCacheMaxBytes(log, defaultFreeSpaceProbe); err != nil {
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return nil, err
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}
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if c.Debug {
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params.Logger.EnableDebugLogging()
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}
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Block a user