routewatch/internal/database/database_internal_test.go

package database

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"math/rand/v2"
	"net/netip"
	"slices"
	"strconv"
	"sync"
	"testing"
	"time"

	"git.eeqj.de/sneak/routewatch/internal/config"
	"git.eeqj.de/sneak/routewatch/internal/logger"
	"github.com/mattn/go-sqlite3"
)

// tempStoreMemory is the PRAGMA temp_store value meaning "hold temp B-trees in
// memory"; the DSN change must leave temp_store below this so they spill to disk.
const tempStoreMemory = 2

// autoVacuumIncremental is the PRAGMA auto_vacuum value meaning "incremental".
const autoVacuumIncremental = 2

// vacuumTestRoutes is how many routes the vacuum test writes and then deletes,
// enough to leave many free pages in the file.
const vacuumTestRoutes = 2000

// heldConnections is how many pooled connections the pragma test holds open at
// once so each is a distinct SQLite connection that parsed the DSN.
const heldConnections = 5

// bytesPerKiB turns a cache_size in KiB into bytes.
const bytesPerKiB = 1024

// testPeerIP is the peer every route in the IP lookup test is learned from.
const testPeerIP = "192.0.2.254"

// Parameters for the checkpoint-contention regression test.
const (
	// contentionIterations is how many batch writes race the checkpoint loop.
	contentionIterations = 400
	// contendedASNCount is the small set of ASNs the batches reuse, so most
	// batches update existing rows and exercise the read-before-write path.
	contendedASNCount = 16
	// asnSecondBand offsets a second ASN per batch so each batch writes more
	// than one row.
	asnSecondBand = 100
)

// Parameters for the tests of maintenance and the database lock.
const (
	// lockMessageBuffer is how many lock messages a test database's logger
	// holds before logging waits for the test to read them.
	lockMessageBuffer = 64
	// operationKey is the log attribute that names the operation taking the
	// lock.
	operationKey = "operation"
	// testBatchWrite is the operation name the tests take the lock under.
	testBatchWrite = "test batch write"
	// lockWaitTimeout is the context timeout of a maintenance call that the
	// tests let run out while it waits for the lock.
	lockWaitTimeout = time.Millisecond
	// lockTestASN is the AS the batch write in the lock tests stores.
	lockTestASN = 64500
)

// Parameters for the prefix-length sample tests.
const (
	// sampleLimit is how many prefixes the tests ask the sample for.
	sampleLimit = 10
	// sampledPrefixCount is how many prefixes the sampling test stores, more
	// than sampleLimit so the sample has to choose among them.
	sampledPrefixCount = 30
	// secondV4PeerIP and secondV6PeerIP are the second peer each prefix is
	// learned from, besides the one mkV4Route and mkV6Route set.
	secondV4PeerIP = "192.0.2.2"
	secondV6PeerIP = "2001:db8::2"
	// largeSamplePrefixCount is how many prefixes the test of a mask length
	// with more than maxPrefixesToShuffle prefixes stores: twice that, so about
	// half of them come after the first maxPrefixesToShuffle+1 in text order.
	largeSamplePrefixCount = 2 * maxPrefixesToShuffle
	// largeSampleLimit is how many prefixes that test asks for. Each random
	// lookup lands after the first maxPrefixesToShuffle+1 in text order about
	// half the time, so none of them doing so is about as likely as
	// largeSampleLimit coin tosses all coming up heads.
	largeSampleLimit = 30
	// liveRoutesV4Table and liveRoutesV6Table are the live route tables the
	// tests pass to the sampling steps.
	liveRoutesV4Table = "live_routes_v4"
	liveRoutesV6Table = "live_routes_v6"
)

// TestGetIPInfoFindsMostSpecificLiveRoute stores nested live prefixes for both
// families and checks that a lookup returns the most specific one covering the
// address, ErrNoRoute when none covers it, and the next less specific prefix
// once the only route of the most specific one is withdrawn.
func TestGetIPInfoFindsMostSpecificLiveRoute(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	// Nested live prefixes, each originated by its own AS.
	origins := map[string]int{
		"10.0.0.0/8":        64500,
		"10.1.0.0/16":       64501,
		"10.1.2.0/24":       64502,
		"2001:db8::/32":     64500,
		"2001:db8:1::/48":   64501,
		"2001:db8:1:2::/64": 64502,
	}
	writeOriginRoutes(t, db, origins)

	// lookup checks that ip resolves to the live prefix want, or to ErrNoRoute
	// when want is empty.
	lookup := func(ip, want string) {
		t.Helper()

		info, err := db.GetIPInfo(ip)
		if want == "" {
			if !errors.Is(err, ErrNoRoute) {
				t.Errorf("GetIPInfo(%s) = %+v, %v; want ErrNoRoute", ip, info, err)
			}

			return
		}

		if err != nil {
			t.Errorf("GetIPInfo(%s): %v", ip, err)

			return
		}

		if info.Netblock != want || info.MaskLength != netip.MustParsePrefix(want).Bits() ||
			info.ASN != origins[want] {
			t.Errorf("GetIPInfo(%s) = %s (mask %d) AS%d, want %s AS%d",
				ip, info.Netblock, info.MaskLength, info.ASN, want, origins[want])
		}
	}

	lookup("10.1.2.3", "10.1.2.0/24")
	lookup("::ffff:10.1.2.3", "10.1.2.0/24")
	lookup("10.1.3.4", "10.1.0.0/16")
	lookup("10.2.0.1", "10.0.0.0/8")
	lookup("192.0.2.1", "")
	lookup("2001:db8:1:2::3", "2001:db8:1:2::/64")
	lookup("2001:db8:1:3::4", "2001:db8:1::/48")
	lookup("2001:db8:2::1", "2001:db8::/32")
	lookup("2001:db9::1", "")

	err = db.DeleteLiveRouteBatch([]LiveRouteDeletion{
		{Prefix: "10.1.2.0/24", PeerIP: testPeerIP, IPVersion: ipVersionV4},
		{Prefix: "2001:db8:1:2::/64", PeerIP: testPeerIP, IPVersion: ipVersionV6},
	})
	if err != nil {
		t.Fatalf("DeleteLiveRouteBatch: %v", err)
	}

	lookup("10.1.2.3", "10.1.0.0/16")
	lookup("2001:db8:1:2::3", "2001:db8:1::/48")
}

// TestGetIPInfoIgnoresShortRoutes checks that the IP lookup does not report a
// default route, or a route shorter than /8 for IPv4 or /16 for IPv6, as the
// route for an address, and that a route of exactly /8 or /16, or longer, still
// is. The prefixes are written out so that a wrong limit fails the test.
func TestGetIPInfoIgnoresShortRoutes(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	// announce writes one live route for prefix, originated by asn.
	announce := func(prefix string, asn int) {
		t.Helper()

		writeOriginRoutes(t, db, map[string]int{prefix: asn})
	}

	// lookup checks that ip resolves to the live prefix netblock from asn.
	lookup := func(ip, netblock string, asn int) {
		t.Helper()

		info, err := db.GetIPInfo(ip)
		if err != nil {
			t.Errorf("GetIPInfo(%s): %v", ip, err)

			return
		}

		if info.Netblock != netblock || info.ASN != asn {
			t.Errorf("GetIPInfo(%s) = %s AS%d, want %s AS%d",
				ip, info.Netblock, info.ASN, netblock, asn)
		}
	}

	// Default and very short routes, and routes one bit shorter than each limit.
	announce("2000::/3", 64500)
	announce("0.0.0.0/0", 64500)
	announce("2000::/15", 64500)
	announce("192.0.0.0/7", 64500)

	for _, ip := range []string{"2001:db8::1", "192.0.2.1"} {
		info, err := db.GetIPInfo(ip)
		if !errors.Is(err, ErrNoRoute) {
			t.Errorf("GetIPInfo(%s) with only short routes = %+v, %v; "+
				"want ErrNoRoute", ip, info, err)
		}
	}

	// Routes of exactly the minimum length are used.
	announce("2001::/16", 64501)
	announce("192.0.0.0/8", 64501)

	lookup("2001:db8::1", "2001::/16", 64501)
	lookup("192.0.2.1", "192.0.0.0/8", 64501)

	announce("2001:db8::/32", 64502)

	lookup("2001:db8::1", "2001:db8::/32", 64502)
}

// TestGetIPInfoNeedsNoWHOISRefreshForOriginZero checks that the IP lookup asks
// for no WHOIS lookup when the address's route has origin 0, no known origin,
// and still asks for one when its origin AS has no WHOIS data.
func TestGetIPInfoNeedsNoWHOISRefreshForOriginZero(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	writeOriginRoutes(t, db, map[string]int{"10.0.0.0/8": 0, "11.0.0.0/8": 64500})

	for ip, want := range map[string]bool{"10.0.0.1": false, "11.0.0.1": true} {
		info, err := db.GetIPInfo(ip)
		if err != nil {
			t.Fatalf("GetIPInfo(%s): %v", ip, err)
		}

		if info.NeedsWHOISRefresh != want {
			t.Errorf("GetIPInfo(%s) asks for a WHOIS lookup of AS%d: %t, want %t",
				ip, info.ASN, info.NeedsWHOISRefresh, want)
		}
	}
}

// TestLiveRouteTablesHoldOneRoutePerPrefixAndPeer checks that each live route
// table refuses a second route from a peer for a prefix, even with another
// origin AS. An upsert updates the peer's route before it would insert one, so
// only an insert straight into the table shows what the table allows.
func TestLiveRouteTablesHoldOneRoutePerPrefixAndPeer(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	const otherOriginASN = 64501

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)

	for _, tt := range []struct {
		route     *LiveRoute
		insertSQL string
	}{
		{
			route:     mkV4Route(t, "198.51.100.0/24", 64500, ts),
			insertSQL: insertLiveRouteV4SQL,
		},
		{
			route:     mkV6Route(testV6Prefix, 64500, ts),
			insertSQL: insertLiveRouteV6SQL,
		},
	} {
		err := db.UpsertLiveRoute(tt.route)
		if err != nil {
			t.Fatalf("UpsertLiveRoute(%s): %v", tt.route.Prefix, err)
		}

		_, err = db.db.ExecContext(t.Context(), tt.insertSQL,
			tt.route.Prefix, tt.route.MaskLength, otherOriginASN,
			tt.route.PeerIP, "[]", tt.route.NextHop, ts)

		var sqliteErr sqlite3.Error
		if !errors.As(err, &sqliteErr) ||
			sqliteErr.ExtendedCode != sqlite3.ErrConstraintUnique {
			t.Errorf("second route from peer %s for %s: error %v, "+
				"want a UNIQUE constraint error",
				tt.route.PeerIP, tt.route.Prefix, err)
		}
	}
}

// writeOriginRoutes writes one live route from testPeerIP for each prefix in
// origins, originated by the AS it maps to.
func writeOriginRoutes(t *testing.T, db *Database, origins map[string]int) {
	t.Helper()

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	routes := make([]*LiveRoute, 0, len(origins))

	for prefix, asn := range origins {
		routes = append(routes, &LiveRoute{
			Prefix:      prefix,
			MaskLength:  netip.MustParsePrefix(prefix).Bits(),
			IPVersion:   detectIPVersion(prefix),
			OriginASN:   asn,
			PeerIP:      testPeerIP,
			ASPath:      []int{asn},
			NextHop:     testPeerIP,
			LastUpdated: ts,
		})
	}

	err := db.UpsertLiveRouteBatch(routes)
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}
}

// TestConnectionPoolPragmas holds several pooled connections open at once and
// checks each one carries the per-connection settings from the DSN, plus the
// process-wide heap limits, and sees the new file with auto_vacuum
// incremental.
func TestConnectionPoolPragmas(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ctx := context.Background()

	// Hold distinct connections open simultaneously so the pool must open a new
	// one (each parsing the DSN) rather than hand back the same connection.
	conns := make([]*sql.Conn, 0, heldConnections)
	defer func() {
		for _, c := range conns {
			_ = c.Close()
		}
	}()

	for i := range heldConnections {
		c, err := db.db.Conn(ctx)
		if err != nil {
			t.Fatalf("failed to open connection %d: %v", i, err)
		}

		conns = append(conns, c)
	}

	for i, c := range conns {
		cacheSize := readPragma(ctx, t, c, i, "cache_size")
		if cacheSize != sqliteReadCacheSizeKiB {
			t.Errorf("conn %d: cache_size = %d, want %d",
				i, cacheSize, sqliteReadCacheSizeKiB)
		}

		busyTimeout := readPragma(ctx, t, c, i, "busy_timeout")
		if busyTimeout != sqliteBusyTimeoutMs {
			t.Errorf("conn %d: busy_timeout = %d, want %d",
				i, busyTimeout, sqliteBusyTimeoutMs)
		}

		tempStore := readPragma(ctx, t, c, i, "temp_store")
		if tempStore == tempStoreMemory {
			t.Errorf("conn %d: temp_store = %d, want anything but %d (MEMORY)",
				i, tempStore, tempStoreMemory)
		}

		softHeapLimit := readPragma(ctx, t, c, i, "soft_heap_limit")
		if softHeapLimit != sqliteSoftHeapLimitBytes {
			t.Errorf("conn %d: soft_heap_limit = %d, want %d",
				i, softHeapLimit, sqliteSoftHeapLimitBytes)
		}

		hardHeapLimit := readPragma(ctx, t, c, i, "hard_heap_limit")
		if hardHeapLimit != sqliteHardHeapLimitBytes {
			t.Errorf("conn %d: hard_heap_limit = %d, want %d",
				i, hardHeapLimit, sqliteHardHeapLimitBytes)
		}

		autoVacuum := readPragma(ctx, t, c, i, "auto_vacuum")
		if autoVacuum != autoVacuumIncremental {
			t.Errorf("conn %d: auto_vacuum = %d, want %d (incremental)",
				i, autoVacuum, autoVacuumIncremental)
		}
	}
}

// TestWritingConnectionCache checks that the connection kept for writing has
// the large cache, and that the soft heap limit is above the caches of all the
// connections together: SQLite shrinks the caches to stay under it.
func TestWritingConnectionCache(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ctx := t.Context()

	var writeCacheSize, readCacheSize, softHeapLimit int64

	err = db.writer.QueryRowContext(ctx, "PRAGMA cache_size").
		Scan(&writeCacheSize)
	if err != nil {
		t.Fatalf("failed to read the writing connection's cache_size: %v", err)
	}

	if writeCacheSize != sqliteWriteCacheSizeKiB {
		t.Errorf("writing connection: cache_size = %d, want %d",
			writeCacheSize, sqliteWriteCacheSizeKiB)
	}

	err = db.db.QueryRowContext(ctx, "PRAGMA cache_size").Scan(&readCacheSize)
	if err != nil {
		t.Fatalf("failed to read a reading connection's cache_size: %v", err)
	}

	err = db.db.QueryRowContext(ctx, "PRAGMA soft_heap_limit").
		Scan(&softHeapLimit)
	if err != nil {
		t.Fatalf("failed to read soft_heap_limit: %v", err)
	}

	cachesBytes := -bytesPerKiB * (writeCacheSize + (maxConns-1)*readCacheSize)
	if softHeapLimit <= cachesBytes {
		t.Errorf("soft_heap_limit = %d, not above the %d bytes of the caches",
			softHeapLimit, cachesBytes)
	}
}

// readPragma reads the integer value of PRAGMA name on connection i, c.
func readPragma(
	ctx context.Context, t *testing.T, c *sql.Conn, i int, name string,
) int64 {
	t.Helper()

	var value int64

	err := c.QueryRowContext(ctx, "PRAGMA "+name).Scan(&value)
	if err != nil {
		t.Fatalf("conn %d: failed to read %s: %v", i, name, err)
	}

	return value
}

// TestVacuumReturnsFreePages checks that after routes are deleted from a new
// database, one Vacuum call returns every page they used. The deletes leave
// fewer free pages than the 1000 Vacuum frees per call, so none may remain.
// With auto_vacuum off (issue https://git.eeqj.de/sneak/routewatch/issues/43)
// the free pages stayed in the file, and with the PRAGMA run by ExecContext
// Vacuum freed only one page per call.
func TestVacuumReturnsFreePages(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ctx := context.Background()
	ts := time.Now().UTC()

	const asn = 64500

	routes := make([]*LiveRoute, 0, vacuumTestRoutes)
	deletions := make([]LiveRouteDeletion, 0, vacuumTestRoutes)

	for i := range vacuumTestRoutes {
		route := mkV4Route(t, fmt.Sprintf("10.%d.%d.0/24", i/256, i%256), asn, ts)
		routes = append(routes, route)
		deletions = append(deletions, LiveRouteDeletion{
			Prefix:    route.Prefix,
			PeerIP:    route.PeerIP,
			IPVersion: ipVersionV4,
		})
	}

	err = db.UpsertLiveRouteBatch(routes)
	if err != nil {
		t.Fatalf("failed to write routes: %v", err)
	}

	err = db.DeleteLiveRouteBatch(deletions)
	if err != nil {
		t.Fatalf("failed to delete routes: %v", err)
	}

	var before int

	err = db.db.QueryRowContext(ctx, "PRAGMA freelist_count").Scan(&before)
	if err != nil {
		t.Fatalf("failed to read freelist_count: %v", err)
	}

	if before == 0 {
		t.Fatalf("no free pages after deleting %d routes", vacuumTestRoutes)
	}

	err = db.Vacuum(ctx)
	if err != nil {
		t.Fatalf("Vacuum failed: %v", err)
	}

	var after int

	err = db.db.QueryRowContext(ctx, "PRAGMA freelist_count").Scan(&after)
	if err != nil {
		t.Fatalf("failed to read freelist_count: %v", err)
	}

	if after != 0 {
		t.Errorf("free pages after Vacuum = %d of %d, want 0", after, before)
	}
}

// TestBatchWriteDuringCheckpoint runs checkpoints back to back while batch
// writes run and checks that every batch write succeeds: a checkpoint holds the
// database lock as a batch write does, and checkpoints must not keep batch
// writes from getting it.
func TestBatchWriteDuringCheckpoint(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ctx, cancel := context.WithCancel(context.Background())

	var wg sync.WaitGroup

	wg.Go(func() {
		for {
			select {
			case <-ctx.Done():
				return
			default:
				_ = db.Checkpoint(ctx) // errors are the checkpoint's own to absorb
			}
		}
	})

	ts := time.Now().UTC()
	for i := range contentionIterations {
		asns := map[int]time.Time{
			i % contendedASNCount:                   ts,
			(i % contendedASNCount) + asnSecondBand: ts,
		}

		err := db.GetOrCreateASNBatch(asns)
		if err != nil {
			cancel()
			wg.Wait()
			t.Fatalf("batch write failed under checkpoint contention: %v", err)
		}
	}

	cancel()
	wg.Wait()
}

// lockMessage is a debug message the database lock logged, and the name of the
// operation that logged it.
type lockMessage struct {
	text      string
	operation string
}

// lockMessages is a log handler that passes on each message the database lock
// logs. The lock tests read it to know that an operation waits for the lock or
// holds it, instead of guessing how long that takes.
type lockMessages chan lockMessage

// Enabled lets every message through, so the lock's debug messages arrive.
func (m lockMessages) Enabled(context.Context, slog.Level) bool { return true }

// Handle passes on a message that names an operation and drops the others.
func (m lockMessages) Handle(_ context.Context, record slog.Record) error {
	record.Attrs(func(attr slog.Attr) bool {
		if attr.Key != operationKey {
			return true
		}

		m <- lockMessage{text: record.Message, operation: attr.Value.String()}

		return false
	})

	return nil
}

// WithAttrs returns m: the tests need no attributes added.
func (m lockMessages) WithAttrs([]slog.Attr) slog.Handler { return m }

// WithGroup returns m: the tests need no groups.
func (m lockMessages) WithGroup(string) slog.Handler { return m }

// newDatabaseWithLockMessages opens a new database whose logger passes the lock's
// messages to the returned channel.
func newDatabaseWithLockMessages(t *testing.T) (*Database, lockMessages) {
	t.Helper()

	messages := make(lockMessages, lockMessageBuffer)
	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, &logger.Logger{Logger: slog.New(messages)})
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}

	t.Cleanup(func() { _ = db.Close() })

	return db, messages
}

// waitForLockMessage waits until operation logs text, and fails the test if
// returned delivers first: the call running operation returned without logging
// text.
func waitForLockMessage(
	t *testing.T,
	messages lockMessages,
	text, operation string,
	returned <-chan error,
) {
	t.Helper()

	for {
		select {
		case message := <-messages:
			if message.text == text && message.operation == operation {
				return
			}
		case err := <-returned:
			t.Fatalf("%s returned (error: %v) without logging %q",
				operation, err, text)
		}
	}
}

// TestVacuumWaitsForBatchWrite holds the database lock as a batch write does and
// checks that Vacuum waits for it and then succeeds. Vacuum ran without the
// lock, met the batch writes at SQLite's write lock and failed with "database
// is locked" (https://git.eeqj.de/sneak/routewatch/issues/94).
func TestVacuumWaitsForBatchWrite(t *testing.T) {
	t.Parallel()

	db, messages := newDatabaseWithLockMessages(t)

	db.lock(testBatchWrite)

	vacuumed := make(chan error, 1)

	go func() { vacuumed <- db.Vacuum(context.Background()) }()

	waitForLockMessage(t, messages, lockWaitMessage, "Vacuum", vacuumed)

	db.unlock()

	err := <-vacuumed
	if err != nil {
		t.Fatalf("Vacuum after the batch write: %v", err)
	}
}

// TestBatchWriteWaitsForAnalyze keeps Analyze waiting for SQLite's write lock,
// which another connection holds, and checks that a batch write started
// meanwhile waits for Analyze to give up the database lock, that both then
// succeed, and that Analyze stored statistics. ANALYZE ran without the database
// lock, and a batch write that waited longer than the busy timeout for it failed
// with "database is locked".
func TestBatchWriteWaitsForAnalyze(t *testing.T) {
	t.Parallel()

	db, messages := newDatabaseWithLockMessages(t)
	ctx := context.Background()
	asns := map[int]time.Time{lockTestASN: time.Now().UTC()}

	// A stored AS gives ANALYZE a table to analyze and statistics to write.
	err := db.GetOrCreateASNBatch(asns)
	if err != nil {
		t.Fatalf("failed to store an AS: %v", err)
	}

	// With _txlock=immediate this transaction takes SQLite's write lock at
	// BEGIN, so ANALYZE has to wait for it while Analyze holds the database lock.
	writer, err := db.db.BeginTx(ctx, nil)
	if err != nil {
		t.Fatalf("failed to begin the transaction ANALYZE waits for: %v", err)
	}

	defer func() { _ = writer.Rollback() }()

	analyzed := make(chan error, 1)

	go func() { analyzed <- db.Analyze(ctx) }()

	waitForLockMessage(t, messages, lockHeldMessage, "Analyze", analyzed)

	written := make(chan error, 1)

	go func() { written <- db.GetOrCreateASNBatch(asns) }()

	waitForLockMessage(t, messages, lockWaitMessage, "GetOrCreateASNBatch", written)

	err = writer.Rollback()
	if err != nil {
		t.Fatalf("failed to end the transaction ANALYZE waits for: %v", err)
	}

	err = <-analyzed
	if err != nil {
		t.Errorf("Analyze: %v", err)
	}

	err = <-written
	if err != nil {
		t.Errorf("batch write after Analyze: %v", err)
	}

	var statistics int

	err = db.db.QueryRowContext(ctx,
		"SELECT count(*) FROM sqlite_stat1 WHERE tbl = 'asns'").Scan(&statistics)
	if err != nil {
		t.Fatalf("failed to read the statistics: %v", err)
	}

	if statistics == 0 {
		t.Error("Analyze stored no statistics for the asns table")
	}
}

// TestCheckpointLockWaitEndsWithContext holds the database lock while the
// context of a waiting Checkpoint times out, and checks that Checkpoint then
// returns the context's error and leaves the lock free.
func TestCheckpointLockWaitEndsWithContext(t *testing.T) {
	t.Parallel()

	db, messages := newDatabaseWithLockMessages(t)

	db.lock(testBatchWrite)

	ctx, cancel := context.WithTimeout(context.Background(), lockWaitTimeout)
	defer cancel()

	checkpointed := make(chan error, 1)

	go func() { checkpointed <- db.Checkpoint(ctx) }()

	waitForLockMessage(t, messages, lockWaitMessage, "Checkpoint", checkpointed)
	<-ctx.Done()
	db.unlock()

	err := <-checkpointed
	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("Checkpoint = %v, want %v", err, context.DeadlineExceeded)
	}

	if !db.mu.TryLock() {
		t.Fatal("Checkpoint kept the database lock after its context ended")
	}

	db.mu.Unlock()
}

// TestGetRandomPrefixesByLengthListsPrefixOnce stores one prefix of each
// family learned from two peers in the same second and checks that the
// prefix-length sample lists each of them once.
func TestGetRandomPrefixesByLengthListsPrefixOnce(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	v4First := mkV4Route(t, "198.51.100.0/24", 64500, ts)
	v4Second := mkV4Route(t, "198.51.100.0/24", 64500, ts)
	v4Second.PeerIP = secondV4PeerIP
	v6First := mkV6Route(testV6Prefix, 64500, ts)
	v6Second := mkV6Route(testV6Prefix, 64500, ts)
	v6Second.PeerIP = secondV6PeerIP

	err = db.UpsertLiveRouteBatch(
		[]*LiveRoute{v4First, v4Second, v6First, v6Second})
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	for _, want := range []*LiveRoute{v4First, v6First} {
		routes, err := db.GetRandomPrefixesByLength(want.MaskLength,
			want.IPVersion, sampleLimit)
		if err != nil {
			t.Fatalf("GetRandomPrefixesByLength(%d, %d): %v",
				want.MaskLength, want.IPVersion, err)
		}

		if len(routes) != 1 || routes[0].Prefix != want.Prefix {
			t.Errorf("GetRandomPrefixesByLength(%d, %d) = %+v, want %s listed once",
				want.MaskLength, want.IPVersion, routes, want.Prefix)
		}
	}
}

// TestGetRandomPrefixesByLengthListsNewestRoute stores a prefix learned from
// two peers at different times, the older route first, and checks that the
// prefix-length sample lists the newer route.
func TestGetRandomPrefixesByLengthListsNewestRoute(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	older := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	olderRoute := mkV4Route(t, "198.51.100.0/24", 64500, older)
	newerRoute := mkV4Route(t, "198.51.100.0/24", 64500, older.Add(time.Minute))
	newerRoute.PeerIP = secondV4PeerIP

	err = db.UpsertLiveRouteBatch([]*LiveRoute{olderRoute, newerRoute})
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	routes, err := db.GetRandomPrefixesByLength(newerRoute.MaskLength,
		ipVersionV4, sampleLimit)
	if err != nil {
		t.Fatalf("GetRandomPrefixesByLength: %v", err)
	}

	if len(routes) != 1 || routes[0].PeerIP != newerRoute.PeerIP {
		t.Errorf("GetRandomPrefixesByLength = %+v, want only the newer route, "+
			"from %s", routes, newerRoute.PeerIP)
	}
}

// TestGetRandomPrefixesByLengthSamplesManyPrefixes stores more /24 prefixes
// than the sample asks for, each followed by a /16 so that routes of another
// mask length sit between the /24 rows, and each prefix learned from two peers
// in the same second. It checks both the sample the pages get, picked from the
// shuffled prefixes, and the random lookups used for a mask length with more
// than maxPrefixesToShuffle prefixes.
func TestGetRandomPrefixesByLengthSamplesManyPrefixes(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)

	var routes []*LiveRoute

	stored := make([]string, 0, sampledPrefixCount)

	for i := range sampledPrefixCount {
		prefix := fmt.Sprintf("10.0.%d.0/24", i)
		for _, p := range []string{prefix, fmt.Sprintf("172.%d.0.0/16", i)} {
			first := mkV4Route(t, p, 64500, ts)
			second := mkV4Route(t, p, 64500, ts)
			second.PeerIP = secondV4PeerIP
			routes = append(routes, first, second)
		}

		stored = append(stored, prefix)
	}

	err = db.UpsertLiveRouteBatch(routes)
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	slices.Sort(stored)

	maskLength := routes[0].MaskLength

	sample, err := db.GetRandomPrefixesByLength(maskLength, ipVersionV4, sampleLimit)
	if err != nil {
		t.Fatalf("GetRandomPrefixesByLength: %v", err)
	}

	listed := make([]string, 0, len(sample))
	for _, route := range sample {
		listed = append(listed, route.Prefix)
	}

	checkPrefixSample(t, "GetRandomPrefixesByLength", listed, stored)

	looked, err := db.samplePrefixesByLength(
		context.Background(), liveRoutesV4Table, maskLength, sampleLimit, nil)
	if err != nil {
		t.Fatalf("samplePrefixesByLength: %v", err)
	}

	checkPrefixSample(t, "samplePrefixesByLength", looked, stored)
}

// checkPrefixSample checks that sample lists sampleLimit prefixes, each once
// and each one of stored, and that it is not just the first sampleLimit of
// stored, which is in text order.
func checkPrefixSample(t *testing.T, name string, sample, stored []string) {
	t.Helper()

	if len(sample) != sampleLimit {
		t.Errorf("%s listed %d prefixes, want %d", name, len(sample), sampleLimit)
	}

	listed := make(map[string]bool)

	for _, prefix := range sample {
		if listed[prefix] || !slices.Contains(stored, prefix) {
			t.Errorf("%s lists %s twice or it is not one of the /24s", name, prefix)
		}

		listed[prefix] = true
	}

	if slices.Equal(slices.Sorted(slices.Values(sample)), stored[:sampleLimit]) {
		t.Errorf("%s lists just the first %d prefixes in text order",
			name, sampleLimit)
	}
}

// TestGetRandomPrefixesByLengthSamplesPastFirstPrefixes stores more prefixes
// of one mask length than maxPrefixesToShuffle. It checks that
// firstPrefixesByLength reads just the first maxPrefixesToShuffle+1 in text
// order, and that the sample lists the prefixes asked for, each once, some of
// them after those first ones, which only the random lookups reach.
func TestGetRandomPrefixesByLengthSamplesPastFirstPrefixes(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	routes := make([]*LiveRoute, 0, largeSamplePrefixCount)
	stored := make([]string, 0, largeSamplePrefixCount)

	for i := range largeSamplePrefixCount {
		route := mkV6Route(fmt.Sprintf("2001:%x::/32", i), 64500, ts)
		routes = append(routes, route)
		stored = append(stored, route.Prefix)
	}

	err = db.UpsertLiveRouteBatch(routes)
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	slices.Sort(stored)
	firstPrefixes := stored[:maxPrefixesToShuffle+1]
	maskLength := routes[0].MaskLength

	read, err := db.firstPrefixesByLength(context.Background(),
		liveRoutesV6Table, maskLength, maxPrefixesToShuffle+1)
	if err != nil {
		t.Fatalf("firstPrefixesByLength: %v", err)
	}

	if !slices.Equal(read, firstPrefixes) {
		t.Errorf("firstPrefixesByLength read %d prefixes, want the first %d "+
			"in text order", len(read), len(firstPrefixes))
	}

	sample, err := db.GetRandomPrefixesByLength(maskLength, ipVersionV6,
		largeSampleLimit)
	if err != nil {
		t.Fatalf("GetRandomPrefixesByLength: %v", err)
	}

	if len(sample) != largeSampleLimit {
		t.Errorf("GetRandomPrefixesByLength listed %d prefixes, want %d",
			len(sample), largeSampleLimit)
	}

	listed := make(map[string]bool)
	pastFirstPrefixes := 0

	for _, route := range sample {
		if listed[route.Prefix] {
			t.Errorf("GetRandomPrefixesByLength lists %s twice", route.Prefix)
		}

		listed[route.Prefix] = true

		if !slices.Contains(firstPrefixes, route.Prefix) {
			pastFirstPrefixes++
		}
	}

	if pastFirstPrefixes == 0 {
		t.Errorf("GetRandomPrefixesByLength lists only prefixes among the first "+
			"%d in text order", len(firstPrefixes))
	}
}

// TestSamplePrefixesByLengthFillsUpFromShuffled stores a single prefix, so
// every random lookup lands on it, and checks that the sample still lists
// sampleLimit prefixes: the stored one, then the shuffled ones in order. The
// stored prefix is the second shuffled one, so the fill-up must skip it.
func TestSamplePrefixesByLengthFillsUpFromShuffled(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	shuffled := make([]string, 0, sampledPrefixCount)
	for i := range sampledPrefixCount {
		shuffled = append(shuffled, fmt.Sprintf("10.0.%d.0/24", i))
	}

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	route := mkV4Route(t, shuffled[1], 64500, ts)

	err = db.UpsertLiveRouteBatch([]*LiveRoute{route})
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	sample, err := db.samplePrefixesByLength(context.Background(),
		liveRoutesV4Table, route.MaskLength, sampleLimit, shuffled)
	if err != nil {
		t.Fatalf("samplePrefixesByLength: %v", err)
	}

	want := append([]string{shuffled[1], shuffled[0]}, shuffled[2:sampleLimit]...)
	if !slices.Equal(sample, want) {
		t.Errorf("samplePrefixesByLength = %v, want %v", sample, want)
	}
}

// TestGetRandomPrefixesByLengthSkipsWithdrawnRoutes withdraws a route after
// storing it, as can happen between the steps of GetRandomPrefixesByLength. It
// checks that the random lookups pick nothing for a mask length with no route
// left, and that only the prefixes that still have a route get their newest
// route listed.
func TestGetRandomPrefixesByLengthSkipsWithdrawnRoutes(t *testing.T) {
	t.Parallel()

	cfg := &config.Config{StateDir: t.TempDir()}

	db, err := New(cfg, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	kept := mkV4Route(t, "198.51.100.0/24", 64500, ts)
	withdrawn := mkV4Route(t, "172.16.0.0/16", 64500, ts)

	err = db.UpsertLiveRouteBatch([]*LiveRoute{kept, withdrawn})
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	err = db.DeleteLiveRoute(withdrawn.Prefix, withdrawn.PeerIP)
	if err != nil {
		t.Fatalf("DeleteLiveRoute: %v", err)
	}

	ctx := context.Background()

	sample, err := db.samplePrefixesByLength(ctx, liveRoutesV4Table,
		withdrawn.MaskLength, sampleLimit, []string{withdrawn.Prefix})
	if err != nil {
		t.Fatalf("samplePrefixesByLength: %v", err)
	}

	if len(sample) != 0 {
		t.Errorf("samplePrefixesByLength = %v, want none for a mask length "+
			"with no route left", sample)
	}

	routes, err := db.newestRouteOfEachPrefix(ctx, liveRoutesV4Table,
		ipVersionV4, []string{withdrawn.Prefix, kept.Prefix})
	if err != nil {
		t.Fatalf("newestRouteOfEachPrefix: %v", err)
	}

	if len(routes) != 1 || routes[0].Prefix != kept.Prefix {
		t.Errorf("newestRouteOfEachPrefix = %+v, want only the route of %s",
			routes, kept.Prefix)
	}
}

// TestLiveRouteUpdateSetsOriginWhenItChanges announces a peer's route for a
// prefix, then again with the same origin AS and a new path, then with a new
// origin AS. Each time the route must carry the announced origin AS, path and
// time, and the AS details must list the prefix under that origin AS only. The
// update sets the origin AS with a statement of its own, which changes nothing
// while the origin AS stays the same.
func TestLiveRouteUpdateSetsOriginWhenItChanges(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	const firstOrigin, secondOrigin = 64500, 64501

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)

	for _, asn := range []int{firstOrigin, secondOrigin} {
		_, err := db.GetOrCreateASN(asn, ts)
		if err != nil {
			t.Fatalf("GetOrCreateASN(%d): %v", asn, err)
		}
	}

	route := mkV4Route(t, "198.51.100.0/24", firstOrigin, ts)

	for _, announced := range []struct {
		origin int
		path   []int
	}{
		{firstOrigin, []int{firstOrigin}},
		{firstOrigin, []int{secondOrigin, firstOrigin}},
		{secondOrigin, []int{firstOrigin, secondOrigin}},
	} {
		ts = ts.Add(time.Minute)
		route.OriginASN, route.ASPath, route.LastUpdated =
			announced.origin, announced.path, ts

		err := db.UpsertLiveRouteBatch([]*LiveRoute{route})
		if err != nil {
			t.Fatalf("UpsertLiveRouteBatch: %v", err)
		}

		routes, _, err := db.GetPrefixDetails(route.Prefix)
		if err != nil {
			t.Fatalf("GetPrefixDetails: %v", err)
		}

		if len(routes) != 1 || routes[0].OriginASN != announced.origin ||
			!slices.Equal(routes[0].ASPath, announced.path) ||
			!routes[0].LastUpdated.Equal(ts) {
			t.Errorf("after announcing origin AS%d, path %v at %s: routes %+v",
				announced.origin, announced.path, ts, routes)
		}

		for _, asn := range []int{firstOrigin, secondOrigin} {
			_, prefixes, err := db.GetASDetails(asn)
			if err != nil {
				t.Fatalf("GetASDetails(%d): %v", asn, err)
			}

			listed := len(prefixes) == 1 && prefixes[0].Prefix == route.Prefix
			if listed != (asn == announced.origin) {
				t.Errorf("after announcing origin AS%d, AS%d lists %+v",
					announced.origin, asn, prefixes)
			}
		}
	}
}

// TestUpdatePrefixesBatchKeepsFirstSeen writes a prefix, then a batch with it
// and a new prefix. Only the new prefix is inserted and counted, and the known
// one keeps its first_seen time.
func TestUpdatePrefixesBatchKeepsFirstSeen(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	const known = "198.51.100.0/24"

	first := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
	later := first.Add(time.Hour)

	err = db.UpdatePrefixesBatch(map[string]time.Time{known: first})
	if err != nil {
		t.Fatalf("UpdatePrefixesBatch: %v", err)
	}

	err = db.UpdatePrefixesBatch(map[string]time.Time{
		known: later, testV6Prefix: later,
	})
	if err != nil {
		t.Fatalf("UpdatePrefixesBatch: %v", err)
	}

	stats, err := db.GetStats()
	if err != nil {
		t.Fatalf("GetStats: %v", err)
	}

	if stats.IPv4Prefixes != 1 || stats.IPv6Prefixes != 1 {
		t.Errorf("prefix counts = (v4 %d, v6 %d), want (1, 1)",
			stats.IPv4Prefixes, stats.IPv6Prefixes)
	}

	for _, tt := range []struct {
		query, prefix string
		firstSeen     time.Time
	}{
		{
			query:  "SELECT first_seen FROM prefixes_v4 WHERE prefix = ?",
			prefix: known, firstSeen: first,
		},
		{
			query:  "SELECT first_seen FROM prefixes_v6 WHERE prefix = ?",
			prefix: testV6Prefix, firstSeen: later,
		},
	} {
		var firstSeen time.Time

		err := db.db.QueryRowContext(t.Context(), tt.query, tt.prefix).
			Scan(&firstSeen)
		if err != nil {
			t.Fatalf("reading %s: %v", tt.prefix, err)
		}

		if !firstSeen.Equal(tt.firstSeen) {
			t.Errorf("%s: first seen %s, want %s", tt.prefix, firstSeen,
				tt.firstSeen)
		}
	}
}

// TestUpsertLiveRouteBatchWritesInKeyOrder writes new routes of two peers out
// of key order, the last one a second announcement of the first, and checks
// that the rows were inserted in key order, peer then prefix (each new row's id
// is one above the last), and that the route announced twice carries the later
// announcement.
func TestUpsertLiveRouteBatchWritesInKeyOrder(t *testing.T) {
	t.Parallel()

	db, err := New(&config.Config{StateDir: t.TempDir()}, logger.New())
	if err != nil {
		t.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	const (
		firstOrigin, laterOrigin = 64500, 64501
		// Three prefixes, in text order.
		firstPrefix  = "192.0.2.0/24"
		secondPrefix = "198.51.100.0/24"
		thirdPrefix  = "203.0.113.0/24"
	)

	type row struct {
		peer, prefix string
		origin       int
	}

	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)

	announcements := []row{
		{secondV4PeerIP, secondPrefix, firstOrigin},
		{testV4PeerIP, thirdPrefix, firstOrigin},
		{secondV4PeerIP, firstPrefix, firstOrigin},
		{testV4PeerIP, secondPrefix, firstOrigin},
		{secondV4PeerIP, secondPrefix, laterOrigin},
	}

	routes := make([]*LiveRoute, 0, len(announcements))

	for _, announced := range announcements {
		route := mkV4Route(t, announced.prefix, announced.origin, ts)
		route.PeerIP = announced.peer
		routes = append(routes, route)
	}

	err = db.UpsertLiveRouteBatch(routes)
	if err != nil {
		t.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	rows, err := db.db.QueryContext(t.Context(),
		"SELECT peer_ip, prefix, origin_asn FROM live_routes_v4 ORDER BY id")
	if err != nil {
		t.Fatalf("reading the routes: %v", err)
	}
	defer func() { _ = rows.Close() }()

	var stored []row

	for rows.Next() {
		var r row

		err := rows.Scan(&r.peer, &r.prefix, &r.origin)
		if err != nil {
			t.Fatalf("reading a route: %v", err)
		}

		stored = append(stored, r)
	}

	err = rows.Err()
	if err != nil {
		t.Fatalf("reading the routes: %v", err)
	}

	want := []row{
		{testV4PeerIP, secondPrefix, firstOrigin},
		{testV4PeerIP, thirdPrefix, firstOrigin},
		{secondV4PeerIP, firstPrefix, firstOrigin},
		{secondV4PeerIP, secondPrefix, laterOrigin},
	}

	if !slices.Equal(stored, want) {
		t.Errorf("routes in insertion order = %+v, want %+v", stored, want)
	}
}

// Parameters for BenchmarkPrefixBatchOnFiveMillionRoutes.
const (
	// benchPeers and benchPrefixes size the table the batches are written to:
	// every peer has a route for every prefix, 5 million routes in all.
	benchPeers    = 10
	benchPrefixes = 500000
	// benchBatchSize is how many updates each batch holds, as many as a full
	// prefix handler batch (prefixBatchSize in internal/routewatch).
	benchBatchSize = 25000
	// benchMaxBatchSize is the largest batch the prefix handler writes, the
	// one it holds while a slow write runs (prefixBatchMaxSize in
	// internal/routewatch).
	benchMaxBatchSize = 250000
	// benchWithdrawalEvery makes every fifth update of a timed batch a
	// withdrawal; the others are announcements.
	benchWithdrawalEvery = 5
	// benchOrigins is how many origin ASes the prefixes are spread over.
	benchOrigins = 50000
	// benchFirstASN is the lowest AS number in the benchmark's AS paths.
	benchFirstASN = 64500
	// benchMaskLength is the mask length of every prefix in the benchmark.
	benchMaskLength = 24
)

// BenchmarkPrefixBatchOnFiveMillionRoutes times the writes the prefix handler
// makes for one batch of announcements and withdrawals of routes picked at
// random, to a database that already holds 5 million live routes: 500,000
// IPv4 prefixes, each from 10 peers. It times a full batch of 25,000 updates,
// then the largest batch, 250,000. It builds that database first, one batch at
// a time, which takes some minutes and a few GB of disk under TMPDIR. It is
// run by hand, not by make test, for example in the test image:
//
//	go test -run '^$' -bench FiveMillion -benchtime 10x ./internal/database/
func BenchmarkPrefixBatchOnFiveMillionRoutes(b *testing.B) {
	db, err := New(&config.Config{StateDir: b.TempDir()}, logger.New())
	if err != nil {
		b.Fatalf("failed to create database: %v", err)
	}
	defer func() { _ = db.Close() }()

	//nolint:gosec // The benchmark needs the same batches every run.
	rng := rand.New(rand.NewPCG(1, 2))
	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)

	// Each peer sends its whole table, as when its session comes up.
	for peer := range benchPeers {
		for first := 0; first < benchPrefixes; first += benchBatchSize {
			routes := make([]*LiveRoute, 0, benchBatchSize)
			for prefix := first; prefix < first+benchBatchSize; prefix++ {
				routes = append(routes, benchRoute(rng, prefix, peer, ts))
			}

			writeBenchBatch(b, db, routes, nil, ts)
		}
	}

	for _, batchSize := range []int{benchBatchSize, benchMaxBatchSize} {
		b.Run(strconv.Itoa(batchSize), func(b *testing.B) {
			for b.Loop() {
				ts = ts.Add(time.Second)

				var (
					routes      []*LiveRoute
					withdrawals []LiveRouteDeletion
				)

				for i := range batchSize {
					route := benchRoute(rng, rng.IntN(benchPrefixes),
						rng.IntN(benchPeers), ts)
					if i%benchWithdrawalEvery == 0 {
						withdrawals = append(withdrawals, LiveRouteDeletion{
							Prefix: route.Prefix, PeerIP: route.PeerIP,
							IPVersion: ipVersionV4,
						})
					} else {
						routes = append(routes, route)
					}
				}

				writeBenchBatch(b, db, routes, withdrawals, ts)
			}
		})
	}
}

// benchRoute returns the route peer has for the prefix numbered prefix, a /24
// from 1.0.0.0/24 on, with a new AS path of three to six ASes from the peer's
// AS to the prefix's origin AS.
func benchRoute(rng *rand.Rand, prefix, peer int, ts time.Time) *LiveRoute {
	const minPathLength, extraPathLength = 3, 4

	origin := benchFirstASN + prefix%benchOrigins
	pathLength := minPathLength + rng.IntN(extraPathLength)

	path := make([]int, 0, pathLength)
	path = append(path, benchFirstASN+peer)

	for len(path) < pathLength-1 {
		path = append(path, benchFirstASN+rng.IntN(benchOrigins))
	}

	path = append(path, origin)
	peerIP := fmt.Sprintf("198.51.100.%d", 1+peer)

	return &LiveRoute{
		Prefix: fmt.Sprintf("%d.%d.%d.0/%d",
			1+prefix>>16, (prefix>>8)%256, prefix%256, benchMaskLength),
		MaskLength:  benchMaskLength,
		IPVersion:   ipVersionV4,
		OriginASN:   origin,
		PeerIP:      peerIP,
		ASPath:      path,
		NextHop:     peerIP,
		LastUpdated: ts,
	}
}

// writeBenchBatch writes what the prefix handler writes for a batch: the
// announced routes, the withdrawals, and every prefix the batch names, of
// which only the ones not stored yet are inserted.
func writeBenchBatch(
	b *testing.B, db *Database, routes []*LiveRoute,
	withdrawals []LiveRouteDeletion, ts time.Time,
) {
	b.Helper()

	prefixes := make(map[string]time.Time, len(routes)+len(withdrawals))
	for _, route := range routes {
		prefixes[route.Prefix] = ts
	}

	for _, withdrawal := range withdrawals {
		prefixes[withdrawal.Prefix] = ts
	}

	err := db.UpsertLiveRouteBatch(routes)
	if err != nil {
		b.Fatalf("UpsertLiveRouteBatch: %v", err)
	}

	err = db.DeleteLiveRouteBatch(withdrawals)
	if err != nil {
		b.Fatalf("DeleteLiveRouteBatch: %v", err)
	}

	err = db.UpdatePrefixesBatch(prefixes)
	if err != nil {
		b.Fatalf("UpdatePrefixesBatch: %v", err)
	}
}