fix: preserve logger byte reservations

logger/queue.go

@@ -54,9 +54,14 @@ type FlushResult struct {
 	Err       error
 }
 
+type queuedEntry struct {
+	entry *LogEntry
+	size  int64
+}
+
 // Queue is an asynchronous, bounded logger. Submit never waits for database work.
 type Queue struct {
-	ch            chan *LogEntry
+	ch            chan queuedEntry
 	pool          *db.Pool
 	batchSize     int
 	batchInterval time.Duration
@@ -101,7 +106,7 @@ func NewQueue(pool *db.Pool, queueSize, batchSize, workers int, batchInterval ti
 		batchInterval = time.Second
 	}
 	return &Queue{
-		ch:            make(chan *LogEntry, queueSize),
+		ch:            make(chan queuedEntry, queueSize),
 		pool:          pool,
 		batchSize:     batchSize,
 		batchInterval: batchInterval,
@@ -210,7 +215,7 @@ func (q *Queue) Submit(e *LogEntry) {
 		return
 	}
 	select {
-	case q.ch <- e:
+	case q.ch <- queuedEntry{entry: e, size: size}:
 		q.enq.Add(1)
 	default:
 		q.release(size)
@@ -252,15 +257,15 @@ func (q *Queue) release(size int64) {
 }
 
 func (q *Queue) discardQueued() {
-	for e := range q.ch {
-		q.release(EstimatedBytes(e))
+	for item := range q.ch {
+		q.release(item.size)
 		q.failed.Add(1)
 	}
 }
 
 func (q *Queue) run(workCtx context.Context) {
 	defer q.wg.Done()
-	batch := make([]*LogEntry, 0, q.batchSize)
+	batch := make([]queuedEntry, 0, q.batchSize)
 	ticker := time.NewTicker(q.batchInterval)
 	defer ticker.Stop()
 
@@ -268,9 +273,13 @@ func (q *Queue) run(workCtx context.Context) {
 		if len(batch) == 0 {
 			return
 		}
-		q.flush(q.flushContext(workCtx), batch)
-		for _, e := range batch {
-			q.release(EstimatedBytes(e))
+		entries := make([]*LogEntry, len(batch))
+		for i, item := range batch {
+			entries[i] = item.entry
+		}
+		q.flush(q.flushContext(workCtx), entries)
+		for _, item := range batch {
+			q.release(item.size)
 		}
 		clear(batch)
 		batch = batch[:0]
@@ -278,12 +287,12 @@ func (q *Queue) run(workCtx context.Context) {
 
 	for {
 		select {
-		case e, ok := <-q.ch:
+		case item, ok := <-q.ch:
 			if !ok {
 				flush()
 				return
 			}
-			batch = append(batch, e)
+			batch = append(batch, item)
 			if len(batch) >= q.batchSize {
 				flush()
 			}

tests/logger/queue_test.go

@@ -267,6 +267,32 @@ func TestQueueStopBeforeStartReleasesBudget(t *testing.T) {
 	}
 }
 
+func TestQueueReleasesSubmittedSizeAfterEntryMutation(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		mutate func(*logger.LogEntry)
+	}{
+		{name: "smaller", mutate: func(entry *logger.LogEntry) { entry.RequestBody = nil }},
+		{name: "larger", mutate: func(entry *logger.LogEntry) { entry.RequestBody = []byte("much larger body") }},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			entry := &logger.LogEntry{RequestID: "queued", RequestBody: []byte("body")}
+			q := logger.NewQueue(nil, 2, 2, 1, time.Hour, logger.EstimatedBytes(entry))
+			q.Submit(entry)
+			tc.mutate(entry)
+
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+			defer cancel()
+			if err := q.Stop(ctx); err != nil {
+				t.Fatalf("Stop: %v", err)
+			}
+			if stats := q.Stats(); stats.Bytes != 0 || stats.Failed != 1 {
+				t.Fatalf("stats=%+v", stats)
+			}
+		})
+	}
+}
+
 func TestQueueCanceledStopEventuallyReleasesAllBudget(t *testing.T) {
 	entry := &logger.LogEntry{RequestID: "queued"}
 	q := logger.NewQueue(nil, 32, 32, 1, time.Hour, 32*logger.EstimatedBytes(entry))