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Allocate batchRequest only on cache miss #123

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Merged
pavelnikolov merged 1 commit into from
May 27, 2026
+7 −4
Merged

Allocate batchRequest only on cache miss #123

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11 changes: 7 additions & 4 deletions dataloader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -227,10 +227,6 @@ func NewBatchedLoader[K comparable, V any](batchFn BatchFunc[K, V], opts ...Opti
// the registered BatchFunc.
func (l *Loader[K, V]) Load(originalContext context.Context, key K) Thunk[V] {
ctx, finish := l.tracer.TraceLoad(originalContext, key)
req := &batchRequest[K, V]{
key: key,
done: make(chan struct{}),
}

// We need to lock both the batchLock and cacheLock because the batcher can
// reset the cache when either the batchCap or the wait time is reached.
Expand All @@ -254,6 +250,13 @@ func (l *Loader[K, V]) Load(originalContext context.Context, key K) Thunk[V] {
return v
}

// Only a cache miss needs a batch request: allocating it (and its channel)
// before the cache check above wastes an allocation on every cache hit.
req := &batchRequest[K, V]{
key: key,
done: make(chan struct{}),
}

thunk := func() (V, error) {
<-req.done
result := req.result.Load()
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