feat(cannon): Wrap GetBeaconBlock in a semaphore

pkg/cannon/ethereum/beacon.go

@@ -202,22 +202,32 @@ func (b *BeaconNode) Synced(ctx context.Context) error {
 }
 
 // GetBeaconBlock returns a beacon block by its identifier. Blocks can be cached internally.
+// This function has been updated to use a semaphore to limit the number of concurrent goroutines.
 func (b *BeaconNode) GetBeaconBlock(ctx context.Context, identifier string, ignoreMetrics ...bool) (*spec.VersionedSignedBeaconBlock, error) {
- // Use singleflight to ensure we only make one request for a block at a time.
- x, err, _ := b.sfGroup.Do(identifier, func() (interface{}, error) {
- // Check the cache first.
- if item := b.blockCache.Get(identifier); item != nil {
- if len(ignoreMetrics) != 0 && ignoreMetrics[0] {
- b.metrics.IncBlockCacheHit(string(b.Metadata().Network.Name))
- }
+ b.metrics.IncBlocksFetched(string(b.Metadata().Network.Name))
 
-  return item.Value(), nil
-  }
+ // Create a buffered channel (semaphore) to limit the number of concurrent goroutines.
+ sem := make(chan struct{}, b.config.BlockPreloadWorkers)
 
+ // Check the cache first.
+ if item := b.blockCache.Get(identifier); item != nil {
  if len(ignoreMetrics) != 0 && ignoreMetrics[0] {
- b.metrics.IncBlockCacheMiss(string(b.Metadata().Network.Name))
+ b.metrics.IncBlockCacheHit(string(b.Metadata().Network.Name))
  }
 
+ return item.Value(), nil
+ }
+
+ if len(ignoreMetrics) != 0 && ignoreMetrics[0] {
+ b.metrics.IncBlockCacheMiss(string(b.Metadata().Network.Name))
+ }
+
+ // Use singleflight to ensure we only make one request for a block at a time.
+ x, err, _ := b.sfGroup.Do(identifier, func() (interface{}, error) {
+ // Acquire a semaphore before proceeding.
+ sem <- struct{}{}
+ defer func() { <-sem }()
+
  // Not in the cache, so fetch it.
  block, err := b.beacon.FetchBlock(ctx, identifier)
  if err != nil {
@@ -237,10 +247,6 @@ func (b *BeaconNode) GetBeaconBlock(ctx context.Context, identifier string, igno
  return nil, err
  }
 
- if len(ignoreMetrics) != 0 && ignoreMetrics[0] {
- b.metrics.IncBlocksFetched(string(b.Metadata().Network.Name))
- }
-
  return x.(*spec.VersionedSignedBeaconBlock), nil
 }