chainio: use errgroup to limit num of goroutines

chainio/dispatcher.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/btcsuite/btclog/v2"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"golang.org/x/sync/errgroup"
 )
 
 // DefaultProcessBlockTimeout is the timeout value used when waiting for one
@@ -229,34 +230,30 @@ func DispatchSequential(b Blockbeat, consumers []Consumer) error {
 // It requires the consumer to finish processing the block within the specified
 // time, otherwise a timeout error is returned.
 func DispatchConcurrent(b Blockbeat, consumers []Consumer) error {
-	// errChans is a map of channels that will be used to receive errors
-	// returned from notifying the consumers.
-	errChans := make(map[string]chan error, len(consumers))
+	eg := &errgroup.Group{}
 
 	// Notify each queue in goroutines.
 	for _, c := range consumers {
-		// Create a signal chan.
-		errChan := make(chan error, 1)
-		errChans[c.Name()] = errChan
-
 		// Notify each consumer concurrently.
-		go func(c Consumer, beat Blockbeat) {
+		eg.Go(func() error {
 			// Send the beat to the consumer.
-			errChan <- notifyAndWait(
-				b, c, DefaultProcessBlockTimeout,
-			)
-		}(c, b)
+			err := notifyAndWait(b, c, DefaultProcessBlockTimeout)
+
+			// Exit early if there's no error.
+			if err == nil {
+				return nil
+			}
+
+			b.logger().Errorf("Consumer=%v failed to process "+
+				"block: %v", c.Name(), err)
+
+			return err
+		})
 	}
 
 	// Wait for all consumers in each queue to finish.
-	for name, errChan := range errChans {
-		err := <-errChan
-		if err != nil {
-			b.logger().Errorf("Consumer=%v failed to process "+
-				"block: %v", name, err)
-
-			return err
-		}
+	if err := eg.Wait(); err != nil {
+		return err
 	}
 
 	return nil