interleaver: Run producer and consumer in separate go routines.

interleaver/main.go

@@ -49,17 +49,32 @@ func selectKeyEncoder(interleaved bool) common.KeyEncoder {
 }
 
 func copyProducerToConsumer(producer BlockProducer, consumer BlockConsumer) (err error) {
-	var block Block
-	i := 0
-	for {
-		if err = producer.Next(&block); err != nil {
-			if err == ErrNoMoreBlocks {
-				err = nil
-				break
+
+	blocks := make(chan *Block)
+	done := make(chan struct{})
+	defer close(done)
+
+	go func() {
+		defer close(blocks)
+		for {
+			block := new(Block)
+			if err = producer.Next(block); err != nil {
+				if err != ErrNoMoreBlocks {
+					log.Printf("Reading failed: %s\n", err)
+				}
+				return
+			}
+			select {
+			case blocks <- block:
+			case <-done:
+				return
 			}
-			return
 		}
-		if err = consumer.Consume(&block); err != nil {
+	}()
+
+	i := 0
+	for block := range blocks {
+		if err = consumer.Consume(block); err != nil {
 			return
 		}
 		i++