Github user NicoK commented on a diff in the pull request: https://github.com/apache/flink/pull/4509#discussion_r152279228 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/RemoteInputChannel.java --- @@ -394,7 +419,63 @@ public BufferProvider getBufferProvider() throws IOException { return inputGate.getBufferProvider(); } - public void onBuffer(Buffer buffer, int sequenceNumber) { + /** + * Requests buffer from input channel directly for receiving network data. + * It should always return an available buffer in credit-based mode unless + * the channel has been released. + * + * @return The available buffer. + */ + @Nullable + public Buffer requestBuffer() { + synchronized (bufferQueue) { + // Take the floating buffer first if possible. + if (bufferQueue.getFloatingBufferSize() > 0) { + return bufferQueue.takeFloatingBuffer(); + } else { + return bufferQueue.takeExclusiveBuffer(); + } + } + } + + /** + * Receives the backlog from the producer's buffer response. If the number of available + * buffers is less than backlog + initialCredit, it will request floating buffers from the buffer + * pool, and then notify unannounced credits to the producer. + * + * @param backlog The number of unsent buffers in the producer's sub partition. + */ + void onSenderBacklog(int backlog) throws IOException { --- End diff -- `@VisibleForTesting`? (otherwise it could be private)
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