zhijiangW commented on a change in pull request #11687: URL: https://github.com/apache/flink/pull/11687#discussion_r419469883
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/consumer/BufferManager.java ########## @@ -0,0 +1,356 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.runtime.io.network.partition.consumer; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.core.memory.MemorySegment; +import org.apache.flink.core.memory.MemorySegmentProvider; +import org.apache.flink.runtime.io.network.buffer.Buffer; +import org.apache.flink.runtime.io.network.buffer.BufferListener; +import org.apache.flink.runtime.io.network.buffer.BufferPool; +import org.apache.flink.runtime.io.network.buffer.BufferRecycler; +import org.apache.flink.runtime.io.network.buffer.NetworkBuffer; +import org.apache.flink.util.ExceptionUtils; + +import javax.annotation.Nullable; +import javax.annotation.concurrent.GuardedBy; + +import java.io.IOException; +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.List; + +import static org.apache.flink.util.Preconditions.checkArgument; +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * The general buffer manager used by {@link InputChannel} to request/recycle + * exclusive or floating buffers. + */ +public class BufferManager implements BufferListener, BufferRecycler { + + /** The available buffer queue wraps both exclusive and requested floating buffers. */ + private final AvailableBufferQueue bufferQueue = new AvailableBufferQueue(); + + /** The buffer provider for requesting exclusive buffers. */ + private final MemorySegmentProvider globalPool; + + /** The input channel to own this buffer manager. */ + private final InputChannel inputChannel; + + /** The tag indicates whether it is waiting for additional floating buffers from the buffer pool. */ + @GuardedBy("bufferQueue") + private boolean isWaitingForFloatingBuffers; + + /** The total number of required buffers for the respective input channel. */ + @GuardedBy("bufferQueue") + private int numRequiredBuffers; + + public BufferManager( + MemorySegmentProvider globalPool, + InputChannel inputChannel, + int numRequiredBuffers) { + + this.globalPool = checkNotNull(globalPool); + this.inputChannel = checkNotNull(inputChannel); + checkArgument(numRequiredBuffers >= 0); + this.numRequiredBuffers = numRequiredBuffers; + } + + // ------------------------------------------------------------------------ + // Buffer request + // ------------------------------------------------------------------------ + + @Nullable + Buffer requestBuffer() { + synchronized (bufferQueue) { + return bufferQueue.takeBuffer(); + } + } + + /** + * Requests exclusive buffers from the provider and returns the number of requested amount. + */ + int requestExclusiveBuffers() throws IOException { + Collection<MemorySegment> segments = globalPool.requestMemorySegments(); + checkArgument(!segments.isEmpty(), "The number of exclusive buffers per channel should be larger than 0."); + + synchronized (bufferQueue) { + for (MemorySegment segment : segments) { + bufferQueue.addExclusiveBuffer(new NetworkBuffer(segment, this), numRequiredBuffers); + } + } + return segments.size(); + } + + /** + * Requests floating buffers from the buffer pool based on the given required amount, and returns the actual + * requested amount. If the required amount is not fully satisfied, it will register as a listener. + */ + int requestFloatingBuffers(int numRequired) throws IOException { + int numRequestedBuffers = 0; + synchronized (bufferQueue) { + // Similar to notifyBufferAvailable(), make sure that we never add a buffer after channel + // released all buffers via releaseAllResources(). + if (inputChannel.isReleased()) { + return numRequestedBuffers; + } + + numRequiredBuffers = numRequired; + + while (bufferQueue.getAvailableBufferSize() < numRequiredBuffers && !isWaitingForFloatingBuffers) { + BufferPool bufferPool = inputChannel.inputGate.getBufferPool(); + Buffer buffer = bufferPool.requestBuffer(); + if (buffer != null) { + bufferQueue.addFloatingBuffer(buffer); + numRequestedBuffers++; + } else if (bufferPool.addBufferListener(this)) { + isWaitingForFloatingBuffers = true; + break; + } + } + } + return numRequestedBuffers; + } + + // ------------------------------------------------------------------------ + // Buffer recycle + // ------------------------------------------------------------------------ + + /** + * Exclusive buffer is recycled to this channel manager directly and it may trigger return extra + * floating buffer based on <tt>numRequiredBuffers</tt>. + * + * @param segment The exclusive segment of this channel. + */ + @Override + public void recycle(MemorySegment segment) { + int numAddedBuffers = 0; + synchronized (bufferQueue) { + try { + // Similar to notifyBufferAvailable(), make sure that we never add a buffer + // after channel released all buffers via releaseAllResources(). + if (inputChannel.isReleased()) { + globalPool.recycleMemorySegments(Collections.singletonList(segment)); + } else { + numAddedBuffers = bufferQueue.addExclusiveBuffer(new NetworkBuffer(segment, this), numRequiredBuffers); + } + } catch (Throwable t) { + ExceptionUtils.rethrow(t); + } + } + inputChannel.notifyBufferAvailable(numAddedBuffers); + } + + /** + * Recycles all the exclusive and floating buffers from the given buffer queue. + */ + void releaseAllBuffers(ArrayDeque<Buffer> buffers) throws IOException { + // Gather all exclusive buffers and recycle them to global pool in batch, because + // we do not want to trigger redistribution of buffers after each recycle. + final List<MemorySegment> exclusiveRecyclingSegments = new ArrayList<>(); + + Buffer buffer; + while ((buffer = buffers.poll()) != null) { + if (buffer.getRecycler() == this) { + exclusiveRecyclingSegments.add(buffer.getMemorySegment()); + } else { + buffer.recycleBuffer(); + } + } + synchronized (bufferQueue) { + bufferQueue.releaseAll(exclusiveRecyclingSegments); + } + + if (exclusiveRecyclingSegments.size() > 0) { + globalPool.recycleMemorySegments(exclusiveRecyclingSegments); + } + } + + // ------------------------------------------------------------------------ + // Buffer listener notification + // ------------------------------------------------------------------------ + + /** + * The buffer pool notifies this listener of an available floating buffer. If the listener is released or + * currently does not need extra buffers, the buffer should be returned to the buffer pool. Otherwise, + * the buffer will be added into the <tt>bufferQueue</tt>. + * + * @param buffer Buffer that becomes available in buffer pool. + * @return NotificationResult indicates whether this channel accepts the buffer and is waiting for + * more floating buffers. + */ + @Override + public BufferListener.NotificationResult notifyBufferAvailable(Buffer buffer) { + BufferListener.NotificationResult notificationResult = BufferListener.NotificationResult.BUFFER_NOT_USED; + Throwable throwable = null; + synchronized (bufferQueue) { + try { + checkState(isWaitingForFloatingBuffers, "This channel should be waiting for floating buffers."); + + // Important: make sure that we never add a buffer after releaseAllResources() + // released all buffers. Following scenarios exist: + // 1) releaseAllBuffers() already released buffers inside bufferQueue + // -> while isReleased is set correctly in InputChannel + // 2) releaseAllBuffers() did not yet release buffers from bufferQueue + // -> we may or may not have set isReleased yet but will always wait for the + // lock on bufferQueue to release buffers + if (inputChannel.isReleased() || bufferQueue.getAvailableBufferSize() >= numRequiredBuffers) { + isWaitingForFloatingBuffers = false; + return notificationResult; + } + + bufferQueue.addFloatingBuffer(buffer); + + if (bufferQueue.getAvailableBufferSize() == numRequiredBuffers) { + isWaitingForFloatingBuffers = false; + notificationResult = BufferListener.NotificationResult.BUFFER_USED_NO_NEED_MORE; + } else { + notificationResult = BufferListener.NotificationResult.BUFFER_USED_NEED_MORE; + } + } catch (Throwable t) { + throwable = t; + } + } + + if (throwable != null) { + inputChannel.setError(throwable); + } else if (notificationResult != NotificationResult.BUFFER_NOT_USED) { + inputChannel.notifyBufferAvailable(1); + } + return notificationResult; + } + + @Override + public void notifyBufferDestroyed() { + // Nothing to do actually. + } + + // ------------------------------------------------------------------------ + // Getter properties + // ------------------------------------------------------------------------ + + int getNumberOfRequiredBuffers() { Review comment: `unsychronized` makes sense, but not for `@VisibleForTesting` because it is also used in formal codes of `RemoteInputChannel` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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