org.apache.flink.runtime.io.network.netty.CreditBasedSequenceNumberingViewReader Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.io.network.netty;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.runtime.io.network.NetworkSequenceViewReader;
import org.apache.flink.runtime.io.network.partition.BufferAvailabilityListener;
import org.apache.flink.runtime.io.network.partition.ResultPartitionID;
import org.apache.flink.runtime.io.network.partition.ResultPartitionProvider;
import org.apache.flink.runtime.io.network.partition.ResultSubpartition.BufferAndBacklog;
import org.apache.flink.runtime.io.network.partition.ResultSubpartitionView;
import org.apache.flink.runtime.io.network.partition.consumer.InputChannel.BufferAndAvailability;
import org.apache.flink.runtime.io.network.partition.consumer.InputChannelID;
import org.apache.flink.runtime.io.network.partition.consumer.LocalInputChannel;
import java.io.IOException;
/**
* Simple wrapper for the subpartition view used in the new network credit-based mode.
*
* It also keeps track of available buffers and notifies the outbound
* handler about non-emptiness, similar to the {@link LocalInputChannel}.
*/
class CreditBasedSequenceNumberingViewReader implements BufferAvailabilityListener, NetworkSequenceViewReader {
private final Object requestLock = new Object();
private final InputChannelID receiverId;
private final PartitionRequestQueue requestQueue;
private volatile ResultSubpartitionView subpartitionView;
/**
* The status indicating whether this reader is already enqueued in the pipeline for transferring
* data or not.
*
*
It is mainly used to avoid repeated registrations but should be accessed by a single
* thread only since there is no synchronisation.
*/
private boolean isRegisteredAsAvailable = false;
/** The number of available buffers for holding data on the consumer side. */
private int numCreditsAvailable;
private int sequenceNumber = -1;
CreditBasedSequenceNumberingViewReader(
InputChannelID receiverId,
int initialCredit,
PartitionRequestQueue requestQueue) {
this.receiverId = receiverId;
this.numCreditsAvailable = initialCredit;
this.requestQueue = requestQueue;
}
@Override
public void requestSubpartitionView(
ResultPartitionProvider partitionProvider,
ResultPartitionID resultPartitionId,
int subPartitionIndex) throws IOException {
synchronized (requestLock) {
if (subpartitionView == null) {
// This this call can trigger a notification we have to
// schedule a separate task at the event loop that will
// start consuming this. Otherwise the reference to the
// view cannot be available in getNextBuffer().
this.subpartitionView = partitionProvider.createSubpartitionView(
resultPartitionId,
subPartitionIndex,
this);
} else {
throw new IllegalStateException("Subpartition already requested");
}
}
}
@Override
public void addCredit(int creditDeltas) {
numCreditsAvailable += creditDeltas;
}
@Override
public void setRegisteredAsAvailable(boolean isRegisteredAvailable) {
this.isRegisteredAsAvailable = isRegisteredAvailable;
}
@Override
public boolean isRegisteredAsAvailable() {
return isRegisteredAsAvailable;
}
/**
* Returns true only if the next buffer is an event or the reader has both available
* credits and buffers.
*/
@Override
public boolean isAvailable() {
// BEWARE: this must be in sync with #isAvailable(BufferAndBacklog)!
return hasBuffersAvailable() &&
(numCreditsAvailable > 0 || subpartitionView.nextBufferIsEvent());
}
/**
* Check whether this reader is available or not (internal use, in sync with
* {@link #isAvailable()}, but slightly faster).
*
*
Returns true only if the next buffer is an event or the reader has both available
* credits and buffers.
*
* @param bufferAndBacklog
* current buffer and backlog including information about the next buffer
*/
private boolean isAvailable(BufferAndBacklog bufferAndBacklog) {
// BEWARE: this must be in sync with #isAvailable()!
return bufferAndBacklog.isMoreAvailable() &&
(numCreditsAvailable > 0 || bufferAndBacklog.nextBufferIsEvent());
}
@Override
public InputChannelID getReceiverId() {
return receiverId;
}
@Override
public int getSequenceNumber() {
return sequenceNumber;
}
@VisibleForTesting
int getNumCreditsAvailable() {
return numCreditsAvailable;
}
@VisibleForTesting
boolean hasBuffersAvailable() {
return subpartitionView.isAvailable();
}
@Override
public BufferAndAvailability getNextBuffer() throws IOException, InterruptedException {
BufferAndBacklog next = subpartitionView.getNextBuffer();
if (next != null) {
sequenceNumber++;
if (next.buffer().isBuffer() && --numCreditsAvailable < 0) {
throw new IllegalStateException("no credit available");
}
return new BufferAndAvailability(
next.buffer(), isAvailable(next), next.buffersInBacklog());
} else {
return null;
}
}
@Override
public void notifySubpartitionConsumed() throws IOException {
subpartitionView.notifySubpartitionConsumed();
}
@Override
public boolean isReleased() {
return subpartitionView.isReleased();
}
@Override
public Throwable getFailureCause() {
return subpartitionView.getFailureCause();
}
@Override
public void releaseAllResources() throws IOException {
subpartitionView.releaseAllResources();
}
@Override
public void notifyDataAvailable() {
requestQueue.notifyReaderNonEmpty(this);
}
@Override
public String toString() {
return "CreditBasedSequenceNumberingViewReader{" +
"requestLock=" + requestLock +
", receiverId=" + receiverId +
", sequenceNumber=" + sequenceNumber +
", numCreditsAvailable=" + numCreditsAvailable +
", isRegisteredAsAvailable=" + isRegisteredAsAvailable +
'}';
}
}