org.apache.flink.runtime.iterative.concurrent.BlockingBackChannel 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
* 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.iterative.concurrent;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.runtime.iterative.io.SerializedUpdateBuffer;
import java.io.IOException;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
/**
* A concurrent datastructure that establishes a backchannel buffer between an iteration head
* and an iteration tail.
*/
public class BlockingBackChannel {
/** Buffer to send back the superstep results. */
private final SerializedUpdateBuffer buffer;
/** A one element queue used for blocking hand over of the buffer. */
private final BlockingQueue queue;
public BlockingBackChannel(SerializedUpdateBuffer buffer) {
this.buffer = buffer;
queue = new ArrayBlockingQueue(1);
}
/**
* Called by iteration head after it has sent all input for the current superstep through the data channel
* (blocks iteration head).
*/
public DataInputView getReadEndAfterSuperstepEnded() {
try {
return queue.take().switchBuffers();
} catch (InterruptedException | IOException e) {
throw new RuntimeException(e);
}
}
/**
* Called by iteration tail to save the output of the current superstep.
*/
public DataOutputView getWriteEnd() {
return buffer;
}
/**
* Called by iteration tail to signal that all input of a superstep has been processed
* (unblocks iteration head).
*/
public void notifyOfEndOfSuperstep() {
queue.offer(buffer);
}
}