/*
* 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.iterative.task;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.flink.api.common.functions.Function;
import org.apache.flink.runtime.io.network.api.BufferWriter;
import org.apache.flink.runtime.io.network.channels.EndOfSuperstepEvent;
import org.apache.flink.runtime.iterative.concurrent.BlockingBackChannel;
import org.apache.flink.runtime.iterative.concurrent.SuperstepKickoffLatch;
import org.apache.flink.runtime.iterative.concurrent.SuperstepKickoffLatchBroker;
import org.apache.flink.runtime.iterative.event.TerminationEvent;
import org.apache.flink.runtime.iterative.io.WorksetUpdateOutputCollector;
import org.apache.flink.util.Collector;
/**
* An intermediate iteration task, which runs a Driver}inside.
* <p/>
* It will propagate {@link EndOfSuperstepEvent}s and {@link TerminationEvent}s to it's connected tasks. Furthermore
* intermediate tasks can also update the iteration state, either the workset or the solution set.
* <p/>
* If the iteration state is updated, the output of this task will be send back to the {@link IterationHeadPactTask} via
* a {@link BlockingBackChannel} for the workset -XOR- a eHashTable for the solution set. In this case
* this task must be scheduled on the same instance as the head.
*/
public class IterationIntermediatePactTask<S extends Function, OT> extends AbstractIterativePactTask<S, OT> {
private static final Logger log = LoggerFactory.getLogger(IterationIntermediatePactTask.class);
private WorksetUpdateOutputCollector<OT> worksetUpdateOutputCollector;
@Override
protected void initialize() throws Exception {
super.initialize();
// set the last output collector of this task to reflect the iteration intermediate state update
// a) workset update
// b) solution set update
// c) none
Collector<OT> delegate = getLastOutputCollector();
if (isWorksetUpdate) {
// sanity check: we should not have a solution set and workset update at the same time
// in an intermediate task
if (isSolutionSetUpdate) {
throw new IllegalStateException("Plan bug: Intermediate task performs workset and solutions set update.");
}
Collector<OT> outputCollector = createWorksetUpdateOutputCollector(delegate);
// we need the WorksetUpdateOutputCollector separately to count the collected elements
if (isWorksetIteration) {
worksetUpdateOutputCollector = (WorksetUpdateOutputCollector<OT>) outputCollector;
}
setLastOutputCollector(outputCollector);
} else if (isSolutionSetUpdate) {
setLastOutputCollector(createSolutionSetUpdateOutputCollector(delegate));
}
}
@Override
public void run() throws Exception {
SuperstepKickoffLatch nextSuperstepLatch = SuperstepKickoffLatchBroker.instance().get(brokerKey());
while (this.running && !terminationRequested()) {
if (log.isInfoEnabled()) {
log.info(formatLogString("starting iteration [" + currentIteration() + "]"));
}
super.run();
// check if termination was requested
verifyEndOfSuperstepState();
if (isWorksetUpdate && isWorksetIteration) {
long numCollected = worksetUpdateOutputCollector.getElementsCollectedAndReset();
worksetAggregator.aggregate(numCollected);
}
if (log.isInfoEnabled()) {
log.info(formatLogString("finishing iteration [" + currentIteration() + "]"));
}
// let the successors know that the end of this superstep data is reached
sendEndOfSuperstep();
if (isWorksetUpdate) {
// notify iteration head if responsible for workset update
worksetBackChannel.notifyOfEndOfSuperstep();
}
boolean terminated = nextSuperstepLatch.awaitStartOfSuperstepOrTermination(currentIteration() + 1);
if (terminated) {
requestTermination();
}
else {
incrementIterationCounter();
}
}
}
private void sendEndOfSuperstep() throws IOException, InterruptedException {
for (BufferWriter eventualOutput : this.eventualOutputs) {
eventualOutput.sendEndOfSuperstep();
}
}
}