/*
* 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.operators.chaining;
import org.apache.flink.api.common.functions.Function;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.functions.util.FunctionUtils;
import org.apache.flink.api.common.typeutils.TypeComparator;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;
import org.apache.flink.runtime.memory.MemoryManager;
import org.apache.flink.runtime.operators.BatchTask;
import org.apache.flink.runtime.operators.DriverStrategy;
import org.apache.flink.runtime.operators.hash.InPlaceMutableHashTable;
import org.apache.flink.runtime.operators.sort.FixedLengthRecordSorter;
import org.apache.flink.runtime.operators.sort.InMemorySorter;
import org.apache.flink.runtime.operators.sort.NormalizedKeySorter;
import org.apache.flink.runtime.operators.sort.QuickSort;
import org.apache.flink.util.Collector;
import org.apache.flink.util.MutableObjectIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.EOFException;
import java.io.IOException;
import java.util.List;
/**
* Chained version of ReduceCombineDriver.
*/
public class ChainedReduceCombineDriver<T> extends ChainedDriver<T, T> {
private static final Logger LOG = LoggerFactory.getLogger(ChainedReduceCombineDriver.class);
/** Fix length records with a length below this threshold will be in-place sorted, if possible. */
private static final int THRESHOLD_FOR_IN_PLACE_SORTING = 32;
private AbstractInvokable parent;
private TypeSerializer<T> serializer;
private TypeComparator<T> comparator;
private ReduceFunction<T> reducer;
private DriverStrategy strategy;
private InMemorySorter<T> sorter;
private QuickSort sortAlgo = new QuickSort();
private InPlaceMutableHashTable<T> table;
private InPlaceMutableHashTable<T>.ReduceFacade reduceFacade;
private List<MemorySegment> memory;
private volatile boolean running;
// ------------------------------------------------------------------------
@Override
public Function getStub() {
return reducer;
}
@Override
public String getTaskName() {
return taskName;
}
@Override
public void setup(AbstractInvokable parent) {
this.parent = parent;
running = true;
strategy = config.getDriverStrategy();
reducer = BatchTask.instantiateUserCode(config, userCodeClassLoader, ReduceFunction.class);
FunctionUtils.setFunctionRuntimeContext(reducer, getUdfRuntimeContext());
}
@Override
public void openTask() throws Exception {
// open the stub first
final Configuration stubConfig = config.getStubParameters();
BatchTask.openUserCode(reducer, stubConfig);
// instantiate the serializer / comparator
serializer = config.<T>getInputSerializer(0, userCodeClassLoader).getSerializer();
comparator = config.<T>getDriverComparator(0, userCodeClassLoader).createComparator();
MemoryManager memManager = parent.getEnvironment().getMemoryManager();
final int numMemoryPages = memManager.computeNumberOfPages(config.getRelativeMemoryDriver());
memory = memManager.allocatePages(parent, numMemoryPages);
LOG.debug("ChainedReduceCombineDriver object reuse: " + (objectReuseEnabled ? "ENABLED" : "DISABLED") + ".");
switch (strategy) {
case SORTED_PARTIAL_REDUCE:
// instantiate a fix-length in-place sorter, if possible, otherwise the out-of-place sorter
if (comparator.supportsSerializationWithKeyNormalization() &&
serializer.getLength() > 0 && serializer.getLength() <= THRESHOLD_FOR_IN_PLACE_SORTING) {
sorter = new FixedLengthRecordSorter<T>(serializer, comparator.duplicate(), memory);
} else {
sorter = new NormalizedKeySorter<T>(serializer, comparator.duplicate(), memory);
}
break;
case HASHED_PARTIAL_REDUCE:
table = new InPlaceMutableHashTable<T>(serializer, comparator, memory);
table.open();
reduceFacade = table.new ReduceFacade(reducer, outputCollector, objectReuseEnabled);
break;
}
}
@Override
public void collect(T record) {
try {
switch (strategy) {
case SORTED_PARTIAL_REDUCE:
collectSorted(record);
break;
case HASHED_PARTIAL_REDUCE:
collectHashed(record);
break;
}
} catch (Exception ex) {
throw new ExceptionInChainedStubException(taskName, ex);
}
}
private void collectSorted(T record) throws Exception {
// try writing to the sorter first
if (!sorter.write(record)) {
// it didn't succeed; sorter is full
// do the actual sorting, combining, and data writing
sortAndCombine();
sorter.reset();
// write the value again
if (!sorter.write(record)) {
throw new IOException("Cannot write record to fresh sort buffer. Record too large.");
}
}
}
private void collectHashed(T record) throws Exception {
try {
reduceFacade.updateTableEntryWithReduce(record);
} catch (EOFException ex) {
// the table has run out of memory
reduceFacade.emitAndReset();
// try again
reduceFacade.updateTableEntryWithReduce(record);
}
}
private void sortAndCombine() throws Exception {
final InMemorySorter<T> sorter = this.sorter;
if (!sorter.isEmpty()) {
sortAlgo.sort(sorter);
final TypeSerializer<T> serializer = this.serializer;
final TypeComparator<T> comparator = this.comparator;
final ReduceFunction<T> function = this.reducer;
final Collector<T> output = this.outputCollector;
final MutableObjectIterator<T> input = sorter.getIterator();
if (objectReuseEnabled) {
// We only need two objects. The first reference stores results and is
// eventually collected. New values are read into the second.
//
// The output value must have the same key fields as the input values.
T reuse1 = input.next();
T reuse2 = serializer.createInstance();
T value = reuse1;
// iterate over key groups
while (running && value != null) {
comparator.setReference(value);
// iterate within a key group
while ((reuse2 = input.next(reuse2)) != null) {
if (comparator.equalToReference(reuse2)) {
// same group, reduce
value = function.reduce(value, reuse2);
// we must never read into the object returned
// by the user, so swap the reuse objects
if (value == reuse2) {
T tmp = reuse1;
reuse1 = reuse2;
reuse2 = tmp;
}
} else {
// new key group
break;
}
}
output.collect(value);
// swap the value from the new key group into the first object
T tmp = reuse1;
reuse1 = reuse2;
reuse2 = tmp;
value = reuse1;
}
} else {
T value = input.next();
// iterate over key groups
while (running && value != null) {
comparator.setReference(value);
T res = value;
// iterate within a key group
while ((value = input.next()) != null) {
if (comparator.equalToReference(value)) {
// same group, reduce
res = function.reduce(res, value);
} else {
// new key group
break;
}
}
output.collect(res);
}
}
}
}
@Override
public void close() {
// send the final batch
try {
switch (strategy) {
case SORTED_PARTIAL_REDUCE:
sortAndCombine();
break;
case HASHED_PARTIAL_REDUCE:
reduceFacade.emit();
break;
}
} catch (Exception ex2) {
throw new ExceptionInChainedStubException(taskName, ex2);
}
outputCollector.close();
}
@Override
public void closeTask() throws Exception {
if (sorter != null) {
sorter.dispose();
}
if (table != null) {
table.close();
}
parent.getEnvironment().getMemoryManager().release(memory);
BatchTask.closeUserCode(reducer);
}
@Override
public void cancelTask() {
running = false;
try {
if (sorter != null) {
sorter.dispose();
}
if (table != null) {
table.close();
}
} catch (Exception e) {
// may happen during concurrent modification
}
parent.getEnvironment().getMemoryManager().release(memory);
}
}