/*
* Java Genetic Algorithm Library (@__identifier__@).
* Copyright (c) @__year__@ Franz Wilhelmstötter
*
* Licensed 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.
*
* Author:
* Franz Wilhelmstötter (franz.wilhelmstoetter@gmx.at)
*/
package org.jenetics.internal.util;
import static java.util.Objects.requireNonNull;
import java.util.List;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import org.jenetics.internal.collection.Stack;
/**
* @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
* @version 2.0
* @since 2.0
*/
public abstract class Concurrency implements Executor, AutoCloseable {
public static final int CORES = Runtime.getRuntime().availableProcessors();
public static final Concurrency SERIAL_EXECUTOR = new SerialConcurrency();
public abstract void execute(final List<? extends Runnable> runnables);
@Override
public abstract void close();
/**
* Return the underlying {@code Executor}, which is used for performing the
* actual task execution.
*
* @return the underlying {@code Executor} object
*/
public Executor getInnerExecutor() {
return this;
}
/**
* Return an new Concurrency object from the given executor.
*
* @param executor the underlying Executor
* @return a new Concurrency object
*/
public static Concurrency with(final Executor executor) {
if (executor instanceof ForkJoinPool) {
return new ForkJoinPoolConcurrency((ForkJoinPool)executor);
} else if (executor instanceof ExecutorService) {
return new ExecutorServiceConcurrency((ExecutorService)executor);
} else if (executor == SERIAL_EXECUTOR) {
return SERIAL_EXECUTOR;
} else {
return new ExecutorConcurrency(executor);
}
}
/**
* Return a new Concurrency object using the common ForkJoinPool.
*
* @return a new Concurrency object using the new ForkJoinPool
*/
public static Concurrency withCommonPool() {
return with(ForkJoinPool.commonPool());
}
/**
* This Concurrency uses a ForkJoinPool.
*/
private static final class ForkJoinPoolConcurrency extends Concurrency {
private final Stack<ForkJoinTask<?>> _tasks = new Stack<>();
private final ForkJoinPool _pool;
ForkJoinPoolConcurrency(final ForkJoinPool pool) {
_pool = requireNonNull(pool);
}
@Override
public void execute(final Runnable runnable) {
_tasks.push(_pool.submit(runnable));
}
@Override
public void execute(final List<? extends Runnable> runnables) {
_tasks.push(_pool.submit(new RunnablesAction(runnables)));
}
@Override
public Executor getInnerExecutor() {
return _pool;
}
@Override
public void close() {
for (ForkJoinTask<?> t = _tasks.pop(); t != null; t = _tasks.pop()) {
t.join();
}
}
}
/**
* This Concurrency uses an ExecutorService.
*/
private static final class ExecutorServiceConcurrency extends Concurrency {
private final Stack<Future<?>> _futures = new Stack<>();
private final ExecutorService _service;
ExecutorServiceConcurrency(final ExecutorService service) {
_service = requireNonNull(service);
}
@Override
public void execute(final Runnable command) {
_futures.push(_service.submit(command));
}
@Override
public void execute(final List<? extends Runnable> runnables) {
final int[] parts = partition(runnables.size(), CORES + 1);
for (int i = 0; i < parts.length - 1; ++i) {
execute(new RunnablesRunnable(runnables, parts[i], parts[i + 1]));
}
}
@Override
public Executor getInnerExecutor() {
return _service;
}
@Override
public void close() {
try {
for (Future<?> f = _futures.pop(); f != null; f = _futures.pop()) {
f.get();
}
} catch (InterruptedException|ExecutionException e) {
final String msg = e.getMessage();
throw (CancellationException)new CancellationException(msg)
.initCause(e);
}
}
}
/**
* This Concurrency uses an Executor.
*/
private static final class ExecutorConcurrency extends Concurrency {
private final Stack<FutureTask<?>> _tasks = new Stack<>();
private final Executor _executor;
ExecutorConcurrency(final Executor executor) {
_executor = requireNonNull(executor);
}
@Override
public void execute(final Runnable command) {
final FutureTask<?> task = new FutureTask<>(command, null);
_tasks.push(task);
_executor.execute(task);
}
@Override
public void execute(final List<? extends Runnable> runnables) {
final int[] parts = partition(runnables.size(), CORES + 1);
for (int i = 0; i < parts.length - 1; ++i) {
execute(new RunnablesRunnable(runnables, parts[i], parts[i + 1]));
}
}
@Override
public void close() {
try {
for (FutureTask<?> t = _tasks.pop(); t != null; t = _tasks.pop()) {
t.get();
}
} catch (InterruptedException|ExecutionException e) {
final String msg = e.getMessage();
throw (CancellationException)new CancellationException(msg)
.initCause(e);
}
}
}
/**
* This Concurrency executes the runnables within the main thread.
*/
private static final class SerialConcurrency extends Concurrency {
@Override
public void execute(final Runnable command) {
command.run();
}
@Override
public void execute(final List<? extends Runnable> runnables) {
for (final Runnable runnable : runnables) {
runnable.run();
}
}
@Override
public void close() {
}
}
/**
* Return a array with the indexes of the partitions of an array with the
* given size. The length of the returned array is {@code min(size, prts) + 1}.
* <p>
* Some examples:
* <pre>
* partition(10, 3): [0, 3, 6, 10]
* partition(15, 6): [0, 2, 4, 6, 9, 12, 15]
* partition(5, 10): [0, 1, 2, 3, 4, 5]
* </pre>
*
* The following examples prints the start index (inclusive) and the end
* index (exclusive) of the {@code partition(15, 6)}.
* <pre>{@code
* int[] parts = partition(15, 6);
* for (int i = 0; i < parts.length - 1; ++i) {
* System.out.println(i + ": " + parts[i] + "\t" + parts[i + 1]);
* }
* }</pre>
* <pre>
* 0: 0 2
* 1: 2 4
* 2: 4 6
* 3: 6 9
* 4: 9 12
* 5: 12 15
* </pre>
*
* This example shows how this can be used in an concurrent environment:
* <pre>{@code
* try (final Concurrency c = Concurrency.start()) {
* final int[] parts = arrays.partition(population.size(), _maxThreads);
*
* for (int i = 0; i < parts.length - 1; ++i) {
* final int part = i;
* c.execute(new Runnable() { @Override public void run() {
* for (int j = parts[part + 1]; --j <= parts[part];) {
* population.get(j).evaluate();
* }
* }});
* }
* }
* }</pre>
*
* @param size the size of the array to partition.
* @param parts the number of parts the (virtual) array should be partitioned.
* @return the partition array with the length of {@code min(size, parts) + 1}.
* @throws IllegalArgumentException if {@code size} or {@code p} is less than one.
*/
private static int[] partition(final int size, final int parts) {
if (size < 1) {
throw new IllegalArgumentException(
"Size must greater than zero: " + size
);
}
if (parts < 1) {
throw new IllegalArgumentException(
"Number of partitions must greater than zero: " + parts
);
}
final int pts = Math.min(size, parts);
final int[] partition = new int[pts + 1];
final int bulk = size/pts;
final int rest = size%pts;
assert (bulk*pts + rest) == size;
for (int i = 0, n = pts - rest; i < n; ++i) {
partition[i] = i*bulk;
}
for (int i = 0, n = rest + 1; i < n; ++i) {
partition[pts - rest + i] = (pts - rest)*bulk + i*(bulk + 1);
}
return partition;
}
}