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/*
* Copyright (c) 2008, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.nio.ch;
import java.util.concurrent.*;
import java.security.AccessController;
import java.security.PrivilegedAction;
import sun.security.action.GetPropertyAction;
/**
* Encapsulates a thread pool associated with a channel group.
*/
public class ThreadPool {
private static final String DEFAULT_THREAD_POOL_THREAD_FACTORY =
"java.nio.channels.DefaultThreadPool.threadFactory";
private static final String DEFAULT_THREAD_POOL_INITIAL_SIZE =
"java.nio.channels.DefaultThreadPool.initialSize";
private final ExecutorService executor;
// indicates if thread pool is fixed size
private final boolean isFixed;
// indicates the pool size (for a fixed thread pool configuratin this is
// the maximum pool size; for other thread pools it is the initial size)
private final int poolSize;
private ThreadPool(ExecutorService executor,
boolean isFixed,
int poolSize)
{
this.executor = executor;
this.isFixed = isFixed;
this.poolSize = poolSize;
}
ExecutorService executor() {
return executor;
}
boolean isFixedThreadPool() {
return isFixed;
}
int poolSize() {
return poolSize;
}
static ThreadFactory defaultThreadFactory() {
// BEGIN Android-changed: System.getSecurityManager always returns null.
/*
if (System.getSecurityManager() == null) {
return (Runnable r) -> {
Thread t = new Thread(r);
t.setDaemon(true);
return t;
};
} else {
return (Runnable r) -> {
PrivilegedAction<Thread> action = () -> {
Thread t = new sun.misc.InnocuousThread(r);
t.setDaemon(true);
return t;
};
return AccessController.doPrivileged(action);
};
}
*/
return (Runnable r) -> {
Thread t = new Thread(r);
t.setDaemon(true);
return t;
};
// END Android-changed: System.getSecurityManager always returns null.
}
private static class DefaultThreadPoolHolder {
final static ThreadPool defaultThreadPool = createDefault();
}
// return the default (system-wide) thread pool
static ThreadPool getDefault() {
return DefaultThreadPoolHolder.defaultThreadPool;
}
// create thread using default settings (configured by system properties)
static ThreadPool createDefault() {
// default the number of fixed threads to the hardware core count
int initialSize = getDefaultThreadPoolInitialSize();
if (initialSize < 0)
initialSize = Runtime.getRuntime().availableProcessors();
// default to thread factory that creates daemon threads
ThreadFactory threadFactory = getDefaultThreadPoolThreadFactory();
if (threadFactory == null)
threadFactory = defaultThreadFactory();
// create thread pool
ExecutorService executor = Executors.newCachedThreadPool(threadFactory);
return new ThreadPool(executor, false, initialSize);
}
// create using given parameters
static ThreadPool create(int nThreads, ThreadFactory factory) {
if (nThreads <= 0)
throw new IllegalArgumentException("'nThreads' must be > 0");
ExecutorService executor = Executors.newFixedThreadPool(nThreads, factory);
return new ThreadPool(executor, true, nThreads);
}
// wrap a user-supplied executor
public static ThreadPool wrap(ExecutorService executor, int initialSize) {
if (executor == null)
throw new NullPointerException("'executor' is null");
// attempt to check if cached thread pool
if (executor instanceof ThreadPoolExecutor) {
int max = ((ThreadPoolExecutor)executor).getMaximumPoolSize();
if (max == Integer.MAX_VALUE) {
if (initialSize < 0) {
initialSize = Runtime.getRuntime().availableProcessors();
} else {
// not a cached thread pool so ignore initial size
initialSize = 0;
}
}
} else {
// some other type of thread pool
if (initialSize < 0)
initialSize = 0;
}
return new ThreadPool(executor, false, initialSize);
}
private static int getDefaultThreadPoolInitialSize() {
String propValue = AccessController.doPrivileged(new
GetPropertyAction(DEFAULT_THREAD_POOL_INITIAL_SIZE));
if (propValue != null) {
try {
return Integer.parseInt(propValue);
} catch (NumberFormatException x) {
throw new Error("Value of property '" + DEFAULT_THREAD_POOL_INITIAL_SIZE +
"' is invalid: " + x);
}
}
return -1;
}
private static ThreadFactory getDefaultThreadPoolThreadFactory() {
String propValue = AccessController.doPrivileged(new
GetPropertyAction(DEFAULT_THREAD_POOL_THREAD_FACTORY));
if (propValue != null) {
try {
Class<?> c = Class
.forName(propValue, true, ClassLoader.getSystemClassLoader());
return ((ThreadFactory)c.newInstance());
} catch (ClassNotFoundException x) {
throw new Error(x);
} catch (InstantiationException x) {
throw new Error(x);
} catch (IllegalAccessException x) {
throw new Error(x);
}
}
return null;
}
}
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