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/*
* Copyright 2005 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package sun.rmi.runtime;
import java.security.AccessController;
import java.security.Permission;
import java.security.PrivilegedAction;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import sun.security.action.GetIntegerAction;
/**
* RMI runtime implementation utilities.
*
* There is a single instance of this class, which can be obtained
* with a GetInstanceAction. Getting the instance requires
* RuntimePermission("sun.rmi.runtime.RuntimeUtil.getInstance")
* because the public methods of this class expose security-sensitive
* capabilities.
*
* @author Peter Jones
**/
public final class RuntimeUtil {
/** runtime package log */
private static final Log runtimeLog =
Log.getLog("sun.rmi.runtime", null, false);
/** number of scheduler threads */
private static final int schedulerThreads = // default 1
AccessController.doPrivileged(
new GetIntegerAction("sun.rmi.runtime.schedulerThreads", 1));
/** permission required to get instance */
private static final Permission GET_INSTANCE_PERMISSION =
new RuntimePermission("sun.rmi.runtime.RuntimeUtil.getInstance");
/** the singleton instance of this class */
private static final RuntimeUtil instance = new RuntimeUtil();
/** thread pool for scheduling delayed tasks */
private final ScheduledThreadPoolExecutor scheduler;
private RuntimeUtil() {
scheduler = new ScheduledThreadPoolExecutor(
schedulerThreads,
new ThreadFactory() {
private final AtomicInteger count = new AtomicInteger(0);
public Thread newThread(Runnable runnable) {
try {
return AccessController.doPrivileged(
new NewThreadAction(runnable,
"Scheduler(" + count.getAndIncrement() + ")",
true));
} catch (Throwable t) {
runtimeLog.log(Level.WARNING,
"scheduler thread factory throws", t);
return null;
}
}
});
/*
* We would like to allow the scheduler's threads to terminate
* if possible, but a bug in DelayQueue.poll can cause code
* like this to result in a busy loop:
*/
// stpe.setKeepAliveTime(10, TimeUnit.MINUTES);
// stpe.allowCoreThreadTimeOut(true);
}
/**
* A PrivilegedAction for getting the RuntimeUtil instance.
**/
public static class GetInstanceAction
implements PrivilegedAction<RuntimeUtil>
{
/**
* Creates an action that returns the RuntimeUtil instance.
**/
public GetInstanceAction() {
}
public RuntimeUtil run() {
return getInstance();
}
}
private static RuntimeUtil getInstance() {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(GET_INSTANCE_PERMISSION);
}
return instance;
}
/**
* Returns the shared thread pool for scheduling delayed tasks.
*
* Note that the returned pool has limited concurrency, so
* submitted tasks should be short-lived and should not block.
**/
public ScheduledThreadPoolExecutor getScheduler() {
return scheduler;
}
}
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