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/**
* Copyright 2010 JogAmp Community. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are
* permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation are those of the
* authors and should not be interpreted as representing official policies, either expressed
* or implied, of JogAmp Community.
*/
package com.jogamp.common.util;
import com.jogamp.common.impl.Debug;
import java.util.LinkedList;
/**
* Reentrance locking toolkit, impl a complete fair FIFO scheduler
*/
public class RecursiveToolkitLock {
static class SyncData {
// owner of the lock
Thread owner = null;
// lock recursion
int recursionCount = 0;
// stack trace of the lock
Exception lockedStack = null;
// waiting thread queue
LinkedList threadQueue = new LinkedList();
// flag signaling unlock has woken up a waiting thread
boolean signaled = false;
}
private SyncData sdata = new SyncData(); // synchronized (flow/mem) mutable access
private long timeout;
private static final long defaultTimeout = 5000; // default maximum wait 5s
// private static final long defaultTimeout = 300000; // default maximum wait 300s / 5min
private static final boolean TRACE_LOCK = Debug.debug("TraceLock");
public RecursiveToolkitLock() {
this.timeout = defaultTimeout;
}
public RecursiveToolkitLock(long timeout) {
this.timeout = timeout;
}
public final Exception getLockedStack() {
synchronized(sdata) {
return sdata.lockedStack;
}
}
public final Thread getOwner() {
synchronized(sdata) {
return sdata.owner;
}
}
public final boolean isOwner() {
return isOwner(Thread.currentThread());
}
public final boolean isOwner(Thread thread) {
synchronized(sdata) {
return sdata.owner == thread ;
}
}
public final boolean isLocked() {
synchronized(sdata) {
return null != sdata.owner;
}
}
public final boolean isLockedByOtherThread() {
synchronized(sdata) {
return null != sdata.owner && Thread.currentThread() != sdata.owner ;
}
}
public final int getRecursionCount() {
synchronized(sdata) {
return sdata.recursionCount;
}
}
public final void validateLocked() {
synchronized(sdata) {
if ( null == sdata.owner ) {
throw new RuntimeException(Thread.currentThread()+": Not locked");
}
if ( Thread.currentThread() != sdata.owner ) {
getLockedStack().printStackTrace();
throw new RuntimeException(Thread.currentThread()+": Not owner, owner is "+sdata.owner);
}
}
}
/** Recursive and blocking lockSurface() implementation */
public final void lock() {
synchronized(sdata) {
Thread cur = Thread.currentThread();
if (sdata.owner == cur) {
++sdata.recursionCount;
if(TRACE_LOCK) {
System.err.println("+++ LOCK 2 ["+this+"], recursions "+sdata.recursionCount+", "+cur);
}
return;
}
if (sdata.owner != null || sdata.signaled || sdata.threadQueue.size() > 0) {
// enqueue due to locked resource or already waiting or signaled threads (be fair)
boolean timedOut = false;
do {
sdata.threadQueue.addFirst(cur); // should only happen once
try {
sdata.wait(timeout);
timedOut = sdata.threadQueue.remove(cur); // timeout if not already removed by unlock
} catch (InterruptedException e) {
if(!sdata.signaled) {
// theoretically we could stay in the loop,
// in case the interrupt wasn't issued by unlock,
// hence the re-enqueue
sdata.threadQueue.remove(cur);
if(TRACE_LOCK) {
System.err.println("XXX LOCK - ["+this+"], recursions "+sdata.recursionCount+", "+cur);
}
}
}
} while (null != sdata.owner && !timedOut) ;
sdata.signaled = false;
if(timedOut || null != sdata.owner) {
sdata.lockedStack.printStackTrace();
throw new RuntimeException("Waited "+timeout+"ms for: "+sdata.owner+" - "+cur+", with recursionCount "+sdata.recursionCount+", lock: "+this+", qsz "+sdata.threadQueue.size());
}
if(TRACE_LOCK) {
System.err.println("+++ LOCK 3 ["+this+"], recursions "+sdata.recursionCount+", qsz "+sdata.threadQueue.size()+", "+cur);
}
} else if(TRACE_LOCK) {
System.err.println("+++ LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", qsz "+sdata.threadQueue.size()+", "+cur);
}
sdata.owner = cur;
sdata.lockedStack = new Exception("Previously locked by "+sdata.owner+", lock: "+this);
}
}
/** Recursive and unblocking unlockSurface() implementation */
public final void unlock() {
unlock(null);
}
/** Recursive and unblocking unlockSurface() implementation */
public final void unlock(Runnable taskAfterUnlockBeforeNotify) {
synchronized(sdata) {
validateLocked();
if (sdata.recursionCount > 0) {
--sdata.recursionCount;
if(TRACE_LOCK) {
System.err.println("--- LOCK 1 ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
}
return;
}
sdata.owner = null;
sdata.lockedStack = null;
if(null!=taskAfterUnlockBeforeNotify) {
taskAfterUnlockBeforeNotify.run();
}
int qsz = sdata.threadQueue.size();
if(qsz > 0) {
Thread parkedThread = (Thread) sdata.threadQueue.removeLast();
if(TRACE_LOCK) {
System.err.println("--- LOCK X ["+this+"], recursions "+sdata.recursionCount+
", "+Thread.currentThread()+", irq "+(qsz-1)+": "+parkedThread);
}
sdata.signaled = true;
if(qsz==1) {
// fast path, just one waiting thread
sdata.notify();
} else {
// signal the oldest one ..
parkedThread.interrupt(); // Propagate SecurityException if it happens
}
} else if(TRACE_LOCK) {
System.err.println("--- LOCK X ["+this+"], recursions "+sdata.recursionCount+", "+Thread.currentThread());
}
}
}
}
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