/**
* Tries to acquire write lock for a given transaction. If <CODE>this.writeCount</CODE> is greater
* than the currents tx's write count or the read count is greater than the currents tx's read
* count the transaction has to wait and the {@link RagManager#checkWaitOn} method is invoked for
* deadlock detection.
*
* <p>If the lock can be acquires the lock count is updated on <CODE>this</CODE> and the
* transaction lock element (tle).
*
* @throws DeadlockDetectedException if a deadlock is detected
*/
synchronized void acquireWriteLock(Object tx) throws DeadlockDetectedException {
TxLockElement tle = getOrCreateLockElement(tx);
try {
tle.movedOn = false;
boolean shouldAddWait = true;
Thread currentThread = currentThread();
while (totalWriteCount > tle.writeCount || totalReadCount > tle.readCount) {
ragManager.checkWaitOn(this, tx);
if (shouldAddWait) {
waitingThreadList.addFirst(new WaitElement(tle, WRITE, currentThread));
}
try {
wait();
shouldAddWait = false;
} catch (InterruptedException e) {
interrupted();
shouldAddWait = true;
}
ragManager.stopWaitOn(this, tx);
}
registerWriteLockAcquired(tx, tle);
} finally {
// if deadlocked, remove marking so lock is removed when empty
tle.movedOn = true;
marked--;
}
}
/**
* Tries to acquire write lock for a given transaction. If <CODE>this.writeCount</CODE> is greater
* than the currents tx's write count or the read count is greater than the currents tx's read
* count the transaction has to wait and the {@link RagManager#checkWaitOn} method is invoked for
* deadlock detection.
*
* <p>If the lock can be acquires the lock count is updated on <CODE>this</CODE> and the
* transaction lock element (tle).
*
* @throws DeadlockDetectedException if a deadlock is detected
*/
synchronized void acquireWriteLock(Object tx) throws DeadlockDetectedException {
TxLockElement tle = getOrCreateLockElement(tx);
try {
tle.movedOn = false;
while (totalWriteCount > tle.writeCount || totalReadCount > tle.readCount) {
deadlockGuardedWait(tx, tle, WRITE);
}
registerWriteLockAcquired(tx, tle);
} finally {
// if deadlocked, remove marking so lock is removed when empty
tle.movedOn = true;
marked--;
}
}
synchronized boolean tryAcquireWriteLock(Object tx) {
TxLockElement tle = getOrCreateLockElement(tx);
try {
tle.movedOn = false;
if (totalWriteCount > tle.writeCount || totalReadCount > tle.readCount) {
return false;
}
registerWriteLockAcquired(tx, tle);
return true;
} finally {
// if deadlocked, remove marking so lock is removed when empty
tle.movedOn = true;
marked--;
}
}
