/**
* Complete the task of acquiring the heavy lock, assuming that the mutex is already acquired
* (locked).
*/
@Unpreemptible
public boolean lockHeavyLocked(Object o) {
if (lockedObject != o) { // lock disappeared before we got here
mutex.unlock(); // thread switching benign
return false;
}
if (STATS) lockOperations++;
RVMThread me = RVMThread.getCurrentThread();
int threadId = me.getLockingId();
if (ownerId == threadId) {
recursionCount++;
} else if (ownerId == 0) {
ownerId = threadId;
recursionCount = 1;
} else {
entering.enqueue(me);
mutex.unlock();
me.monitor().lockNoHandshake();
while (entering.isQueued(me)) {
me.monitor().waitWithHandshake(); // this may spuriously return
}
me.monitor().unlock();
return false;
}
mutex.unlock(); // thread-switching benign
return true;
}
/**
* Releases this heavy-weight lock on the indicated object.
*
* @param o the object to be unlocked
*/
@Unpreemptible
public void unlockHeavy(Object o) {
boolean deflated = false;
mutex.lock(); // Note: thread switching is not allowed while mutex is held.
RVMThread me = RVMThread.getCurrentThread();
if (ownerId != me.getLockingId()) {
mutex.unlock(); // thread-switching benign
raiseIllegalMonitorStateException("heavy unlocking", o);
}
recursionCount--;
if (0 < recursionCount) {
mutex.unlock(); // thread-switching benign
return;
}
if (STATS) unlockOperations++;
ownerId = 0;
RVMThread toAwaken = entering.dequeue();
if (toAwaken == null && entering.isEmpty() && waiting.isEmpty()) { // heavy lock can be deflated
// Possible project: decide on a heuristic to control when lock should be deflated
Offset lockOffset = Magic.getObjectType(o).getThinLockOffset();
if (!lockOffset.isMax()) { // deflate heavy lock
deflate(o, lockOffset);
deflated = true;
}
}
mutex.unlock(); // does a Magic.sync(); (thread-switching benign)
if (toAwaken != null) {
toAwaken.monitor().lockedBroadcastNoHandshake();
}
}