/**
* Acquire the lock so that the scene can be acted upon.
*
* <p>This returns null if the lock was just acquired, otherwise it returns {@link
* Result.Status#SUCCESS} if the lock already belonged to that thread, or another instance (see
* {@link Result#getStatus()}) if an error occurred.
*
* @param timeout the time to wait if another rendering is happening.
* @return null if the lock was just acquire or another result depending on the state.
* @throws IllegalStateException if the current context is different than the one owned by the
* scene.
*/
private Result acquireLock(long timeout) {
ReentrantLock lock = Bridge.getLock();
if (!lock.isHeldByCurrentThread()) {
try {
boolean acquired = lock.tryLock(timeout, TimeUnit.MILLISECONDS);
if (!acquired) {
return ERROR_TIMEOUT.createResult();
}
} catch (InterruptedException e) {
return ERROR_LOCK_INTERRUPTED.createResult();
}
} else {
// This thread holds the lock already. Checks that this wasn't for a different context.
// If this is called by init, mContext will be null and so should sCurrentContext
// anyway
if (mContext != sCurrentContext) {
throw new IllegalStateException(
"Acquiring different scenes from same thread without releases");
}
return SUCCESS.createResult();
}
return null;
}
/**
* Checks that the lock is owned by the current thread and that the current context is the one
* from this scene.
*
* @throws IllegalStateException if the current context is different than the one owned by the
* scene, or if {@link #acquire(long)} was not called.
*/
protected void checkLock() {
ReentrantLock lock = Bridge.getLock();
if (!lock.isHeldByCurrentThread()) {
throw new IllegalStateException("scene must be acquired first. see #acquire(long)");
}
if (sCurrentContext != mContext) {
throw new IllegalStateException("Thread acquired a scene but is rendering a different one");
}
}
/** Cleans up the scene after an action. */
public void release() {
ReentrantLock lock = Bridge.getLock();
// with the use of finally blocks, it is possible to find ourself calling this
// without a successful call to prepareScene. This test makes sure that unlock() will
// not throw IllegalMonitorStateException.
if (lock.isHeldByCurrentThread()) {
tearDown();
lock.unlock();
}
}