I have a GenericKeyedObjectPool in my application.
I can close it with the close method but how should I wait for the clients to return (and the pool destroys) every borrowed object to the pool?
I need something like ExecutorService.awaitTermination.
Create a wrapper for the GenericKeyedObjectPool which has the required awaitTermination method. You can check the close and the returnObject calls and decrement a latch if the pool is closed and every object was returned (= the total number of instances current borrowed from this pool is zero).
public final class ListenablePool<K, V> {
private final GenericKeyedObjectPool<K, V> delegate;
private final CountDownLatch closeLatch = new CountDownLatch(1);
private final AtomicBoolean closed = new AtomicBoolean();
public ListenablePool(final KeyedPoolableObjectFactory<K, V> factory) {
this.delegate = new GenericKeyedObjectPool<K, V>(factory);
}
public V borrowObject(final K key) throws Exception {
return delegate.borrowObject(key);
}
public void returnObject(final K key, final V obj) throws Exception {
try {
delegate.returnObject(key, obj);
} finally {
countDownIfRequired();
}
}
private void countDownIfRequired() {
if (closed.get() && delegate.getNumActive() == 0) {
closeLatch.countDown();
}
}
public void close() throws Exception {
try {
delegate.close();
} finally {
closed.set(true);
countDownIfRequired();
}
}
public void awaitTermination() throws InterruptedException {
closeLatch.await();
}
public void awaitTermination(final long timeout, final TimeUnit unit)
throws InterruptedException {
closeLatch.await(timeout, unit);
}
public int getNumActive() {
return delegate.getNumActive();
}
// other delegate methods
}
You should be safe just closing it, without waiting for all objects to be returned.
From the docs of GenericKeyedObjectPool.html#close():
Closes the pool. Once the pool is closed, borrowObject() will fail with IllegalStateException, but returnObject(Object) and invalidateObject(Object) will continue to work, with returned objects destroyed on return.
