AbstractChannelPoolMap Class — netty Architecture

Source Code

transport/src/main/java/io/netty/channel/pool/AbstractChannelPoolMap.java lines 35–149

public abstract class AbstractChannelPoolMap<K, P extends ChannelPool>
        implements ChannelPoolMap<K, P>, Iterable<Entry<K, P>>, Closeable {
    private final ConcurrentMap<K, P> map = new ConcurrentHashMap<>();

    @Override
    public final P get(K key) {
        P pool = map.get(checkNotNull(key, "key"));
        if (pool == null) {
            pool = newPool(key);
            P old = map.putIfAbsent(key, pool);
            if (old != null) {
                // We need to destroy the newly created pool as we not use it.
                poolCloseAsyncIfSupported(pool);
                pool = old;
            }
        }
        return pool;
    }
    /**
     * Remove the {@link ChannelPool} from this {@link AbstractChannelPoolMap}. Returns {@code true} if removed,
     * {@code false} otherwise.
     *
     * If the removed pool extends {@link SimpleChannelPool} it will be closed asynchronously to avoid blocking in
     * this method.
     *
     * Please note that {@code null} keys are not allowed.
     */
    public final boolean remove(K key) {
        P pool =  map.remove(checkNotNull(key, "key"));
        if (pool != null) {
            poolCloseAsyncIfSupported(pool);
            return true;
        }
        return false;
    }

    /**
     * Remove the {@link ChannelPool} from this {@link AbstractChannelPoolMap}. Returns a future that comletes with a
     * {@code true} result if the pool has been removed by this call, otherwise the result is {@code false}.
     *
     * If the removed pool extends {@link SimpleChannelPool} it will be closed asynchronously to avoid blocking in
     * this method. The returned future will be completed once this asynchronous pool close operation completes.
     */
    private Future<Boolean> removeAsyncIfSupported(K key) {
        P pool =  map.remove(checkNotNull(key, "key"));
        if (pool != null) {
            final Promise<Boolean> removePromise = GlobalEventExecutor.INSTANCE.newPromise();
            poolCloseAsyncIfSupported(pool).addListener(future -> {
                if (future.isSuccess()) {
                    removePromise.setSuccess(Boolean.TRUE);
                } else {
                    removePromise.setFailure(future.cause());
                }
            });
            return removePromise;
        }
        return GlobalEventExecutor.INSTANCE.newSucceededFuture(Boolean.FALSE);
    }

    /**
     * If the pool implementation supports asynchronous close, then use it to avoid a blocking close call in case
     * the ChannelPoolMap operations are called from an EventLoop.
     *
     * @param pool the ChannelPool to be closed
     */
    private static Future<Void> poolCloseAsyncIfSupported(ChannelPool pool) {
        if (pool instanceof SimpleChannelPool) {
            return ((SimpleChannelPool) pool).closeAsync();
        } else {
            try {
                pool.close();
                return GlobalEventExecutor.INSTANCE.newSucceededFuture(null);
            } catch (Exception e) {
                return GlobalEventExecutor.INSTANCE.newFailedFuture(e);
            }
        }
    }

    @Override
    public final Iterator<Entry<K, P>> iterator() {
        return new ReadOnlyIterator<Entry<K, P>>(map.entrySet().iterator());