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/**
 * Copyright 2018 Nikita Koksharov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.redisson.pubsub;

import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicReference;

import org.redisson.PubSubEntry;
import org.redisson.api.RFuture;
import org.redisson.client.BaseRedisPubSubListener;
import org.redisson.client.ChannelName;
import org.redisson.client.RedisPubSubListener;
import org.redisson.client.codec.LongCodec;
import org.redisson.client.protocol.pubsub.PubSubType;
import org.redisson.misc.RPromise;
import org.redisson.misc.RedissonPromise;
import org.redisson.misc.TransferListener;

import io.netty.util.internal.PlatformDependent;

/**
 * 
 * @author Nikita Koksharov
 *
 */
abstract class PublishSubscribe> {

    private final ConcurrentMap entries = PlatformDependent.newConcurrentHashMap();

    public void unsubscribe(final E entry, final String entryName, final String channelName, final PublishSubscribeService subscribeService) {
        final AsyncSemaphore semaphore = subscribeService.getSemaphore(new ChannelName(channelName));
        semaphore.acquire(new Runnable() {
            @Override
            public void run() {
                if (entry.release() == 0) {
                    // just an assertion
                    boolean removed = entries.remove(entryName) == entry;
                    if (!removed) {
                        throw new IllegalStateException();
                    }
                    subscribeService.unsubscribe(new ChannelName(channelName), semaphore);
                } else {
                    semaphore.release();
                }
            }
        });

    }

    public E getEntry(String entryName) {
        return entries.get(entryName);
    }

    public RFuture subscribe(final String entryName, final String channelName, final PublishSubscribeService subscribeService) {
        final AtomicReference listenerHolder = new AtomicReference();
        final AsyncSemaphore semaphore = subscribeService.getSemaphore(new ChannelName(channelName));
        final RPromise newPromise = new RedissonPromise() {
            @Override
            public boolean cancel(boolean mayInterruptIfRunning) {
                return semaphore.remove(listenerHolder.get());
            }
        };

        Runnable listener = new Runnable() {

            @Override
            public void run() {
                E entry = entries.get(entryName);
                if (entry != null) {
                    entry.aquire();
                    semaphore.release();
                    entry.getPromise().addListener(new TransferListener(newPromise));
                    return;
                }
                
                E value = createEntry(newPromise);
                value.aquire();
                
                E oldValue = entries.putIfAbsent(entryName, value);
                if (oldValue != null) {
                    oldValue.aquire();
                    semaphore.release();
                    oldValue.getPromise().addListener(new TransferListener(newPromise));
                    return;
                }
                
                RedisPubSubListener