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Netty進(jìn)階之ChannelPoolMap源碼解析

更新時間：2023年11月16日 09:32:54 作者：立小研先森

這篇文章主要介紹了Netty進(jìn)階之ChannelPoolMap源碼解析,ChannelPoolMap是用來存儲ChannelPool和指定key的一個集合Map,實(shí)際的應(yīng)用場景就是服務(wù)器端是一個分布式集群服務(wù),擁有多個配置地址,這樣我們就可以配置多個服務(wù)地址,減輕單臺服務(wù)器的壓力,需要的朋友可以參考下

前言

ChannelPoolMap是用來存儲ChannelPool和指定key的一個集合Map，實(shí)際的應(yīng)用場景就是服務(wù)器端是一個分布式集群服務(wù)，擁有多個配置地址，這樣我們就可以配置多個服務(wù)地址，減輕單臺服務(wù)器的壓力；Netty框架提供了ChannelPoolMap接口和AbstractChannelPoolMap抽象方法。

一、ChannelPoolMap接口源碼分析

package io.netty.channel.pool;

/**
 * Allows to map {@link ChannelPool} implementations to a specific key.
 *
 * @param <K> the type of the key
 * @param <P> the type of the {@link ChannelPool}
 */
public interface ChannelPoolMap<K, P extends ChannelPool> {
    /**
     * Return the {@link ChannelPool} for the {@code code}. This will never return {@code null},
     * but create a new {@link ChannelPool} if non exists for they requested {@code key}.
     *
     * Please note that {@code null} keys are not allowed.
     */
    P get(K key);

    /**
     * Returns {@code true} if a {@link ChannelPool} exists for the given {@code key}.
     *
     * Please note that {@code null} keys are not allowed.
     */
    boolean contains(K key);
}

接口提供了兩個方法，get方法用于獲取指定key對應(yīng)的ChannelPool，contains方法用來判定Map集合中是否存在指定key對應(yīng)的ChannelPool。

二、AbstractChannelPoolMap抽象實(shí)現(xiàn)類

1.get方法分析

    private final ConcurrentMap<K, P> map = PlatformDependent.newConcurrentHashMap();

    @Override
    public final P get(K key) {
      //獲取ChannelPool
        P pool = map.get(checkNotNull(key, "key"));
        if (pool == null) {
          //創(chuàng)建一個新的ChannelPool
            pool = newPool(key);
          //如果集合中存在ChannelPool,則返回老的ChannelPool對象
            P old = map.putIfAbsent(key, pool);
           //若果老的ChannelPool真實(shí)存在
            if (old != null) {
               //異步銷毀新創(chuàng)建的ChannelPool
                // We need to destroy the newly created pool as we not use it.
                poolCloseAsyncIfSupported(pool);
                pool = old;
            }
        }
        return pool;
    }

定義了一個ConcurrentMap類型的map類變量，用來存放key及其對應(yīng)的ChannelPool；
首先會從集合中獲取ChannelPool，如果不存在則創(chuàng)建一個新的ChannelPool；

    /**
     * Called once a new {@link ChannelPool} needs to be created as non exists yet for the {@code key}.
     */
    protected abstract P newPool(K key);

newPool方法是一個抽象方法，需要用戶自己實(shí)現(xiàn)ChannelPool的創(chuàng)建操作；

    /**
     * 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);
            }
        }
    }

異步關(guān)閉ChannelPool，如果是SimpleChannelPool的實(shí)現(xiàn)，則調(diào)用異步方法closeAsync；如果是其它實(shí)現(xiàn)，則調(diào)用close方法。

2.remove方法分析

    public final boolean remove(K key) {
      //移除指定key的ChannelPool
        P pool =  map.remove(checkNotNull(key, "key"));
        if (pool != null) {
          //如果移除成功，則異步的關(guān)閉ChannelPool，避免阻塞方法
            poolCloseAsyncIfSupported(pool);
            return true;
        }
        return false;
    }

到此這篇關(guān)于Netty進(jìn)階之ChannelPoolMap源碼解析的文章就介紹到這了,更多相關(guān)ChannelPoolMap源碼內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

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