剖析Netty之底層原理(三)

神秘北極圈 阿拉斯加的山巔

誰(shuí)的臉出現(xiàn)海角的天邊

忽然的瞬間在那遙遠(yuǎn)的地點(diǎn)

我看見(jiàn)戀人幸福的光點(diǎn)

靈魂在招喚唱著古老

陌生熟悉的歌謠 天空 在微笑

我的世界繽紛閃耀

前面渾渾噩噩的把服務(wù)端的實(shí)現(xiàn)底層源碼來(lái)了個(gè)大致，感覺(jué)頭有點(diǎn)大，這里用圖例的方式來(lái)理下思緒。

一、EventLoopGroup bossGroup = new NioEventLoopGroup();

這是服務(wù)端的第一句代碼，類(lèi)似的還new了一個(gè)workGroup，工作線程組

這兩句代碼，Netty底層的各種初始化動(dòng)作，前面也都說(shuō)過(guò)了，這里做個(gè)總結(jié)：

底層逐步初始化調(diào)用程序如下圖：

其類(lèi)調(diào)用時(shí)序圖如下所示

這里，需要重點(diǎn)看下

io.netty.util.concurrent.MultithreadEventExecutorGroup#MultithreadEventExecutorGroup

(int,?

java.util.concurrent.Executor,

io.netty.util.concurrent.EventExecutorChooserFactory, java.lang.Object...

)方法

源碼如下：

protected MultithreadEventExecutorGroup(int nThreads, Executor executor,                                            EventExecutorChooserFactory chooserFactory, Object... args) {????????????????//當(dāng)線程數(shù)沒(méi)有的時(shí)候，拋出異常，根據(jù)前面分析，這里的線程數(shù)為服務(wù)器內(nèi)核數(shù)量*2        if (nThreads <= 0) {            throw new IllegalArgumentException(String.format("nThreads: %d (expected: > 0)", nThreads));        }
????????//這里的Executor是null,所以初始化一個(gè)        if (executor == null) {            //初始化一個(gè)類(lèi)型是io.netty.util.concurrent.ThreadPerTaskExecutor的線程池            //線程池類(lèi)型為io.netty.util.concurrent.DefaultThreadFactory            executor = new ThreadPerTaskExecutor(newDefaultThreadFactory());        }
        // 設(shè)置事件驅(qū)動(dòng)數(shù)組，大小根據(jù)設(shè)定或者默認(rèn)的來(lái)        children = new EventExecutor[nThreads];
        for (int i = 0; i < nThreads; i ++) {            boolean success = false;            try {????????????????//設(shè)定每個(gè)事件驅(qū)動(dòng)數(shù)組為io.netty.channel.nio.NioEventLoop????????????????//這里調(diào)用的newChild,下面會(huì)有詳細(xì)解釋                children[i] = newChild(executor, args);                success = true;            } catch (Exception e) {                // TODO: Think about if this is a good exception type                throw new IllegalStateException("failed to create a child event loop", e);            } finally {                if (!success) {                    for (int j = 0; j < i; j ++) {                        //如果添加失敗，則關(guān)閉每一個(gè)io.netty.channel.nio.NioEventLoop                        children[j].shutdownGracefully();                    }
                    for (int j = 0; j < i; j ++) {                        EventExecutor e = children[j];                        try {                            while (!e.isTerminated()) {                                e.awaitTermination(Integer.MAX_VALUE, TimeUnit.SECONDS);                            }                        } catch (InterruptedException interrupted) {                            // Let the caller handle the interruption.                            Thread.currentThread().interrupt();                            break;                        }                    }                }            }        }
????????//初始化io.netty.util.concurrent.EventExecutorChooserFactory.EventExecutorChooser????????//其結(jié)果值為io.netty.util.concurrent.DefaultEventExecutorChooserFactory.PowerOfTwoEventExecutorChooser#PowerOfTwoEventExecutorChooser????????//或者io.netty.util.concurrent.DefaultEventExecutorChooserFactory.GenericEventExecutorChooser#GenericEventExecutorChooser        chooser = chooserFactory.newChooser(children);
        final FutureListener