前文传送门：Netty源码分析 NioEventLoop
NioEventLoopGroup之NioEventLoop的创建
回到上一小节的MultithreadEventExecutorGroup类的构造方法:
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protected MultithreadEventExecutorGroup(int nThreads, Executor executor, EventExecutorChooserFactory chooserFactory, Object... args) { //代码省略 if (executor == null) { //创建一个新的线程执行器(1) executor = new ThreadPerTaskExecutor(newDefaultThreadFactory()); } //构造NioEventLoop(2) children = new EventExecutor[nThreads]; for (int i = 0; i < nThreads; i ++) { boolean success = false; try { children[i] = newChild(executor, args); success = true; } catch (Exception e) { throw new IllegalStateException("failed to create a child event loop", e); } finally { //代码省略 } } //创建线程选择器(3) chooser = chooserFactory.newChooser(children); //代码省略} |
我们来看第二步构造NioEventLoop
这里通过 children = new EventExecutor[nThreads] 初始化了children属性, 看下这个属性的定义:
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private final EventExecutor[] children |
这里的children是EventExecutor类型的数组, 其实就是NioEventLoop的集合, 因为NioEventLoop也是EventExecutor的子类
所以这里初始化了children数组, 大小为参数nThreads传入的线程数量, 默认为cpu核数的两倍
后面就是通过for循环来创建NioEventLoop线程,
在循环体里通过 children[i] = newChild(executor, args) 创建NioEventLoop, 我们跟newChild(executor, args)方法
因为是NioEventLoopGroup调用的,所以跟到NioEventLoop的newChild方法中:
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protected EventLoop newChild(Executor executor, Object... args) throws Exception { return new NioEventLoop(this, executor, (SelectorProvider) args[0], ((SelectStrategyFactory) args[1]).newSelectStrategy(), (RejectedExecutionHandler) args[2]);} |
这里我们看到创建了一个NioEventLoop对象, 其中this是NioEventLoopGroup自身, executor就是上一小节讲到的线程执行器
我们继续跟到NioEventLoop的构造方法
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NioEventLoop(NioEventLoopGroup parent, Executor executor, SelectorProvider selectorProvider, SelectStrategy strategy, RejectedExecutionHandler rejectedExecutionHandler) { super(parent, executor, false, DEFAULT_MAX_PENDING_TASKS, rejectedExecutionHandler); //代码省略 provider = selectorProvider; selector = openSelector(); selectStrategy = strategy;} |
首先看到了调用了父类的构造方法, 然后初始化了几个属性:
selector = openSelector() 这种方式创建个NioEventLoop绑定的selector对象, 有关创建过程, 之后会讲到
跟进父类SingleThreadEventLoop类构造方法:
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protected SingleThreadEventLoop(EventLoopGroup parent, Executor executor, boolean addTaskWakesUp, int maxPendingTasks, RejectedExecutionHandler rejectedExecutionHandler) { super(parent, executor, addTaskWakesUp, maxPendingTasks, rejectedExecutionHandler); tailTasks = newTaskQueue(maxPendingTasks);} |
再跟到父类SingleThreadEventExecutor构造方法:
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protected SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor, boolean addTaskWakesUp, int maxPendingTasks, RejectedExecutionHandler rejectedHandler) { super(parent); this.addTaskWakesUp = addTaskWakesUp; this.maxPendingTasks = Math.max(16, maxPendingTasks); this.executor = ObjectUtil.checkNotNull(executor, "executor"); taskQueue = newTaskQueue(this.maxPendingTasks); rejectedExecutionHandler = ObjectUtil.checkNotNull(rejectedHandler, "rejectedHandler");} |
this.executor = ObjectUtil.checkNotNull(executor, "executor")
这里初始化了线程执行器
taskQueue = newTaskQueue(this.maxPendingTasks)
是创建一个任务队列, 这个任务队列可以将不属于NioEventLoop线程的任务放到这个任务队列中, 通过NioEventLoop线程执行, 具体使用场景之后我们会看到
跟到父类AbstractScheduledEventExecutor的构造方法中:
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protected AbstractScheduledEventExecutor(EventExecutorGroup parent) { super(parent);} |
最后跟到AbstractEventExecutor类的构造方法
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protected AbstractEventExecutor(EventExecutorGroup parent) { this.parent = parent;} |
这里初始化了parent, 这个parent就NioEventLoop所属的线程组NioEventLoopGroup对象
至此, NioEventLoop创建完成
以上就是Netty源码解析NioEventLoop创建的构造方法的详细内容，更多关于Netty NioEventLoop构造方法的资料请关注服务器之家其它相关文章！
原文链接：https://www.cnblogs.com/xiangnan6122/p/10202910.html
