netty4.1.74源码分享

new.super()

异步删除复制出的fd管理对象  SelectorImpl.processDeregisterQueue()   ->WindowsSelectorImpl.implDereg(SelectionKeyImpl ski)     ->AbstractSelectableChannel.removeKey(SelectionKey k)     ->SocketChannelImpl.kill()        ->SocketDispatcher.close(FileDescriptor fd) ->native void close0(FileDescriptor fd) 关闭复制的FD

ServerBootstrap

2. 完成doClose0方法后，执行netty对象的关闭流程AbstractChannel.fireChannelInactiveAndDeregister(wasActive)

startThread()

findContextInbound

option

生成Runnable

invokeChannelRead

native poll0

NioEventLoopGroup

1. fd内容读取不到，即返回-1，并设置close=true，关闭fdAbstractChannel.doClose0(promise)

启动异步任务消费

AbstractBootstrap

SingleThreadEventExecutor

execute

通过NioEventLoop.run()触发，关注参数strategy

DefaultChannelPipeline

fireChannelRead

SingleThreadEventLoop

epoll

初始化NioServerSocketChannel

select(curDeadlineNanos)监听客户端事件，没有任务时死等，直到客户端发请求

循环NioSocketChannel触发fireChannelRead

消费Runnablepipeline添加ServerBootstrapAcceptor

step1NioEventLoopGroup初始化过程

bind

DefaultSelectorProvider

MultithreadEventLoopGroup

1. 将work的handler加入到pipeline2. 设置work的参数3. register channel，逻辑同boss

ChannelInitializer

根据线程数参数循环创建出对应NioEventLoop

doBind

初始化children的EventExecutor

read()

boss biz handler

select

pipeline.fireChannelRead(byteBuf);pipeline.fireChannelReadComplete();

AbstractNioByteChannel.NioByteUnsafe.closeOnRead(ChannelPipeline pipeline)  AbstractChannel.doClose0(promise);    NioSocketChannel.doClose()      -> AbstractInterruptibleChannel.close()           ->AbstractSelectableChannel.implCloseChannel()               ->SocketChannelImpl.implCloseSelectableChannel                 ->SocketDispatcher.preClose(FileDescriptor fd)->native preClose0（关闭底层FD并复制已关闭的fd）          ->AbstractSelectableChannel..cancel()          ->AbstractSelector.cancel(SelectionKey k) 

同select线性遍历，pollfd结构，没有最大文件描述符数量限制，原因是它是基于链表来存储

HeadContext.channelRead

事件监听回调，没有最大文件描述符数量限制，只监听“活跃”连接，使用mmap减少复制开销

channel

doStartThread()

AbstractNioMessageChannel

run()

监听触发加入一个doBind0任务

MultithreadEventExecutorGroup

OP_CONNECT=8

solaris\\classes\\sun\io\\ch\\DefaultSelectorProvidermacosx\\classes\\sun\io\\ch\\DefaultSelectorProviderwindows\\classes\\sun\io\\ch\\DefaultSelectorProvider

channelRead

WindowsSelectorImpl

监听FD

OP_WRITE=4

doReadMessages

OP_READ=1

打开选择器，openSelector

initAndRegister

返回fd攒着的NioSocketChannel  SocketUtils.accept(javaChannel())  serverSocketChannel.accept()

register

AbstractScheduledEventExecutor

processSelectedKeys

初始化选择器chooser

NioEventLoop

AbstractChannelHandlerContext

doRegister注册到javaChannel

OP_ACCEPT=16

AbstractEventExecutor

初始化childHandler

触发boss initChannel

NioServerSocketChannel

register0

group

public static SelectorProvider create() {        String osname = AccessController            .doPrivileged(new GetPropertyAction(\"os.name\"));        if (osname.equals(\"SunOS\"))            return createProvider(\"sun.nio.ch.DevPollSelectorProvider\");        if (osname.equals(\"Linux\"))            return createProvider(\"sun.nio.ch.EPollSelectorProvider\");        return new sun.nio.ch.PollSelectorProvider();    }

init

轮询FD，其实不活跃的Socket没有必要扫描，fd集合在用户态与内核态之间拷贝传递，费力

AbstractNioByteChannel.read()  doReadBytes(byteBuf)   pipeline.fireChannelRead  pipeline.fireChannelReadComplete

pipeline.invokeHandlerAddedIfNeeded

将当前执行放入队列：ThreadExecutorMap.apply

poll

invokeChannelRead直接根据传入的head执行

ServerBootstrap.ServerBootstrapAcceptor

doBind0

DefaultChannelPromise.addListener

pipeline.fireChannelRegisteredd

runAllTasks

AbstractChannel

step2ServerBootstrap绑定过程

NioSocketChannel.doReadBytes

DefaultSelectStrategyFactory

step3ServerBootstrap客户端接入