netty中pipeline异常事件分析

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    throw new Exception("throw Exception");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println(cause.getMessage());
}

private void invokeChannelRead(Object msg) {
    if (invokeHandler()) {
        try {
            //调用了当前handler的channelRead方法, 其实就是head对象调用自身的channelRead方法
            ((ChannelInboundHandler) handler()).channelRead(this, msg);
        } catch (Throwable t) {
            //发生异常的时候在这里捕获异常
            notifyHandlerException(t);
        }
    } else {
        fireChannelRead(msg);
    }
}

private void notifyHandlerException(Throwable cause) {
    //代码省略
    invokeExceptionCaught(cause);
}

private void invokeExceptionCaught(final Throwable cause) {
    if (invokeHandler()) {
        try {
            //当前handler调用exceptionCaught()方法
            handler().exceptionCaught(this, cause);
        } catch (Throwable error) {
            //代码省略
        }
    } else {
        fireExceptionCaught(cause);
    }
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println(cause.getMessage());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    //写法1
    ctx.fireChannelRead(cause);
    //写法2
    ctx.pipeline().fireExceptionCaught(cause);
}

public final ChannelPipeline fireExceptionCaught(Throwable cause) {
    AbstractChannelHandlerContext.invokeExceptionCaught(head, cause);
    return this;
}

static void invokeExceptionCaught(final AbstractChannelHandlerContext next, final Throwable cause) {
    ObjectUtil.checkNotNull(cause, "cause");
    EventExecutor executor = next.executor();
    if (executor.inEventLoop()) {
        //执行下一个节点的异常方法
        next.invokeExceptionCaught(cause);
    } else {
        try {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    next.invokeExceptionCaught(cause);
                }
            });
        } catch (Throwable t) {
            //忽略代码
        }
    }
}

private void invokeExceptionCaught(final Throwable cause) {
    if (invokeHandler()) {
        try {
            //当前handler调用exceptionCaught()方法
            handler().exceptionCaught(this, cause);
        } catch (Throwable error) {
            //代码省略
        }
    } else {
        fireExceptionCaught(cause);
    }
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    ctx.fireExceptionCaught(cause);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    //写法1
    ctx.fireChannelRead(cause);
    //写法2
    ctx.pipeline().fireExceptionCaught(cause);
}

public ChannelHandlerContext fireExceptionCaught(final Throwable cause) {
    //传播异常事件的时候, 直接拿了当前节点的下一个节点
    invokeExceptionCaught(next, cause);
    return this;
}

static void invokeExceptionCaught(final AbstractChannelHandlerContext next, final Throwable cause) {
    ObjectUtil.checkNotNull(cause, "cause");
    EventExecutor executor = next.executor();
    if (executor.inEventLoop()) { 
        next.invokeExceptionCaught(cause);
    } else {
        try {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    next.invokeExceptionCaught(cause);
                }
            });
        } catch (Throwable t) {
            //代码省略
        }
    }
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
        throws Exception {
    ctx.fireExceptionCaught(cause);
}

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    onUnhandledInboundException(cause);
}