说在前面
接上次
源码解析
netty连接管理handler
class NettyConnectManageHandler extends ChannelDuplexHandler {
@Override
public void connect(ChannelHandlerContext ctx, SocketAddress remoteAddress, SocketAddress localAddress,
ChannelPromise promise) throws Exception {
final String local = localAddress == null ? "UNKNOWN" : RemotingHelper.parseSocketAddressAddr(localAddress);
final String remote = remoteAddress == null ? "UNKNOWN" : RemotingHelper.parseSocketAddressAddr(remoteAddress);
log.info("NETTY CLIENT PIPELINE: CONNECT {} => {}", local, remote);
// 创建netty连接
super.connect(ctx, remoteAddress, localAddress, promise);
if (NettyRemotingClient.this.channelEventListener != null) {
// 发布netty事件，阻塞队列实现同步=》
NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CONNECT, remote, ctx.channel()));
}
}
@Override
public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
log.info("NETTY CLIENT PIPELINE: DISCONNECT {}", remoteAddress);
// 关闭连接=》
closeChannel(ctx.channel());
super.disconnect(ctx, promise);
if (NettyRemotingClient.this.channelEventListener != null) {
// 发布关闭连接事件=》
NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CLOSE, remoteAddress, ctx.channel()));
}
}
@Override
public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
log.info("NETTY CLIENT PIPELINE: CLOSE {}", remoteAddress);
// =》
closeChannel(ctx.channel());
super.close(ctx, promise);
// 快速失败=》
NettyRemotingClient.this.failFast(ctx.channel());
if (NettyRemotingClient.this.channelEventListener != null) {
// 发布连接关闭事件
NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CLOSE, remoteAddress, ctx.channel()));
}
}
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
if (evt instanceof IdleStateEvent) {
IdleStateEvent event = (IdleStateEvent) evt;
if (event.state().equals(IdleState.ALL_IDLE)) {
final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
log.warn("NETTY CLIENT PIPELINE: IDLE exception [{}]", remoteAddress);
// 超过空闲时间，关闭channel=》
closeChannel(ctx.channel());
if (NettyRemotingClient.this.channelEventListener != null) {
// 发布channel空闲超时事件=》
NettyRemotingClient.this
.putNettyEvent(new NettyEvent(NettyEventType.IDLE, remoteAddress, ctx.channel()));
}
}
}
ctx.fireUserEventTriggered(evt);
}
发布事件这里用阻塞队列实现异步，进入这个方法org.apache.rocketmq.remoting.netty.NettyRemotingAbstract.NettyEventExecutor#putNettyEvent
public void putNettyEvent(final NettyEvent event) {
if (this.eventQueue.size() <= maxSize) {
this.eventQueue.add(event);
} else {
log.warn("event queue size[{}] enough, so drop this event {}", this.eventQueue.size(), event.toString());
}
}
往上返回进入这个方法，org.apache.rocketmq.remoting.netty.NettyRemotingClient#closeChannel(io.netty.channel.Channel) 关闭连接
public void closeChannel(final Channel channel) {
if (null == channel)
return;
try {
if (this.lockChannelTables.tryLock(LOCK_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) {
try {
boolean removeItemFromTable = true;
ChannelWrapper prevCW = null;
String addrRemote = null;
// 遍历channel列表
for (Map.Entry entry : channelTables.entrySet()) {
String key = entry.getKey();
ChannelWrapper prev = entry.getValue();
if (prev.getChannel() != null) {
if (prev.getChannel() == channel) {
prevCW = prev;
addrRemote = key;
break;
}
}
}
if (null == prevCW) {
log.info("eventCloseChannel: the channel[{}] has been removed from the channel table before", addrRemote);
removeItemFromTable = false;
}
if (removeItemFromTable) {
// 删除channel
this.channelTables.remove(addrRemote);
log.info("closeChannel: the channel[{}] was removed from channel table", addrRemote);
RemotingUtil.closeChannel(channel);
}
} catch (Exception e) {
log.error("closeChannel: close the channel exception", e);
} finally {
this.lockChannelTables.unlock();
}
} else {
log.warn("closeChannel: try to lock channel table, but timeout, {}ms", LOCK_TIMEOUT_MILLIS);
}
} catch (InterruptedException e) {
log.error("closeChannel exception", e);
}
}
往上返回进入这个方法，org.apache.rocketmq.remoting.netty.NettyRemotingAbstract#failFast，channel关闭后对这个channel的请求快快速失败
protected void failFast(final Channel channel) {
Iterator> it = responseTable.entrySet().iterator();
while (it.hasNext()) {
Entry entry = it.next();
if (entry.getValue().getProcessChannel() == channel) {
Integer opaque = entry.getKey();
if (opaque != null) {
// 请求失败=》
requestFail(opaque);
}
}
}
}
进入这个方法org.apache.rocketmq.remoting.netty.NettyRemotingAbstract#requestFail
private void requestFail(final int opaque) {
ResponseFuture responseFuture = responseTable.remove(opaque);
if (responseFuture != null) {
responseFuture.setSendRequestOK(false);
responseFuture.putResponse(null);
try {
// 执行响应回调=》
executeInvokeCallback(responseFuture);
} catch (Throwable e) {
log.warn("execute callback in requestFail, and callback throw", e);
} finally {
responseFuture.release();
}
}
}
进入这个方法，异步执行回调处理org.apache.rocketmq.remoting.netty.NettyRemotingAbstract#executeInvokeCallback
private void executeInvokeCallback(final ResponseFuture responseFuture) {
boolean runInThisThread = false;
ExecutorService executor = this.getCallbackExecutor();
if (executor != null) {
try {
executor.submit(new Runnable() {
@Override
public void run() {
try {
// 异步执行回调处理=》
responseFuture.executeInvokeCallback();
} catch (Throwable e) {
log.warn("execute callback in executor exception, and callback throw", e);
} finally {
responseFuture.release();
}
}
});
} catch (Exception e) {
runInThisThread = true;
log.warn("execute callback in executor exception, maybe executor busy", e);
}
} else {
runInThisThread = true;
}
if (runInThisThread) {
try {
responseFuture.executeInvokeCallback();
} catch (Throwable e) {
log.warn("executeInvokeCallback Exception", e);
} finally {
responseFuture.release();
}
}
}
进入这个方法org.apache.rocketmq.remoting.netty.ResponseFuture#executeInvokeCallback
public void executeInvokeCallback() {
if (invokeCallback != null) {
// 自旋锁实现
if (this.executeCallbackOnlyOnce.compareAndSet(false, true)) {
// 执行响应回调=》
invokeCallback.operationComplete(this);
}
}
}
nettt client处理handler，NettyClientHandler
class NettyClientHandler extends SimpleChannelInboundHandler{ @Override protected void channelRead0(ChannelHandlerContext ctx, RemotingCommand msg) throws Exception { // 消息读取=》 processMessageReceived(ctx, msg); } }
进入这个方法org.apache.rocketmq.remoting.netty.NettyRemotingAbstract#processMessageReceived
public void processMessageReceived(ChannelHandlerContext ctx, RemotingCommand msg) throws Exception {
final RemotingCommand cmd = msg;
if (cmd != null) {
switch (cmd.getType()) {
case REQUEST_COMMAND:
// 请求消息处理 =》
processRequestCommand(ctx, cmd);
break;
case RESPONSE_COMMAND:
// 响应消息处理
processResponseCommand(ctx, cmd);
break;
default:
break;
}
}
}
进入这个方法请求处理org.apache.rocketmq.remoting.netty.NettyRemotingAbstract#processRequestCommand
public void processRequestCommand(final ChannelHandlerContext ctx, final RemotingCommand cmd) {
// 公平的处理请求
final Pair matched = this.processorTable.get(cmd.getCode());
final Pair pair = null == matched ? this.defaultRequestProcessor : matched;
final int opaque = cmd.getOpaque();
if (pair != null) {
Runnable run = new Runnable() {
@Override
public void run() {
try {
// 客户自定义的钩子实现类
RPCHook rpcHook = NettyRemotingAbstract.this.getRPCHook();
if (rpcHook != null) {
// 这里mq提供了一些钩子方法可以扩展的地方，请求前处理逻辑可以在这里扩展
rpcHook.doBeforeRequest(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd);
}
// 处理请求，有各个实现，主要都是netty通信 =》TODO 文章
final RemotingCommand response = pair.getObject1().processRequest(ctx, cmd);
if (rpcHook != null) {
// 执行rocketmq请求的后置处理钩子方法
rpcHook.doAfterResponse(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd, response);
}
// 如果不是单线请求
if (!cmd.isOnewayRPC()) {
if (response != null) {
response.setOpaque(opaque);
response.markResponseType();
try {
ctx.writeAndFlush(response);
} catch (Throwable e) {
log.error("process request over, but response failed", e);
log.error(cmd.toString());
log.error(response.toString());
}
} else {
}
}
} catch (Throwable e) {
log.error("process request exception", e);
log.error(cmd.toString());
if (!cmd.isOnewayRPC()) {
final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_ERROR,
RemotingHelper.exceptionSimpleDesc(e));
response.setOpaque(opaque);
ctx.writeAndFlush(response);
}
}
}
};
if (pair.getObject1().rejectRequest()) {
final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_BUSY,
"[REJECTREQUEST]system busy, start flow control for a while");
response.setOpaque(opaque);
ctx.writeAndFlush(response);
return;
}
try {
final RequestTask requestTask = new RequestTask(run, ctx.channel(), cmd);
pair.getObject2().submit(requestTask);
} catch (RejectedExecutionException e) {
if ((System.currentTimeMillis() % 10000) == 0) {
log.warn(RemotingHelper.parseChannelRemoteAddr(ctx.channel())
+ ", too many requests and system thread pool busy, RejectedExecutionException "
+ pair.getObject2().toString()
+ " request code: " + cmd.getCode());
}
if (!cmd.isOnewayRPC()) {
final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_BUSY,
"[OVERLOAD]system busy, start flow control for a while");
response.setOpaque(opaque);
ctx.writeAndFlush(response);
}
}
} else {
String error = " request type " + cmd.getCode() + " not supported";
final RemotingCommand response =
RemotingCommand.createResponseCommand(RemotingSysResponseCode.REQUEST_CODE_NOT_SUPPORTED, error);
response.setOpaque(opaque);
ctx.writeAndFlush(response);
log.error(RemotingHelper.parseChannelRemoteAddr(ctx.channel()) + error);
}
}
未完待续。
说在最后
本次解析仅代表个人观点，仅供参考。
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