Said ahead
Next, the introduction of namesrvController startup
Source code analysis
Return method, process request, org. apache. rocketmq. remoting. netty. Netty Remoting Abstract # process RequestCommand
public void processRequestCommand(final ChannelHandlerContext ctx, final RemotingCommand cmd) {
// Fair processing of requests
final Pair<NettyRequestProcessor, ExecutorService> matched = this.processorTable.get(cmd.getCode());
final Pair<NettyRequestProcessor, ExecutorService> pair = null == matched ? this.defaultRequestProcessor : matched;
final int opaque = cmd.getOpaque();
if (pair != null) {
Runnable run = new Runnable() {
@Override
public void run() {
try {
// Customer-defined hook implementation class
RPCHook rpcHook = NettyRemotingAbstract.this.getRPCHook();
if (rpcHook != null) {
// Here mq provides some extensibility for hook methods, where request preprocessing logic can be extended
rpcHook.doBeforeRequest(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd);
}
// Processing requests, there are various implementations, mainly netty communication ="TODO
final RemotingCommand response = pair.getObject1().processRequest(ctx, cmd);
if (rpcHook != null) {
// Post-processing hook method for executing rocketmq requests
rpcHook.doAfterResponse(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd, response);
}
// If it's not a single-line request
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);
}
}
}
};
// System busy, temporarily start flow control
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);
// Asynchronous submission of requests
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 not one way, the system is busy, temporarily start flow control
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";
// Request encoding does not support
final RemotingCommand response =
RemotingCommand.createResponseCommand(RemotingSysResponseCode.REQUEST_CODE_NOT_SUPPORTED, error);
response.setOpaque(opaque);
ctx.writeAndFlush(response);
log.error(RemotingHelper.parseChannelRemoteAddr(ctx.channel()) + error);
}
}
Enter the method, execute the post-processing hook method of rocketmq request, and the user of org.apache.rocketmq.remoting.RPCHook#doAfterResponse needs to implement the hook method.
Return method, response message processing, org. apache. rocketmq. remoting. netty. Netty RemotingAbstract # processResponseCommand
public void processResponseCommand(ChannelHandlerContext ctx, RemotingCommand cmd) {
final int opaque = cmd.getOpaque();
// Getting Response Future from Response Cache Information
final ResponseFuture responseFuture = responseTable.get(opaque);
if (responseFuture != null) {
responseFuture.setResponseCommand(cmd);
responseTable.remove(opaque);
if (responseFuture.getInvokeCallback() != null) {
// If the response object has callback processing, the callback function= is processed.
executeInvokeCallback(responseFuture);
} else {
responseFuture.putResponse(cmd);
responseFuture.release();
}
} else {
log.warn("receive response, but not matched any request, " + RemotingHelper.parseChannelRemoteAddr(ctx.channel()));
log.warn(cmd.toString());
}
}
Enter the method and process the callback function if the response object has a callback processing, org. apache. rocketmq. remoting. netty. Netty RemotingAbstract # 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 {
// Asynchronous Callback Processing =
responseFuture.executeInvokeCallback();
} catch (Throwable e) {
log.warn("execute callback in executor exception, and callback throw", e);
} finally {
// Release signal =
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();
}
}
}
Enter method, asynchronously execute callback processing, org.apache.rocketmq.remoting.netty.ResponseFuture#executeInvokeCallback
public void executeInvokeCallback() {
if (invokeCallback != null) {
// Spinlock Implementation
if (this.executeCallbackOnlyOnce.compareAndSet(false, true)) {
// Execution response callback =
invokeCallback.operationComplete(this);
}
}
}
To enter a method, the user of org. apache. rocketmq. remoting. InvokeCallback # operation Complete needs to implement this method.
Said at the end
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