rocketmq学习笔记 五 源码之rocketmq-remoting

之前学习过netty源码，所以看rocketmq-remoting 就比较简单了

核心流程

解析请求

public void processRequestCommand(final ChannelHandlerContext ctx, final RemotingCommand cmd) {
        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 {
                        RPCHook rpcHook = NettyRemotingAbstract.this.getRPCHook();
                        if (rpcHook != null) {
                            rpcHook.doBeforeRequest(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd);
                        }

                        final RemotingCommand response = pair.getObject1().processRequest(ctx, cmd);
                        if (rpcHook != null) {
                            rpcHook.doAfterResponse(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd, response);
                        }

                        if (!cmd.isOnewayRPC()) {
                            if (response != null) {
                                response.setOpaque(opaque);
                                response.markResponseType();
                                try {
                                    ctx.writeAndFlush(response);
                                } catch (Throwable e) {
                                    plog.error("process request over, but response failed", e);
                                    plog.error(cmd.toString());
                                    plog.error(response.toString());
                                }
                            } else {

                            }
                        }
                    } catch (Throwable e) {
                        if (!"com.aliyun.openservices.ons.api.impl.authority.exception.AuthenticationException"
                                .equals(e.getClass().getCanonicalName())) {
                            plog.error("process request exception", e);
                            plog.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) {
                    plog.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);
            plog.error(RemotingHelper.parseChannelRemoteAddr(ctx.channel()) + error);
        }
    }

解析相应

    public void processResponseCommand(ChannelHandlerContext ctx, RemotingCommand cmd) {
        final int opaque = cmd.getOpaque();
        final ResponseFuture responseFuture = responseTable.get(opaque);
        if (responseFuture != null) {
            responseFuture.setResponseCommand(cmd);

            responseFuture.release();

            responseTable.remove(opaque);

            if (responseFuture.getInvokeCallback() != null) {
                boolean runInThisThread = false;
                ExecutorService executor = this.getCallbackExecutor();
                if (executor != null) {
                    try {
                        executor.submit(new Runnable() {
                            @Override
                            public void run() {
                                try {
                                    responseFuture.executeInvokeCallback();
                                } catch (Throwable e) {
                                    plog.warn("execute callback in executor exception, and callback throw", e);
                                }
                            }
                        });
                    } catch (Exception e) {
                        runInThisThread = true;
                        plog.warn("execute callback in executor exception, maybe executor busy", e);
                    }
                } else {
                    runInThisThread = true;
                }

                if (runInThisThread) {
                    try {
                        responseFuture.executeInvokeCallback();
                    } catch (Throwable e) {
                        plog.warn("executeInvokeCallback Exception", e);
                    }
                }
            } else {
                responseFuture.putResponse(cmd);
            }
        } else {
            plog.warn("receive response, but not matched any request, " + RemotingHelper.parseChannelRemoteAddr(ctx.channel()));
            plog.warn(cmd.toString());
        }
    }