c++ - 一些进展。发送调用没有到达 nodejs 土地

Question

我已经使用 AsyncProgressWorker 线程制作了一个 Node 插件来处理我的套接字消息。这是我的代码:

class ProgressWorker : public AsyncProgressWorker {
 public:
  ProgressWorker(
      Callback *callback
    , Callback *progress)
    : AsyncProgressWorker(callback), progress(progress) {}
  ~ProgressWorker() {}

  void Execute (const AsyncProgressWorker::ExecutionProgress& progress) {
    char response[4096];
    int result;
    int connected = 1;
    int timeout = 0;
    int pending = 0;

    while(connected) {
        result = sctp_recvmsg(sock, (void *)&response, (size_t)sizeof(response), NULL, 0, 0, 0);
        if (result > 0 && result < 4095) {
            if (debug) {
                printf("Server replied (size %d)\n", result);
            }
            pending = 0;
            progress.Send((const char *)response, size_t(result));
            result = 0;
        }
        else {
            // Don't mind my timeout mechanism. :))
            if ((result == -1 && errno != EWOULDBLOCK) || pending) {
                if (timeout == 0) {
                    printf("Can't receive from other end. Waiting for 3 seconds. Error code: %d\n", errno);
                    pending = 1;
                }
                if (timeout >= 3000) {
                    connected = 0;
                    close(sock);
                }
                else {
                    timeout += 5;
                    usleep(5000);
                }
            }
            else {
                usleep(5000);
            }
        }
    }

  }

  void HandleProgressCallback(const char *data, size_t count) {
    HandleScope scope;

    v8::Local<v8::Value> argv[] = {
        CopyBuffer(const_cast<char*>(data), count).ToLocalChecked()
    };
    progress->Call(1, argv); // This is the callback to nodejs
  }

 private:
  Callback *progress;
};

直到今晚我才对此进行压力测试，然后我注意到有些消息不会返回到 Node 。它将打印我的“服务器回复”调试日志，但不会记录我放在进度回调中的调试日志。我在这里错过了什么吗？提前致谢。

Answer 1

AsyncProgressWorker基于uv_async_t ，它允许任何线程唤醒主线程。但是，如 documentation 中所述:

libuv will coalesce calls to uv_async_send(), that is, not every call to it will yield an execution of the callback. For example: if uv_async_send() is called 5 times in a row before the callback is called, the callback will only be called once. If uv_async_send() is called again after the callback was called, it will be called again.

^^ 这就是当您的应用程序处于压力下时，您有时可能无法收到某些事件的原因。这条线上方是问题的答案。以下是我处理您的问题的“超越”可能的解决方案:

碰巧我正在为 AsyncProgressWorker 添加一个新的替代品 promise 传递每个事件，就像AsyncProgressWorker一样确实如此，但使用队列。此功能最近已合并到 NAN 中。如果您想测试它，请尝试位于 https://github.com/nodejs/nan 的 git 存储库。 , 然后替换你的 AsyncProgressWorker与 AsyncProgressQueueWorker<char>重新运行您的测试，所有事件都将被传送。

添加此新功能的拉取请求在这里:https://github.com/nodejs/nan/pull/692 - 2017 年 10 月 6 日合并。

此新功能已在 NAN 2.8.0 版本中发布

您可以通过更改 package.json 来使用这个新的类模板使用 nan 2.8.0 或更高版本:

   "dependencies": {
     "nan": "^2.8.0"
   },