Question

鉴于以下计划 -

#include <iostream>
#include <uv.h>

int main()
{
    uv_loop_t loop;
    uv_loop_init(&loop);

    std::cout << "Libuv version: " << UV_VERSION_MAJOR << "."
              << UV_VERSION_MINOR << std::endl;

    int r = 0;

    uv_timer_t t1_handle;
    r = uv_timer_init(&loop, &t1_handle);
    uv_timer_start(&t1_handle,
      [](uv_timer_t *t) { std::cout << "Timer1 called\n"; }, 0, 2000);

    uv_run(&loop, UV_RUN_DEFAULT);

    // second timer
    uv_timer_t t2_handle;
    r = uv_timer_init(&loop, &t2_handle);
    uv_timer_start(&t2_handle,
      [](uv_timer_t *t) { std::cout << "Timer2 called\n"; }, 0, 1000);

    uv_loop_close(&loop);
}

第二个计时器句柄永远不会在循环上运行，因为循环已在运行，并且＆＃34; Timer2调用＆＃34;永远不会打印。所以我尝试在运行它之后暂时停止循环，然后添加第二个计时器 -

....
uv_run(&loop, UV_RUN_DEFAULT);

// some work

uv_stop(&loop);
// now add second timer
uv_run(&loop, UV_RUN_DEFAULT); // run again
....

但是这再次没有奏效，可能是因为在第一个循环开始运行重复计时器之后，后面的行不会被执行。那么我应该如何为已经运行的uvloop添加一个新的计时器句柄？

Answer 1

你是正确的，循环需要在注册新句柄之前停止。在uv_stop之后立即调用uv_run函数无法实现，因为uv_run需要先返回。例如，可以通过使用句柄回调来停止它来实现。这是一个非常愚蠢的例子，说明如何使用现有的Timer1句柄完成它。它在第一次运行时完全停止循环一次。

#include <iostream>
#include <uv.h>

int main() {
  uv_loop_t loop;
  uv_loop_init(&loop);

  std::cout << "Libuv version: " << UV_VERSION_MAJOR << "." << UV_VERSION_MINOR
            << std::endl;

  int r = 0;

  uv_timer_t t1_handle;
  r = uv_timer_init(&loop, &t1_handle);
  *(bool *)t1_handle.data = true; // need to stop the loop
  uv_timer_start(&t1_handle,
                 [](uv_timer_t *t) {
                   std::cout << "Timer1 called\n";
                   bool to_stop = *(bool *)t->data;
                   if (to_stop) {
                     std::cout << "Stopping loop and resetting the flag\n";
                     uv_stop(t->loop);
                     *(bool *)t->data = false; // do not stop the loop again
                   }
                 },
                 0, 2000);
  uv_run(&loop, UV_RUN_DEFAULT);
  std::cout << "After uv_run\n";

  // second timer
  uv_timer_t t2_handle;
  r = uv_timer_init(&loop, &t2_handle);
  uv_timer_start(&t2_handle,
                 [](uv_timer_t *t) { std::cout << "Timer2 called\n"; }, 0,
                 1000);
  std::cout << "Start loop again\n";
  uv_run(&loop, UV_RUN_DEFAULT);

  uv_loop_close(&loop);
}

所以输出是

Libuv version: 1.9
Timer1 called
Stopping loop and resetting the flag
After uv_run
Start loop again
Timer2 called
Timer2 called
Timer1 called
Timer2 called
Timer2 called
Timer1 called

在已经运行的循环上添加另一个计时

1 个答案: