libuv库定时器的使用

老大前几天提到libuv，我只看过一点libevent, 听说过libev，没听说过libuv，查了一下才知道libuv。

先到github git clone 源码，编译，测试，看测试代码

头文件uv.h定时器部分的函数，头文件有详细的注释

/*
 * uv_timer_t is a subclass of uv_handle_t.
 *
 * Used to get woken up at a specified time in the future.
 */
struct uv_timer_s {
  UV_HANDLE_FIELDS
  UV_TIMER_PRIVATE_FIELDS
};

UV_EXTERN int uv_timer_init(uv_loop_t*, uv_timer_t* handle);

/*
 * Start the timer. `timeout` and `repeat` are in milliseconds.
 *
 * If timeout is zero, the callback fires on the next tick of the event loop.
 *
 * If repeat is non-zero, the callback fires first after timeout milliseconds
 * and then repeatedly after repeat milliseconds.
 */
UV_EXTERN int uv_timer_start(uv_timer_t* handle,
                             uv_timer_cb cb,
                             uint64_t timeout,
                             uint64_t repeat);

UV_EXTERN int uv_timer_stop(uv_timer_t* handle);

/*
 * Stop the timer, and if it is repeating restart it using the repeat value
 * as the timeout. If the timer has never been started before it returns -1 and
 * sets the error to UV_EINVAL.
 */
UV_EXTERN int uv_timer_again(uv_timer_t* handle);

/*
 * Set the repeat value in milliseconds. Note that if the repeat value is set
 * from a timer callback it does not immediately take effect. If the timer was
 * non-repeating before, it will have been stopped. If it was repeating, then
 * the old repeat value will have been used to schedule the next timeout.
 */
UV_EXTERN void uv_timer_set_repeat(uv_timer_t* handle, uint64_t repeat);

UV_EXTERN uint64_t uv_timer_get_repeat(const uv_timer_t* handle);

 /* uv_timer_test.c */


 #include
 #include
 #include
 #include
 #include

 static void timer_cb(uv_timer_t *handle, int status)
 {
     static int count;
     printf("count %d now %d\n", count++, time(NULL));
 }

 int main(int argc, char *argv[])
 {
     int r;
     uv_timer_t timer;
     r = uv_timer_init(uv_default_loop(), &timer);
     assert(r == 0);

     assert(!uv_is_active((uv_handle_t *) &timer));
     assert(!uv_is_closing((uv_handle_t *) &timer));
     printf("start %d\n", time(NULL));
     r = uv_timer_start(&timer, timer_cb, atoi(argv[1]), 0);

     r = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
     assert(r == 0);
     return 0;
 }

测试程序流程非常简单，

初始化定时器uv_timer_init

注册自己的定时回调函数uv_timer_start

运行 uv_run

编译：gcc -o test-uv-timer test_uv_timer.c -luv

注意在uv_timer_start函数的参数repeat设置为1的话，time_cb在第一次定时时间到后之后会一直回调

最后贴上修改的test-acitive.c代码，从这个测试代码和uv.h的函数注释基本可以学会使用定时器的使用。

 #include
 #include
 #include
 #include

 #define ASSERT assert
 static int close_cb_called = 0;


 static void close_cb(uv_handle_t* handle) {
   ASSERT(handle != NULL);
   close_cb_called++;
 }


 static void timer_cb(uv_timer_t* handle, int status) {
   ASSERT(0 && "timer_cb should not have been called");
 }


 int main()
 {
   int r;
   uv_timer_t timer;

   r = uv_timer_init(uv_default_loop(), &timer);
   ASSERT(r == 0);

   ASSERT(!uv_is_active((uv_handle_t*) &timer));
   ASSERT(!uv_is_closing((uv_handle_t*) &timer));

   r = uv_timer_start(&timer, timer_cb, 1000, 0);
   ASSERT(r == 0);

   ASSERT(uv_is_active((uv_handle_t*) &timer));
   ASSERT(!uv_is_closing((uv_handle_t*) &timer));

   r = uv_timer_stop(&timer);
   ASSERT(r == 0);

   ASSERT(!uv_is_active((uv_handle_t*) &timer));
   ASSERT(!uv_is_closing((uv_handle_t*) &timer));

   r = uv_timer_start(&timer, timer_cb, 1000, 0);
   ASSERT(r == 0);

   ASSERT(uv_is_active((uv_handle_t*) &timer));
   ASSERT(!uv_is_closing((uv_handle_t*) &timer));

   uv_close((uv_handle_t*) &timer, close_cb);

   ASSERT(!uv_is_active((uv_handle_t*) &timer));
   ASSERT(uv_is_closing((uv_handle_t*) &timer));

   r = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
   ASSERT(r == 0);

   ASSERT(close_cb_called == 1);

   return 0;
 }