huenchao / libuv-study-v1.x Goto Github PK

void uv_close(uv_handle_t* handle, uv_close_cb close_cb) {
  assert(!uv__is_closing(handle));

  handle->flags |= UV_HANDLE_CLOSING;
  handle->close_cb = close_cb;

  switch (handle->type) {
  case UV_NAMED_PIPE:
    uv__pipe_close((uv_pipe_t*)handle);
    break;

  case UV_TTY:
    uv__stream_close((uv_stream_t*)handle);
    break;

  case UV_TCP:
    uv__tcp_close((uv_tcp_t*)handle);
    break;

  case UV_UDP:
    uv__udp_close((uv_udp_t*)handle);
    break;

  case UV_PREPARE:
    uv__prepare_close((uv_prepare_t*)handle);
    break;

  case UV_CHECK:
    uv__check_close((uv_check_t*)handle);
    break;

  case UV_IDLE:
    uv__idle_close((uv_idle_t*)handle);
    break;

  case UV_ASYNC:
    uv__async_close((uv_async_t*)handle);
    break;

  case UV_TIMER:
    uv__timer_close((uv_timer_t*)handle);
    break;

  case UV_PROCESS:
    uv__process_close((uv_process_t*)handle);
    break;

  case UV_FS_EVENT:
    uv__fs_event_close((uv_fs_event_t*)handle);
    break;

  case UV_POLL:
    uv__poll_close((uv_poll_t*)handle);
    break;

  case UV_FS_POLL:
    uv__fs_poll_close((uv_fs_poll_t*)handle);
    /* Poll handles use file system requests, and one of them may still be
     * running. The poll code will call uv__make_close_pending() for us. */
    return;

  case UV_SIGNAL:
    uv__signal_close((uv_signal_t*) handle);
    /* Signal handles may not be closed immediately. The signal code will
     * itself close uv__make_close_pending whenever appropriate. */
    return;

  default:
    assert(0);
  }

  uv__make_close_pending(handle);
}

//deps/uv/src/unix/core.c
int uv_run(uv_loop_t *loop, uv_run_mode mode) {
	int timeout;
	int r;
	int ran_pending;
	//uv__loop_alive返回的是event loop中是否还有待处理的handle或者request
	//以及closing_handles是否为NULL,如果均没有,则返回0
	r = uv__loop_alive(loop);
	//更新当前event loop的时间戳,单位是ms
	if (!r)
    	uv__update_time(loop);
	while (r != 0 && loop->stop_flag == 0) {
    	//使用Linux下的高精度Timer hrtime更新loop->time,即event loop的时间戳
    	uv__update_time(loop);
    	//执行判断当前loop->time下有无到期的Timer,显然在同一个loop里面timer拥有最高的优先级
    	uv__run_timers(loop);
    	//判断当前的pending_queue是否有事件待处理,并且一次将&loop->pending_queue中的uv__io_t对应的cb全部拿出来执行
    	ran_pending = uv__run_pending(loop);
    	//实现在loop-watcher.c文件中,一次将&loop->idle_handles中的idle_cd全部执行完毕(如果存在的话)
    	uv__run_idle(loop);
    	//实现在loop-watcher.c文件中,一次将&loop->prepare_handles中的prepare_cb全部执行完毕(如果存在的话)
    	uv__run_prepare(loop);

    	timeout = 0;
    	//如果是UV_RUN_ONCE的模式,并且pending_queue队列为空,或者采用UV_RUN_DEFAULT(在一个loop中处理所有事件),则将timeout参数置为
    	//最近的一个定时器的超时时间,防止在uv_io_poll中阻塞住无法进入超时的timer中
    	if ((mode == UV_RUN_ONCE && !ran_pending) || mode == UV_RUN_DEFAULT)
        	timeout = uv_backend_timeout(loop);
    	//进入I/O处理的函数(重点分析的部分),此处挂载timeout是为了防止在uv_io_poll中陷入阻塞无法执行timers;并且对于mode为
    	//UV_RUN_NOWAIT类型的uv_run执行,timeout为0可以保证其立即跳出uv__io_poll,达到了非阻塞调用的效果
    	uv__io_poll(loop, timeout);
    	//实现在loop-watcher.c文件中,一次将&loop->check_handles中的check_cb全部执行完毕(如果存在的话)
    	uv__run_check(loop);
    	//执行结束时的资源释放,loop->closing_handles指针指向NULL
    	uv__run_closing_handles(loop);

    	if (mode == UV_RUN_ONCE) {
        	//如果是UV_RUN_ONCE模式,继续更新当前event loop的时间戳
        	uv__update_time(loop);
        	//执行timers,判断是否有已经到期的timer
        	uv__run_timers(loop);
    	}
    	r = uv__loop_alive(loop);
    	//在UV_RUN_ONCE和UV_RUN_NOWAIT模式中,跳出当前的循环
    	if (mode == UV_RUN_ONCE || mode == UV_RUN_NOWAIT)
        	break;
		}
		
	//标记当前的stop_flag为0,表示当前的loop执行完毕
	if (loop->stop_flag != 0)
    	loop->stop_flag = 0;
	//返回r的值
	return r;
}

static uv_loop_t default_loop_struct;
static uv_loop_t* default_loop_ptr;

uv_loop_t* uv_default_loop(void) {
  if (default_loop_ptr != NULL)
    return default_loop_ptr;

  if (uv_loop_init(&default_loop_struct))
    return NULL;

  default_loop_ptr = &default_loop_struct;
  return default_loop_ptr;
}

#include "uv.h"
#include "task.h"

static uv_prepare_t prepare_handle;
static uv_timer_t timer_handle;
static int prepare_called = 0;
static int timer_called = 0;
static int num_ticks = 10;


static void prepare_cb(uv_prepare_t* handle) {
  ASSERT(handle == &prepare_handle);
  prepare_called++;
  if (prepare_called == num_ticks)
    uv_prepare_stop(handle);
}


static void timer_cb(uv_timer_t* handle) {
  ASSERT(handle == &timer_handle);
  timer_called++;
  if (timer_called == 1)
    uv_stop(uv_default_loop());
  else if (timer_called == num_ticks)
    uv_timer_stop(handle);
}


TEST_IMPL(loop_stop) {
  int r;
  uv_prepare_init(uv_default_loop(), &prepare_handle);
  uv_prepare_start(&prepare_handle, prepare_cb);
  uv_timer_init(uv_default_loop(), &timer_handle);
  uv_timer_start(&timer_handle, timer_cb, 100, 100);

  r = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
  ASSERT(r != 0);
  ASSERT(timer_called == 1);

  r = uv_run(uv_default_loop(), UV_RUN_NOWAIT);
  ASSERT(r != 0);
  ASSERT(prepare_called > 1);

  r = uv_run(uv_default_loop(), UV_RUN_DEFAULT);
  ASSERT(r == 0);
  ASSERT(timer_called == 10);
  ASSERT(prepare_called == 10);

  return 0;
}

struct uv_loop_s {
  /* User data - use this for whatever. */
  void* data;
  /* Loop reference counting. */
  unsigned int active_handles;            //每次我们start一个handle的时候，就会+1，到时候会讲到。
  void* handle_queue[2];                     //理解一下queue.h，里面存的是每个具体类型的hander，利用双向循环列表的数据结构，加快访问和操作。
  union {
    void* unused[2];
    unsigned int count;
  } active_reqs;
  /* Internal flag to signal loop stop. */
  unsigned int stop_flag;                    //影响 uv_run这个函数里的循环。
  UV_LOOP_PRIVATE_FIELDS
};

#define QUEUE_SPLIT(h, q, n)                                                  \
  do {                                                                        \
    QUEUE_PREV(n) = QUEUE_PREV(h);                                            \
    QUEUE_PREV_NEXT(n) = (n);                                                 \
    QUEUE_NEXT(n) = (q);                                                      \
    QUEUE_PREV(h) = QUEUE_PREV(q);                                            \
    QUEUE_PREV_NEXT(h) = (h);                                                 \
    QUEUE_PREV(q) = (n);                                                      \
  }                                                                           \
  while (0)

#define QUEUE_MOVE(h, n)                                                      \
  do {                                                                        \
    if (QUEUE_EMPTY(h))                                                       \
      QUEUE_INIT(n);                                                          \
    else {                                                                    \
      QUEUE* q = QUEUE_HEAD(h);                                               \
      QUEUE_SPLIT(h, q, n);                                                   \
    }                                                                         \
  }                                                                           \
  while (0)

#define go(h, n)                                                              \
  do {                                                                        \
    QUEUE_PREV_NEXT(h) = QUEUE_NEXT(n);                                       \
    QUEUE_NEXT_PREV(n) = QUEUE_PREV(h);                                       \
    QUEUE_PREV(h) = QUEUE_PREV(n);                                            \
    QUEUE_PREV_NEXT(h) = (h);                                                 \
  }                                                                           \
  while (0)