6

前言

swooletimer 模块功能有三个:用户定时任务、剔除空闲连接、更新 server 时间。timer 模块的底层有两种,一种是基于 alarm 信号,一种是基于 timefd

timer 数据结构

timer 数据结构是 swTimer。其中 heap 是多个 swTimer_node 类型构成的一个数据堆,该数据堆按照下一次执行时间来排序,下次执行时间离当前时间越近,元素的位置越靠前;mapswTimer_node 类型的 map,其 keyswTimer_node 类型的 id,该数据结构可以通过 id 快速查找对应的 swTimer_node 元素;numswTimer_node 元素个数;use_pipe 标志着 worker 进程中是否使用管道 pipe 来获知 alarm 信号已触发;fd 用于 timefd_current_id 是当前最大 swTimer_nodeid_next_id 就是下一个新建的 swTimer_nodeid 值,是 _current_id + 1;_next_msec 是下次检查定时器的时间。

_swTimer_nodeheap_node_swTimer 中的数据堆元素;data 一般存储 servercallback 是定时器触发后需要执行的回调函数;exec_msec 是该元素应该执行的时间;id 是元素在 swTimer 中的 idtype 有三种:SW_TIMER_TYPE_KERNELserver 内置定时函数)、SW_TIMER_TYPE_CORO(协程定时函数)、SW_TIMER_TYPE_PHP(PHP 定时函数)

struct _swTimer
{
    /*--------------timerfd & signal timer--------------*/
    swHeap *heap;
    swHashMap *map;
    int num;
    int use_pipe;
    int lasttime;
    int fd;
    long _next_id;
    long _current_id;
    long _next_msec;
    swPipe pipe;
    /*-----------------for EventTimer-------------------*/
    struct timeval basetime;
    /*--------------------------------------------------*/
    int (*set)(swTimer *timer, long exec_msec);
    swTimer_node* (*add)(swTimer *timer, int _msec, int persistent, void *data, swTimerCallback callback);
};

struct _swTimer_node
{
    swHeap_node *heap_node;
    void *data;
    swTimerCallback callback;
    int64_t exec_msec;
    uint32_t interval;
    long id;
    int type;                 //0 normal node 1 node for client_coro
    uint8_t remove;
};

Timer 定时器

swTimer_init 创建定时器

  • 创建定时器需要给定一个间隔时间,每隔这个时间就要检查 swTimer 中的 _swTimer_node 元素,如果时间已经超过了 _swTimer_node 元素的 exec_msec 时间,就要执行定时函数。
  • swTimer_now 函数初始化 basetimeswTimer_now 函数可以获取当前时间,使用的是 clock_gettimeCLOCK_MONOTONIC 获取绝对时间,或者使用 gettimeofday 函数
  • 如果是 worker 进程,那么调用 swSystemTimer_init 函数对定时器进行初始化;如果是 master 进程,那么调用 swReactorTimer_init 进行初始化
int swTimer_now(struct timeval *time)
{
#if defined(SW_USE_MONOTONIC_TIME) && defined(CLOCK_MONOTONIC)
    struct timespec _now;
    if (clock_gettime(CLOCK_MONOTONIC, &_now) < 0)
    {
        swSysError("clock_gettime(CLOCK_MONOTONIC) failed.");
        return SW_ERR;
    }
    time->tv_sec = _now.tv_sec;
    time->tv_usec = _now.tv_nsec / 1000;
#else
    if (gettimeofday(time, NULL) < 0)
    {
        swSysError("gettimeofday() failed.");
        return SW_ERR;
    }
#endif
    return SW_OK;
}

int swTimer_init(long msec)
{
    if (swTimer_now(&SwooleG.timer.basetime) < 0)
    {
        return SW_ERR;
    }


    SwooleG.timer.heap = swHeap_new(1024, SW_MIN_HEAP);
    if (!SwooleG.timer.heap)
    {
        return SW_ERR;
    }

    SwooleG.timer.map = swHashMap_new(SW_HASHMAP_INIT_BUCKET_N, NULL);
    if (!SwooleG.timer.map)
    {
        swHeap_free(SwooleG.timer.heap);
        SwooleG.timer.heap = NULL;
        return SW_ERR;
    }

    SwooleG.timer._current_id = -1;
    SwooleG.timer._next_msec = msec;
    SwooleG.timer._next_id = 1;
    SwooleG.timer.add = swTimer_add;

    if (swIsTaskWorker())
    {
        swSystemTimer_init(msec, SwooleG.use_timer_pipe);
    }
    else
    {
        swReactorTimer_init(msec);
    }

    return SW_OK;
}

swReactorTimer_init 初始化

对于 master 进程,只需要设置 main_reactor 的超时时间即可,当发生超时事件之后,main_reactor 会调用 onTimeout 函数;或者一个事件循环最后,会调用 onFinish 函数;这两个函数都会最终调用 swTimer_select,来筛选那些已经到了执行时间的元素。

static int swReactorTimer_init(long exec_msec)
{
    SwooleG.main_reactor->check_timer = SW_TRUE;
    SwooleG.main_reactor->timeout_msec = exec_msec;
    SwooleG.timer.set = swReactorTimer_set;
    SwooleG.timer.fd = -1;
    return SW_OK;
}

static int swReactorEpoll_wait(swReactor *reactor, struct timeval *timeo)
{
    ...
    
    if (reactor->timeout_msec == 0)
    {
        if (timeo == NULL)
        {
            reactor->timeout_msec = -1;
        }
        else
        {
            reactor->timeout_msec = timeo->tv_sec * 1000 + timeo->tv_usec / 1000;
        }
    }
    
    while (reactor->running > 0)
    {
        msec = reactor->timeout_msec;
        n = epoll_wait(epoll_fd, events, max_event_num, msec);
        if (n < 0)
        {
           ...
        }
        else if (n == 0)
        {
            if (reactor->onTimeout != NULL)
            {
                reactor->onTimeout(reactor);
            }
            continue;
        }
        
        ...
        
        if (reactor->onFinish != NULL)
        {
            reactor->onFinish(reactor);
        }
        
        ...
    }
    
    ...
}

static void swReactor_onTimeout(swReactor *reactor)
{
    swReactor_onTimeout_and_Finish(reactor);

    if (reactor->disable_accept)
    {
        reactor->enable_accept(reactor);
        reactor->disable_accept = 0;
    }
}

static void swReactor_onFinish(swReactor *reactor)
{
    //check signal
    if (reactor->singal_no)
    {
        swSignal_callback(reactor->singal_no);
        reactor->singal_no = 0;
    }
    swReactor_onTimeout_and_Finish(reactor);
}

static void swReactor_onTimeout_and_Finish(swReactor *reactor)
{
    if (reactor->check_timer)
    {
        swTimer_select(&SwooleG.timer);
    }
    
    ...
}

swSystemTimer_init 初始化

  • 对于 worker 进程来说,由于定时任务比较多而且复杂,就不能简单使用 reactor 超时来实现功能。
  • swSystemTimer_init 采用 SIGALRM 闹钟信号或者 timefd 来触发中断 reactor 的等待。
  • 对于 timefd 来说,需要使用 timerfd_settime 系统调用来设置超时时间,然后将 timefd 加入 workerreactor 监控中,将其当做文件描述符来监控。当其就绪时,会调用 swTimer_select 执行定时函数。
  • 对于普通 SIGALRM 信号来说,将 timer->pipe 放入 reactor 的监控中,使用 setitimer 来定时触发 SIGALRM 信号,设置信号处理函数。信号处理函数中,会向 timer->pipe 写入数据,进而触发 swTimer_select 执行定时函数。
int swSystemTimer_init(int interval, int use_pipe)
{
    swTimer *timer = &SwooleG.timer;
    timer->lasttime = interval;

#ifndef HAVE_TIMERFD
    SwooleG.use_timerfd = 0;
#endif

    if (SwooleG.use_timerfd)
    {
        if (swSystemTimer_timerfd_set(timer, interval) < 0)
        {
            return SW_ERR;
        }
        timer->use_pipe = 0;
    }
    else
    {
        if (use_pipe)
        {
            if (swPipeNotify_auto(&timer->pipe, 0, 0) < 0)
            {
                return SW_ERR;
            }
            timer->fd = timer->pipe.getFd(&timer->pipe, 0);
            timer->use_pipe = 1;
        }
        else
        {
            timer->fd = 1;
            timer->use_pipe = 0;
        }

        if (swSystemTimer_signal_set(timer, interval) < 0)
        {
            return SW_ERR;
        }
        swSignal_add(SIGALRM, swSystemTimer_signal_handler);
    }

    if (timer->fd > 1)
    {
        SwooleG.main_reactor->setHandle(SwooleG.main_reactor, SW_FD_TIMER, swSystemTimer_event_handler);
        SwooleG.main_reactor->add(SwooleG.main_reactor, SwooleG.timer.fd, SW_FD_TIMER);
    }
    timer->set = swSystemTimer_set;
    return SW_OK;
}

swSystemTimer_timerfd_set 设置 timefd

  • 该函数目的是使用 timerfd_settime 系统调用,该系统调用需要 timefditimerspec 类型对象
  • timefd 可以由 timerfd_create 系统函数创建
  • itimerspec 对象需要当前时间和 interval 间隔时间共同设置。it_value 是首次超时时间,需要填写当前时间,并加上要超时的时间,值得注意的是 tv_nsec 加上去后一定要判断是否超出1000000000(如果超过要秒加一),否则会设置失败;it_interval 是后续周期性超时时间。
static int swSystemTimer_timerfd_set(swTimer *timer, long interval)
{

    struct timeval now;
    int sec = interval / 1000;
    int msec = (((float) interval / 1000) - sec) * 1000;

    if (gettimeofday(&now, NULL) < 0)
    {
        swWarn("gettimeofday() failed. Error: %s[%d]", strerror(errno), errno);
        return SW_ERR;
    }

    struct itimerspec timer_set;
    bzero(&timer_set, sizeof(timer_set));

    if (interval < 0)
    {
        if (timer->fd == 0)
        {
            return SW_OK;
        }
    }
    else
    {
        timer_set.it_interval.tv_sec = sec;
        timer_set.it_interval.tv_nsec = msec * 1000 * 1000;

        timer_set.it_value.tv_sec = now.tv_sec + sec;
        timer_set.it_value.tv_nsec = (now.tv_usec * 1000) + timer_set.it_interval.tv_nsec;

        if (timer_set.it_value.tv_nsec > 1e9)
        {
            timer_set.it_value.tv_nsec = timer_set.it_value.tv_nsec - 1e9;
            timer_set.it_value.tv_sec += 1;
        }

        if (timer->fd == 0)
        {
            timer->fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK | TFD_CLOEXEC);
            if (timer->fd < 0)
            {
                swWarn("timerfd_create() failed. Error: %s[%d]", strerror(errno), errno);
                return SW_ERR;
            }
        }
    }

    if (timerfd_settime(timer->fd, TFD_TIMER_ABSTIME, &timer_set, NULL) == -1)
    {
        swWarn("timerfd_settime() failed. Error: %s[%d]", strerror(errno), errno);
        return SW_ERR;
    }
    return SW_OK;
#else
    swWarn("kernel not support timerfd.");
    return SW_ERR;
#endif
}

swSystemTimer_signal_set 设置信号超时时间

  • setitimer 是一个比较常用的函数,可用来实现延时和定时的功能。

    • ITIMER_REAL:以系统真实的时间来计算,它送出 SIGALRM 信号。
    • ITIMER_VIRTUAL:以该进程在用户态下花费的时间来计算,它送出 SIGVTALRM 信号。
    • ITIMER_PROF:以该进程在用户态下和内核态下所费的时间来计算,它送出 SIGPROF 信号。
    • it_interval 为计时间隔,it_value 为延时时长,也就是距离现有时间第一次延迟触发的相对时间,而不是绝对时间。(所以我认为代码中 gettimeofday 函数是多余的,并不需要获取当前时间)
 */
static int swSystemTimer_signal_set(swTimer *timer, long interval)
{
    struct itimerval timer_set;
    int sec = interval / 1000;
    int msec = (((float) interval / 1000) - sec) * 1000;

    struct timeval now;
    if (gettimeofday(&now, NULL) < 0)
    {
        swWarn("gettimeofday() failed. Error: %s[%d]", strerror(errno), errno);
        return SW_ERR;
    }
    bzero(&timer_set, sizeof(timer_set));

    if (interval > 0)
    {
        timer_set.it_interval.tv_sec = sec;
        timer_set.it_interval.tv_usec = msec * 1000;

        timer_set.it_value.tv_sec = sec;
        timer_set.it_value.tv_usec = timer_set.it_interval.tv_usec;

        if (timer_set.it_value.tv_usec > 1e6)
        {
            timer_set.it_value.tv_usec = timer_set.it_value.tv_usec - 1e6;
            timer_set.it_value.tv_sec += 1;
        }
    }

    if (setitimer(ITIMER_REAL, &timer_set, NULL) < 0)
    {
        swWarn("setitimer() failed. Error: %s[%d]", strerror(errno), errno);
        return SW_ERR;
    }
    return SW_OK;
}

swSystemTimer_signal_handler 超时信号处理函数

swSystemTimer_signal_handler 函数是 SIGALARM 信号的处理函数,该函数被触发说明 epoll_wait 函数被闹钟信号中断,此时本函数向 timer.pipe 写入数据,然后即返回。reactor 会检测到 timer.pipe 的写就绪,进而调用对应的回调函数 swSystemTimer_event_handler

void swSystemTimer_signal_handler(int sig)
{
    SwooleG.signal_alarm = 1;
    uint64_t flag = 1;

    if (SwooleG.timer.use_pipe)
    {
        SwooleG.timer.pipe.write(&SwooleG.timer.pipe, &flag, sizeof(flag));
    }
}

swSystemTimer_event_handler 写就绪回调函数

写就绪回调函数可能是由 timer.pipe 的写就绪触发,也可能是 timefd 的写就绪触发,无论哪个都会调用 swTimer_select 函数执行对应的定时函数。

int swSystemTimer_event_handler(swReactor *reactor, swEvent *event)
{
    uint64_t exp;
    swTimer *timer = &SwooleG.timer;

    if (read(timer->fd, &exp, sizeof(uint64_t)) != sizeof(uint64_t))
    {
        return SW_ERR;
    }
    SwooleG.signal_alarm = 0;
    return swTimer_select(timer);
}

swTimer_add 添加元素

  • swTimer_add 用于添加定时函数元素。本函数逻辑比较简单,新建一个 swTimer_node 对象,初始化赋值之后加入到 timer->heap 中,程序会自动根据其 exec_msec 进行有小到大的排序,然后再更新 timer->map 哈希表。
  • 值得注意的是,当新添加的定时函数需要执行的时间小于当前 timer 下次执行时间的时候,我们需要调用 timer->set 函数更新 time 的间隔时间。在 master 进程中,这个 set 函数是 swReactorTimer_set,用于设置 reactor 的超时时间;在 worker 进程中,set 函数是 swSystemTimer_set,用于更新 timerfd_settimesetitimer 函数。
static swTimer_node* swTimer_add(swTimer *timer, int _msec, int interval, void *data, swTimerCallback callback)
{
    swTimer_node *tnode = sw_malloc(sizeof(swTimer_node));
    if (!tnode)
    {
        swSysError("malloc(%ld) failed.", sizeof(swTimer_node));
        return NULL;
    }

    int64_t now_msec = swTimer_get_relative_msec();
    if (now_msec < 0)
    {
        sw_free(tnode);
        return NULL;
    }

    tnode->data = data;
    tnode->type = SW_TIMER_TYPE_KERNEL;
    tnode->exec_msec = now_msec + _msec;
    tnode->interval = interval ? _msec : 0;
    tnode->remove = 0;
    tnode->callback = callback;

    if (timer->_next_msec < 0 || timer->_next_msec > _msec)
    {
        timer->set(timer, _msec);
        timer->_next_msec = _msec;
    }

    tnode->id = timer->_next_id++;
    if (unlikely(tnode->id < 0))
    {
        tnode->id = 1;
        timer->_next_id = 2;
    }
    timer->num++;

    tnode->heap_node = swHeap_push(timer->heap, tnode->exec_msec, tnode);
    if (tnode->heap_node == NULL)
    {
        sw_free(tnode);
        return NULL;
    }
    swHashMap_add_int(timer->map, tnode->id, tnode);
    return tnode;
}

static int swSystemTimer_set(swTimer *timer, long new_interval)
{
    if (new_interval == current_interval)
    {
        return SW_OK;
    }
    current_interval = new_interval;
    if (SwooleG.use_timerfd)
    {
        return swSystemTimer_timerfd_set(timer, new_interval);
    }
    else
    {
        return swSystemTimer_signal_set(timer, new_interval);
    }
}

swTimer_del 删除元素

int swTimer_del(swTimer *timer, swTimer_node *tnode)
{
    if (tnode->remove)
    {
        return SW_FALSE;
    }
    if (SwooleG.timer._current_id > 0 && tnode->id == SwooleG.timer._current_id)
    {
        tnode->remove = 1;
        return SW_TRUE;
    }
    if (swHashMap_del_int(timer->map, tnode->id) < 0)
    {
        return SW_ERR;
    }
    if (tnode->heap_node)
    {
        //remove from min-heap
        swHeap_remove(timer->heap, tnode->heap_node);
        sw_free(tnode->heap_node);
    }
    sw_free(tnode);
    timer->num --;
    return SW_TRUE;
}

swTimer_select 筛选定时函数

  • swTimer_select 函数的筛选原理是从 timer->heap 中不断 pop 出定时元素,比较它们的 exec_msec 是否超过了当前时间,如果超过了时间,就执行对应的定时函数;如果没有超过,由于 timer->heap 是排序过后的数据堆,因此当前定时元素之后的都不会超过当前时间,也就是还没有到执行的时间。
  • 如果当前的定时元素超过了当前时间,说明该元素应该执行定时函数。设置 timer->_current_id 为当前的 id 后,执行 tnode->callback 回调函数;如果当前定时元素不是一次执行的任务,而是需要每隔一段时间定时的任务,就要再次将元素放入 timer->heap 中;如果当前定时元素是一次执行的任务,就要将元素从 timer->maptimer->map 中删除
  • 循环结束后,tnode 就是下一个要执行的定时元素,我们需要调用 timer->set 函数设置闹钟信号(worker 进程)或者 reactor 超时时间(master 进程)。
int swTimer_select(swTimer *timer)
{
    int64_t now_msec = swTimer_get_relative_msec();
    if (now_msec < 0)
    {
        return SW_ERR;
    }

    swTimer_node *tnode = NULL;
    swHeap_node *tmp;
    long timer_id;

    while ((tmp = swHeap_top(timer->heap)))
    {
        tnode = tmp->data;
        if (tnode->exec_msec > now_msec)
        {
            break;
        }

        timer_id = timer->_current_id = tnode->id;
        if (!tnode->remove)
        {
            tnode->callback(timer, tnode);
        }
        timer->_current_id = -1;

        //persistent timer
        if (tnode->interval > 0 && !tnode->remove)
        {
            while (tnode->exec_msec <= now_msec)
            {
                tnode->exec_msec += tnode->interval;
            }
            swHeap_change_priority(timer->heap, tnode->exec_msec, tmp);
            continue;
        }

        timer->num--;
        swHeap_pop(timer->heap);
        swHashMap_del_int(timer->map, timer_id);
        sw_free(tnode);
    }

    if (!tnode || !tmp)
    {
        timer->_next_msec = -1;
        timer->set(timer, -1);
    }
    else
    {
        timer->set(timer, tnode->exec_msec - now_msec);
    }
    return SW_OK;
}

Timer 定时器的使用

master 进程 swServer_start_proxy

timer 模块在 master 进程中最重要的作用是每隔一秒更新 serv->gs->now 的值。除此之外,当 reactor 线程调度 worker 进程时,如果一段时间内没有任何空闲的 worker 进程空闲,timer 模块还负责写入错误日志。

static int swServer_start_proxy(swServer *serv)
{
    ...
    if (swTimer_init(1000) < 0)
    {
        return SW_ERR;
    }
    
    if (SwooleG.timer.add(&SwooleG.timer, 1000, 1, serv, swServer_master_onTimer) == NULL)
    {
        return SW_ERR;
    }
    ...
}

void swServer_master_onTimer(swTimer *timer, swTimer_node *tnode)
{
    swServer *serv = (swServer *) tnode->data;
    swServer_update_time(serv);
    if (serv->scheduler_warning && serv->warning_time < serv->gs->now)
    {
        serv->scheduler_warning = 0;
        serv->warning_time = serv->gs->now;
        swoole_error_log(SW_LOG_WARNING, SW_ERROR_SERVER_NO_IDLE_WORKER, "No idle worker is available.");
    }

    if (serv->hooks[SW_SERVER_HOOK_MASTER_TIMER])
    {
        swServer_call_hook(serv, SW_SERVER_HOOK_MASTER_TIMER, serv);
    }
}

void swServer_update_time(swServer *serv)
{
    time_t now = time(NULL);
    if (now < 0)
    {
        swWarn("get time failed. Error: %s[%d]", strerror(errno), errno);
    }
    else
    {
        serv->gs->now = now;
    }
}

worker 进程超时停止

worker 进程将要停止时,并不会立刻停止,而是会等待事件循环结束后停止,这时为了防止 worker 进程不退出,还设置了 30s 的延迟,超过 30s 就会停止该进程。

static void swWorker_stop()
{
    swWorker *worker = SwooleWG.worker;
    swServer *serv = SwooleG.serv;
    worker->status = SW_WORKER_BUSY;
    
    ...

    try_to_exit: SwooleWG.wait_exit = 1;
    if (SwooleG.timer.fd == 0)
    {
        swTimer_init(serv->max_wait_time * 1000);
    }
    SwooleG.timer.add(&SwooleG.timer, serv->max_wait_time * 1000, 0, NULL, swWorker_onTimeout);

    swWorker_try_to_exit();
}

static void swWorker_onTimeout(swTimer *timer, swTimer_node *tnode)
{
    SwooleG.running = 0;
    SwooleG.main_reactor->running = 0;
    swoole_error_log(SW_LOG_WARNING, SW_ERROR_SERVER_WORKER_EXIT_TIMEOUT, "worker exit timeout, forced to terminate.");
}

swoole_timer_tick 添加定时任务

timer 模块另一个非常重要的功能是添加定时任务,一般是使用 swoole_timer_tick 函数、swoole_timer_after 函数、swoole_server->tick 函数、swoole_server->after 函数:

PHP_FUNCTION(swoole_timer_tick)
{
    long after_ms;
    zval *callback;
    zval *param = NULL;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "lz|z", &after_ms, &callback, &param) == FAILURE)
    {
        return;
    }

    long timer_id = php_swoole_add_timer(after_ms, callback, param, 1 TSRMLS_CC);
    if (timer_id < 0)
    {
        RETURN_FALSE;
    }
    else
    {
        RETURN_LONG(timer_id);
    }
}

PHP_FUNCTION(swoole_timer_after)
{
    long after_ms;
    zval *callback;
    zval *param = NULL;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "lz|z", &after_ms, &callback, &param) == FAILURE)
    {
        return;
    }

    long timer_id = php_swoole_add_timer(after_ms, callback, param, 0 TSRMLS_CC);
    if (timer_id < 0)
    {
        RETURN_FALSE;
    }
    else
    {
        RETURN_LONG(timer_id);
    }
}

php_swoole_add_timer 函数

本函数主要调用 SwooleG.timer.add 函数将添加新的定时任务,值得注意的是 swTimer_callback 类型的对象 cb 和两个回调函数 php_swoole_onIntervalphp_swoole_onTimeout,真正的回调函数存放在了 swTimer_callback 对象中,如果用户有参数设置,也会放入 cb->data 中。

long php_swoole_add_timer(int ms, zval *callback, zval *param, int persistent TSRMLS_DC)
{
    char *func_name = NULL;

    if (!swIsTaskWorker())
    {
        php_swoole_check_reactor();
    }

    php_swoole_check_timer(ms);
    swTimer_callback *cb = emalloc(sizeof(swTimer_callback));

    cb->data = &cb->_data;
    cb->callback = &cb->_callback;
    memcpy(cb->callback, callback, sizeof(zval));
    if (param)
    {
        memcpy(cb->data, param, sizeof(zval));
    }
    else
    {
        cb->data = NULL;
    }

    swTimerCallback timer_func;
    if (persistent)
    {
        cb->type = SW_TIMER_TICK;
        timer_func = php_swoole_onInterval;
    }
    else
    {
        cb->type = SW_TIMER_AFTER;
        timer_func = php_swoole_onTimeout;
    }

    sw_zval_add_ref(&cb->callback);
    if (cb->data)
    {
        sw_zval_add_ref(&cb->data);
    }

    swTimer_node *tnode = SwooleG.timer.add(&SwooleG.timer, ms, persistent, cb, timer_func);
    {
        tnode->type = SW_TIMER_TYPE_PHP;
        return tnode->id;
    }
}

void php_swoole_check_timer(int msec)
{
    if (unlikely(SwooleG.timer.fd == 0))
    {
        swTimer_init(msec);
    }
}

php_swoole_onInterval 函数

本函数主要调用 cb->callback,如果有用户参数,还要将 cb->data 放入调用函数中。

void php_swoole_onInterval(swTimer *timer, swTimer_node *tnode)
{
    zval *retval = NULL;
    int argc = 1;

    zval *ztimer_id;

    swTimer_callback *cb = tnode->data;

    SW_MAKE_STD_ZVAL(ztimer_id);
    ZVAL_LONG(ztimer_id, tnode->id);

    {
        zval **args[2];
        if (cb->data)
        {
            argc = 2;
            sw_zval_add_ref(&cb->data);
            args[1] = &cb->data;
        }
        args[0] = &ztimer_id;

        if (sw_call_user_function_ex(EG(function_table), NULL, cb->callback, &retval, argc, args, 0, NULL TSRMLS_CC) == FAILURE)
        {
            swoole_php_fatal_error(E_WARNING, "swoole_timer: onTimerCallback handler error");
            return;
        }
    }

    if (tnode->remove)
    {
        php_swoole_del_timer(tnode TSRMLS_CC);
    }
}

php_swoole_onTimeout 函数

与上一个函数类似,只是这次直接从 timer 中删除对应的元素。

void php_swoole_onTimeout(swTimer *timer, swTimer_node *tnode)
{
    {
        swTimer_callback *cb = tnode->data;
        zval *retval = NULL;

        {
            zval **args[2];
            int argc;

            if (NULL == cb->data)
            {
                argc = 0;
                args[0] = NULL;
            }
            else
            {
                argc = 1;
                args[0] = &cb->data;
            }

            if (sw_call_user_function_ex(EG(function_table), NULL, cb->callback, &retval, argc, args, 0, NULL TSRMLS_CC) == FAILURE)
            {
                swoole_php_fatal_error(E_WARNING, "swoole_timer: onTimeout handler error");
                return;
            }
        }

        php_swoole_del_timer(tnode TSRMLS_CC);
    }
}

Timer 模块时间轮算法

时间轮算法是各大网络模块采用的剔除空闲连接的方法,原理是构建一个首尾相连的循环数组,每隔数组元素中有若干个连接。如果某个连接有数据发送过来,将连接从所在的数组元素中删除,将连接放入最新的数组元素中,这样有数据来往的连接会一直在新数组元素中,空闲的连接所在的数组元素渐渐的变成了旧数组元素。每隔一段时间就按顺序清空旧数组元素的全部连接。

swTimeWheel_new 创建时间轮

时间轮的数据结构比较简单,由哈希表、size(循环数组总数量),current (循环数组当前最旧的数组元素,current-1 是循环数组中最新的数组元素)。swTimeWheel_new 函数很简单,就是创建这三个属性。

typedef struct
{
    uint16_t current;
    uint16_t size;
    swHashMap **wheel;

} swTimeWheel;

swTimeWheel* swTimeWheel_new(uint16_t size)
{
    swTimeWheel *tw = sw_malloc(sizeof(swTimeWheel));
    if (!tw)
    {
        swWarn("malloc(%ld) failed.", sizeof(swTimeWheel));
        return NULL;
    }

    tw->size = size;
    tw->current = 0;
    tw->wheel = sw_calloc(size, sizeof(void*));
    if (tw->wheel == NULL)
    {
        swWarn("malloc(%ld) failed.", sizeof(void*) * size);
        sw_free(tw);
        return NULL;
    }

    int i;
    for (i = 0; i < size; i++)
    {
        tw->wheel[i] = swHashMap_new(16, NULL);
        if (tw->wheel[i] == NULL)
        {
            swTimeWheel_free(tw);
            return NULL;
        }
    }
    return tw;
}

swTimeWheel_add 添加连接

main_reactor 有新连接进入的时候,需要将新的连接添加到时间轮中,新的连接会被放到最新的数组元素中,也就是 current-1 的元素中,然后设置 swConnection 中的 timewheel_index

void swTimeWheel_add(swTimeWheel *tw, swConnection *conn)
{
    uint16_t index = tw->current == 0 ? tw->size - 1 : tw->current - 1;
    swHashMap *new_set = tw->wheel[index];
    swHashMap_add_int(new_set, conn->fd, conn);

    conn->timewheel_index = index;

    swTraceLog(SW_TRACE_REACTOR, "current=%d, fd=%d, index=%d.", tw->current, conn->fd, index);
}

swTimeWheel_update 函数

当连接有数据传输的时候,需要更新该连接在时间轮中的位置,将该连接从原有的数组元素中删除,然后添加到最新的数组元素中,也就是 current-1 中,然后更新 swConnection 中的 timewheel_index

#define swTimeWheel_new_index(tw)   (tw->current == 0 ? tw->size - 1 : tw->current - 1)

void swTimeWheel_update(swTimeWheel *tw, swConnection *conn)
{
    uint16_t new_index = swTimeWheel_new_index(tw);
    swHashMap *new_set = tw->wheel[new_index];
    swHashMap_add_int(new_set, conn->fd, conn);

    swHashMap *old_set = tw->wheel[conn->timewheel_index];
    swHashMap_del_int(old_set, conn->fd);

    swTraceLog(SW_TRACE_REACTOR, "current=%d, fd=%d, old_index=%d, new_index=%d.", tw->current, conn->fd, new_index, conn->timewheel_index);

    conn->timewheel_index = new_index;
}

swTimeWheel_remove 函数

在时间轮中删除该连接,

void swTimeWheel_remove(swTimeWheel *tw, swConnection *conn)
{
    swHashMap *set = tw->wheel[conn->timewheel_index];
    swHashMap_del_int(set, conn->fd);
    swTraceLog(SW_TRACE_REACTOR, "current=%d, fd=%d.", tw->current, conn->fd);
}

swTimeWheel_forward 删除空闲连接

swTimeWheel_forward 将最旧的数组元素 current 中所有连接都关闭掉,然后将 current 递增。

void swTimeWheel_forward(swTimeWheel *tw, swReactor *reactor)
{
    swHashMap *set = tw->wheel[tw->current];
    tw->current = tw->current == tw->size - 1 ? 0 : tw->current + 1;

    swTraceLog(SW_TRACE_REACTOR, "current=%d.", tw->current);

    swConnection *conn;
    uint64_t fd;

    while (1)
    {
        conn = swHashMap_each_int(set, &fd);
        if (conn == NULL)
        {
            break;
        }

        conn->close_force = 1;
        conn->close_notify = 1;
        conn->close_wait = 1;
        conn->close_actively = 1;

        //notify to reactor thread
        if (conn->removed)
        {
            reactor->close(reactor, (int) fd);
        }
        else
        {
            reactor->set(reactor, fd, SW_FD_TCP | SW_EVENT_WRITE);
        }
    }
}

reactor 线程中时间轮的创建

  • 时间轮的创建在 reactor 线程进行事件循环之前,按照用户设置的连接最大空闲时间设置不同大小的时间轮,值得注意的是,时间轮最大是 SW_TIMEWHEEL_SIZE,也就是循环数组大小最大是 60。如果超过 60s 空闲时间,也仅仅建立 60 个元素的数组,但是这样会造成每个数组元素存放更多的连接。
  • 值得注意的是,当允许空闲时间超过 60s 时,heartbeat_interval * 1000reactor 的超时时间,例如空闲时间是 60s,那么每隔 6s,reactor 都会超时来检测空闲连接。当允许空闲时间小于 60s 时,reactor 统一每隔 1s 检测空闲连接。
  • 不同于 master 进程和 worker 线程,reactoronFinishonTimeout 不再采用默认的 swReactor_onTimeoutswReactor_onFinish 函数,而是采用空闲连接检测的 swReactorThread_onReactorCompleted 函数,该函数会调用 swTimeWheel_forward 来剔除空闲连接。
#define SW_TIMEWHEEL_SIZE          60

static int swReactorThread_loop(swThreadParam *param)
{
    ...
    
    if (serv->heartbeat_idle_time > 0)
    {
        if (serv->heartbeat_idle_time < SW_TIMEWHEEL_SIZE)
        {
            reactor->timewheel = swTimeWheel_new(serv->heartbeat_idle_time);
            reactor->heartbeat_interval = 1;
        }
        else
        {
            reactor->timewheel = swTimeWheel_new(SW_TIMEWHEEL_SIZE);
            reactor->heartbeat_interval = serv->heartbeat_idle_time / SW_TIMEWHEEL_SIZE;
        }
        reactor->last_heartbeat_time = 0;
        if (reactor->timewheel == NULL)
        {
            swSysError("thread->timewheel create failed.");
            return SW_ERR;
        }
        reactor->timeout_msec = reactor->heartbeat_interval * 1000;
        reactor->onFinish = swReactorThread_onReactorCompleted;
        reactor->onTimeout = swReactorThread_onReactorCompleted;
    }
    
    reactor->wait(reactor, NULL);
}

reactor 线程中时间轮的添加

当有新连接的时候,conn->connect_notify 会被置为 1,此时该连接文件描述符写就绪,然后就会调用 swReactorThread_onWrite,此时 reactor 线程将该连接添加到时间轮中。

static int swReactorThread_onWrite(swReactor *reactor, swEvent *ev)
{
    ...
    
    if (conn->connect_notify)
    {
        conn->connect_notify = 0;
        if (reactor->timewheel)
        {
            swTimeWheel_add(reactor->timewheel, conn);
        }
        
        ...
    }
    ...
}

reactor 线程中时间轮的更新

static int swReactorThread_onRead(swReactor *reactor, swEvent *event)
{
    ...
    if (reactor->timewheel && swTimeWheel_new_index(reactor->timewheel) != event->socket->timewheel_index)
    {
        swTimeWheel_update(reactor->timewheel, event->socket);
    }
    ...
}

reactor 线程中时间轮的剔除

当连接在允许的空闲时间之内没有任何数据发送,那么时间轮算法就要关闭该连接。关闭连接并不是直接 close 套接字,而是需要通知对应的 worker 进程调用 onClose 函数,然后才能关闭。具体的做法是设置 swConnectionclose_forceclose_notify 等成员变量为 1,并且关闭该连接的读就绪监听事件。

static void swReactorThread_onReactorCompleted(swReactor *reactor)
{
    swServer *serv = reactor->ptr;
    if (reactor->heartbeat_interval > 0 && reactor->last_heartbeat_time < serv->gs->now - reactor->heartbeat_interval)
    {
        swTimeWheel_forward(reactor->timewheel, reactor);
        reactor->last_heartbeat_time = serv->gs->now;
    }
}

void swTimeWheel_forward(swTimeWheel *tw, swReactor *reactor)
{
    ...
    
    conn->close_force = 1;
    conn->close_notify = 1;
    conn->close_wait = 1;
    conn->close_actively = 1;
    
    if (conn->removed)
    {
        reactor->close(reactor, (int) fd);
    }
    else
    {
        reactor->set(reactor, fd, SW_FD_TCP | SW_EVENT_WRITE);
    }
    ...
}

当该连接写就绪的时候,会调用 swReactorThread_onWrite 函数。这个时候就会调用 swServer_tcp_notify 函数,进而调用 swFactoryProcess_notifyswFactoryProcess_dispatch,最后调用 swReactorThread_send2worker 发送给了 worker 进程。

由于 reactor 启用的是水平触发,由于并未向该连接写入数据,因此很快又会触发写就绪事件调用 swReactorThread_onWrite 函数,这时如果 disable_notify 为 1(dispatch_mode 为 1 或 3),会直接执行 swReactorThread_close 函数关闭连接,假如此时 conn->out_buffer 中还有数据未发送,也会被抛弃。如果 disable_notify 为 0,则会继续向将要关闭的连接发送数据,直到接收到 SW_CHUNK_CLOSE 类型的消息。

static int swReactorThread_onWrite(swReactor *reactor, swEvent *ev)
{
    ...
    else if (conn->close_notify)
    {
        swServer_tcp_notify(serv, conn, SW_EVENT_CLOSE);
        conn->close_notify = 0;
        return SW_OK;
    }
    else if (serv->disable_notify && conn->close_force)
    {
        return swReactorThread_close(reactor, fd);
    }
    ...
}

int swServer_tcp_notify(swServer *serv, swConnection *conn, int event)
{
    swDataHead notify_event;
    notify_event.type = event;
    notify_event.from_id = conn->from_id;
    notify_event.fd = conn->fd;
    notify_event.from_fd = conn->from_fd;
    notify_event.len = 0;
    return serv->factory.notify(&serv->factory, &notify_event);
}

static int swFactoryProcess_notify(swFactory *factory, swDataHead *ev)
{
    memcpy(&sw_notify_data._send, ev, sizeof(swDataHead));
    sw_notify_data._send.len = 0;
    sw_notify_data.target_worker_id = -1;
    return factory->dispatch(factory, (swDispatchData *) &sw_notify_data);
}

static int swFactoryProcess_dispatch(swFactory *factory, swDispatchData *task)
{ 
   ...
   
   if (swEventData_is_stream(task->data.info.type))
   {
       swConnection *conn = swServer_connection_get(serv, fd);
       if (conn->closed)
        {
            //Connection has been clsoed by server
            if (!(task->data.info.type == SW_EVENT_CLOSE && conn->close_force))
            {
                return SW_OK;
            }
        }
        //converted fd to session_id
        task->data.info.fd = conn->session_id;
        task->data.info.from_fd = conn->from_fd;
   }
   
   return swReactorThread_send2worker((void *) &(task->data), send_len, target_worker_id);
}

worker 进程收到消息后会调用 swWorker_onTask 函数,进而调用 swFactoryProcess_end 函数,调用 serv->onClose 函数,并设置 swConnection 对象的 closed 为 1,然后调用 swFactoryProcess_finish 函数将数据包发送给 reactor 线程。

int swWorker_onTask(swFactory *factory, swEventData *task)
{
    switch (task->info.type)
    {
        ... 
        factory->end(factory, task->info.fd);
        break;
        ...
    }
}

static int swFactoryProcess_end(swFactory *factory, int fd)
{
    bzero(&_send, sizeof(_send));
    _send.info.fd = fd;
    _send.info.len = 0;
    _send.info.type = SW_EVENT_CLOSE;
   
   swConnection *conn = swWorker_get_connection(serv, fd);
   
   if (conn->close_force)
   {
       goto do_close;
   }
   else if (conn->closing)
   {
       swoole_error_log(SW_LOG_NOTICE, SW_ERROR_SESSION_CLOSING, "The connection[%d] is closing.", fd);
       return SW_ERR;
   }
   else if (conn->closed)
   {
       return SW_ERR;
   }
   else
   {
        do_close:
        conn->closing = 1;
        if (serv->onClose != NULL)
        {
            info.fd = fd;
            if (conn->close_actively)
            {
                info.from_id = -1;
            }
            else
            {
                info.from_id = conn->from_id;
            }
            info.from_fd = conn->from_fd;
            serv->onClose(serv, &info);
        }
        conn->closing = 0;
        conn->closed = 1;
        conn->close_errno = 0;
        return factory->finish(factory, &_send);
   }

}

reactor 通过 swReactorThread_onPipeReceive 收到 worker 进程的连接关闭通知后,调用 swReactorThread_send 函数。如果连接已经被关闭,或者缓冲区中没有任何数据的时候,直接调用 reactor->close 函数,也就是 swReactorThread_close 函数;如果缓冲区还有数据,那么需要将消息放到 conn->out_buffer 中等待着该连接写就绪回调 swReactorThread_close 函数(此时 close_notify 已经为 0)。

int swReactorThread_send(swSendData *_send)
{
    ...
    if (_send->info.type == SW_EVENT_CLOSE && (conn->close_reset || conn->removed))
    {
        goto close_fd;
    }
    
    ...
    if (swBuffer_empty(conn->out_buffer))
    {
        if (_send->info.type == SW_EVENT_CLOSE)
        {
            close_fd:
            reactor->close(reactor, fd);
            return SW_OK;
        }
    }
    
    swBuffer_chunk *chunk;
    //close connection
    if (_send->info.type == SW_EVENT_CLOSE)
    {
        chunk = swBuffer_new_chunk(conn->out_buffer, SW_CHUNK_CLOSE, 0);
        chunk->store.data.val1 = _send->info.type;
    }
    
    if (reactor->set(reactor, fd, SW_EVENT_TCP | SW_EVENT_WRITE | SW_EVENT_READ) < 0
            && (errno == EBADF || errno == ENOENT))
    {
        goto close_fd;
    }

    ...
    close_fd:
        reactor->close(reactor, fd);
        return SW_OK;
}

static int swReactorThread_onWrite(swReactor *reactor, swEvent *ev)
{
    ...
    else if (conn->close_notify)
    {
        swServer_tcp_notify(serv, conn, SW_EVENT_CLOSE);
        conn->close_notify = 0;
        return SW_OK;
    }
    else if (serv->disable_notify && conn->close_force)
    {
        return swReactorThread_close(reactor, fd);
    }

    _pop_chunk: while (!swBuffer_empty(conn->out_buffer))
    {
        chunk = swBuffer_get_chunk(conn->out_buffer);
        if (chunk->type == SW_CHUNK_CLOSE)
        {
            close_fd: reactor->close(reactor, fd);
            return SW_OK;
        }
        ...
    }
    ...
}

swReactorThread_close 函数会删除 swConnectionserver 中的所有痕迹,包括 reactor 中的监控,serv->stats 的成员变量,port->connection_num 递减,从时间轮中删除、sessionfd 置空等等工作。而且,还要清空套接字缓存中的所有数据,直接向客户端发送关闭请求。swReactor_close 函数释放内存,关闭套接字文件描述符。

int swReactorThread_close(swReactor *reactor, int fd)
{
    swServer *serv = SwooleG.serv;

    if (conn->removed == 0 && reactor->del(reactor, fd) < 0)
    {
        return SW_ERR;
    }

    sw_atomic_fetch_add(&serv->stats->close_count, 1);
    sw_atomic_fetch_sub(&serv->stats->connection_num, 1);

    swTrace("Close Event.fd=%d|from=%d", fd, reactor->id);

    //free the receive memory buffer
    swServer_free_buffer(serv, fd);

    swListenPort *port = swServer_get_port(serv, fd);
    sw_atomic_fetch_sub(&port->connection_num, 1);

#ifdef SW_USE_SOCKET_LINGER
    if (conn->close_force)
    {
        struct linger linger;
        linger.l_onoff = 1;
        linger.l_linger = 0;
        if (setsockopt(fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(struct linger)) == -1)
        {
            swWarn("setsockopt(SO_LINGER) failed. Error: %s[%d]", strerror(errno), errno);
        }
    }
#endif

#ifdef SW_REACTOR_USE_SESSION
    swSession *session = swServer_get_session(serv, conn->session_id);
    session->fd = 0;
#endif

#ifdef SW_USE_TIMEWHEEL
    if (reactor->timewheel)
    {
        swTimeWheel_remove(reactor->timewheel, conn);
    }
#endif

    return swReactor_close(reactor, fd);
}

int swReactor_close(swReactor *reactor, int fd)
{
    swConnection *socket = swReactor_get(reactor, fd);
    if (socket->out_buffer)
    {
        swBuffer_free(socket->out_buffer);
    }
    if (socket->in_buffer)
    {
        swBuffer_free(socket->in_buffer);
    }
    if (socket->websocket_buffer)
    {
        swString_free(socket->websocket_buffer);
    }
    bzero(socket, sizeof(swConnection));
    socket->removed = 1;
    swTraceLog(SW_TRACE_CLOSE, "fd=%d.", fd);
    return close(fd);
}

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