php-fpm定时器

php-fpm有三种定时器

1）主进程接收到用户的信号，例如sigusr,主进程执行kill(子进程号,sigquit),的同时，设置定时器，在一个无限循环里如果当前时间 大于或等于 该定时器的过期时间，则主进程执行kill(子进程号，sigterm);

2)对于在php-fpm里设置了request_terminate_timeout 和request_slowlog_timeout

　　注:set_time_limit()和max_execution_time只影响脚本本身执行的时间。

　　（这两个参数在php.ini中）任何发生在诸如使用system()的系统调用，流操作，数据库操作等的脚本执行的最大时间不包括其中.

　　建立定时器是在函数fpm_event_loop中的fpm_pctl_heartbeat函数，调用前有个判断条件 fpm_globals.heartbeat需要大于0

在解析php-fpm.conf文件中，fpm_globals.heartbeat最终为request_terminate_timeout和request_slowlog_timeout较小的一个

static int fpm_conf_process_all_pools(){
    //省略无关代码 

    if (wp->config->request_terminate_timeout) {
        fpm_globals.heartbeat = fpm_globals.heartbeat ? MIN(fpm_globals.heartbeat, (wp->config->request_terminate_timeout * 1000) / 3) : (wp->config->request_terminate_timeout * 1000) / 3;
    }

    if (wp->config->request_slowlog_timeout) {
        fpm_globals.heartbeat = fpm_globals.heartbeat ? MIN(fpm_globals.heartbeat, (wp->config->request_slowlog_timeout * 1000) / 3) : (wp->config->request_slowlog_timeout * 1000) / 3;

    }  
}

/* a minimum of 130ms heartbeat for pctl */

#define FPM_PCTL_MIN_HEARTBEAT (130)

void fpm_pctl_heartbeat(struct fpm_event_s *ev, short which, void *arg) /* {{{ */
{
    static struct fpm_event_s heartbeat;
    struct timeval now;

    if (fpm_globals.parent_pid != getpid()) {
        return; /* sanity check */
    }

    if (which == FPM_EV_TIMEOUT) {
        fpm_clock_get(&now);
        fpm_pctl_check_request_timeout(&now);
        return;
    }

    /* ensure heartbeat is not lower than FPM_PCTL_MIN_HEARTBEAT */      //这里又和默认的相比,取最大的
    fpm_globals.heartbeat = MAX(fpm_globals.heartbeat, FPM_PCTL_MIN_HEARTBEAT);

    /* first call without setting to initialize the timer */
    zlog(ZLOG_DEBUG, "heartbeat have been set up with a timeout of %dms", fpm_globals.heartbeat);
    fpm_event_set_timer(&heartbeat, FPM_EV_PERSIST, &fpm_pctl_heartbeat, NULL);
    fpm_event_add(&heartbeat, fpm_globals.heartbeat);
}

3)对于dynamic方式的子进程，需要定时检查，例如：当空闲的子进程个数小于允许最小的空闲子进程个数时，需要fork;当空闲的子进程个数大于允许的最大的空闲子进程个数时，需要kill掉

/* 1s (in ms) heartbeat for idle server maintenance */
#define FPM_IDLE_SERVER_MAINTENANCE_HEARTBEAT (1000)

　　即每1S执行一次

　　假设当前时间为10:00:00,那么超时时间为10:01:00, 在fpm_event_loop这个无限循环中,当 当前 时间 大于或等于这个超时时间时，会触发fpm_pctl_perform_idle_server_maintenance这个函数，当空闲的子进程个数小于允许最小的空闲子进程个数时，需要fork;当空闲的子进程个数大于允许的最大的空闲子进程个数时，需要kill掉，执行完函数后，假设当前时间为10:05:00,那么下一次超时时间为10:06:00,依次类推 ，参考这里

　　建立定时器是在函数fpm_event_loop中的fpm_pctl_perform_idle_server_maintenance_heartbeat(NULL, 0, NULL)

　　

void fpm_pctl_perform_idle_server_maintenance_heartbeat(struct fpm_event_s *ev, short which, void *arg) /* {{{ */
{
    static struct fpm_event_s heartbeat;
    struct timeval now;

    if (fpm_globals.parent_pid != getpid()) {
        return; /* sanity check */
    }

    if (which == FPM_EV_TIMEOUT) {
        fpm_clock_get(&now);
        if (fpm_pctl_can_spawn_children()) {
            fpm_pctl_perform_idle_server_maintenance(&now);

            /* if it's a child, stop here without creating the next event
             * this event is reserved to the master process
             */
            if (fpm_globals.is_child) {
                return;
            }
        }
        return;
    }

    /* first call without setting which to initialize the timer */
    fpm_event_set_timer(&heartbeat, FPM_EV_PERSIST, &fpm_pctl_perform_idle_server_maintenance_heartbeat, NULL);
    fpm_event_add(&heartbeat, FPM_IDLE_SERVER_MAINTENANCE_HEARTBEAT);
}

因为是第一次调用 ，所以直接走到倒数第二，第三行， FPM_EV_TIMEOUT 为1 

#define FPM_EV_TIMEOUT  (1 << 0)
#define FPM_EV_READ     (1 << 1)
#define FPM_EV_PERSIST  (1 << 2)
#define FPM_EV_EDGE     (1 << 3)

fpm_event_set_timer其实是个宏，

#define fpm_event_set_timer(ev, flags, cb, arg) fpm_event_set((ev), -1, (flags), (cb), (arg))

fpm_event_set中的fd参数传的是-1,因为是定时器，故没有文件描述符，并且调用回调函数
得到现在当前时间，由于是每1分钟执行一次,所以超时时间是当前时间+1分钟

int fpm_event_set(struct fpm_event_s *ev, int fd, int flags, void (*callback)(struct fpm_event_s *, short, void *), void *arg) /* {{{ */
{
    if (!ev || !callback || fd < -1) {
        return -1;
    }
    memset(ev, 0, sizeof(struct fpm_event_s));
    ev->fd = fd;
    ev->callback = callback;
    ev->arg = arg;
    ev->flags = flags;
    return 0;
}
/* }}} */

int fpm_event_add(struct fpm_event_s *ev, unsigned long int frequency) /* {{{ */
{
    struct timeval now;
    struct timeval tmp;

    if (!ev) {
        return -1;
    }

    ev->index = -1;

    /* it's a triggered event on incoming data */
    if (ev->flags & FPM_EV_READ) {
        ev->which = FPM_EV_READ;
        if (fpm_event_queue_add(&fpm_event_queue_fd, ev) != 0) {
            return -1;
        }
        return 0;
    }

    /* it's a timer event */
    ev->which = FPM_EV_TIMEOUT;

    fpm_clock_get(&now);
    if (frequency >= 1000) {
        tmp.tv_sec = frequency / 1000;
        tmp.tv_usec = (frequency % 1000) * 1000;
    } else {
        tmp.tv_sec = 0;
        tmp.tv_usec = frequency * 1000;
    }
    ev->frequency = tmp;
    fpm_event_set_timeout(ev, now);  //#define fpm_event_set_timeout(ev, now) timeradd(&(now), &(ev)->frequency, &(ev)->timeout);

    if (fpm_event_queue_add(&fpm_event_queue_timer, ev) != 0) {
        return -1;
    }

    return 0;
}

将该定时器放到定时器专属的队列中

static int fpm_event_queue_add(struct fpm_event_queue_s **queue, struct fpm_event_s *ev) /* {{{ */
{
    struct fpm_event_queue_s *elt;

    if (!queue || !ev) {
        return -1;
    }

    if (fpm_event_queue_isset(*queue, ev)) {
        return 0;
    }

    if (!(elt = malloc(sizeof(struct fpm_event_queue_s)))) {
        zlog(ZLOG_SYSERROR, "Unable to add the event to queue: malloc() failed");
        return -1;
    }
    elt->prev = NULL;
    elt->next = NULL;
    elt->ev = ev;

    if (*queue) {
        (*queue)->prev = elt;
        elt->next = *queue;
    }
    *queue = elt;

    /* ask the event module to add the fd from its own queue */ //定时器不会走到这里
    if (*queue == fpm_event_queue_fd && module->add) {
        module->add(ev);
    }

    return 0;    
}

定时器队列结构体， static struct fpm_event_queue_s *fpm_event_queue_timer = NULL; 是个全局变量

typedef struct fpm_event_queue_s {
    struct fpm_event_queue_s *prev;
    struct fpm_event_queue_s *next;
    struct fpm_event_s *ev;
} fpm_event_queue;