Nginx学习笔记（八） Nginx进程启动分析

Nginx进程启动分析

　　worker子进程的执行循环的函数是ngx_worker_process_cycle (src/os/unix/ngx_process_cycle.c)。

　　其中，捕获事件、分发事件的函数是ngx_process_events_and_timers(cycle);

static void
ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
{
    ngx_int_t worker = (intptr_t) data;

    ngx_uint_t         i;
    ngx_connection_t  *c;

    ngx_process = NGX_PROCESS_WORKER;//将全局变量ngx_process设置为worker进程
    ngx_worker_process_init(cycle, worker);//对worker进程进行初始化操作

    ngx_setproctitle("worker process");

#if (NGX_THREADS)
    {
    ngx_int_t         n;
    ngx_err_t         err;
    ngx_core_conf_t  *ccf;

    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

    if (ngx_threads_n) {
        if (ngx_init_threads(ngx_threads_n, ccf->thread_stack_size, cycle)
            == NGX_ERROR)
        {
            /* fatal */
            exit(2);
        }

        err = ngx_thread_key_create(&ngx_core_tls_key);
        if (err != 0) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, err,
                          ngx_thread_key_create_n " failed");
            /* fatal */
            exit(2);
        }

        for (n = 0; n < ngx_threads_n; n++) {

            ngx_threads[n].cv = ngx_cond_init(cycle->log);

            if (ngx_threads[n].cv == NULL) {
                /* fatal */
                exit(2);
            }

            if (ngx_create_thread((ngx_tid_t *) &ngx_threads[n].tid,
                                  ngx_worker_thread_cycle,
                                  (void *) &ngx_threads[n], cycle->log)
                != 0)
            {
                /* fatal */
                exit(2);
            }
        }
    }
    }
#endif

    for ( ;; ) {
        //ngx_exiting是在worker进程收到SIGQUIT信号后设置的
        if (ngx_exiting) {

            c = cycle->connections;
            //退出前，处理每个连接上的事件
            for (i = 0; i < cycle->connection_n; i++) {

                /* THREAD: lock */

                if (c[i].fd != -1 && c[i].idle) {
                    c[i].close = 1;
                    c[i].read->handler(c[i].read);
                }
            }

            if (ngx_event_timer_rbtree.root == ngx_event_timer_rbtree.sentinel)
            {
                ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");

                ngx_worker_process_exit(cycle);
            }
        }

        ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "worker cycle");
        //处理各种事件，主要的处理函数！！！
        ngx_process_events_and_timers(cycle);
       //worker进程收到了SIGINT信号
        if (ngx_terminate) {
            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");

            ngx_worker_process_exit(cycle);
        }
        //进程收到了SIGQUIT信号，ngx_exiting设置为1，同时关闭监听套接口
        if (ngx_quit) {
            ngx_quit = 0;
            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
                          "gracefully shutting down");
            ngx_setproctitle("worker process is shutting down");

            if (!ngx_exiting) {
                ngx_close_listening_sockets(cycle);
                ngx_exiting = 1;
            }
        }
        //worker进程收到了SIGUSR1信号
        if (ngx_reopen) {
            ngx_reopen = 0;
            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");
            ngx_reopen_files(cycle, -1);
        }
    }
}

　　其中初始化函数分析，如下：

static void
ngx_worker_process_init(ngx_cycle_t *cycle, ngx_int_t worker)
{
    sigset_t          set;
    uint64_t          cpu_affinity;
    ngx_int_t         n;
    ngx_uint_t        i;
    struct rlimit     rlmt;
    ngx_core_conf_t  *ccf;
    ngx_listening_t  *ls;
　　//配置一些环境变量
    if (ngx_set_environment(cycle, NULL) == NULL) {
        /* fatal */
        exit(2);
    }
　　 //获取配置信息
    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

    if (worker >= 0 && ccf->priority != 0) {
        if (setpriority(PRIO_PROCESS, 0, ccf->priority) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "setpriority(%d) failed", ccf->priority);
        }
    }
    if (ccf->rlimit_nofile != NGX_CONF_UNSET) {
        rlmt.rlim_cur = (rlim_t) ccf->rlimit_nofile;
        rlmt.rlim_max = (rlim_t) ccf->rlimit_nofile;

        if (setrlimit(RLIMIT_NOFILE, &rlmt) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "setrlimit(RLIMIT_NOFILE, %i) failed",
                          ccf->rlimit_nofile);
        }
    }
    if (ccf->rlimit_core != NGX_CONF_UNSET) {
        rlmt.rlim_cur = (rlim_t) ccf->rlimit_core;
        rlmt.rlim_max = (rlim_t) ccf->rlimit_core;
        if (setrlimit(RLIMIT_CORE, &rlmt) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "setrlimit(RLIMIT_CORE, %O) failed",
                          ccf->rlimit_core);
        }
    }
#ifdef RLIMIT_SIGPENDING
    if (ccf->rlimit_sigpending != NGX_CONF_UNSET) {
        rlmt.rlim_cur = (rlim_t) ccf->rlimit_sigpending;
        rlmt.rlim_max = (rlim_t) ccf->rlimit_sigpending;

        if (setrlimit(RLIMIT_SIGPENDING, &rlmt) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "setrlimit(RLIMIT_SIGPENDING, %i) failed",
                          ccf->rlimit_sigpending);
        }
    }
#endif
    //设置UID GROUPUID
    if (geteuid() == 0) {
        if (setgid(ccf->group) == -1) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                          "setgid(%d) failed", ccf->group);
            /* fatal */
            exit(2);
        }
        if (initgroups(ccf->username, ccf->group) == -1) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                          "initgroups(%s, %d) failed",
                          ccf->username, ccf->group);
        }
        if (setuid(ccf->user) == -1) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                          "setuid(%d) failed", ccf->user);
            /* fatal */
            exit(2);
        }
    }
    //设置CPU亲和性
    if (worker >= 0) {
        cpu_affinity = ngx_get_cpu_affinity(worker);

        if (cpu_affinity) {
            ngx_setaffinity(cpu_affinity, cycle->log);
        }
    }
#if (NGX_HAVE_PR_SET_DUMPABLE)

    /* allow coredump after setuid() in Linux 2.4.x */

    if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) == -1) {
        ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                      "prctl(PR_SET_DUMPABLE) failed");
    }
#endif
    //切换工作目录
    if (ccf->working_directory.len) {
        if (chdir((char *) ccf->working_directory.data) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "chdir("%s") failed", ccf->working_directory.data);
            /* fatal */
            exit(2);
        }
    }
    sigemptyset(&set);
    //清除所有信号
    if (sigprocmask(SIG_SETMASK, &set, NULL) == -1) {
        ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                      "sigprocmask() failed");
    }

    /*
     * disable deleting previous events for the listening sockets because
     * in the worker processes there are no events at all at this point
     */
    ls = cycle->listening.elts;
　　//清除监听socket上以前的事件 
    for (i = 0; i < cycle->listening.nelts; i++) {
        ls[i].previous = NULL;
    }
　　//对所有模块进行初始化
    for (i = 0; ngx_modules[i]; i++) {
        if (ngx_modules[i]->init_process) {
            if (ngx_modules[i]->init_process(cycle) == NGX_ERROR) {
                /* fatal */
                exit(2);
            }
        }
    }
    //将其他进程的channel[1]关闭，自己的channel[0]关闭
    for (n = 0; n < ngx_last_process; n++) {
        if (ngx_processes[n].pid == -1) {
            continue;
        }
        if (n == ngx_process_slot) {
            continue;
        }
        if (ngx_processes[n].channel[1] == -1) {
            continue;
        }
        if (close(ngx_processes[n].channel[1]) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "close() channel failed");
        }
    }

    if (close(ngx_processes[ngx_process_slot].channel[0]) == -1) {
        ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                      "close() channel failed");
    }
#if 0
    ngx_last_process = 0;
#endif
　　//给ngx_channel注册一个读事件处理函数
    if (ngx_add_channel_event(cycle, ngx_channel, NGX_READ_EVENT,
                              ngx_channel_handler)== NGX_ERROR){
        /* fatal */
        exit(2);
    }
}