ngx_master_process_cycle函数详解

ngx_master_process_cycle在src/os/unix/ngx_process_cycle.c中定义， 该方法是个无限循环函数， 用于实现nginx的主功能。

下面是该函数的详细代码：

voidngx_master_process_cycle(ngx_cycle_t *cycle){    char              *title;    u_char            *p;    size_t             size;    ngx_int_t          i;    ngx_uint_t         n, sigio;    sigset_t           set;    struct itimerval   itv;    ngx_uint_t         live;    ngx_msec_t         delay;    ngx_listening_t   *ls;    ngx_core_conf_t   *ccf;    sigemptyset(&set);    sigaddset(&set, SIGCHLD);    sigaddset(&set, SIGALRM);    sigaddset(&set, SIGIO);    sigaddset(&set, SIGINT);    sigaddset(&set, ngx_signal_value(NGX_RECONFIGURE_SIGNAL));    sigaddset(&set, ngx_signal_value(NGX_REOPEN_SIGNAL));    sigaddset(&set, ngx_signal_value(NGX_NOACCEPT_SIGNAL));    sigaddset(&set, ngx_signal_value(NGX_TERMINATE_SIGNAL));    sigaddset(&set, ngx_signal_value(NGX_SHUTDOWN_SIGNAL));    sigaddset(&set, ngx_signal_value(NGX_CHANGEBIN_SIGNAL));    if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {        ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,                      "sigprocmask() failed");    }    sigemptyset(&set);    size = sizeof(master_process);    for (i = 0; i < ngx_argc; i++) {        size += ngx_strlen(ngx_argv[i]) + 1;    }    title = ngx_pnalloc(cycle->pool, size);    p = ngx_cpymem(title, master_process, sizeof(master_process) - 1);    for (i = 0; i < ngx_argc; i++) {        *p++ = ' ';        p = ngx_cpystrn(p, (u_char *) ngx_argv[i], size);    }    ngx_setproctitle(title);    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);    ngx_start_worker_processes(cycle, ccf->worker_processes,                               NGX_PROCESS_RESPAWN);    ngx_start_cache_manager_processes(cycle, 0);    ngx_new_binary = 0;    delay = 0;    sigio = 0;    live = 1;    for ( ;; ) {        if (delay) {            if (ngx_sigalrm) {                sigio = 0;                delay *= 2;                ngx_sigalrm = 0;            }            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,                           "termination cycle: %d", delay);            itv.it_interval.tv_sec = 0;            itv.it_interval.tv_usec = 0;            itv.it_value.tv_sec = delay / 1000;            itv.it_value.tv_usec = (delay % 1000 ) * 1000;            if (setitimer(ITIMER_REAL, &itv, NULL) == -1) {                ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,                              "setitimer() failed");            }        }        ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "sigsuspend");        sigsuspend(&set);        ngx_time_update();        ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,                       "wake up, sigio %i", sigio);        if (ngx_reap) {            ngx_reap = 0;            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children");            live = ngx_reap_children(cycle);        }        if (!live && (ngx_terminate || ngx_quit)) {            ngx_master_process_exit(cycle);        }        if (ngx_terminate) {            if (delay == 0) {                delay = 50;            }            if (sigio) {                sigio--;                continue;            }            sigio = ccf->worker_processes + 2 /* cache processes */;            if (delay > 1000) {                ngx_signal_worker_processes(cycle, SIGKILL);            } else {                ngx_signal_worker_processes(cycle,                                       ngx_signal_value(NGX_TERMINATE_SIGNAL));            }            continue;        }        if (ngx_quit) {            ngx_signal_worker_processes(cycle,                                        ngx_signal_value(NGX_SHUTDOWN_SIGNAL));            ls = cycle->listening.elts;            for (n = 0; n < cycle->listening.nelts; n++) {                if (ngx_close_socket(ls[n].fd) == -1) {                    ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,                                  ngx_close_socket_n " %V failed",                                  &ls[n].addr_text);                }            }            cycle->listening.nelts = 0;            continue;        }        if (ngx_reconfigure) {            ngx_reconfigure = 0;            if (ngx_new_binary) {                ngx_start_worker_processes(cycle, ccf->worker_processes,                                           NGX_PROCESS_RESPAWN);                ngx_start_cache_manager_processes(cycle, 0);                ngx_noaccepting = 0;                continue;            }            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reconfiguring");            cycle = ngx_init_cycle(cycle);            if (cycle == NULL) {                cycle = (ngx_cycle_t *) ngx_cycle;                continue;            }            ngx_cycle = cycle;            ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx,                                                   ngx_core_module);            ngx_start_worker_processes(cycle, ccf->worker_processes,                                       NGX_PROCESS_JUST_RESPAWN);            ngx_start_cache_manager_processes(cycle, 1);            /* allow new processes to start */            ngx_msleep(100);            live = 1;            ngx_signal_worker_processes(cycle,                                        ngx_signal_value(NGX_SHUTDOWN_SIGNAL));        }        if (ngx_restart) {            ngx_restart = 0;            ngx_start_worker_processes(cycle, ccf->worker_processes,                                       NGX_PROCESS_RESPAWN);            ngx_start_cache_manager_processes(cycle, 0);            live = 1;        }        if (ngx_reopen) {            ngx_reopen = 0;            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");            ngx_reopen_files(cycle, ccf->user);            ngx_signal_worker_processes(cycle,                                        ngx_signal_value(NGX_REOPEN_SIGNAL));        }        if (ngx_change_binary) {            ngx_change_binary = 0;            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "changing binary");            ngx_new_binary = ngx_exec_new_binary(cycle, ngx_argv);        }        if (ngx_noaccept) {            ngx_noaccept = 0;            ngx_noaccepting = 1;            ngx_signal_worker_processes(cycle,                                        ngx_signal_value(NGX_SHUTDOWN_SIGNAL));        }    }}