Nginx學習之六-nginx核心程序模型
阿新 • • 發佈：2019-01-23
master程序中for(::)無限迴圈內有一個關鍵的sigsuspend()函式呼叫，該函式呼叫是的master程序的大部分時間都處於掛起狀態，直到master程序收到訊號為止。
master程序通過檢查一下7個標誌位來決定ngx_master_process_cycle方法的執行：
sig_atomic_t ngx_reap;
sig_atomic_t ngx_terminate;
sig_atomic_t ngx_quit;
sig_atomic_t ngx_reconfigure;
sig_atomic_t ngx_reopen;
sig_atomic_t ngx_change_binary;
sig_atomic_t ngx_noaccept;
程序中接收到的訊號對Nginx框架的意義：
還有一個標誌位會用到：ngx_restart，它僅僅是在master工作流程中作為標誌位使用，與訊號無關。
核心程式碼（ngx_process_cycle.c）：
ngx_start_worker_processes函式：
sig_atomic_t ngx_quit;
sig_atomic_t ngx_reconfigure;
sig_atomic_t ngx_reopen;
sig_atomic_t ngx_change_binary;
sig_atomic_t ngx_noaccept;
程序中接收到的訊號對Nginx框架的意義：
| 訊號 | 對應程序中的全域性標誌位變數 | 意義 |
| QUIT | ngx_quit | 優雅地關閉整個服務 |
| TERM或INT | ngx_terminate | 強制關閉整個服務 |
| USR1 | ngx_reopen | 重新開啟服務中的所有檔案 |
| WINCH | ngx_noaccept | 所有子程序不再接受處理新的連線，實際相當於對所有子程序傳送QUIT訊號 |
| USR2 | ngx_change_binary | 平滑升級到新版本的Nginx程式 |
| HUP | ng_reconfigure | 重讀配置檔案 |
| CHLD | ngx_reap | 有子程序以外結束，需要監控所有子程序 |
void ngx_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; //訊號處理設定工作 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); //其中包含了fork產生子程序的內容 ngx_start_worker_processes(cycle, ccf->worker_processes, NGX_PROCESS_RESPAWN); //Cache管理程序與cache載入程序的主流程 ngx_start_cache_manager_processes(cycle, 0); ngx_new_binary = 0; delay = 0; sigio = 0; live = 1; for ( ;; ) {//迴圈 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);//master程序休眠，等待接受訊號被啟用 ngx_time_update(); ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "wake up, sigio %i", sigio); //標誌位為1表示需要監控所有子程序 if (ngx_reap) { ngx_reap = 0; ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children"); live = ngx_reap_children(cycle);//管理子程序 } //當live標誌位為0（表示所有子程序已經退出）、ngx_terminate標誌位為1或者ngx_quit標誌位為1表示要退出master程序 if (!live && (ngx_terminate || ngx_quit)) { ngx_master_process_exit(cycle);//退出master程序 } //ngx_terminate標誌位為1，強制關閉服務，傳送TERM訊號到所有子程序 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; } //ngx_quit標誌位為1，優雅的關閉服務 if (ngx_quit) { ngx_signal_worker_processes(cycle, ngx_signal_value(NGX_SHUTDOWN_SIGNAL));//向所有子程序傳送quit訊號 ls = cycle->listening.elts; for (n = 0; n < cycle->listening.nelts; n++) {//關閉監聽埠 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; } //ngx_reconfigure標誌位為1，重新讀取配置檔案 //nginx不會讓原來的worker子程序再重新讀取配置檔案，其策略是重新初始化ngx_cycle_t結構體，用它來讀取新的額配置檔案 //再建立新的額worker子程序，銷燬舊的worker子程序 if (ngx_reconfigure) { ngx_reconfigure = 0; //ngx_new_binary標誌位為1，平滑升級Nginx 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"); //初始化ngx_cycle_t結構體 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); //建立新的worker子程序 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; //向所有子程序傳送QUIT訊號 ngx_signal_worker_processes(cycle, ngx_signal_value(NGX_SHUTDOWN_SIGNAL)); } //ngx_restart標誌位在ngx_noaccepting（表示正在停止接受新的連線）為1的時候被設定為1. //重啟子程序 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; } //ngx_reopen標誌位為1，重新開啟所有檔案 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)); } //平滑升級Nginx 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); } //ngx_noaccept為1，表示所有子程序不再處理新的連線 if (ngx_noaccept) { ngx_noaccept = 0; ngx_noaccepting = 1; ngx_signal_worker_processes(cycle, ngx_signal_value(NGX_SHUTDOWN_SIGNAL)); } } }
ngx_start_worker_processes函式：