信号处理

worker信号主要是ngx_signal_handler函数来处理，它接收到某信号后会设置对应的全局标志位。

worker进程会调用ngx_worker_process_cycle函数循环检测标志位并进行对应操作。

ngx_worker_process_cycle函数

ngx_worker_process_cycle函数主要关注4个全局标志位：

>
| 标志位 | 含义 |
| ————————— | ————————— |
| ngx_quit | 优雅地关闭整个服务 |
| ngx_terminate | 强制关闭整个服务 |
| ngx_reopen | 重新打开服务中的所有文件 |
| ngx_exiting | 退出进程标志位 |

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;

    ngx_worker_process_init(cycle, worker);

    ngx_setproctitle("worker process");

    for ( ;; ) {

ngx_exiting 标志位

对进程的连接进行清理并进程退出

        if (ngx_exiting) {

            c = cycle->connections;

            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");

        ngx_process_events_and_timers(cycle);

SIGINT信号

检测到SIGINT信号，调用ngx_worker_process进程退出

        if (ngx_terminate) {
            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");

            ngx_worker_process_exit(cycle);
        }

SIGQUIT信号

检测到SIGQUIT信号, 管理套接字设置ngx_exiting标志位

        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;
            }
        }

SIGINT信号

检测到SIGINT信号，重新打开文件

        if (ngx_reopen) {
            ngx_reopen = 0;
            ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");
            ngx_reopen_files(cycle, -1);
        }
    }
}