lighttpd中的watcher workers模型

/* start watcher and workers */
	num_childs = srv->srvconf.max_worker;
	if (num_childs > 0) {
		int child = 0;
		while (!child && !srv_shutdown && !graceful_shutdown) {
			if (num_childs > 0) {
				switch (fork()) {
				case -1:/*出错返回父进-1*/
					return -1;
				case 0:/*fork成功 返回给子进程 0*/
					child = 1;
					break;
				default::/*fork成功 返回给父进程的是子进程ID*/
					num_childs--;
					break;
				}
			} else {
				int status;

				if (-1 != wait(&status)) {
					/** 
					 * one of our workers went away 
					 */
					num_childs++;
				} else {
					switch (errno) {
					case EINTR:
						/**
						 * if we receive a SIGHUP we have to close our logs ourself as we don't 
						 * have the mainloop who can help us here
						 */
						if (handle_sig_hup) {
							handle_sig_hup = 0;

							log_error_cycle(srv);

							/**
							 * forward to all procs in the process-group
							 * 
							 * we also send it ourself
							 */
							if (!forwarded_sig_hup) {
								forwarded_sig_hup = 1;
								kill(0, SIGHUP);
							}
						}
						break;
					default:
						break;
					}
				}
			}
		}

		/**
		 * for the parent this is the exit-point 
		 */
		if (!child) {
			/** 
			 * kill all children too 
			 */
			if (graceful_shutdown) {
				kill(0, SIGINT);
			} else if (srv_shutdown) {
				kill(0, SIGTERM);
			}

			log_error_close(srv);
			network_close(srv);
			connections_free(srv);
			plugins_free(srv);
			server_free(srv);
			return 0;
		}
	}

这个模型主要是利用了fork函数的特性，fork函数 成功的时候，在子进程中获得返回值0，在父进程中获得为子进程的ID,失败出错时 是在父进程中获得-1