evsignal.h

/*
 * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef _EVSIGNAL_H_
#define _EVSIGNAL_H_

typedef void (*ev_sighandler_t)(int);

struct evsignal_info {
    // EVLIST_INTERNAL EV_PERSIST
    struct event ev_signal;
    // ev_signal_pair[1]作为read放入事件循环中监听，当有信号发生的时候，
    // 通过写入ev_signal_pair[0]，可以唤醒并回调与ev_signal_pair[1]关联
    // 的事件回调，这样的作用是可以让所有回调在事件循环中
    // 执行，不用担心中断问题，同时有多个信号发生的时候，
    // 处理更快，因为只需要往ev_signal_pair[1]写入一个字节进行
    // 通知即可，memcache源码中master线程唤醒worker线程处理客户
    // 客户连接也是这么做
    int ev_signal_pair[2];
    // ev_signal是否已经放入event loop当中
    int ev_signal_added;
    // 表示已经捕捉到信号，不管什么信号
    volatile sig_atomic_t evsignal_caught;
    // 监听不同信号的event，每种信号一个链表，多个event可以监听同一个信号
    struct event_list evsigevents[NSIG];

    // 不同信号捕捉到的次数
    sig_atomic_t evsigcaught[NSIG];

    // 一个信号一个信号处理回调，HAVE_SIGACTION是否有sigaction函数
    // 用于保存之前的信号信息，以信号值为下标取对应的元素
#ifdef HAVE_SIGACTION
    struct sigaction** sh_old;
#else
    ev_sighandler_t** sh_old;
#endif
    // 信号类型的最大值
    int sh_old_max;
};
int evsignal_init(struct event_base*);
void evsignal_process(struct event_base*);
int evsignal_add(struct event*);
int evsignal_del(struct event*);
void evsignal_dealloc(struct event_base*);

#endif /* _EVSIGNAL_H_ */