static int
evsig_add(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
{
struct evsig_info *sig = &base->sig;
(void)p;
EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
/* catch signals if they happen quickly */
EVSIGBASE_LOCK();
if (evsig_base != base && evsig_base_n_signals_added) {
event_warnx("Added a signal to event base %p with signals "
"already added to event_base %p. Only one can have "
"signals at a time with the %s backend. The base with "
"the most recently added signal or the most recent "
"event_base_loop() call gets preference; do "
"not rely on this behavior in future Libevent versions.",
base, evsig_base, base->evsel->name);
}
evsig_base = base;
evsig_base_n_signals_added = ++sig->ev_n_signals_added;
evsig_base_fd = base->sig.ev_signal_pair[1];
EVSIGBASE_UNLOCK();
event_debug(("%s: %d: changing signal handler", __func__, (int)evsignal));
if (evsig_set_handler_(base, (int)evsignal, evsig_handler) == -1) {
goto err;
}
if (!sig->ev_signal_added) {
if (event_add(&sig->ev_signal, NULL))
goto err;
sig->ev_signal_added = 1;
}
return (0);
err:
EVSIGBASE_LOCK();
--evsig_base_n_signals_added;
--sig->ev_n_signals_added;
EVSIGBASE_UNLOCK();
return (-1);
}
void
evsig_set_base_(struct event_base *base)
{
EVSIGBASE_LOCK();
evsig_base = base;
evsig_base_n_signals_added = base->sig.ev_n_signals_added;
evsig_base_fd = base->sig.ev_signal_pair[1];
EVSIGBASE_UNLOCK();
}
void
evsig_set_base(struct event_base *base)
{
EVSIGBASE_LOCK();
evsig_base = base;
evsig_base_n_signals_added = base->sig.ev_n_signals_added;
evsig_base_fd = base->sig.ev_signal_pair[0];//0用来信号处理函数发送给base，1已用base接收信号
EVSIGBASE_UNLOCK();
}
static int
evsig_del(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
{
EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
event_debug(("%s: %d: restoring signal handler", __func__, evsignal));
EVSIGBASE_LOCK();
--evsig_base_n_signals_added;
--base->sig.ev_n_signals_added;
EVSIGBASE_UNLOCK();
return (evsig_restore_handler_(base, (int)evsignal));
}
void
evsig_dealloc(struct event_base *base)
{
int i = 0;
if (base->sig.ev_signal_added) {
event_del(&base->sig.ev_signal);//删除信号事件
base->sig.ev_signal_added = 0;
}
/* debug event is created in evsig_init/event_assign even when
* ev_signal_added == 0, so unassign is required */
event_debug_unassign(&base->sig.ev_signal);
//恢复所有的信号处理函数
for (i = 0; i < NSIG; ++i) {
if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
_evsig_restore_handler(base, i);
}
EVSIGBASE_LOCK();
if (base == evsig_base) {
evsig_base = NULL;
evsig_base_n_signals_added = 0;
evsig_base_fd = -1;
}
EVSIGBASE_UNLOCK();
//关闭socketpair描述府
if (base->sig.ev_signal_pair[0] != -1) {
evutil_closesocket(base->sig.ev_signal_pair[0]);
base->sig.ev_signal_pair[0] = -1;
}
if (base->sig.ev_signal_pair[1] != -1) {
evutil_closesocket(base->sig.ev_signal_pair[1]);
base->sig.ev_signal_pair[1] = -1;
}
base->sig.sh_old_max = 0;
/* per index frees are handled in evsig_del() */
if (base->sig.sh_old) {
mm_free(base->sig.sh_old);
base->sig.sh_old = NULL;
}
}
void
evsig_dealloc(struct event_base *base)
{
int i = 0;
if (base->sig.ev_signal_added) {
event_del(&base->sig.ev_signal);
event_debug_unassign(&base->sig.ev_signal);
base->sig.ev_signal_added = 0;
}
for (i = 0; i < NSIG; ++i) {
if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
_evsig_restore_handler(base, i);
}
EVSIGBASE_LOCK();
if (base == evsig_base) {
evsig_base = NULL;
evsig_base_n_signals_added = 0;
evsig_base_fd = -1;
}
EVSIGBASE_UNLOCK();
if (base->sig.ev_signal_pair[0] != -1) {
evutil_closesocket(base->sig.ev_signal_pair[0]);
base->sig.ev_signal_pair[0] = -1;
}
if (base->sig.ev_signal_pair[1] != -1) {
evutil_closesocket(base->sig.ev_signal_pair[1]);
base->sig.ev_signal_pair[1] = -1;
}
base->sig.sh_old_max = 0;
/* per index frees are handled in evsig_del() */
if (base->sig.sh_old) {
mm_free(base->sig.sh_old);
base->sig.sh_old = NULL;
}
}
