ae_epoll,顾名思义,它底层的实现就是epoll(),相比于select(),epoll()的更加优秀,他会把就绪的描述符放到一个链表里面,并返回给调用者(具体是通过eventpoll来实现的,这个后续讲网络编程的时候会详细说下),省去了遍历时间。
redis当中将epoll()封装如下:
-
typedef struct aeApiState {
-
int epfd;
-
struct epoll_event *events;
-
} aeApiState;
一般api如下:
-
static int aeApiCreate(aeEventLoop *eventLoop) {
-
aeApiState *state = zmalloc(sizeof(aeApiState));
-
-
if (!state) return -1;
-
state->events = zmalloc(sizeof(struct epoll_event)*eventLoop->setsize);
-
if (!state->events) {
-
zfree(state);
-
return -1;
-
}
-
state->epfd = epoll_create(1024); /* 1024 is just a hint for the kernel */
-
if (state->epfd == -1) {
-
zfree(state->events);
-
zfree(state);
-
return -1;
-
}
-
eventLoop->apidata = state;
-
return 0;
-
}
-
-
static int aeApiResize(aeEventLoop *eventLoop, int setsize) {
-
aeApiState *state = eventLoop->apidata;
-
-
state->events = zrealloc(state->events, sizeof(struct epoll_event)*setsize);
-
return 0;
-
}
-
-
static void aeApiFree(aeEventLoop *eventLoop) {
-
aeApiState *state = eventLoop->apidata;
-
-
close(state->epfd);
-
zfree(state->events);
-
zfree(state);
-
}
-
-
static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {
-
aeApiState *state = eventLoop->apidata;
-
struct epoll_event ee = {0}; /* avoid valgrind warning */
-
/* If the fd was already monitored for some event, we need a MOD
-
* operation. Otherwise we need an ADD operation. */
-
int op = eventLoop->events[fd].mask == AE_NONE ?
-
EPOLL_CTL_ADD : EPOLL_CTL_MOD;
-
-
ee.events = 0;
-
mask |= eventLoop->events[fd].mask; /* Merge old events */
-
if (mask & AE_READABLE) ee.events |= EPOLLIN;
-
if (mask & AE_WRITABLE) ee.events |= EPOLLOUT;
-
ee.data.fd = fd;
-
if (epoll_ctl(state->epfd,op,fd,&ee) == -1) return -1;
-
return 0;
-
}
-
-
static void aeApiDelEvent(aeEventLoop *eventLoop, int fd, int delmask) {
-
aeApiState *state = eventLoop->apidata;
-
struct epoll_event ee = {0}; /* avoid valgrind warning */
-
int mask = eventLoop->events[fd].mask & (~delmask);
-
-
ee.events = 0;
-
if (mask & AE_READABLE) ee.events |= EPOLLIN;
-
if (mask & AE_WRITABLE) ee.events |= EPOLLOUT;
-
ee.data.fd = fd;
-
if (mask != AE_NONE) {
-
epoll_ctl(state->epfd,EPOLL_CTL_MOD,fd,&ee);
-
} else {
-
/* Note, Kernel < 2.6.9 requires a non null event pointer even for
-
* EPOLL_CTL_DEL. */
-
epoll_ctl(state->epfd,EPOLL_CTL_DEL,fd,&ee);
-
}
-
}
-
static char *aeApiName(void) {
-
return "epoll";
-
}
核心调用如下:
-
static int aeApiPoll(aeEventLoop *eventLoop, struct timeval *tvp) {
-
aeApiState *state = eventLoop->apidata;
-
int retval, numevents = 0;
-
-
retval = epoll_wait(state->epfd,state->events,eventLoop->setsize,
-
tvp ? (tvp->tv_sec*1000 + tvp->tv_usec/1000) : -1);
-
if (retval > 0) {
-
int j;
-
-
numevents = retval;
-
for (j = 0; j < numevents; j++) {
-
int mask = 0;
-
struct epoll_event *e = state->events+j;
-
-
if (e->events & EPOLLIN) mask |= AE_READABLE;
-
if (e->events & EPOLLOUT) mask |= AE_WRITABLE;
-
if (e->events & EPOLLERR) mask |= AE_WRITABLE;
-
if (e->events & EPOLLHUP) mask |= AE_WRITABLE;
-
eventLoop->fired[j].fd = e->data.fd;
-
eventLoop->fired[j].mask = mask;
-
}
-
}
-
return numevents;
-
}
阅读(7817) | 评论(0) | 转发(0) |