漫话Redis源码之八十二

本文主要是介绍漫话Redis源码之八十二，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

看最后的kqueue, 这是为了兼容不同平台，其实你可以理解为它和select/poll/epoll差不多就行：

#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>typedef struct aeApiState {int kqfd;struct kevent *events;/* Events mask for merge read and write event.* To reduce memory consumption, we use 2 bits to store the mask* of an event, so that 1 byte will store the mask of 4 events. */char *eventsMask; 
} aeApiState;#define EVENT_MASK_MALLOC_SIZE(sz) (((sz) + 3) / 4)
#define EVENT_MASK_OFFSET(fd) ((fd) % 4 * 2)
#define EVENT_MASK_ENCODE(fd, mask) (((mask) & 0x3) << EVENT_MASK_OFFSET(fd))static inline int getEventMask(const char *eventsMask, int fd) {return (eventsMask[fd/4] >> EVENT_MASK_OFFSET(fd)) & 0x3;
}static inline void addEventMask(char *eventsMask, int fd, int mask) {eventsMask[fd/4] |= EVENT_MASK_ENCODE(fd, mask);
}static inline void resetEventMask(char *eventsMask, int fd) {eventsMask[fd/4] &= ~EVENT_MASK_ENCODE(fd, 0x3);
}static int aeApiCreate(aeEventLoop *eventLoop) {aeApiState *state = zmalloc(sizeof(aeApiState));if (!state) return -1;state->events = zmalloc(sizeof(struct kevent)*eventLoop->setsize);if (!state->events) {zfree(state);return -1;}state->kqfd = kqueue();if (state->kqfd == -1) {zfree(state->events);zfree(state);return -1;}anetCloexec(state->kqfd);state->eventsMask = zmalloc(EVENT_MASK_MALLOC_SIZE(eventLoop->setsize));memset(state->eventsMask, 0, EVENT_MASK_MALLOC_SIZE(eventLoop->setsize));eventLoop->apidata = state;return 0;
}static int aeApiResize(aeEventLoop *eventLoop, int setsize) {aeApiState *state = eventLoop->apidata;state->events = zrealloc(state->events, sizeof(struct kevent)*setsize);state->eventsMask = zrealloc(state->eventsMask, EVENT_MASK_MALLOC_SIZE(setsize));memset(state->eventsMask, 0, EVENT_MASK_MALLOC_SIZE(setsize));return 0;
}static void aeApiFree(aeEventLoop *eventLoop) {aeApiState *state = eventLoop->apidata;close(state->kqfd);zfree(state->events);zfree(state->eventsMask);zfree(state);
}static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {aeApiState *state = eventLoop->apidata;struct kevent ke;if (mask & AE_READABLE) {EV_SET(&ke, fd, EVFILT_READ, EV_ADD, 0, 0, NULL);if (kevent(state->kqfd, &ke, 1, NULL, 0, NULL) == -1) return -1;}if (mask & AE_WRITABLE) {EV_SET(&ke, fd, EVFILT_WRITE, EV_ADD, 0, 0, NULL);if (kevent(state->kqfd, &ke, 1, NULL, 0, NULL) == -1) return -1;}return 0;
}static void aeApiDelEvent(aeEventLoop *eventLoop, int fd, int mask) {aeApiState *state = eventLoop->apidata;struct kevent ke;if (mask & AE_READABLE) {EV_SET(&ke, fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);kevent(state->kqfd, &ke, 1, NULL, 0, NULL);}if (mask & AE_WRITABLE) {EV_SET(&ke, fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);kevent(state->kqfd, &ke, 1, NULL, 0, NULL);}
}static int aeApiPoll(aeEventLoop *eventLoop, struct timeval *tvp) {aeApiState *state = eventLoop->apidata;int retval, numevents = 0;if (tvp != NULL) {struct timespec timeout;timeout.tv_sec = tvp->tv_sec;timeout.tv_nsec = tvp->tv_usec * 1000;retval = kevent(state->kqfd, NULL, 0, state->events, eventLoop->setsize,&timeout);} else {retval = kevent(state->kqfd, NULL, 0, state->events, eventLoop->setsize,NULL);}if (retval > 0) {int j;/* Normally we execute the read event first and then the write event.* When the barrier is set, we will do it reverse.* * However, under kqueue, read and write events would be separate* events, which would make it impossible to control the order of* reads and writes. So we store the event's mask we've got and merge* the same fd events later. */for (j = 0; j < retval; j++) {struct kevent *e = state->events+j;int fd = e->ident;int mask = 0; if (e->filter == EVFILT_READ) mask = AE_READABLE;else if (e->filter == EVFILT_WRITE) mask = AE_WRITABLE;addEventMask(state->eventsMask, fd, mask);}/* Re-traversal to merge read and write events, and set the fd's mask to* 0 so that events are not added again when the fd is encountered again. */numevents = 0;for (j = 0; j < retval; j++) {struct kevent *e = state->events+j;int fd = e->ident;int mask = getEventMask(state->eventsMask, fd);if (mask) {eventLoop->fired[numevents].fd = fd;eventLoop->fired[numevents].mask = mask;resetEventMask(state->eventsMask, fd);numevents++;}}}return numevents;
}static char *aeApiName(void) {return "kqueue";
}

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