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redis/src/ae.c

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/* A simple event-driven programming library. Originally I wrote this code
* for the Jim's event-loop (Jim is a Tcl interpreter) but later translated
* it in form of a library for easy reuse.
*
* Copyright (c) 2006-Present, Redis Ltd.
* All rights reserved.
*
* Licensed under your choice of the Redis Source Available License 2.0
* (RSALv2) or the Server Side Public License v1 (SSPLv1).
*/
#include "ae.h"
#include "anet.h"
#include "redisassert.h"
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <poll.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include "zmalloc.h"
#include "config.h"
/* Include the best multiplexing layer supported by this system.
* The following should be ordered by performances, descending. */
#ifdef HAVE_EVPORT
#include "ae_evport.c"
#else
#ifdef HAVE_EPOLL
#include "ae_epoll.c"
#else
#ifdef HAVE_KQUEUE
#include "ae_kqueue.c"
#else
#include "ae_select.c"
#endif
#endif
#endif
aeEventLoop *aeCreateEventLoop(int setsize) {
aeEventLoop *eventLoop;
int i;
monotonicInit(); /* just in case the calling app didn't initialize */
if ((eventLoop = zmalloc(sizeof(*eventLoop))) == NULL) goto err;
eventLoop->events = zmalloc(sizeof(aeFileEvent)*setsize);
eventLoop->fired = zmalloc(sizeof(aeFiredEvent)*setsize);
if (eventLoop->events == NULL || eventLoop->fired == NULL) goto err;
eventLoop->setsize = setsize;
eventLoop->timeEventHead = NULL;
eventLoop->timeEventNextId = 0;
eventLoop->stop = 0;
eventLoop->maxfd = -1;
eventLoop->beforesleep = NULL;
eventLoop->aftersleep = NULL;
eventLoop->flags = 0;
if (aeApiCreate(eventLoop) == -1) goto err;
/* Events with mask == AE_NONE are not set. So let's initialize the
* vector with it. */
for (i = 0; i < setsize; i++)
eventLoop->events[i].mask = AE_NONE;
return eventLoop;
err:
if (eventLoop) {
zfree(eventLoop->events);
zfree(eventLoop->fired);
zfree(eventLoop);
}
return NULL;
}
/* Return the current set size. */
int aeGetSetSize(aeEventLoop *eventLoop) {
return eventLoop->setsize;
}
/*
* Tell the event processing to change the wait timeout as soon as possible.
*
* Note: it just means you turn on/off the global AE_DONT_WAIT.
*/
void aeSetDontWait(aeEventLoop *eventLoop, int noWait) {
if (noWait)
eventLoop->flags |= AE_DONT_WAIT;
else
eventLoop->flags &= ~AE_DONT_WAIT;
}
/* Resize the maximum set size of the event loop.
* If the requested set size is smaller than the current set size, but
* there is already a file descriptor in use that is >= the requested
* set size minus one, AE_ERR is returned and the operation is not
* performed at all.
*
* Otherwise AE_OK is returned and the operation is successful. */
int aeResizeSetSize(aeEventLoop *eventLoop, int setsize) {
int i;
if (setsize == eventLoop->setsize) return AE_OK;
if (eventLoop->maxfd >= setsize) return AE_ERR;
if (aeApiResize(eventLoop,setsize) == -1) return AE_ERR;
eventLoop->events = zrealloc(eventLoop->events,sizeof(aeFileEvent)*setsize);
eventLoop->fired = zrealloc(eventLoop->fired,sizeof(aeFiredEvent)*setsize);
eventLoop->setsize = setsize;
/* Make sure that if we created new slots, they are initialized with
* an AE_NONE mask. */
for (i = eventLoop->maxfd+1; i < setsize; i++)
eventLoop->events[i].mask = AE_NONE;
return AE_OK;
}
void aeDeleteEventLoop(aeEventLoop *eventLoop) {
aeApiFree(eventLoop);
zfree(eventLoop->events);
zfree(eventLoop->fired);
/* Free the time events list. */
aeTimeEvent *next_te, *te = eventLoop->timeEventHead;
while (te) {
next_te = te->next;
if (te->finalizerProc)
te->finalizerProc(eventLoop, te->clientData);
zfree(te);
te = next_te;
}
zfree(eventLoop);
}
void aeStop(aeEventLoop *eventLoop) {
eventLoop->stop = 1;
}
int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
aeFileProc *proc, void *clientData)
{
if (fd >= eventLoop->setsize) {
errno = ERANGE;
return AE_ERR;
}
aeFileEvent *fe = &eventLoop->events[fd];
if (aeApiAddEvent(eventLoop, fd, mask) == -1)
return AE_ERR;
fe->mask |= mask;
if (mask & AE_READABLE) fe->rfileProc = proc;
if (mask & AE_WRITABLE) fe->wfileProc = proc;
fe->clientData = clientData;
if (fd > eventLoop->maxfd)
eventLoop->maxfd = fd;
return AE_OK;
}
void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask)
{
if (fd >= eventLoop->setsize) return;
aeFileEvent *fe = &eventLoop->events[fd];
if (fe->mask == AE_NONE) return;
/* We want to always remove AE_BARRIER if set when AE_WRITABLE
* is removed. */
if (mask & AE_WRITABLE) mask |= AE_BARRIER;
aeApiDelEvent(eventLoop, fd, mask);
fe->mask = fe->mask & (~mask);
if (fd == eventLoop->maxfd && fe->mask == AE_NONE) {
/* Update the max fd */
int j;
for (j = eventLoop->maxfd-1; j >= 0; j--)
if (eventLoop->events[j].mask != AE_NONE) break;
eventLoop->maxfd = j;
}
}
void *aeGetFileClientData(aeEventLoop *eventLoop, int fd) {
if (fd >= eventLoop->setsize) return NULL;
aeFileEvent *fe = &eventLoop->events[fd];
if (fe->mask == AE_NONE) return NULL;
return fe->clientData;
}
int aeGetFileEvents(aeEventLoop *eventLoop, int fd) {
if (fd >= eventLoop->setsize) return 0;
aeFileEvent *fe = &eventLoop->events[fd];
return fe->mask;
}
long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
aeTimeProc *proc, void *clientData,
aeEventFinalizerProc *finalizerProc)
{
long long id = eventLoop->timeEventNextId++;
aeTimeEvent *te;
te = zmalloc(sizeof(*te));
if (te == NULL) return AE_ERR;
te->id = id;
te->when = getMonotonicUs() + milliseconds * 1000;
te->timeProc = proc;
te->finalizerProc = finalizerProc;
te->clientData = clientData;
te->prev = NULL;
te->next = eventLoop->timeEventHead;
te->refcount = 0;
if (te->next)
te->next->prev = te;
eventLoop->timeEventHead = te;
return id;
}
int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id)
{
aeTimeEvent *te = eventLoop->timeEventHead;
while(te) {
if (te->id == id) {
te->id = AE_DELETED_EVENT_ID;
return AE_OK;
}
te = te->next;
}
return AE_ERR; /* NO event with the specified ID found */
}
/* How many microseconds until the first timer should fire.
* If there are no timers, -1 is returned.
*
* Note that's O(N) since time events are unsorted.
* Possible optimizations (not needed by Redis so far, but...):
* 1) Insert the event in order, so that the nearest is just the head.
* Much better but still insertion or deletion of timers is O(N).
* 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
*/
static int64_t usUntilEarliestTimer(aeEventLoop *eventLoop) {
aeTimeEvent *te = eventLoop->timeEventHead;
if (te == NULL) return -1;
aeTimeEvent *earliest = NULL;
while (te) {
if ((!earliest || te->when < earliest->when) && te->id != AE_DELETED_EVENT_ID)
earliest = te;
te = te->next;
}
monotime now = getMonotonicUs();
return (now >= earliest->when) ? 0 : earliest->when - now;
}
/* Process time events */
static int processTimeEvents(aeEventLoop *eventLoop) {
int processed = 0;
aeTimeEvent *te;
long long maxId;
te = eventLoop->timeEventHead;
maxId = eventLoop->timeEventNextId-1;
monotime now = getMonotonicUs();
while(te) {
long long id;
/* Remove events scheduled for deletion. */
if (te->id == AE_DELETED_EVENT_ID) {
aeTimeEvent *next = te->next;
/* If a reference exists for this timer event,
* don't free it. This is currently incremented
* for recursive timerProc calls */
if (te->refcount) {
te = next;
continue;
}
if (te->prev)
te->prev->next = te->next;
else
eventLoop->timeEventHead = te->next;
if (te->next)
te->next->prev = te->prev;
if (te->finalizerProc) {
te->finalizerProc(eventLoop, te->clientData);
now = getMonotonicUs();
}
zfree(te);
te = next;
continue;
}
/* Make sure we don't process time events created by time events in
* this iteration. Note that this check is currently useless: we always
* add new timers on the head, however if we change the implementation
* detail, this check may be useful again: we keep it here for future
* defense. */
if (te->id > maxId) {
te = te->next;
continue;
}
if (te->when <= now) {
int retval;
id = te->id;
te->refcount++;
retval = te->timeProc(eventLoop, id, te->clientData);
te->refcount--;
processed++;
now = getMonotonicUs();
if (retval != AE_NOMORE) {
te->when = now + (monotime)retval * 1000;
} else {
te->id = AE_DELETED_EVENT_ID;
}
}
te = te->next;
}
return processed;
}
/* Process every pending file event, then every pending time event
* (that may be registered by file event callbacks just processed).
* Without special flags the function sleeps until some file event
* fires, or when the next time event occurs (if any).
*
* If flags is 0, the function does nothing and returns.
* if flags has AE_ALL_EVENTS set, all the kind of events are processed.
* if flags has AE_FILE_EVENTS set, file events are processed.
* if flags has AE_TIME_EVENTS set, time events are processed.
* if flags has AE_DONT_WAIT set, the function returns ASAP once all
* the events that can be handled without a wait are processed.
* if flags has AE_CALL_AFTER_SLEEP set, the aftersleep callback is called.
* if flags has AE_CALL_BEFORE_SLEEP set, the beforesleep callback is called.
*
* The function returns the number of events processed. */
int aeProcessEvents(aeEventLoop *eventLoop, int flags)
{
int processed = 0, numevents;
/* Nothing to do? return ASAP */
if (!(flags & AE_TIME_EVENTS) && !(flags & AE_FILE_EVENTS)) return 0;
/* Note that we want to call aeApiPoll() even if there are no
* file events to process as long as we want to process time
* events, in order to sleep until the next time event is ready
* to fire. */
if (eventLoop->maxfd != -1 ||
((flags & AE_TIME_EVENTS) && !(flags & AE_DONT_WAIT))) {
int j;
struct timeval tv, *tvp = NULL; /* NULL means infinite wait. */
int64_t usUntilTimer;
if (eventLoop->beforesleep != NULL && (flags & AE_CALL_BEFORE_SLEEP))
eventLoop->beforesleep(eventLoop);
/* The eventLoop->flags may be changed inside beforesleep.
* So we should check it after beforesleep be called. At the same time,
* the parameter flags always should have the highest priority.
* That is to say, once the parameter flag is set to AE_DONT_WAIT,
* no matter what value eventLoop->flags is set to, we should ignore it. */
if ((flags & AE_DONT_WAIT) || (eventLoop->flags & AE_DONT_WAIT)) {
tv.tv_sec = tv.tv_usec = 0;
tvp = &tv;
} else if (flags & AE_TIME_EVENTS) {
usUntilTimer = usUntilEarliestTimer(eventLoop);
if (usUntilTimer >= 0) {
tv.tv_sec = usUntilTimer / 1000000;
tv.tv_usec = usUntilTimer % 1000000;
tvp = &tv;
}
}
/* Call the multiplexing API, will return only on timeout or when
* some event fires. */
numevents = aeApiPoll(eventLoop, tvp);
/* Don't process file events if not requested. */
if (!(flags & AE_FILE_EVENTS)) {
numevents = 0;
}
/* After sleep callback. */
if (eventLoop->aftersleep != NULL && flags & AE_CALL_AFTER_SLEEP)
eventLoop->aftersleep(eventLoop);
for (j = 0; j < numevents; j++) {
int fd = eventLoop->fired[j].fd;
aeFileEvent *fe = &eventLoop->events[fd];
int mask = eventLoop->fired[j].mask;
int fired = 0; /* Number of events fired for current fd. */
/* Normally we execute the readable event first, and the writable
* event later. This is useful as sometimes we may be able
* to serve the reply of a query immediately after processing the
* query.
*
* However if AE_BARRIER is set in the mask, our application is
* asking us to do the reverse: never fire the writable event
* after the readable. In such a case, we invert the calls.
* This is useful when, for instance, we want to do things
* in the beforeSleep() hook, like fsyncing a file to disk,
* before replying to a client. */
int invert = fe->mask & AE_BARRIER;
/* Note the "fe->mask & mask & ..." code: maybe an already
* processed event removed an element that fired and we still
* didn't processed, so we check if the event is still valid.
*
* Fire the readable event if the call sequence is not
* inverted. */
if (!invert && fe->mask & mask & AE_READABLE) {
fe->rfileProc(eventLoop,fd,fe->clientData,mask);
fired++;
fe = &eventLoop->events[fd]; /* Refresh in case of resize. */
}
/* Fire the writable event. */
if (fe->mask & mask & AE_WRITABLE) {
if (!fired || fe->wfileProc != fe->rfileProc) {
fe->wfileProc(eventLoop,fd,fe->clientData,mask);
fired++;
}
}
/* If we have to invert the call, fire the readable event now
* after the writable one. */
if (invert) {
fe = &eventLoop->events[fd]; /* Refresh in case of resize. */
if ((fe->mask & mask & AE_READABLE) &&
(!fired || fe->wfileProc != fe->rfileProc))
{
fe->rfileProc(eventLoop,fd,fe->clientData,mask);
fired++;
}
}
processed++;
}
}
/* Check time events */
if (flags & AE_TIME_EVENTS)
processed += processTimeEvents(eventLoop);
return processed; /* return the number of processed file/time events */
}
/* Wait for milliseconds until the given file descriptor becomes
* writable/readable/exception */
int aeWait(int fd, int mask, long long milliseconds) {
struct pollfd pfd;
int retmask = 0, retval;
memset(&pfd, 0, sizeof(pfd));
pfd.fd = fd;
if (mask & AE_READABLE) pfd.events |= POLLIN;
if (mask & AE_WRITABLE) pfd.events |= POLLOUT;
if ((retval = poll(&pfd, 1, milliseconds))== 1) {
if (pfd.revents & POLLIN) retmask |= AE_READABLE;
if (pfd.revents & POLLOUT) retmask |= AE_WRITABLE;
if (pfd.revents & POLLERR) retmask |= AE_WRITABLE;
if (pfd.revents & POLLHUP) retmask |= AE_WRITABLE;
return retmask;
} else {
return retval;
}
}
void aeMain(aeEventLoop *eventLoop) {
eventLoop->stop = 0;
while (!eventLoop->stop) {
aeProcessEvents(eventLoop, AE_ALL_EVENTS|
AE_CALL_BEFORE_SLEEP|
AE_CALL_AFTER_SLEEP);
}
}
char *aeGetApiName(void) {
return aeApiName();
}
void aeSetBeforeSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *beforesleep) {
eventLoop->beforesleep = beforesleep;
}
void aeSetAfterSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *aftersleep) {
eventLoop->aftersleep = aftersleep;
}
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