void redisProcessCallbacks(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
redisCallback cb;
void *reply = NULL;
int status;
while((status = redisGetReply(c,&reply)) == REDIS_OK) {
if (reply == NULL) {
/* When the connection is being disconnected and there are
* no more replies, this is the cue to really disconnect. */
if (c->flags & REDIS_DISCONNECTING && sdslen(c->obuf) == 0) {
__redisAsyncDisconnect(ac);
return;
}
/* When the connection is not being disconnected, simply stop
* trying to get replies and wait for the next loop tick. */
break;
}
/* Even if the context is subscribed, pending regular callbacks will
* get a reply before pub/sub messages arrive. */
if (__redisShiftCallback(&ac->replies,&cb) != REDIS_OK) {
/* No more regular callbacks, the context *must* be subscribed. */
/* assert(c->flags & REDIS_SUBSCRIBED); */
if (c->flags & REDIS_SUBSCRIBED) {
__redisGetSubscribeCallback(ac,reply,&cb);
}
/* lig: monitor callback */
if (c->flags & REDIS_MONITOR) {
__redisGetMonitorCallback(ac,&cb);
}
}
if (cb.fn != NULL) {
__redisRunCallback(ac,&cb,reply);
c->fn->freeObject(reply);
/* Proceed with free'ing when redisAsyncFree() was called. */
if (c->flags & REDIS_FREEING) {
__redisAsyncFree(ac);
return;
}
} else {
/* No callback for this reply. This can either be a NULL callback,
* or there were no callbacks to begin with. Either way, don't
* abort with an error, but simply ignore it because the client
* doesn't know what the server will spit out over the wire. */
c->fn->freeObject(reply);
}
}
/* Disconnect when there was an error reading the reply */
if (status != REDIS_OK)
__redisAsyncDisconnect(ac);
}
void redisAsyncHandleWrite(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
int done = 0;
// 连接创建失败？？？
if (!(c->flags & REDIS_CONNECTED)) {
/* Abort connect was not successful. */
if (__redisAsyncHandleConnect(ac) != REDIS_OK)
return;
// 再尝试检测 flag
/* Try again later when the context is still not connected. */
if (!(c->flags & REDIS_CONNECTED))
return;
}
if (redisBufferWrite(c,&done) == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Continue writing when not done, stop writing otherwise */
// 当缓冲区中还有数据待发送时，会再次注册写事件
if (!done)
_EL_ADD_WRITE(ac);
// 当缓冲区中没有数据待发送时，会再次注册写事件
else
_EL_DEL_WRITE(ac);
/* Always schedule reads after writes */
_EL_ADD_READ(ac);
}
}
/* This function should be called when the socket is readable.
* It processes all replies that can be read and executes their callbacks.
*/
void redisAsyncHandleRead(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
// 如果连接已经断开，尝试连接
if (!(c->flags & REDIS_CONNECTED)) {
/* Abort connect was not successful. */
if (__redisAsyncHandleConnect(ac) != REDIS_OK)
return;
/* Try again later when the context is still not connected. */
if (!(c->flags & REDIS_CONNECTED))
return;
}
// 读取数据
if (redisBufferRead(c) == REDIS_ERR) {
// 读取错误，断开连接并做一些清理工作
__redisAsyncDisconnect(ac);
} else {
// 读取数据成功，再次注册读事件，
/* Always re-schedule reads */
_EL_ADD_READ(ac);
// 并处理回调函数
redisProcessCallbacks(ac);
}
}
void redisAsyncHandleWrite(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
int done = 0;
int status;
if (!(c->flags & REDIS_CONNECTED)) {
/* Abort connect was not successful. */
if (__redisAsyncHandleConnect(ac) != REDIS_OK)
return;
/* Try again later when the context is still not connected. */
if (!(c->flags & REDIS_CONNECTED))
return;
}
pthread_mutex_lock(&ac->lock);
status = redisBufferWrite(c,&done);
pthread_mutex_unlock(&ac->lock);
if (status == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Continue writing when not done, stop writing otherwise */
if (!done)
_EL_ADD_WRITE(ac);
else
_EL_DEL_WRITE(ac);
/* Always schedule reads after writes */
_EL_ADD_READ(ac);
}
}
void redisAsyncHandleWrite(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
int done = 0;
if (redisBufferWrite(c, &done) == REDIS_ERR) {
__redisAsyncDisconnect(ac);
}
else {
/* Continue writing when not done, stop writing otherwise */
if (!done) {
if (ac->ev.addWrite) ac->ev.addWrite(ac->ev.data);
}
else {
if (ac->ev.delWrite) ac->ev.delWrite(ac->ev.data);
}
/* Always schedule reads after writes */
if (ac->ev.addRead) ac->ev.addRead(ac->ev.data);
/* Fire onConnect when this is the first write event. */
if (!(c->flags & REDIS_CONNECTED)) {
c->flags |= REDIS_CONNECTED;
if (ac->onConnect) ac->onConnect(ac);
}
}
}
/* This function should be called when the socket is readable.
* It processes all replies that can be read and executes their callbacks.
*/
void redisAsyncHandleRead(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
if (!(c->flags & REDIS_CONNECTED)) {
/* Abort connect was not successful. */
if (__redisAsyncHandleConnect(ac) != REDIS_OK)
return;
/* Try again later when the context is still not connected. */
if (!(c->flags & REDIS_CONNECTED))
return;
}
if (redisBufferRead(c) == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Always re-schedule reads */
#ifdef _WIN32
// There appears to be a bug in the Linux version of _EL_ADD_READ which will not reschedule
// the read if already reading. This is a problem if there is a large number of async GET
// operations. If the receive buffer is exhausted with the data returned, the read would
// not be rescheduled, and the async operations would cease. This forces the read to recur.
_EL_FORCE_ADD_READ(ac);
#else
_EL_ADD_READ(ac);
#endif
redisProcessCallbacks(ac);
}
}
/* This function should be called when the socket is readable.
* It processes all replies that can be read and executes their callbacks.
*/
void redisAsyncHandleRead(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
if (redisBufferRead(c) == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Always re-schedule reads */
if (ac->ev.addRead) ac->ev.addRead(ac->ev.data);
redisProcessCallbacks(ac);
}
}
/* Internal helper function to detect socket status the first time a read or
* write event fires. When connecting was not succesful, the connect callback
* is called with a REDIS_ERR status and the context is free'd. */
static int __redisAsyncHandleConnect(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
if (redisCheckSocketError(c) == REDIS_ERR) {
/* Try again later when connect(2) is still in progress. */
if (errno == EINPROGRESS)
return REDIS_OK;
if (ac->onConnect) ac->onConnect(ac,REDIS_ERR);
__redisAsyncDisconnect(ac);
return REDIS_ERR;
}
/* Mark context as connected. */
c->flags |= REDIS_CONNECTED;
if (ac->onConnect) ac->onConnect(ac,REDIS_OK);
return REDIS_OK;
}
/* This function should be called when the socket is readable.
* It processes all replies that can be read and executes their callbacks.
*/
void redisAsyncHandleRead(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
if (!(c->flags & REDIS_CONNECTED)) {
/* Abort connect was not successful. */
if (__redisAsyncHandleConnect(ac) != REDIS_OK)
return;
/* Try again later when the context is still not connected. */
if (!(c->flags & REDIS_CONNECTED))
return;
}
if (redisBufferRead(c) == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Always re-schedule reads */
_EL_ADD_READ(ac);
redisProcessCallbacks(ac);
}
}
int redisAsyncHandleWriteComplete(redisAsyncContext *ac, int written) {
redisContext *c = &(ac->c);
int done = 0;
int rc;
rc = redisBufferWriteDone(c, written, &done);
if (rc == REDIS_ERR) {
__redisAsyncDisconnect(ac);
} else {
/* Continue writing when not done, stop writing otherwise */
if (!done)
_EL_ADD_WRITE(ac);
else
_EL_DEL_WRITE(ac);
/* Always schedule reads after writes */
_EL_ADD_READ(ac);
}
return REDIS_OK;
}
/* Internal helper function to detect socket status the first time a read or
* write event fires. When connecting was not succesful, the connect callback
* is called with a REDIS_ERR status and the context is free'd. */
static int __redisAsyncHandleConnect(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
// 当一个套接口出错时，它会被 select 调用标记为既可读又可写。
// 因此，我们要用 getsockopt() 判断是否连接真的创建成功了
// 检测 socket 错误
if (redisCheckSocketError(c,c->fd) == REDIS_ERR) {
/* Try again later when connect(2) is still in progress. */
if (errno == EINPROGRESS)
return REDIS_OK;
if (ac->onConnect) ac->onConnect(ac,REDIS_ERR);
__redisAsyncDisconnect(ac);
return REDIS_ERR;
}
// 连接是成功的
/* Mark context as connected. */
c->flags |= REDIS_CONNECTED;
if (ac->onConnect) ac->onConnect(ac,REDIS_OK);
return REDIS_OK;
}
void redisProcessCallbacks(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
redisCallback cb;
void *reply = NULL;
int status;
while((status = redisGetReply(c,&reply)) == REDIS_OK) {
// 回复内容为空
if (reply == NULL) {
// REDIS_DISCONNECTING 表示连接断开的时候遇到了错误，如果此时
// 写缓冲区为空，会再次尝试断开。之后的回调函数都得不到执行
// 的机会
/* When the connection is being disconnected and there are
* no more replies, this is the cue to really disconnect. */
if (c->flags & REDIS_DISCONNECTING && sdslen(c->obuf) == 0) {
__redisAsyncDisconnect(ac);
return;
}
// 监视模式下
/* If monitor mode, repush callback */
if(c->flags & REDIS_MONITORING) {
__redisPushCallback(&ac->replies,&cb);
}
/* When the connection is not being disconnected, simply stop
* trying to get replies and wait for the next loop tick. */
break;
}
/* Even if the context is subscribed, pending regular callbacks will
* get a reply before pub/sub messages arrive. */
// 获取回调函数 redisCallback
if (__redisShiftCallback(&ac->replies,&cb) != REDIS_OK) {
/*
* A spontaneous reply in a not-subscribed context can be the error
* reply that is sent when a new connection exceeds the maximum
* number of allowed connections on the server side.
*
* This is seen as an error instead of a regular reply because the
* server closes the connection after sending it.
*
* To prevent the error from being overwritten by an EOF error the
* connection is closed here. See issue #43.
*
* Another possibility is that the server is loading its dataset.
* In this case we also want to close the connection, and have the
* user wait until the server is ready to take our request.
*/
if (((redisReply*)reply)->type == REDIS_REPLY_ERROR) {
c->err = REDIS_ERR_OTHER;
snprintf(c->errstr,sizeof(c->errstr),"%s",((redisReply*)reply)->str);
__redisAsyncDisconnect(ac);
return;
}
/* No more regular callbacks and no errors, the context *must* be subscribed or monitoring. */
assert((c->flags & REDIS_SUBSCRIBED || c->flags & REDIS_MONITORING));
if(c->flags & REDIS_SUBSCRIBED)
__redisGetSubscribeCallback(ac,reply,&cb);
}
// 执行回调函数
if (cb.fn != NULL) {
__redisRunCallback(ac,&cb,reply);
c->reader->fn->freeObject(reply);
// 可能是之前遇到了不可修复的错误，被标记了 REDIS_FREEING。
// 倘若是在 callback 里面遇到的错误，redis 不能立即释放连接，
// 因为可能需要返回一些数据给客户端。因此 redis 选择在 callback
// 执行过后，才释放（关闭）连接。这个方法好酷。
/* Proceed with free'ing when redisAsyncFree() was called. */
if (c->flags & REDIS_FREEING) {
__redisAsyncFree(ac);
return;
}
// 没有设置回调函数，直接释放收到的数据
} else {
/* No callback for this reply. This can either be a NULL callback,
* or there were no callbacks to begin with. Either way, don't
* abort with an error, but simply ignore it because the client
* doesn't know what the server will spit out over the wire. */
c->reader->fn->freeObject(reply);
}
}
// 出错了，则直接关闭
/* Disconnect when there was an error reading the reply */
if (status != REDIS_OK)
__redisAsyncDisconnect(ac);
}
/* Tries to do a clean disconnect from Redis, meaning it stops new commands
* from being issued, but tries to flush the output buffer and execute
* callbacks for all remaining replies. When this function is called from a
* callback, there might be more replies and we can safely defer disconnecting
* to redisProcessCallbacks(). Otherwise, we can only disconnect immediately
* when there are no pending callbacks. */
void redisAsyncDisconnect(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
c->flags |= REDIS_DISCONNECTING;
if (!(c->flags & REDIS_IN_CALLBACK) && ac->replies.head == NULL)
__redisAsyncDisconnect(ac);
}
void redisProcessCallbacks(redisAsyncContext *ac) {
redisContext *c = &(ac->c);
redisCallback cb;
void *reply = NULL;
int status;
while((status = redisGetReply(c,&reply)) == REDIS_OK) {
if (reply == NULL) {
/* When the connection is being disconnected and there are
* no more replies, this is the cue to really disconnect. */
if (c->flags & REDIS_DISCONNECTING && sdslen(c->obuf) == 0) {
__redisAsyncDisconnect(ac);
return;
}
/* When the connection is not being disconnected, simply stop
* trying to get replies and wait for the next loop tick. */
break;
}
/* Even if the context is subscribed, pending regular callbacks will
* get a reply before pub/sub messages arrive. */
if (__redisShiftCallback(&ac->replies,&cb) != REDIS_OK) {
/* A spontaneous reply in a not-subscribed context can only be the
* error reply that is sent when a new connection exceeds the
* maximum number of allowed connections on the server side. This
* is seen as an error instead of a regular reply because the
* server closes the connection after sending it. To prevent the
* error from being overwritten by an EOF error the connection is
* closed here. See issue #43. */
if ( !(c->flags & REDIS_SUBSCRIBED) && ((redisReply*)reply)->type == REDIS_REPLY_ERROR ) {
c->err = REDIS_ERR_OTHER;
snprintf(c->errstr,sizeof(c->errstr),"%s",((redisReply*)reply)->str);
__redisAsyncDisconnect(ac);
return;
}
/* No more regular callbacks and no errors, the context *must* be subscribed. */
assert(c->flags & REDIS_SUBSCRIBED);
__redisGetSubscribeCallback(ac,reply,&cb);
}
if (cb.fn != NULL) {
__redisRunCallback(ac,&cb,reply);
c->reader->fn->freeObject(reply);
/* Proceed with free'ing when redisAsyncFree() was called. */
if (c->flags & REDIS_FREEING) {
__redisAsyncFree(ac);
return;
}
} else {
/* No callback for this reply. This can either be a NULL callback,
* or there were no callbacks to begin with. Either way, don't
* abort with an error, but simply ignore it because the client
* doesn't know what the server will spit out over the wire. */
c->reader->fn->freeObject(reply);
}
}
/* Disconnect when there was an error reading the reply */
if (status != REDIS_OK)
__redisAsyncDisconnect(ac);
}
