void execCommand(redisClient *c) {
int j;
robj **orig_argv;
int orig_argc;
struct redisCommand *orig_cmd;
if (!(c->flags & REDIS_MULTI)) {
addReplyError(c,"EXEC without MULTI");
return;
}
/* Check if we need to abort the EXEC if some WATCHed key was touched.
* A failed EXEC will return a multi bulk nil object. */
if (c->flags & REDIS_DIRTY_CAS) {
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
unwatchAllKeys(c);
addReply(c,shared.nullmultibulk);
return;
}
/* Replicate a MULTI request now that we are sure the block is executed.
* This way we'll deliver the MULTI/..../EXEC block as a whole and
* both the AOF and the replication link will have the same consistency
* and atomicity guarantees. */
execCommandReplicateMulti(c);
/* Exec all the queued commands */
unwatchAllKeys(c); /* Unwatch ASAP otherwise we'll waste CPU cycles */
orig_argv = c->argv;
orig_argc = c->argc;
orig_cmd = c->cmd;
addReplyMultiBulkLen(c,c->mstate.count);
for (j = 0; j < c->mstate.count; j++) {
c->argc = c->mstate.commands[j].argc;
c->argv = c->mstate.commands[j].argv;
c->cmd = c->mstate.commands[j].cmd;
call(c);
/* Commands may alter argc/argv, restore mstate. */
c->mstate.commands[j].argc = c->argc;
c->mstate.commands[j].argv = c->argv;
c->mstate.commands[j].cmd = c->cmd;
}
c->argv = orig_argv;
c->argc = orig_argc;
c->cmd = orig_cmd;
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
/* Make sure the EXEC command is always replicated / AOF, since we
* always send the MULTI command (we can't know beforehand if the
* next operations will contain at least a modification to the DB). */
server.dirty++;
}
/* In Redis commands are always executed in the context of a client, so in
* order to load the append only file we need to create a fake client. */
struct redisClient *createFakeClient(void) {
struct redisClient *c = zmalloc(sizeof(*c));
selectDb(c,0);
c->fd = -1;
c->name = NULL;
c->querybuf = sdsempty();
c->querybuf_peak = 0;
c->argc = 0;
c->argv = NULL;
c->bufpos = 0;
c->flags = 0;
c->btype = REDIS_BLOCKED_NONE;
/* We set the fake client as a slave waiting for the synchronization
* so that Redis will not try to send replies to this client. */
c->replstate = REDIS_REPL_WAIT_BGSAVE_START;
c->reply = listCreate();
c->reply_bytes = 0;
c->obuf_soft_limit_reached_time = 0;
c->watched_keys = listCreate();
listSetFreeMethod(c->reply,decrRefCountVoid);
listSetDupMethod(c->reply,dupClientReplyValue);
initClientMultiState(c);
return c;
}
redisClient *createClient(int fd) {
redisClient *c = zmalloc(sizeof(redisClient));
/* passing -1 as fd it is possible to create a non connected client.
* This is useful since all the Redis commands needs to be executed
* in the context of a client. When commands are executed in other
* contexts (for instance a Lua script) we need a non connected client. */
if (fd != -1) {
anetNonBlock(NULL,fd);
anetEnableTcpNoDelay(NULL,fd);
if (server.tcpkeepalive)
anetKeepAlive(NULL,fd,server.tcpkeepalive);
if (aeCreateFileEvent(server.el,fd,AE_READABLE,
readQueryFromClient, c) == AE_ERR)
{
close(fd);
zfree(c);
return NULL;
}
}
selectDb(c,0);
c->fd = fd;
c->name = NULL;
c->bufpos = 0;
c->querybuf = sdsempty();
c->querybuf_peak = 0;
c->reqtype = 0;
c->argc = 0;
c->argv = NULL;
c->cmd = c->lastcmd = NULL;
c->multibulklen = 0;
c->bulklen = -1;
c->sentlen = 0;
c->flags = 0;
c->ctime = c->lastinteraction = server.unixtime;
c->authenticated = 0;
c->replstate = REDIS_REPL_NONE;
c->slave_listening_port = 0;
c->reply = listCreate();
c->reply_bytes = 0;
c->obuf_soft_limit_reached_time = 0;
listSetFreeMethod(c->reply,decrRefCount);
listSetDupMethod(c->reply,dupClientReplyValue);
c->bpop.keys = dictCreate(&setDictType,NULL);
c->bpop.timeout = 0;
c->bpop.target = NULL;
c->io_keys = listCreate();
c->watched_keys = listCreate();
listSetFreeMethod(c->io_keys,decrRefCount);
c->pubsub_channels = dictCreate(&setDictType,NULL);
c->pubsub_patterns = listCreate();
listSetFreeMethod(c->pubsub_patterns,decrRefCount);
listSetMatchMethod(c->pubsub_patterns,listMatchObjects);
if (fd != -1) listAddNodeTail(server.clients,c);
initClientMultiState(c);
return c;
}
void discardTransaction(client *c) {
/* 释放动态内存 */
freeClientMultiState(c);
/* 重新初始化 事务状态 */
initClientMultiState(c);
/* 去除事务标识 */
c->flags &= ~(CLIENT_MULTI|CLIENT_DIRTY_CAS|CLIENT_DIRTY_EXEC);
/* 释放所有WATCH的键 */
unwatchAllKeys(c);
}
// 取消事务状态
void discardTransaction(client *c) {
// 释放客户端的事务状态的所有资源
freeClientMultiState(c);
// 初始化client的事务状态
initClientMultiState(c);
// 取消客户端的事务有关的状态标识
c->flags &= ~(CLIENT_MULTI|CLIENT_DIRTY_CAS|CLIENT_DIRTY_EXEC);
// 取消对客户端的所有的键的监视
unwatchAllKeys(c);
}
// 取消事务
void discardTransaction(redisClient *c) {
// 清空命令队列
freeClientMultiState(c);
// 初始化命令队列
initClientMultiState(c);
// 取消标记 flag
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);;
unwatchAllKeys(c);
}
/*
* 放弃事务，清理并重置客户端的事务状态
*
* T = O(N^2)
*/
void discardTransaction(redisClient *c)
{
// 释放参数空间
freeClientMultiState(c);
// 重置事务状态
initClientMultiState(c);
// 关闭相关的 flag
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);;
// 取消所有 key 的监视, O(N^2)
unwatchAllKeys(c);
}
void discardCommand(redisClient *c) {
if (!(c->flags & REDIS_MULTI)) {
addReplyError(c,"DISCARD without MULTI");
return;
}
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= (~REDIS_MULTI);
unwatchAllKeys(c);
addReply(c,shared.ok);
}
void discardTransaction(redisClient *c) {
// 重置事务状态
freeClientMultiState(c);
initClientMultiState(c);
// 屏蔽事务状态
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);;
// 取消对所有键的监视
unwatchAllKeys(c);
}
redisClient *createClient(int fd) {
redisClient *c = zmalloc(sizeof(redisClient));
c->bufpos = 0;
anetNonBlock(NULL,fd);
anetTcpNoDelay(NULL,fd);
if (!c) return NULL;
if (aeCreateFileEvent(server.el,fd,AE_READABLE,
readQueryFromClient, c) == AE_ERR)
{
#ifdef _WIN32
closesocket(fd);
#else
close(fd);
#endif
zfree(c);
return NULL;
}
selectDb(c,0);
c->fd = fd;
c->querybuf = sdsempty();
c->reqtype = 0;
c->argc = 0;
c->argv = NULL;
c->multibulklen = 0;
c->bulklen = -1;
c->sentlen = 0;
c->flags = 0;
c->lastinteraction = time(NULL);
c->authenticated = 0;
c->replstate = REDIS_REPL_NONE;
c->reply = listCreate();
listSetFreeMethod(c->reply,decrRefCount);
listSetDupMethod(c->reply,dupClientReplyValue);
c->bpop.keys = NULL;
c->bpop.count = 0;
c->bpop.timeout = 0;
c->bpop.target = NULL;
c->io_keys = listCreate();
c->watched_keys = listCreate();
listSetFreeMethod(c->io_keys,decrRefCount);
c->pubsub_channels = dictCreate(&setDictType,NULL);
c->pubsub_patterns = listCreate();
listSetFreeMethod(c->pubsub_patterns,decrRefCount);
listSetMatchMethod(c->pubsub_patterns,listMatchObjects);
listAddNodeTail(server.clients,c);
initClientMultiState(c);
return c;
}
// 放弃执行事务
void discardTransaction(redisClient *c) {
freeClientMultiState(c); // 释放事务资源
initClientMultiState(c); // 重置事务状态
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);; // 关闭 FLAG
unwatchAllKeys(c); // 取消对所有 key 的 WATCH
}
// 执行事务
void execCommand(redisClient *c) {
int j;
robj **orig_argv;
int orig_argc;
struct redisCommand *orig_cmd;
// 如果没执行过 MULTI ，报错
if (!(c->flags & REDIS_MULTI)) {
addReplyError(c,"EXEC without MULTI");
return;
}
/* Check if we need to abort the EXEC if some WATCHed key was touched.
* A failed EXEC will return a multi bulk nil object. */
// 如果在执行事务之前，有监视中（WATCHED）的 key 被改变
// 那么取消这个事务
if (c->flags & REDIS_DIRTY_CAS) {
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
unwatchAllKeys(c);
addReply(c,shared.nullmultibulk);
return;
}
/* Replicate a MULTI request now that we are sure the block is executed.
* This way we'll deliver the MULTI/..../EXEC block as a whole and
* both the AOF and the replication link will have the same consistency
* and atomicity guarantees. */
// 为保证一致性和原子性
// 如果处在 AOF 模式中，向 AOF 文件发送 MULTI
// 如果处在复制模式中，向附属节点发送 MULTI
execCommandReplicateMulti(c);
/* Exec all the queued commands */
// 开始执行所有事务中的命令（FIFO 方式）
unwatchAllKeys(c); /* Unwatch ASAP otherwise we'll waste CPU cycles */
// 备份所有参数和命令
orig_argv = c->argv;
orig_argc = c->argc;
orig_cmd = c->cmd;
addReplyMultiBulkLen(c,c->mstate.count);
for (j = 0; j < c->mstate.count; j++) {
c->argc = c->mstate.commands[j].argc; // 取出参数数量
c->argv = c->mstate.commands[j].argv; // 取出参数
c->cmd = c->mstate.commands[j].cmd; // 取出要执行的命令
call(c,REDIS_CALL_FULL); // 执行命令
/* Commands may alter argc/argv, restore mstate. */
c->mstate.commands[j].argc = c->argc;
c->mstate.commands[j].argv = c->argv;
c->mstate.commands[j].cmd = c->cmd;
}
// 恢复所有参数和命令
c->argv = orig_argv;
c->argc = orig_argc;
c->cmd = orig_cmd;
// 重置事务状态
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
/* Make sure the EXEC command is always replicated / AOF, since we
* always send the MULTI command (we can't know beforehand if the
* next operations will contain at least a modification to the DB). */
// 更新状态值，确保事务执行之后的状态为脏
server.dirty++;
}
void discardTransaction(redisClient *c) {
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);;
unwatchAllKeys(c);
}
void execCommand(redisClient *c) {
int j;
robj **orig_argv;
int orig_argc;
struct redisCommand *orig_cmd;
if (!(c->flags & REDIS_MULTI)) {
addReplyError(c,"EXEC without MULTI");
return;
}
/* Check if we need to abort the EXEC if some WATCHed key was touched.
* A failed EXEC will return a multi bulk nil object. */
if (c->flags & REDIS_DIRTY_CAS) {
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
unwatchAllKeys(c);
addReply(c,shared.nullmultibulk);
goto handle_monitor;
}
/* Replicate a MULTI request now that we are sure the block is executed.
* This way we'll deliver the MULTI/..../EXEC block as a whole and
* both the AOF and the replication link will have the same consistency
* and atomicity guarantees. */
execCommandReplicateMulti(c);
/* Exec all the queued commands */
unwatchAllKeys(c); /* Unwatch ASAP otherwise we'll waste CPU cycles */
orig_argv = c->argv;
orig_argc = c->argc;
orig_cmd = c->cmd;
addReplyMultiBulkLen(c,c->mstate.count);
for (j = 0; j < c->mstate.count; j++) {
c->argc = c->mstate.commands[j].argc;
c->argv = c->mstate.commands[j].argv;
c->cmd = c->mstate.commands[j].cmd;
call(c,REDIS_CALL_FULL);
/* Commands may alter argc/argv, restore mstate. */
c->mstate.commands[j].argc = c->argc;
c->mstate.commands[j].argv = c->argv;
c->mstate.commands[j].cmd = c->cmd;
}
c->argv = orig_argv;
c->argc = orig_argc;
c->cmd = orig_cmd;
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
/* Make sure the EXEC command is always replicated / AOF, since we
* always send the MULTI command (we can't know beforehand if the
* next operations will contain at least a modification to the DB). */
server.dirty++;
handle_monitor:
/* Send EXEC to clients waiting data from MONITOR. We do it here
* since the natural order of commands execution is actually:
* MUTLI, EXEC, ... commands inside transaction ...
* Instead EXEC is flagged as REDIS_CMD_SKIP_MONITOR in the command
* table, and we do it here with correct ordering. */
if (listLength(server.monitors) && !server.loading)
replicationFeedMonitors(c,server.monitors,c->db->id,c->argv,c->argc);
}
/*
* EXEC 命令的实现
*/
void execCommand(redisClient *c)
{
int j;
// 用于保存执行命令、命令的参数和参数数量的副本
robj **orig_argv;
int orig_argc;
struct redisCommand *orig_cmd;
// 只能在 MULTI 已启用的情况下执行
if (!(c->flags & REDIS_MULTI))
{
addReplyError(c,"EXEC without MULTI");
return;
}
/* Check if we need to abort the EXEC because:
* 以下情况发生时，取消事务
*
* 1) Some WATCHed key was touched.
* 某些被监视的键已被修改（状态为 REDIS_DIRTY_CAS）
*
* 2) There was a previous error while queueing commands.
* 有命令在入队时发生错误（状态为 REDIS_DIRTY_EXEC）
*
* A failed EXEC in the first case returns a multi bulk nil object
* (technically it is not an error but a special behavior), while
* in the second an EXECABORT error is returned.
*
* 第一种情况返回多个空白 NULL 对象，
* 第二种情况返回一个 EXECABORT 错误。
*/
if (c->flags & (REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC))
{
// 根据状态，决定返回的错误的类型
addReply(c, c->flags & REDIS_DIRTY_EXEC ? shared.execaborterr :
shared.nullmultibulk);
// 以下四句可以用 discardTransaction() 来替换
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);
unwatchAllKeys(c);
goto handle_monitor;
}
/* Replicate a MULTI request now that we are sure the block is executed.
* This way we'll deliver the MULTI/..../EXEC block as a whole and
* both the AOF and the replication link will have the same consistency
* and atomicity guarantees. */
// 向所有附属节点和 AOF 文件发送 MULTI 命令
execCommandReplicateMulti(c);
/* Exec all the queued commands */
unwatchAllKeys(c); /* Unwatch ASAP otherwise we'll waste CPU cycles */
// 将三个原始参数备份起来
orig_argv = c->argv;
orig_argc = c->argc;
orig_cmd = c->cmd;
addReplyMultiBulkLen(c,c->mstate.count);
// 执行所有入队的命令
for (j = 0; j < c->mstate.count; j++)
{
// 因为 call 可能修改命令，而命令需要传送给其他同步节点
// 所以这里将要执行的命令（及其参数）先备份起来
c->argc = c->mstate.commands[j].argc;
c->argv = c->mstate.commands[j].argv;
c->cmd = c->mstate.commands[j].cmd;
// 执行命令
call(c,REDIS_CALL_FULL);
/* Commands may alter argc/argv, restore mstate. */
// 还原原始的参数到队列里
c->mstate.commands[j].argc = c->argc;
c->mstate.commands[j].argv = c->argv;
c->mstate.commands[j].cmd = c->cmd;
}
// 还原三个原始命令
c->argv = orig_argv;
c->argc = orig_argc;
c->cmd = orig_cmd;
// 以下三句也可以用 discardTransaction() 来替换
freeClientMultiState(c);
initClientMultiState(c);
c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS|REDIS_DIRTY_EXEC);
/* Make sure the EXEC command is always replicated / AOF, since we
* always send the MULTI command (we can't know beforehand if the
* next operations will contain at least a modification to the DB). */
server.dirty++;
handle_monitor:
/* Send EXEC to clients waiting data from MONITOR. We do it here
* since the natural order of commands execution is actually:
* MUTLI, EXEC, ... commands inside transaction ...
* Instead EXEC is flagged as REDIS_CMD_SKIP_MONITOR in the command
* table, and we do it here with correct ordering. */
// 向同步节点发送命令
if (listLength(server.monitors) && !server.loading)
replicationFeedMonitors(c,server.monitors,c->db->id,c->argv,c->argc);
}
