redisAssert(fakeClient->bufpos == 0 && listLength(fakeClient->reply) == 0);
/* The fake client should never get blocked */
redisAssert((fakeClient->flags & REDIS_BLOCKED) == 0);
/* Clean up. Command code may have changed argv/argc so we use the
* argv/argc of the client instead of the local variables. */
for (j = 0; j < fakeClient->argc; j++)
decrRefCount(fakeClient->argv[j]);
zfree(fakeClient->argv);
}
/* This point can only be reached when EOF is reached without errors.
* If the client is in the middle of a MULTI/EXEC, log error and quit. */
if (fakeClient->flags & REDIS_MULTI) goto readerr;
fclose(fp);
freeFakeClient(fakeClient);
server.aof_state = old_aof_state;
stopLoading();
aofUpdateCurrentSize(); //更新server.aof_current_size，AOF文件大小
server.aof_rewrite_base_size = server.aof_current_size;
return REDIS_OK;
…………
}
在前面一篇关于AOF参数配置的博客遗留了一个问题，server.aof_current_size参数的初始化，下面解决这个疑问。
void aofUpdateCurrentSize(void) {
struct redis_stat sb;
if (redis_fstat(server.aof_fd,&sb) == -1) {
redisLog(REDIS_WARNING,"Unable to obtain the AOF file length. stat: %s",
strerror(errno));
} else {
server.aof_current_size = sb.st_size;
}
}
redis_fstat是作者对Linux中fstat64函数的重命名，该还是就是获取文件相关的参数信息，具体可以Google之，sb.st_size就是当前AOF文件的大小。这里需要知道server.aof_fd即AOF文件描述符，该参数的初始化在initServer()函数中
/* Open the AOF file if needed. */
if (server.aof_state == REDIS_AOF_ON) {
server.aof_fd = open(server.aof_filename,O_WRONLY|O_APPEND|O_CREAT,0644);
if (server.aof_fd == -1) {
redisLog(REDIS_WARNING, "Can't open the append-only file: %s",strerror(errno));
exit(1);
}
}
至此，Redis Server启动加载硬盘中AOF文件数据的操作就成功结束了。
Server数据库产生新数据如何持久化到硬盘
当客户端执行Set等修改数据库中字段的指令时就会造成Server数据库中数据被修改，这些修改的数据应该被实时更新到AOF文件中，并且也要按照一定的fsync机制刷新到硬盘中，保证数据不会丢失。
在上一篇博客中，提到了三种fsync方式:appendfsync always, appendfsync everysec, appendfsync no. 具体体现在server.aof_fsync参数中。
首先看当客户端请求的指令造成数据被修改，Redis是如何将修改数据的指令添加到server.aof_buf中的。
call() -> propagate() -> feedAppendOnlyFile()，call()函数判断执行指令后是否造成数据被修改。
feedAppendOnlyFile函数首先会判断Server是否开启了AOF，如果开启AOF，那么根据Redis通讯协议将修改数据的指令重现成请求的字符串，注意在超时设置的处理方式，接着将字符串append到server.aof_buf中即可。该函数最后两行代码需要注意，这才是重点，如果server.aof_child_pid != -1那么表明此时Server正在重写rewrite AOF文件，需要将被修改的数据追加到server.aof_rewrite_buf_blocks链表中，等待rewrite结束后，追加到AOF文件中。具体见下面代码的注释。
/* Propagate the specified command (in the context of the specified database id)
* to AOF and Slaves.
*
* flags are an xor between:
* + REDIS_PROPAGATE_NONE (no propagation of command at all)
* + REDIS_PROPAGATE_AOF (propagate into the AOF file if is enabled)
* + REDIS_PROPAGATE_REPL (propagate into the replication link)
*/
void propagate(struct redisCommand *cmd, int dbid, robj **argv, int argc,
int flags)
{
//将cmd指令变动的数据追加到AOF文件中
if (server.aof_state != REDIS_AOF_OFF && flags & REDIS_PROPAGATE_AOF)
feedAppendOnlyFile(cmd,dbid,argv,argc);
if (flags & REDIS_PROPAGATE_REPL)
replicationFeedSlaves(server.slaves,dbid,argv,argc);
}
//cmd指令修改了数据，先将更新的数据写到server.aof_buf中
void feedAppendOnlyFile(struct redisCommand *cmd, int dictid, robj **argv, int argc) {
sds buf = sdsempty();
robj *tmpargv[3];
/* The DB this command was targeting is not the same as the last command
* we appendend. To issue a SELECT command is needed. */
// 当前 db 不是指定的 aof db，通过创建 SEL