Redis源码剖析之命令

以下涉及到的源码均为redis5.0-rc3版本的代码【点击查看官方源码】

redis命令

在redis服务器中，对命令进行了结构封装，如下所示（server.h头文件中）：

struct redisCommand {
    char *name;             //命令名称
    redisCommandProc *proc; //指向命令函数实现的指针
    int arity;              //参数的数量        
    char *sflags; /* Flags as string representation, one char per flag. */
    int flags;    /* The actual flags, obtained from the 'sflags' field. */
    /* Use a function to determine keys arguments in a command line.
     * Used for Redis Cluster redirect. */
    redisGetKeysProc *getkeys_proc;
    int firstkey; /* The first argument that's a key (0 = no keys) */
    int lastkey;  /* The last argument that's a key */
    int keystep;  /* The step between first and last key */
    long long microseconds, calls;//microseconds：命令执行时间；calls：命令调用的总次数
};

其中flags,microseconds和calls字段都是由redis来计算的，所以才初始化的时候应该设置为0。

在redisCommand结构中，flags字段的值很重要。源码注释中可见flags的值和每个值的详细意义如下:

w: write command (may modify the key space).
r: read command  (will never modify the key space).
m: may increase memory usage once called. Don't allow if out of memory.
a: admin command, like SAVE or SHUTDOWN.
p: Pub/Sub related command.
f: force replication of this command, regardless of server.dirty.
s: command not allowed in scripts.
R: random command. Command is not deterministic, that is, the same command with the same arguments, with the same key space, may have different results. For instance SPOP and RANDOMKEY are two random commands.
S: Sort command output array if called from script, so that the output is deterministic.
l: Allow command while loading the database.
t: Allow command while a slave has stale data but is not allowed to server this data. Normally no command is accepted in this condition but just a few.
M: Do not automatically propagate the command on MONITOR.
k: Perform an implicit ASKING for this command, so the command will be accepted in cluster mode if the slot is marked as 'importing'.
F: Fast command: O(1) or O(log(N)) command that should never delay its execution as long as the kernel scheduler is giving us time. Note that commands that may trigger a DEL as a side effect (like SET) are not fast commands.

redis命令表

在redis服务器中，服务器启动的时候会对redis命令进行一个初始化，放到一个数组中，形成命令表。命令表如下所示（server.c文件中）：

struct redisCommand redisCommandTable[] = {
    {"module",moduleCommand,-2,"as",0,NULL,0,0,0,0,0},
    {"get",getCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"set",setCommand,-3,"wm",0,NULL,1,1,1,0,0},
    {"setnx",setnxCommand,3,"wmF",0,NULL,1,1,1,0,0},
    {"setex",setexCommand,4,"wm",0,NULL,1,1,1,0,0},
    {"psetex",psetexCommand,4,"wm",0,NULL,1,1,1,0,0},
    {"append",appendCommand,3,"wm",0,NULL,1,1,1,0,0},
    {"strlen",strlenCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"del",delCommand,-2,"w",0,NULL,1,-1,1,0,0},
    {"unlink",unlinkCommand,-2,"wF",0,NULL,1,-1,1,0,0},
    {"exists",existsCommand,-2,"rF",0,NULL,1,-1,1,0,0},
    {"setbit",setbitCommand,4,"wm",0,NULL,1,1,1,0,0},
    {"getbit",getbitCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"bitfield",bitfieldCommand,-2,"wm",0,NULL,1,1,1,0,0},
    {"setrange",setrangeCommand,4,"wm",0,NULL,1,1,1,0,0},
    {"getrange",getrangeCommand,4,"r",0,NULL,1,1,1,0,0},
    {"substr",getrangeCommand,4,"r",0,NULL,1,1,1,0,0},
    {"incr",incrCommand,2,"wmF",0,NULL,1,1,1,0,0},
    {"decr",decrCommand,2,"wmF",0,NULL,1,1,1,0,0},
    {"mget",mgetCommand,-2,"rF",0,NULL,1,-1,1,0,0},
    {"rpush",rpushCommand,-3,"wmF",0,NULL,1,1,1,0,0},
    {"lpush",lpushCommand,-3,"wmF",0,NULL,1,1,1,0,0},
    {"rpushx",rpushxCommand,-3,"wmF",0,NULL,1,1,1,0,0},
    {"lpushx",lpushxCommand,-3,"wmF",0,NULL,1,1,1,0,0},
    {"linsert",linsertCommand,5,"wm",0,NULL,1,1,1,0,0},
    {"rpop",rpopCommand,2,"wF",0,NULL,1,1,1,0,0},
    {"lpop",lpopCommand,2,"wF",0,NULL,1,1,1,0,0},
    {"brpop",brpopCommand,-3,"ws",0,NULL,1,-2,1,0,0},
    {"brpoplpush",brpoplpushCommand,4,"wms",0,NULL,1,2,1,0,0},
    {"blpop",blpopCommand,-3,"ws",0,NULL,1,-2,1,0,0},
    {"llen",llenCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"lindex",lindexCommand,3,"r",0,NULL,1,1,1,0,0},
    {"lset",lsetCommand,4,"wm",0,NULL,1,1,1,0,0},
    {"lrange",lrangeCommand,4,"r",0,NULL,1,1,1,0,0},
    {"ltrim",ltrimCommand,4,"w",0,NULL,1,1,1,0,0},
    {"lrem",lremCommand,4,"w",0,NULL,1,1,1,0,0},
    {"rpoplpush",rpoplpushCommand,3,"wm",0,NULL,1,2,1,0,0},
    {"sadd",saddCommand,-3,"wmF",0,NULL,1,1,1,0,0},
    {"srem",sremCommand,-3,"wF",0,NULL,1,1,1,0,0},
    {"smove",smoveCommand,4,"wF",0,NULL,1,2,1,0,0},
    {"sismember",sismemberCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"scard",scardCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"spop",spopCommand,-2,"wRF",0,NULL,1,1,1,0,0},
    {"srandmember",srandmemberCommand,-2,"rR",0,NULL,1,1,1,0,0},
    {"sinter",sinterCommand,-2,"rS",0,NULL,1,-1,1,0,0},
    {"sinterstore",sinterstoreCommand,-3,"wm",0,NULL,1,-1,1,0,0},
    {"sunion",sunionCommand,-2,"rS",0,NULL,1,-1,1,0,0},
    {"sunionstore",sunionstoreCommand,-3,"wm",0,NULL,1,-1,1,0,0},
    {"sdiff",sdiffCommand,-2,"rS",0,NULL,1,-1,1,0,0},
    {"sdiffstore",sdiffstoreCommand,-3,"wm",0,NULL,1,-1,1,0,0},
    {"smembers",sinterCommand,2,"rS",0,NULL,1,1,1,0,0},
    {"sscan",sscanCommand,-3,"rR",0,NULL,1,1,1,0,0},
    {"zadd",zaddCommand,-4,"wmF",0,NULL,1,1,1,0,0},
    {"zincrby",zincrbyCommand,4,"wmF",0,NULL,1,1,1,0,0},
    {"zrem",zremCommand,-3,"wF",0,NULL,1,1,1,0,0},
    {"zremrangebyscore",zremrangebyscoreCommand,4,"w",0,NULL,1,1,1,0,0},
    {"zremrangebyrank",zremrangebyrankCommand,4,"w",0,NULL,1,1,1,0,0},
    {"zremrangebylex",zremrangebylexCommand,4,"w",0,NULL,1,1,1,0,0},
    {"zunionstore",zunionstoreCommand,-4,"wm",0,zunionInterGetKeys,0,0,0,0,0},
    {"zinterstore",zinterstoreCommand,-4,"wm",0,zunionInterGetKeys,0,0,0,0,0},
    {"zrange",zrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zrangebyscore",zrangebyscoreCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zrevrangebyscore",zrevrangebyscoreCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zrangebylex",zrangebylexCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zrevrangebylex",zrevrangebylexCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zcount",zcountCommand,4,"rF",0,NULL,1,1,1,0,0},
    {"zlexcount",zlexcountCommand,4,"rF",0,NULL,1,1,1,0,0},
    {"zrevrange",zrevrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"zcard",zcardCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"zscore",zscoreCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"zrank",zrankCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"zrevrank",zrevrankCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"zscan",zscanCommand,-3,"rR",0,NULL,1,1,1,0,0},
    {"zpopmin",zpopminCommand,-2,"wF",0,NULL,1,-1,1,0,0},
    {"zpopmax",zpopmaxCommand,-2,"wF",0,NULL,1,-1,1,0,0},
    {"bzpopmin",bzpopminCommand,-2,"wsF",0,NULL,1,-2,1,0,0},
    {"bzpopmax",bzpopmaxCommand,-2,"wsF",0,NULL,1,-2,1,0,0},
    {"hset",hsetCommand,-4,"wmF",0,NULL,1,1,1,0,0},
    {"hsetnx",hsetnxCommand,4,"wmF",0,NULL,1,1,1,0,0},
    {"hget",hgetCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"hmset",hsetCommand,-4,"wmF",0,NULL,1,1,1,0,0},
    {"hmget",hmgetCommand,-3,"rF",0,NULL,1,1,1,0,0},
    {"hincrby",hincrbyCommand,4,"wmF",0,NULL,1,1,1,0,0},
    {"hincrbyfloat",hincrbyfloatCommand,4,"wmF",0,NULL,1,1,1,0,0},
    {"hdel",hdelCommand,-3,"wF",0,NULL,1,1,1,0,0},
    {"hlen",hlenCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"hstrlen",hstrlenCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"hkeys",hkeysCommand,2,"rS",0,NULL,1,1,1,0,0},
    {"hvals",hvalsCommand,2,"rS",0,NULL,1,1,1,0,0},
    {"hgetall",hgetallCommand,2,"r",0,NULL,1,1,1,0,0},
    {"hexists",hexistsCommand,3,"rF",0,NULL,1,1,1,0,0},
    {"hscan",hscanCommand,-3,"rR",0,NULL,1,1,1,0,0},
    {"incrby",incrbyCommand,3,"wmF",0,NULL,1,1,1,0,0},
    {"decrby",decrbyCommand,3,"wmF",0,NULL,1,1,1,0,0},
    {"incrbyfloat",incrbyfloatCommand,3,"wmF",0,NULL,1,1,1,0,0},
    {"getset",getsetCommand,3,"wm",0,NULL,1,1,1,0,0},
    {"mset",msetCommand,-3,"wm",0,NULL,1,-1,2,0,0},
    {"msetnx",msetnxCommand,-3,"wm",0,NULL,1,-1,2,0,0},
    {"randomkey",randomkeyCommand,1,"rR",0,NULL,0,0,0,0,0},
    {"select",selectCommand,2,"lF",0,NULL,0,0,0,0,0},
    {"swapdb",swapdbCommand,3,"wF",0,NULL,0,0,0,0,0},
    {"move",moveCommand,3,"wF",0,NULL,1,1,1,0,0},
    {"rename",renameCommand,3,"w",0,NULL,1,2,1,0,0},
    {"renamenx",renamenxCommand,3,"wF",0,NULL,1,2,1,0,0},
    {"expire",expireCommand,3,"wF",0,NULL,1,1,1,0,0},
    {"expireat",expireatCommand,3,"wF",0,NULL,1,1,1,0,0},
    {"pexpire",pexpireCommand,3,"wF",0,NULL,1,1,1,0,0},
    {"pexpireat",pexpireatCommand,3,"wF",0,NULL,1,1,1,0,0},
    {"keys",keysCommand,2,"rS",0,NULL,0,0,0,0,0},
    {"scan",scanCommand,-2,"rR",0,NULL,0,0,0,0,0},
    {"dbsize",dbsizeCommand,1,"rF",0,NULL,0,0,0,0,0},
    {"auth",authCommand,2,"sltF",0,NULL,0,0,0,0,0},
    {"ping",pingCommand,-1,"tF",0,NULL,0,0,0,0,0},
    {"echo",echoCommand,2,"F",0,NULL,0,0,0,0,0},
    {"save",saveCommand,1,"as",0,NULL,0,0,0,0,0},
    {"bgsave",bgsaveCommand,-1,"a",0,NULL,0,0,0,0,0},
    {"bgrewriteaof",bgrewriteaofCommand,1,"a",0,NULL,0,0,0,0,0},
    {"shutdown",shutdownCommand,-1,"alt",0,NULL,0,0,0,0,0},
    {"lastsave",lastsaveCommand,1,"RF",0,NULL,0,0,0,0,0},
    {"type",typeCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"multi",multiCommand,1,"sF",0,NULL,0,0,0,0,0},
    {"exec",execCommand,1,"sM",0,NULL,0,0,0,0,0},
    {"discard",discardCommand,1,"sF",0,NULL,0,0,0,0,0},
    {"sync",syncCommand,1,"ars",0,NULL,0,0,0,0,0},
    {"psync",syncCommand,3,"ars",0,NULL,0,0,0,0,0},
    {"replconf",replconfCommand,-1,"aslt",0,NULL,0,0,0,0,0},
    {"flushdb",flushdbCommand,-1,"w",0,NULL,0,0,0,0,0},
    {"flushall",flushallCommand,-1,"w",0,NULL,0,0,0,0,0},
    {"sort",sortCommand,-2,"wm",0,sortGetKeys,1,1,1,0,0},
    {"info",infoCommand,-1,"lt",0,NULL,0,0,0,0,0},
    {"monitor",monitorCommand,1,"as",0,NULL,0,0,0,0,0},
    {"ttl",ttlCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"touch",touchCommand,-2,"rF",0,NULL,1,1,1,0,0},
    {"pttl",pttlCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"persist",persistCommand,2,"wF",0,NULL,1,1,1,0,0},
    {"slaveof",slaveofCommand,3,"ast",0,NULL,0,0,0,0,0},
    {"role",roleCommand,1,"lst",0,NULL,0,0,0,0,0},
    {"debug",debugCommand,-2,"as",0,NULL,0,0,0,0,0},
    {"config",configCommand,-2,"lat",0,NULL,0,0,0,0,0},
    {"subscribe",subscribeCommand,-2,"pslt",0,NULL,0,0,0,0,0},
    {"unsubscribe",unsubscribeCommand,-1,"pslt",0,NULL,0,0,0,0,0},
    {"psubscribe",psubscribeCommand,-2,"pslt",0,NULL,0,0,0,0,0},
    {"punsubscribe",punsubscribeCommand,-1,"pslt",0,NULL,0,0,0,0,0},
    {"publish",publishCommand,3,"pltF",0,NULL,0,0,0,0,0},
    {"pubsub",pubsubCommand,-2,"pltR",0,NULL,0,0,0,0,0},
    {"watch",watchCommand,-2,"sF",0,NULL,1,-1,1,0,0},
    {"unwatch",unwatchCommand,1,"sF",0,NULL,0,0,0,0,0},
    {"cluster",clusterCommand,-2,"a",0,NULL,0,0,0,0,0},
    {"restore",restoreCommand,-4,"wm",0,NULL,1,1,1,0,0},
    {"restore-asking",restoreCommand,-4,"wmk",0,NULL,1,1,1,0,0},
    {"migrate",migrateCommand,-6,"w",0,migrateGetKeys,0,0,0,0,0},
    {"asking",askingCommand,1,"F",0,NULL,0,0,0,0,0},
    {"readonly",readonlyCommand,1,"F",0,NULL,0,0,0,0,0},
    {"readwrite",readwriteCommand,1,"F",0,NULL,0,0,0,0,0},
    {"dump",dumpCommand,2,"r",0,NULL,1,1,1,0,0},
    {"object",objectCommand,-2,"r",0,NULL,2,2,1,0,0},
    {"memory",memoryCommand,-2,"r",0,NULL,0,0,0,0,0},
    {"client",clientCommand,-2,"as",0,NULL,0,0,0,0,0},
    {"eval",evalCommand,-3,"s",0,evalGetKeys,0,0,0,0,0},
    {"evalsha",evalShaCommand,-3,"s",0,evalGetKeys,0,0,0,0,0},
    {"slowlog",slowlogCommand,-2,"a",0,NULL,0,0,0,0,0},
    {"script",scriptCommand,-2,"s",0,NULL,0,0,0,0,0},
    {"time",timeCommand,1,"RF",0,NULL,0,0,0,0,0},
    {"bitop",bitopCommand,-4,"wm",0,NULL,2,-1,1,0,0},
    {"bitcount",bitcountCommand,-2,"r",0,NULL,1,1,1,0,0},
    {"bitpos",bitposCommand,-3,"r",0,NULL,1,1,1,0,0},
    {"wait",waitCommand,3,"s",0,NULL,0,0,0,0,0},
    {"command",commandCommand,0,"lt",0,NULL,0,0,0,0,0},
    {"geoadd",geoaddCommand,-5,"wm",0,NULL,1,1,1,0,0},
    {"georadius",georadiusCommand,-6,"w",0,georadiusGetKeys,1,1,1,0,0},
    {"georadius_ro",georadiusroCommand,-6,"r",0,georadiusGetKeys,1,1,1,0,0},
    {"georadiusbymember",georadiusbymemberCommand,-5,"w",0,georadiusGetKeys,1,1,1,0,0},
    {"georadiusbymember_ro",georadiusbymemberroCommand,-5,"r",0,georadiusGetKeys,1,1,1,0,0},
    {"geohash",geohashCommand,-2,"r",0,NULL,1,1,1,0,0},
    {"geopos",geoposCommand,-2,"r",0,NULL,1,1,1,0,0},
    {"geodist",geodistCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"pfselftest",pfselftestCommand,1,"a",0,NULL,0,0,0,0,0},
    {"pfadd",pfaddCommand,-2,"wmF",0,NULL,1,1,1,0,0},
    {"pfcount",pfcountCommand,-2,"r",0,NULL,1,-1,1,0,0},
    {"pfmerge",pfmergeCommand,-2,"wm",0,NULL,1,-1,1,0,0},
    {"pfdebug",pfdebugCommand,-3,"w",0,NULL,0,0,0,0,0},
    {"xadd",xaddCommand,-5,"wmF",0,NULL,1,1,1,0,0},
    {"xrange",xrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"xrevrange",xrevrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
    {"xlen",xlenCommand,2,"rF",0,NULL,1,1,1,0,0},
    {"xread",xreadCommand,-3,"rs",0,xreadGetKeys,1,1,1,0,0},
    {"xreadgroup",xreadCommand,-3,"ws",0,xreadGetKeys,1,1,1,0,0},
    {"xgroup",xgroupCommand,-2,"wm",0,NULL,2,2,1,0,0},
    {"xack",xackCommand,-3,"wF",0,NULL,1,1,1,0,0},
    {"xpending",xpendingCommand,-3,"r",0,NULL,1,1,1,0,0},
    {"xclaim",xclaimCommand,-5,"wF",0,NULL,1,1,1,0,0},
    {"xinfo",xinfoCommand,-2,"r",0,NULL,2,2,1,0,0},
    {"xdel",xdelCommand,-2,"wF",0,NULL,1,1,1,0,0},
    {"xtrim",xtrimCommand,-2,"wF",0,NULL,1,1,1,0,0},
    {"post",securityWarningCommand,-1,"lt",0,NULL,0,0,0,0,0},
    {"host:",securityWarningCommand,-1,"lt",0,NULL,0,0,0,0,0},
    {"latency",latencyCommand,-2,"aslt",0,NULL,0,0,0,0,0}
};