Redis 命令映射表

Redis 命令映射表初始化

redis 命令映射表存储，使用hashTable

struct redisServer {
	dict *commands;             /* Command table */
}

redis command结构体

最重要的是处理函数，以及name属性

typedef void redisCommandProc(client *c);
typedef int *redisGetKeysProc(struct redisCommand *cmd, robj **argv, int argc, int *numkeys);
struct redisCommand {
    char *name;
    redisCommandProc *proc;
    int arity;
    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;
    /* What keys should be loaded in background when calling this command? */
    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;
};

redisCommandTable 声明

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},
   	...
    {"lolwut",lolwutCommand,-1,"r",0,NULL,0,0,0,0,0}
};

将name当作key，redisCommand结构体存储到hash表中

/* Populates the Redis Command Table starting from the hard coded list
 * we have on top of redis.c file. */
void populateCommandTable(void) {
    int j;
    int numcommands = sizeof(redisCommandTable)/sizeof(struct redisCommand);

    for (j = 0; j < numcommands; j++) {
        struct redisCommand *c = redisCommandTable+j;
        char *f = c->sflags;
        int retval1, retval2;

        while(*f != '\0') {
            switch(*f) {
            case 'w': c->flags |= CMD_WRITE; break;
            case 'r': c->flags |= CMD_READONLY; break;
            case 'm': c->flags |= CMD_DENYOOM; break;
            case 'a': c->flags |= CMD_ADMIN; break;
            case 'p': c->flags |= CMD_PUBSUB; break;
            case 's': c->flags |= CMD_NOSCRIPT; break;
            case 'R': c->flags |= CMD_RANDOM; break;
            case 'S': c->flags |= CMD_SORT_FOR_SCRIPT; break;
            case 'l': c->flags |= CMD_LOADING; break;
            case 't': c->flags |= CMD_STALE; break;
            case 'M': c->flags |= CMD_SKIP_MONITOR; break;
            case 'k': c->flags |= CMD_ASKING; break;
            case 'F': c->flags |= CMD_FAST; break;
            default: serverPanic("Unsupported command flag"); break;
            }
            f++;
        }

        retval1 = dictAdd(server.commands, sdsnew(c->name), c);
        /* Populate an additional dictionary that will be unaffected
         * by rename-command statements in redis.conf. */
        retval2 = dictAdd(server.orig_commands, sdsnew(c->name), c);
        serverAssert(retval1 == DICT_OK && retval2 == DICT_OK);
    }
}

处理redis command请求

int processCommand(client *c){
	c->cmd = c->lastcmd = lookupCommand(c->argv[0]->ptr);
	call(c,CMD_CALL_FULL);
	return C_OK;
}

• c-argv[0]->ptr 为redisCommand名称，例如get set等
• lookupCommand从server.commands字典向查找到RedisCommand
• call 调用对应的处理函数