/* The setGenericCommand() function implements the SET operation with different
 * options and variants. This function is called in order to implement the
 * following commands: SET, SETEX, PSETEX, SETNX, GETSET.
 * setGenericCommand()函数实现了SET操作，它有多个不同的选项和变体。调用这个函数可以实现下面几个命令：SET, SETEX, PSETEX, SETNX, GETSET.
 *
 * 'flags' changes the behavior of the command (NX, XX or GET, see below).
 * 'flags'影响命令（NX,XX或GET，详情见下面）的操作。
 *
 * 'expire' represents an expire to set in form of a Redis object as passed
 * by the user. It is interpreted according to the specified 'unit'.
 * 'expire'代表了一个由用户传递的过期时间，它是Redis对象形式。会根据不同的单位对其进行解析。
 *
 * 'ok_reply' and 'abort_reply' is what the function will reply to the client
 * if the operation is performed, or when it is not because of NX or
 * XX flags.
 * 'ok_reply' 和 'abort_reply' 是函数在操作成功或者因为NX或XX标志而没有执行操作时，会回复给客户端的内容。
 *
 * If ok_reply is NULL "+OK" is used.
 * If abort_reply is NULL, "$-1" is used.
 * 如果ok_reply为NULL，会使用"+OK"。
 * 如果abort_reply为NULL，会使用"$-1"。
 * 
 *  */

#define OBJ_NO_FLAGS 0
#define OBJ_SET_NX (1 << 0)  /* Set if key not exists. */
#define OBJ_SET_XX (1 << 1)  /* Set if key exists. */
#define OBJ_EX (1 << 2)      /* Set if time in seconds is given */
#define OBJ_PX (1 << 3)      /* Set if time in ms in given */
#define OBJ_KEEPTTL (1 << 4) /* Set and keep the ttl */
#define OBJ_SET_GET (1 << 5) /* Set if want to get key before set */
#define OBJ_EXAT (1 << 6)    /* Set if timestamp in second is given */
#define OBJ_PXAT (1 << 7)    /* Set if timestamp in ms is given */
#define OBJ_PERSIST (1 << 8) /* Set if we need to remove the ttl */

/* Forward declaration */
static int getExpireMillisecondsOrReply(client *c, robj *expire, int flags, int unit, long long *milliseconds);

void setGenericCommand(client *c, int flags, robj *key, robj *val, robj *expire, int unit, robj *ok_reply, robj *abort_reply)
{
    long long milliseconds = 0; /* initialized to avoid any harmness warning */
    int found = 0;
    int setkey_flags = 0;

    if (expire && getExpireMillisecondsOrReply(c, expire, flags, unit, &milliseconds) != C_OK)
    {
        return;
    }

    if (flags & OBJ_SET_GET)
    {
        if (getGenericCommand(c) == C_ERR)
            return;
    }

    found = (lookupKeyWrite(c->db, key) != NULL);

    if ((flags & OBJ_SET_NX && found) ||
        (flags & OBJ_SET_XX && !found))
    {
        if (!(flags & OBJ_SET_GET))
        {
            addReply(c, abort_reply ? abort_reply : shared.null[c->resp]);
        }
        return;
    }

    setkey_flags |= (flags & OBJ_KEEPTTL) ? SETKEY_KEEPTTL : 0;
    setkey_flags |= found ? SETKEY_ALREADY_EXIST : SETKEY_DOESNT_EXIST;

    setKey(c, c->db, key, val, setkey_flags);
    server.dirty++;
    notifyKeyspaceEvent(NOTIFY_STRING, "set", key, c->db->id);

    if (expire)
    {
        setExpire(c, c->db, key, milliseconds);
        /* Propagate as SET Key Value PXAT millisecond-timestamp if there is
         * EX/PX/EXAT/PXAT flag. */
        robj *milliseconds_obj = createStringObjectFromLongLong(milliseconds);
        rewriteClientCommandVector(c, 5, shared.set, key, val, shared.pxat, milliseconds_obj);
        decrRefCount(milliseconds_obj);
        notifyKeyspaceEvent(NOTIFY_GENERIC, "expire", key, c->db->id);
    }

    if (!(flags & OBJ_SET_GET))
    {
        addReply(c, ok_reply ? ok_reply : shared.ok);
    }

    /* Propagate without the GET argument (Isn't needed if we had expire since in that case we completely re-written the command argv) */
    if ((flags & OBJ_SET_GET) && !expire)
    {
        int argc = 0;
        int j;
        robj **argv = zmalloc((c->argc - 1) * sizeof(robj *));
        for (j = 0; j < c->argc; j++)
        {
            char *a = c->argv[j]->ptr;
            /* Skip GET which may be repeated multiple times. */
            if (j >= 3 &&
                (a[0] == 'g' || a[0] == 'G') &&
                (a[1] == 'e' || a[1] == 'E') &&
                (a[2] == 't' || a[2] == 'T') && a[3] == '\0')
                continue;
            argv[argc++] = c->argv[j];
            incrRefCount(c->argv[j]);
        }
        replaceClientCommandVector(c, argc, argv);
    }
}

int getGenericCommand(client *c) {

robj *o;

  

if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp])) == NULL)

return C_OK;

  

if (checkType(c,o,OBJ_STRING)) {

return C_ERR;

}

  

addReplyBulk(c,o);

return C_OK;

}

  

void getCommand(client *c) {

getGenericCommand(c);

}