Function emptyDb

app/redis-6.2.6/src/db.c:426–463

Remove all keys from all the databases in a Redis server. * If callback is given the function is called from time to time to * signal that work is in progress. * * The dbnum can be -1 if all the DBs should be flushed, or the specified * DB number if we want to flush only a single Redis database number. * * Flags are be EMPTYDB_NO_FLAGS if no special flags are specified or * EMPTYDB_ASYNC i

 * database(s). Otherwise -1 is returned in the specific case the
 * DB number is out of range, and errno is set to EINVAL. */
long long emptyDb(int dbnum, int flags, void(callback)(void*)) {
    int async = (flags & EMPTYDB_ASYNC);
    RedisModuleFlushInfoV1 fi = {REDISMODULE_FLUSHINFO_VERSION,!async,dbnum};
    long long removed = 0;

    if (dbnum < -1 || dbnum >= server.dbnum) {
        errno = EINVAL;
        return -1;
    }

    /* Fire the flushdb modules event. */
    moduleFireServerEvent(REDISMODULE_EVENT_FLUSHDB,
                          REDISMODULE_SUBEVENT_FLUSHDB_START,
                          &fi);

    /* Make sure the WATCHed keys are affected by the FLUSH* commands.
     * Note that we need to call the function while the keys are still
     * there. */
    signalFlushedDb(dbnum, async);

    /* Empty redis database structure. */
    removed = emptyDbStructure(server.db, dbnum, async, callback);

    /* Flush slots to keys map if enable cluster, we can flush entire
     * slots to keys map whatever dbnum because only support one DB
     * in cluster mode. */
    if (server.cluster_enabled) slotToKeyFlush(async);

    if (dbnum == -1) flushSlaveKeysWithExpireList();

    /* Also fire the end event. Note that this event will fire almost
     * immediately after the start event if the flush is asynchronous. */
    moduleFireServerEvent(REDISMODULE_EVENT_FLUSHDB,
                          REDISMODULE_SUBEVENT_FLUSHDB_END,
                          &fi);

    return removed;
}

/* Store a backup of the database for later use, and put an empty one
 * instead of it. */