Function getNodeByQuery

src/cluster.cpp:5897–6091

Return the pointer to the cluster node that is able to serve the command. * For the function to succeed the command should only target either: * * 1) A single key (even multiple times like LPOPRPUSH mylist mylist). * 2) Multiple keys in the same hash slot, while the slot is stable (no * resharding in progress). * * On success the function returns the node that is able to serve the reques

 * CLUSTER_REDIR_DOWN_STATE and CLUSTER_REDIR_DOWN_RO_STATE if the cluster is
 * down but the user attempts to execute a command that addresses one or more keys. */
clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *error_code) {
    clusterNode *n = NULL;
    robj *firstkey = NULL;
    int multiple_keys = 0;
    multiState *ms, _ms;
    multiCmd mc;
    int i, slot = 0, migrating_slot = 0, importing_slot = 0, missing_keys = 0;
    serverAssert((c->cmd->flags & CMD_ASYNC_OK) || GlobalLocksAcquired());

    /* Allow any key to be set if a module disabled cluster redirections. */
    if (g_pserver->cluster_module_flags & CLUSTER_MODULE_FLAG_NO_REDIRECTION)
        return myself;

    /* Allow any key to be set if a module disabled cluster redirections. */
    if (g_pserver->cluster_module_flags & CLUSTER_MODULE_FLAG_NO_REDIRECTION)
        return myself;

    /* Set error code optimistically for the base case. */
    if (error_code) *error_code = CLUSTER_REDIR_NONE;

    /* Modules can turn off Redis Cluster redirection: this is useful
     * when writing a module that implements a completely different
     * distributed system. */

    /* We handle all the cases as if they were EXEC commands, so we have
     * a common code path for everything */
    if (cmd->proc == execCommand) {
        /* If CLIENT_MULTI flag is not set EXEC is just going to return an
         * error. */
        if (!(c->flags & CLIENT_MULTI)) return myself;
        ms = &c->mstate;
    } else {
        /* In order to have a single codepath create a fake Multi State
         * structure if the client is not in MULTI/EXEC state, this way
         * we have a single codepath below. */
        ms = &_ms;
        _ms.commands = &mc;
        _ms.count = 1;
        mc.argv = argv;
        mc.argc = argc;
        mc.cmd = cmd;
    }

    /* Check that all the keys are in the same hash slot, and obtain this
     * slot and the node associated. */
    for (i = 0; i < ms->count; i++) {
        struct redisCommand *mcmd;
        robj **margv;
        int margc, *keyindex, numkeys, j;

        mcmd = ms->commands[i].cmd;
        margc = ms->commands[i].argc;
        margv = ms->commands[i].argv;

        getKeysResult result = GETKEYS_RESULT_INIT;
        numkeys = getKeysFromCommand(mcmd,margv,margc,&result);
        keyindex = result.keys;