Function moduleBlockClient

app/redis-6.2.6/src/module.c:5283–5326

Block a client in the context of a module: this function implements both * RM_BlockClient() and RM_BlockClientOnKeys() depending on the fact the * keys are passed or not. * * When not blocking for keys, the keys, numkeys, and privdata parameters are * not needed. The privdata in that case must be NULL, since later is * RM_UnblockClient() that will provide some private data that the reply *

 *
 */
RedisModuleBlockedClient *moduleBlockClient(RedisModuleCtx *ctx, RedisModuleCmdFunc reply_callback, RedisModuleCmdFunc timeout_callback, void (*free_privdata)(RedisModuleCtx*,void*), long long timeout_ms, RedisModuleString **keys, int numkeys, void *privdata) {
    client *c = ctx->client;
    int islua = server.in_eval;
    int ismulti = server.in_exec;

    c->bpop.module_blocked_handle = zmalloc(sizeof(RedisModuleBlockedClient));
    RedisModuleBlockedClient *bc = c->bpop.module_blocked_handle;
    ctx->module->blocked_clients++;

    /* We need to handle the invalid operation of calling modules blocking
     * commands from Lua or MULTI. We actually create an already aborted
     * (client set to NULL) blocked client handle, and actually reply with
     * an error. */
    mstime_t timeout = timeout_ms ? (mstime()+timeout_ms) : 0;
    bc->client = (islua || ismulti) ? NULL : c;
    bc->module = ctx->module;
    bc->reply_callback = reply_callback;
    bc->timeout_callback = timeout_callback;
    bc->disconnect_callback = NULL; /* Set by RM_SetDisconnectCallback() */
    bc->free_privdata = free_privdata;
    bc->privdata = privdata;
    bc->reply_client = createClient(NULL);
    bc->reply_client->flags |= CLIENT_MODULE;
    bc->dbid = c->db->id;
    bc->blocked_on_keys = keys != NULL;
    bc->unblocked = 0;
    bc->background_timer = 0;
    bc->background_duration = 0;
    c->bpop.timeout = timeout;

    if (islua || ismulti) {
        c->bpop.module_blocked_handle = NULL;
        addReplyError(c, islua ?
            "Blocking module command called from Lua script" :
            "Blocking module command called from transaction");
    } else {
        if (keys) {
            blockForKeys(c,BLOCKED_MODULE,keys,numkeys,timeout,NULL,NULL,NULL);
        } else {
            blockClient(c,BLOCKED_MODULE);
        }
    }
    return bc;
}

/* This function is called from module.c in order to check if a module
 * blocked for BLOCKED_MODULE and subtype 'on keys' (bc->blocked_on_keys true)