Function addReplyDeferredLen

app/redis-6.2.6/src/networking.c:564–572

Adds an empty object to the reply list that will contain the multi bulk * length, which is not known when this function is called. */

/* Adds an empty object to the reply list that will contain the multi bulk
 * length, which is not known when this function is called. */
void *addReplyDeferredLen(client *c) {
    /* Note that we install the write event here even if the object is not
     * ready to be sent, since we are sure that before returning to the
     * event loop setDeferredAggregateLen() will be called. */
    if (prepareClientToWrite(c) != C_OK) return NULL;
    trimReplyUnusedTailSpace(c);
    listAddNodeTail(c->reply,NULL); /* NULL is our placeholder. */
    return listLast(c->reply);
}

void setDeferredReply(client *c, void *node, const char *s, size_t length) {
    listNode *ln = (listNode*)node;