Function clientInstallWriteHandler

app/redis-6.2.6/src/networking.c:213–230

This function puts the client in the queue of clients that should write * their output buffers to the socket. Note that it does not *yet* install * the write handler, to start clients are put in a queue of clients that need * to write, so we try to do that before returning in the event loop (see the * handleClientsWithPendingWrites() function). * If we fail and there is more data to write, co

 * If we fail and there is more data to write, compared to what the socket
 * buffers can hold, then we'll really install the handler. */
void clientInstallWriteHandler(client *c) {
    /* Schedule the client to write the output buffers to the socket only
     * if not already done and, for slaves, if the slave can actually receive
     * writes at this stage. */
    if (!(c->flags & CLIENT_PENDING_WRITE) &&
        (c->replstate == REPL_STATE_NONE ||
         (c->replstate == SLAVE_STATE_ONLINE && !c->repl_put_online_on_ack)))
    {
        /* Here instead of installing the write handler, we just flag the
         * client and put it into a list of clients that have something
         * to write to the socket. This way before re-entering the event
         * loop, we can try to directly write to the client sockets avoiding
         * a system call. We'll only really install the write handler if
         * we'll not be able to write the whole reply at once. */
        c->flags |= CLIENT_PENDING_WRITE;
        listAddNodeHead(server.clients_pending_write,c);
    }
}

/* This function is called every time we are going to transmit new data
 * to the client. The behavior is the following: