Question

I have a memcached state in which I want to save something. When a node connects to the topology of my application, I would like it to add itself to the list of connected nodes of that kind. I’m trying to do this through nesting queries:

mc_cli.connect(function() {
mc_cli.get( key, function(err, response) {
    if(err.type == 'NOT_FOUND'){
        //save myself
        mc_cli.connect(function() {
            mc_cli.add( GLOBAL_KEY, uid, { flags: 0, exptime: 0}, function(err, status) {
                if (!err) { 
                    console.log(status);
                }
                else {
                    console.log(err);
                }
            });
        });
    }
[...]

This code falls in the else with the following error:

{ type: 'CONNECTION_ERROR',
  description: 'Lost connection to server.' }

Basically what the code is doing is that since nobody set up the array of IDs connected, the first node to execute the code is the one in charge of doing it. I’m not showing the following code, which simply takes the list of IDs and adds its own. The error happens in the shown snippet. Now, the code that prints this error in the library is the following:

try {
    this.sock.write(command + crlf);
    if (value) {
      this.sock.write(value);
      this.sock.write(crlf);
    }
    this.queue.enqueue({ handler: handler, callback: callback });
}
catch (x) {
    callback({ type: 'CONNECTION_ERROR', description: 'Lost connection to server.' }, null);
}

Which is not so helpful, since I can’t understand what’s causing it.I’m wondering if what I’m doing is wrong. I’m using some nested thing that I’m used to with mongoDB, but I’m not sure I can do the same with memcached, especially this library. Has anyone with experience an idea on how to solve this issue? Thanks.

EDIT: I forgot to add the link to the library I’m using: overclocked/mc

Answer 1

After a while trying to fight with this I realized that nested connections are possible, the error was not caused by that. I discovered that I was passing badly structured data to the .add() method. What it accepts is not something as simple as a Number or a String, but Buffers. So I had to convert every data I wanted to save like so:

new Buffer(data)

With default encoding (which I believe it’s utf8). I hope this is going to save somebody from hell. The main problem with my issue is that the error I received was not meaningful at all.