Creating multiple contexts causes real problems

[pghalliday]

While investigating workarounds for issue #37 I tried to create multiple contexts pointing to the same server.

First I tried this:

var rabbitJS = require('rabbit.js');
var context0 = rabbitJS.createContext('amqp://localhost');
context0.on('ready', function() {
  var pub = context0.socket('PUB');
  pub.connect('events', function() {
    var context1 = rabbitJS.createContext('amqp://localhost');
    context1.on('ready', function() {
      var sub1 = context1.socket('SUB');
      sub1.setEncoding('utf8');
      sub1.on('data', function(data) {
        console.log('subscriber 1');
        console.log(data);
      });
      sub1.connect('events', function() {
        var context2 = rabbitJS.createContext('amqp://localhost');
        context2.on('ready', function() {
          var sub2 = context2.socket('SUB');
          sub2.setEncoding('utf8');
          sub2.on('data', function(data) {
            console.log('subscriber 2');
            console.log(data);
          });
          sub2.connect('events', function() {
            console.log('publish');
            pub.write(JSON.stringify({welcome: 'rabbit.js', source: 'pub'}), 'utf8');
          });
        });
      });
    });
  });
});

with the following result:

Unhandled connection error: COMMAND_INVALID - second 'channel.open' seen

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: COMMAND_INVALID - second 'channel.open' seen
    at Connection._onMethod (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:1155:15)
    at AMQPParser.parser.onMethod (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:897:12)
    at AMQPParser._parseMethodFrame (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:451:10)
    at frameEnd (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:192:16)
    at frame (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:177:14)
    at AMQPParser.header [as parse] (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:163:14)
    at AMQPParser.execute (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:236:21)
    at Connection.<anonymous> (/home/pghalliday/Development/testRabbitMQ/node_modules/rabbit.js/node_modules/amqp/amqp.js:935:14)
    at Connection.EventEmitter.emit (events.js:95:17)
    at Connection.<anonymous> (_stream_readable.js:710:14)

I'm guessing multiple contexts are not supported (although I think they may be useful/vital when I get round to creating unit and integration tests)

I then tried a similar experiment with just 2 contexts:

var rabbitJS = require('rabbit.js');
var context0 = rabbitJS.createContext('amqp://localhost');
context0.on('ready', function() {
  var pub = context0.socket('PUB');
  pub.connect('events', function() {
    var context1 = rabbitJS.createContext('amqp://localhost');
    context1.on('ready', function() {
      var sub = context1.socket('SUB');
      sub.setEncoding('utf8');
      sub.on('data', function(data) {
        console.log('subscriber 1');
        console.log(data);
      });
      sub.connect('events', function() {
        console.log('publish');
        pub.write(JSON.stringify({welcome: 'rabbit.js', source: 'pub'}), 'utf8');
      });
    });
  });
});

This time I got the following result:

publish
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
{"welcome":"rabbit.js","source":"pub"}
subscriber 1
... etc forever ...

This was clearly an infinite loop. Again am I misunderstanding something about how RabbitMQ works. This seems like a pretty serious issue too but possibly not as bad as the last #37

[squaremo]

OK I think that second thing is fixed in #35. Specifically, with "works" meaning it prints out things just once, it

• always works with Node.JS v0.8
• works with Node.JS and rabbit.js master
• does not work with Node.JS v0.10.4 and rabbit.js after git checkout f493e78

I'll look into the first thing ..

[squaremo]

I'll look into the first thing ..

The first test case above also appears to be due to EventEmitter not working the way it used to. (It used to work by coincidence; now it's broken by coincidence).

If you have a moment would you check with a master checkout? Thanks!

[pghalliday]

i'll take a look

[pghalliday]

Indeed this works with master :)

[pghalliday]

looking forward to the next release then :D

[squaremo]

Ha, yes good point, well made. Yeah I ought to do a trawl for any other breakages, and post a new release. It's been a while.