clarify delivery concurrency is per client

[behrad]

No description provided.

[coveralls]

Coverage remained the same at 96.998% when pulling 4ab42d8 on behrad:clarifyConcurrency into a66ae34 on mcollina:master.

[mcollina]

This is not true. Delivery concurrency is for the whole broker, and the limit is on the fan in, not on the fan out.

[behrad]

and how this is achieved by conn.setMaxListeners(opts.concurrency * 2) ?

[behrad]

@mcollina Can you clarify me on this man?

[mcollina]

A piece of code is probably worth more :).

conn.setMaxListeners(opts.concurrency * 2)

is needed to avoid a bad warning. Nothing more. It's set to twice the max concurrency, just because I had to account for QoS 1/2 messages.

regarding the actual concurrency limit, this is is:
https://github.com/mcollina/mqemitter/blob/master/mqemitter.js#L97-L114

[mcollina]

It is also invoked in mqemitter-redis: https://github.com/mcollina/mqemitter-redis/blob/master/mqemitter-redis.js#L33.

[behrad]

Now it makes sense, thank you :)

implementation shows the limit is number of parallel publish matchings done inside the broker, however each publish may match any number of clients :)

[mcollina]

Would you mind sending a PR against the README? It might be helpful to others.

[behrad]

implementation shows the limit is number of parallel publish matchings done inside the broker, however each publish may match any number of clients :)

and this means the max number of messages delivered concurrently may be higher than conncurrency!? in current implementation. Yes?

[mcollina]

concurrency is the number of unique messages being delivered, not considering the number of clients we are delivering them to.

[behrad]

concurrency is the number of unique messages being delivered, not considering the number of clients we are delivering them to.

But here https://github.com/mcollina/mqemitter/blob/master/mqemitter.js#L126 current is incremented per _do, despite the actual matches size!!!

[mcollina]

there is no check on the matches, the check is on the message that is being published, not on the messages it is being delivered.

[behrad]

the check is on the message that is being published, not on the messages it is being delivered.

Exactly! and hence we need to emphasize the word unique message, and may be change the word delivered to forwarded or published since delivered increases the chance for ambiguous.

[mcollina]

Published is a good term I think. PR?

[behrad]

👍 Yup, will create one.