Emit queue event

[rwky]

When a connection pool has to queue a connection then emit a queue event with the number of connections in the queue as the first argument.

[felixge]

Thx. Needs docs. Also curious to hear what the use case is.

[rwky]

I've added docs to the readme, let me know if you need more.
There are two use cases I found this useful for.

1. I was running some batch queries every 0.5 seconds, some of the batches would take longer than 0.5 seconds to run so the connection pool would be used. This was causing a bottle neck when the queue hit the default 10. Listening for the queue event made it easy to find out when I was hitting the limit and then increase it.

2. This was really just me being forgetful, but I forgot to release the connections which caused the queue to fill up and then the batch process would just hang. Watching the queue event makes it easy to see why it's hanging and go 'oops I'm not releasing connections'

[sidorares]

does it have to be an event? Maybe have some public pool methods like 'queueSise', 'numActiveConnections' etc?

[rwky]

I find the event the most useful, otherwise I'd have to check the queue periodically at specific points in the app or with some hacky setInterval.

[pwlmaciejewski]

👍