notify/listen on channels longer than 63 characters silently fails without any error or warning

[jedwards1211]

System

• Docker container: timescale/timescaledb:2.3.0-pg13
• pg version: 8.6.0
• pg-ipc version: 1.0.5

Repro code

const pgIPC = require('pg-ipc')
const pg = require('pg')
async function go() {
  var client = new pg.Client({...})
  var ipc = new pgIPC(client)
  ipc.on('error', console.error)
  await client.connect()
  ipc.on('test', console.log)
  ipc.notify('test', {value: 'test'})
  ipc.on('1234567890123456789012345678901234567890123456789012345678901234', console.log)
  ipc.notify('1234567890123456789012345678901234567890123456789012345678901234', {value: '64 chars'})
  ipc.notify('123456789012345678901234567890123456789012345678901234567890123', {value: '63 chars'})
}
go()

Actual behavior

I only see the output

NotificationResponseMessage {
  length: 30,
  processId: 2603,
  channel: 'test',
  payload: { value: 'test' },
  name: 'notification'
}

Expected behavior

Either it emits an 'error' of some kind, or I my listener for the 64-character '...1234' channel gets called.

What happens

The LISTEN/NOTIFY calls get truncated in Postgres to 63 characters. Postgres doesn't emit any errors for this, though it will raise a notice about it in the console.

So the last two notify calls, both for the 64-character '...1234' and the 63-character '...123' cause the pg.Client to emit notification events for the 63-character '...123' channel.

pg-ipc then emits events on that 63-character '...123' channel...but the listener was registered on the EventEmitter with the 64-character '...1234' channel. So the listener never gets called.

Solutions

I'd say either

• truncate the channel to 63 characters when registering the listener on the EventEmitter (matching Postgres behavior)
• OR throw an error if on/notify is called with a channel longer than 63 characters.