Listen/Notify support

[deem0n]

Hello,

Is it possible to add support for http://www.postgresql.org/docs/9.4/static/sql-listen.html ?
The use case might be:

1. Lua/moon calls LISTEN in PostgreSQL session and register async callback written in Lua/moon
2. Lua/Moon callback is asynchronously called as result of NOTIFY inside PostgreSQL
3. Callback process the data, and send changes to the client via WebSocket

Thank you !

[mkozjak]

Since there's nothing in docs, but 1.5.0 changelog says it's there, is this now supported?

[leafo]

It should, here's the code: https://github.com/leafo/pgmoon/pull/28/files

Docs are indeed missing though.

[mkozjak]

Nice!

[AdrienPensart]

Have you got a little example ? Because I can't get to have only one connection to postgresql (I can see it in pg_top) when I open multiple tab of my websocket html...and setkeepalive just mess up the socket...

[valpackett]

@AdrienPensart you can use a background worker (init_worker_by_lua_block { ngx.timer.at(0, your_function) }) and something like lua-resty-worker-events to communicate from that worker to your websocket handler.