TODOs (#18)

Author: levkk

CONTRIBUTING.md

@@ -1,6 +1,21 @@
+## Introduction
+
 Thank you for contributing! Just a few tips here:
 
 1. `cargo fmt` your code before opening up a PR
 2. Run the "test suite" (i.e. PgBench) to make sure everything still works.
 
 Happy hacking!
+
+## TODOs
+
+A non-exhaustive list of things that would be useful to implement.
+
+#### Client authentication
+MD5 is probably sufficient, but maybe others too.
+
+#### Statistics
+Same as PgBouncer, e.g. client wait, transactions, timings, etc. I'm thinking we can use `mpsc` here ([docs](https://tokio.rs/tokio/tutorial/channels)), with clients sending stats and a task collecting and aggregating them. This should avoid atomics/mutexes. Caveat is the task should make sure not to crash, so the channels don't get backed up.
+
+#### Admin
+Admin database for stats collection and pooler administration. PgBouncer gives us a nice example on how to do that, specifically how to implement `RowDescription` and `DataRow` messages, [example here](https://github.com/pgbouncer/pgbouncer/blob/4f9ced8e63d317a6ff45c8b0efa876b32161f6db/src/admin.c#L813).