Generic (connection) pools for Crystal

A pool tailored for sharing connections across coroutines.

Connections will be checkout from the pool and tied to the current fiber, until they are checkin, and thus be usable by another coroutine. Otherwise they behave the same than the generic pool.

require "pg"
require "pool/connection"

pg = ConnectionPool.new(capacity: 25, timeout: 0.01) do
  PG.connect(ENV["DATABASE_URL"])
end

You may checkout as many connections in parallel as needed, then checkin the connections as required:

conn = pg.checkout
result = conn.exec("SELECT * FROM posts")
pg.checkin(conn)

You may checkout a single connection per coroutine. Trying to checkout another one will always return the same single connection:

conn = pg.connection
result = conn.exec("SELECT * FROM posts")
pg.release

You may also use a block, so the connection will be checkin back into the pool, unless the connection was already checkout, in which case it will be passed to the block, but not returned to the pool:

pg.connection do |conn|
  result = conn.exec("SELECT * FROM posts")
end

Licensed under the Apache License, Version 2.0