davidgregory084 / pool

A generic resource pooling library for Scala

pool

pool is a Scala port of Bryan O'Sullivan's excellent Haskell resource-pooling library bos/pool.

pool makes extensive use of the facilities provided by the Monix library.

Example

implicit val scheduler = Scheduler.io(
  name = "pool-test",
  reporter = UncaughtExceptionReporter(
    logger.error(s"pool-test: Uncaught exception in IO scheduler", _)))

// Run a `Pool[Unit] => Task[Unit]`
val usePool = Pool.withPool[Unit, Unit](
  name = "test",
  create = Task.eval(logger.info("Creating entry")),
  destroy = a => Task.eval(logger.info(s"Destroying entry $a")),
  minIdle = 5,
  maxEntries = 10,
  idleTimeout = 60.seconds,
  creatorDelay = 1.second,
  creatorInterval = 1.second,
  reaperDelay = 1.second,
  reaperInterval = 1.second
) { pool =>

    pool.withResource(a => Task.fork(Task.eval(Thread.sleep(5000))))
  }

Await.result(usePool.runAsync, Duration.Inf)

pool's Issues

Connection acquisition less than ideal

This pool is susceptible to the problem described here, namely that once it has committed to creating a connection, it no longer takes a connection from the pool if one becomes available while the connection is being created.
Therefore, if connection creation takes a long time then there may be connections waiting when they could be using a connection that has just been returned to the pool instead.