From b128bc7a09601bc44ebe2f28cf9569fde8835bb8 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Thu, 26 Dec 2013 16:55:26 +0200
Subject: [PATCH] Remove System.IO.Pool (use resource-pool instead)

---
 System/IO/Pool.hs | 66 -----------------------------------------------
 mongoDB.cabal     |  1 -
 2 files changed, 67 deletions(-)
 delete mode 100644 System/IO/Pool.hs

diff --git a/System/IO/Pool.hs b/System/IO/Pool.hs
deleted file mode 100644
index c97367b..0000000
--- a/System/IO/Pool.hs
+++ /dev/null
@@ -1,66 +0,0 @@
-{- | Cycle through a set of resources (randomly), recreating them when they expire -}
-
-{-# LANGUAGE RecordWildCards, NamedFieldPuns, FlexibleContexts #-}
-
-module System.IO.Pool where
-
-import Control.Applicative ((<$>))
-import Control.Exception (assert)
-import Data.Array.IO (IOArray, readArray, writeArray, newArray, newListArray,
-                      getElems, getBounds, rangeSize, range)
-import Data.Maybe (catMaybes)
-import System.Random (randomRIO)
-
-import Control.Concurrent.MVar.Lifted (MVar, newMVar, withMVar, modifyMVar_)
-import Control.Monad.Error (ErrorT, Error)
-import Control.Monad.Trans (liftIO)
-
--- | Creator, destroyer, and checker of resources of type r. Creator may throw error or type e.
-data Factory e r = Factory {
-	newResource :: ErrorT e IO r,
-	killResource :: r -> IO (),
-	isExpired :: r -> IO Bool }
-
-newPool :: Factory e r -> Int -> IO (Pool e r)
--- ^ Create new pool of initial max size, which must be >= 1
-newPool f n = assert (n > 0) $ do
-	arr <- newArray (0, n-1) Nothing
-	var <- newMVar arr
-	return (Pool f var)
-
-data Pool e r = Pool {factory :: Factory e r, resources :: MVar (IOArray Int (Maybe r))}
--- ^ Pool of maximum N resources. Resources may expire on their own or be killed. Resources will initially be created on demand up N resources then recycled in random fashion. N may be changed by resizing the pool. Random is preferred to round-robin to distribute effect of pathological use cases that use every Xth resource the most and N is a multiple of X.
--- Resources *must* close/kill themselves when garbage collected ('resize' relies on this).
-
-aResource :: (Error e) => Pool e r -> ErrorT e IO r
--- ^ Return a random live resource in pool or create new one if expired or not yet created
-aResource Pool{..} = withMVar resources $ \array -> do
-	i <- liftIO $ randomRIO =<< getBounds array
-	mr <- liftIO $ readArray array i
-	r <- maybe (new array i) (check array i) mr
-	return r
- where
-	new array i = do
-		r <- newResource factory
-		liftIO $ writeArray array i (Just r)
-		return r
-	check array i r = do
-		bad <- liftIO $ isExpired factory r
-		if bad then new array i else return r
-
-poolSize :: Pool e r -> IO Int
--- ^ current max size of pool
-poolSize Pool{resources} = withMVar resources (fmap rangeSize . getBounds)
-
-resize :: Pool e r -> Int -> IO ()
--- ^ resize max size of pool. When shrinking some resource will be dropped without closing since they may still be in use. They are expected to close themselves when garbage collected.
-resize Pool{resources} n = modifyMVar_ resources $ \array -> do
-	rs <- take n <$> getElems array
-	array' <- newListArray (0, n-1) (rs ++ repeat Nothing)
-	return array'
-
-killAll :: Pool e r -> IO ()
--- ^ Kill all resources in pool so subsequent access creates new ones
-killAll (Pool Factory{killResource} resources) = withMVar resources $ \array -> do
-	mapM_ killResource . catMaybes =<< getElems array
-	mapM_ (\i -> writeArray array i Nothing) . range =<< getBounds array
diff --git a/mongoDB.cabal b/mongoDB.cabal
index 77795eb..62ca88b 100644
--- a/mongoDB.cabal
+++ b/mongoDB.cabal
@@ -46,4 +46,3 @@ Library
                     Database.MongoDB.Internal.Util
                     Database.MongoDB.Query
                     System.IO.Pipeline
-                    System.IO.Pool