{-# LANGUAGE MagicHash #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE UnboxedTuples #-}
module Regressions (tests) where
import Control.Exception (evaluate)
import Control.Monad (replicateM)
import Data.Hashable (Hashable (..))
import Data.List (delete)
import Data.Maybe (isJust, isNothing)
import GHC.Exts (touch#)
import GHC.IO (IO (..))
import System.Mem (performGC)
import System.Mem.Weak (deRefWeak, mkWeakPtr)
import System.Random (randomIO)
import Test.HUnit (Assertion, assert)
import Test.QuickCheck
import Test.Tasty (TestTree, testGroup)
import Test.Tasty.HUnit (testCase)
import Test.Tasty.QuickCheck (testProperty)
import qualified Data.HashMap.Lazy as HML
import qualified Data.HashMap.Strict as HMS
issue32 :: Assertion
issue32 = assert $ isJust $ HMS.lookup 7 m'
where
ns = [0..16] :: [Int]
m = HMS.fromList (zip ns (repeat []))
m' = HMS.delete 10 m
------------------------------------------------------------------------
-- Issue #39
-- First regression
issue39 :: Assertion
issue39 = assert $ hm1 == hm2
where
hm1 = HMS.fromList ([a, b] `zip` [1, 1 :: Int ..])
hm2 = HMS.fromList ([b, a] `zip` [1, 1 :: Int ..])
a = (1, -1) :: (Int, Int)
b = (-1, 1) :: (Int, Int)
-- Second regression
newtype Keys = Keys [Int]
deriving Show
instance Arbitrary Keys where
arbitrary = sized $ \l -> do
pis <- replicateM (l+1) positiveInt
return (Keys $ prefixSum pis)
shrink (Keys ls) =
let l = length ls
in if l == 1
then []
else [ Keys (dropAt i ls) | i <- [0..l-1] ]
positiveInt :: Gen Int
positiveInt = (+1) . abs <$> arbitrary
prefixSum :: [Int] -> [Int]
prefixSum = loop 0
where
loop _ [] = []
loop prefix (l:ls) = let n = l + prefix
in n : loop n ls
dropAt :: Int -> [a] -> [a]
dropAt _ [] = []
dropAt i (l:ls) | i == 0 = ls
| otherwise = l : dropAt (i-1) ls
propEqAfterDelete :: Keys -> Bool
propEqAfterDelete (Keys keys) =
let keyMap = mapFromKeys keys
k = head keys
in HMS.delete k keyMap == mapFromKeys (delete k keys)
mapFromKeys :: [Int] -> HMS.HashMap Int ()
mapFromKeys keys = HMS.fromList (zip keys (repeat ()))
------------------------------------------------------------------------
-- Issue #254
-- Key type that always collides.
newtype KC = KC Int
deriving (Eq, Ord, Show)
instance Hashable KC where
hashWithSalt salt _ = salt
touch :: a -> IO ()
touch a = IO (\s -> (# touch# a s, () #))
-- We want to make sure that old values in the HashMap are evicted when new values are inserted,
-- even if they aren't evaluated. To do that, we use the WeakPtr trick described at
-- http://simonmar.github.io/posts/2018-06-20-Finding-fixing-space-leaks.html.
-- We insert a value named oldV into the HashMap, then insert over it, checking oldV is no longer reachable.
--
-- To make the test robust, it's important that oldV isn't hoisted up to the top or shared.
-- To do that, we generate it randomly.
issue254Lazy :: Assertion
issue254Lazy = do
i :: Int <- randomIO
let oldV = error $ "Should not be evaluated: " ++ show i
weakV <- mkWeakPtr oldV Nothing -- add the ability to test whether oldV is alive
mp <- evaluate $ HML.insert (KC 1) (error "Should not be evaluated") $ HML.fromList [(KC 0, "1"), (KC 1, oldV)]
performGC
res <- deRefWeak weakV -- gives Just if oldV is still alive
touch mp -- makes sure that we didn't GC away the whole HashMap, just oldV
assert $ isNothing res
-- Like issue254Lazy, but using strict HashMap
issue254Strict :: Assertion
issue254Strict = do
i :: Int <- randomIO
let oldV = show i
weakV <- mkWeakPtr oldV Nothing
mp <- evaluate $ HMS.insert (KC 1) "3" $ HMS.fromList [(KC 0, "1"), (KC 1, oldV)]
performGC
res <- deRefWeak weakV
touch mp
assert $ isNothing res
------------------------------------------------------------------------
-- * Test list
tests :: TestTree
tests = testGroup "Regression tests"
[
testCase "issue32" issue32
, testCase "issue39a" issue39
, testProperty "issue39b" propEqAfterDelete
, testCase "issue254 lazy" issue254Lazy
, testCase "issue254 strict" issue254Strict
]