expiring-cache-map- General purpose simple caching.

Copyright(c) 2014 Edward L. Blake
MaintainerEdward L. Blake <edwardlblake@gmail.com>
Safe HaskellSafe-Inferred



TestSequence monad for testing caching behaviour.

{-# LANGUAGE OverloadedStrings #-}

import Caching.ExpiringCacheMap.HashECM (newECMForM, lookupECM, CacheSettings(..), consistentDuration)
import qualified Caching.ExpiringCacheMap.Utils.TestSequence as TestSeq

import qualified Data.ByteString.Char8 as BS

test = do
  (TestSeq.TestSequenceState (_, events, _), return_value) <- TestSeq.runTestSequence test'
  (putStrLn . show . reverse) events
  return ()
    test' = do
      filecache <- newECMForM
            (consistentDuration 100 -- Duration between access and expiry time of each item, no state needed.
              (\state _id -> do number <- TestSeq.readNumber
                                return (state, number)))
            (TestSeq.getCurrentTime >>= return)
            12000 -- Time check frequency: (accumulator `mod` this_number) == 0.
              6   -- Expected size of key-value map when removing elements.
              6   -- Size of map when to remove items from key-value map.
              12  -- Size of list when to compact
            TestSeq.newTestSVar TestSeq.enterTestSVar TestSeq.readTestSVar
      -- Use lookupECM whenever the contents of "file1" is needed.
      b <- lookupECM filecache ("file1" :: BS.ByteString)
      TestSeq.haveNumber b
      b <- lookupECM filecache "file1"
      b <- lookupECM filecache "file2"
      TestSeq.haveNumber b
      return b

Evaluating the test function results in a list of events.

>>> test
[GetVar 3,ReadNumber 4,GetTime 7,PutVar 11,HaveNumber 4,GetVar 14,PutVar 17,
 GetVar 19,ReadNumber 20,GetTime 23,PutVar 27,HaveNumber 20]

In this example the history shows 2 time accesses (GetTime 7 and GetTime 23) since the time check frequency number is a high value (12000), but regardless the high value a time check is still requested again because of the new key request for "file2".

Changing the time frequency to 1 will alter the list of events with more frequent time checks:

>>> test
[GetVar 3,ReadNumber 4,GetTime 7,PutVar 11,HaveNumber 4,GetVar 14,GetTime 15,
 GetTime 18,PutVar 22,GetVar 24,ReadNumber 25,GetTime 28,PutVar 32,
 HaveNumber 25]


enterTestSVar :: TestSVar a -> (a -> TestSequence a (a, b)) -> TestSequence a b Source

newtype TestSVar a Source


TestSVar a