lockpool (empty) → 0.1.0.0

raw patch · 5 files changed

+175/−0 lines, 5 filesdep +basedep +clockdep +stmsetup-changed

Dependencies added: base, clock, stm

Files

• ChangeLog.md +5/−0
• Control/Concurrent/LockPool.hs +114/−0
• LICENSE +30/−0
• Setup.hs +2/−0
• lockpool.cabal +24/−0

@@ -0,0 +1,5 @@+# Revision history for lockpool++## 0.1.0.0  -- YYYY-mm-dd++* First version. Released on an unsuspecting world.

@@ -0,0 +1,114 @@+{-# LANGUAGE BangPatterns #-}++module Control.Concurrent.LockPool+  ( LockPool+  , LockingStats(..)+  , withLockPool+  , withLockPoolStats+  , incrementLockPoolSize+  , decrementLockPoolSize+  , readLockPoolSize+  , newLockPool+  ) where++import Control.Monad.STM+import Control.Concurrent.STM.TVar+import Control.Exception (bracket_,bracket)+import qualified System.Clock as CLK++-- | A LockPool lets us set an upper bound on the number of threads+--   that are doing something simultaneously.+data LockPool = LockPool +  Int        -- ^ absolute maximum holders+  (TVar Int) -- ^ maximum number of lock holders+  (TVar Int) -- ^ current number of lock holders++data Clocked a = Clocked !Integer !a++-- | The result of a computation along with some information+--   about how long we had to wait to acquire a lock and how+--   long the computation took.+data LockingStats = LockingStats+  { lsWaitedNanoseconds :: !Integer+  , lsActionNanoseconds :: !Integer+  , lsTakenLocks :: !Int+    -- ^ Count of taken locks before releasing the lock+  , lsTotalLocks :: !Int +    -- ^ Count of total locks before adjusting the total+  }++stopwatch :: IO a -> IO (Clocked a)+stopwatch x = do+  t1 <- CLK.getTime CLK.Monotonic+  a <- x+  t2 <- CLK.getTime CLK.Monotonic+  return (Clocked (CLK.toNanoSecs (CLK.diffTimeSpec t2 t1)) a)++stopwatch_ :: IO a -> IO Integer+stopwatch_ x = do+  t1 <- CLK.getTime CLK.Monotonic+  _ <- x+  t2 <- CLK.getTime CLK.Monotonic+  return (CLK.toNanoSecs (CLK.diffTimeSpec t2 t1))++withLockPool :: LockPool -> IO a -> IO a+withLockPool (LockPool _ maxHoldersVar currentHoldersVar) action = +  bracket_ acquire release action+  where+  acquire = atomically $ do+    maxHolders <- readTVar maxHoldersVar+    currentHolders <- readTVar currentHoldersVar+    check (currentHolders < maxHolders)+    writeTVar currentHoldersVar $! (currentHolders + 1)+  release = atomically $ modifyTVar' currentHoldersVar (subtract 1)++withLockPoolStats :: LockPool -> IO a -> IO (LockingStats,a)+withLockPoolStats (LockPool _ maxHoldersVar currentHoldersVar) x = +  bracket acquire release action+  where+  acquire = stopwatch_ $ atomically $ do+    maxHolders <- readTVar maxHoldersVar+    currentHolders <- readTVar currentHoldersVar+    check (currentHolders < maxHolders)+    writeTVar currentHoldersVar $! (currentHolders + 1)+  action waitedNs = do+    Clocked actionNs a <- stopwatch x+    taken <- readTVarIO currentHoldersVar+    total <- readTVarIO maxHoldersVar+    return (LockingStats waitedNs actionNs taken total, a)+  release _ = atomically $ modifyTVar' currentHoldersVar (subtract 1)++-- | We do not allow the size to drop to zero since that+--   would halt all progress.+decrementLockPoolSize :: LockPool -> IO Int+decrementLockPoolSize (LockPool _ maxHoldersVar _) = atomically $ do+  i <- readTVar maxHoldersVar+  let i' = max 1 (i - 1)+  writeTVar maxHoldersVar $! i'+  return i'++incrementLockPoolSize :: LockPool -> IO Int+incrementLockPoolSize (LockPool absMax maxHoldersVar _) = atomically $ do+  i <- readTVar maxHoldersVar+  let i' = min absMax (i + 1)+  writeTVar maxHoldersVar $! i'+  return i'++readLockPoolSize :: LockPool -> IO Int+readLockPoolSize (LockPool _ maxHoldersVar _) = +  readTVarIO maxHoldersVar++_readLockPoolHolds :: LockPool -> IO Int+_readLockPoolHolds (LockPool _ _ currentHoldersVar) = +  readTVarIO currentHoldersVar++newLockPool :: +     Int -- ^ absolute maximum number of holders+  -> IO LockPool+newLockPool n = LockPool n+  <$> newTVarIO 1+  <*> newTVarIO 0++-- setLockPoolSize :: LockPool -> Int -> IO ()+-- setLockPoolSize (LockPool maxHoldersVar _) !newMax =+--   atomically (writeTVar maxHoldersVar newMax)

@@ -0,0 +1,30 @@+Copyright (c) 2018, Layer 3 Communications, Andrew Martin++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions are met:++    * Redistributions of source code must retain the above copyright+      notice, this list of conditions and the following disclaimer.++    * Redistributions in binary form must reproduce the above+      copyright notice, this list of conditions and the following+      disclaimer in the documentation and/or other materials provided+      with the distribution.++    * Neither the name of chessai nor the names of other+      contributors may be used to endorse or promote products derived+      from this software without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,24 @@+name:                lockpool+version:             0.1.0.0+synopsis:            set a maximum on the number of concurrent actions +description:         with a 'LockPool', you can specify the+                     maximum number of threads that are running+                     concurrently.+homepage:            https://github.com/chessai/lockpool.git+license:             BSD3+license-file:        LICENSE+author:              Andrew Martin+maintainer:          chessai1996@gmail.com+copyright:           Layer 3 Communications, Andrew Martin +category:            Concurrency+build-type:          Simple+extra-source-files:  ChangeLog.md+cabal-version:       >=1.10++library+  exposed-modules:     Control.Concurrent.LockPool+  other-extensions:    BangPatterns+  build-depends:       base >=4.10 && <5.0+                     , clock+                     , stm+  default-language:    Haskell2010