packages feed

hasql-pool 1.4.2.3 → 1.5.1.1

raw patch · 33 files changed

Files

CHANGELOG.md view
@@ -1,3 +1,54 @@+# v1.5.1.1++## Fixes++- After the server closes an idle pooled connection (a Postgres restart,+  `pg_terminate_backend`, a server-side idle timeout), the first session on+  it can fail with `UnexpectedRowCountStatementError` instead of a connection+  error. Hasql maps the extra result that reports the closed connection to+  that error, and a `singleRow` statement that returns two rows fails the+  same way on a healthy connection, so the error alone cannot justify a+  discard: the dead connection got returned to the pool and failed one more+  session before it was discarded, so after a database restart every pooled+  connection failed two sessions. Now, when a session fails with an error+  that does not require a discard, `use` also checks the status that the+  adapter reports for the connection and discards it when it is marked bad.++# v1.5.1.0++## Fixes++- Fix pool capacity leak when `use` gets interrupted during connection+  establishment, connection refresh, or an observation (#60)+- Fix pool state corruption from throwing observation handlers; handlers+  are now contained (see the updated `observationHandler` docs)+- Fix background reaper dying permanently from a failed connection+  release or observation+- Fix `release` leaking flushed entries on failure+- Fix waiters waiting forever on a garbage-collected pool++## Added++- `reuseOrder` setting (#59): LIFO reuse lets the pool shrink to the+  connections the load needs and keeps caches warm; FIFO stays the default+- One background timer for acquisition timeouts instead of one+  uncancelable timer per waiting request (#58)++## Changed++- Connections are handed to waiting requests in arrival order; a request+  no longer takes a connection while others wait (#58)++# v1.5.0.1++- Allow newer pqi.++# v1.5.0.0++## Breaking++- Migrate to `hasql-2`, replacing `postgresql-libpq` with the `pqi` connection-adapter interface. `acquire` now takes a `Pqi.Adapter` as its first argument; pick one from an adapter package such as `pqi-ffi` or `pqi-native`.+ # v1.4.2.3  ## Fixes
hasql-pool.cabal view
@@ -1,6 +1,6 @@ cabal-version: 3.0 name: hasql-pool-version: 1.4.2.3+version: 1.5.1.1 category: Hasql, Database, PostgreSQL synopsis: Pool of connections for Hasql homepage: https://github.com/nikita-volkov/hasql-pool@@ -78,6 +78,7 @@    other-modules:     Hasql.Pool.Config.Config+    Hasql.Pool.Config.ReuseOrder     Hasql.Pool.Config.Setting     Hasql.Pool.Prelude     Hasql.Pool.SessionErrorDestructors@@ -85,7 +86,8 @@   build-depends:     base >=4.11 && <5,     bytestring >=0.10 && <0.14,-    hasql >=1.10 && <1.11,+    hasql ^>=2.0,+    pqi >=1.0 && <1.2,     stm >=2.5 && <3,     text >=1.2 && <3,     time >=1.9 && <2,@@ -97,19 +99,21 @@   hs-source-dirs: src/integration-tests   main-is: Main.hs   other-modules:+    Helpers.Adapters     Helpers.Hooks     Helpers.Scripts     Helpers.Sessions-    Specs.BySubject.Config.AgingTimeoutSpec-    Specs.BySubject.Config.IdlenessTimeoutSpec-    Specs.BySubject.Config.InitSessionSpec-    Specs.BySubject.Helpers.Sessions.CountConnectionsSpec-    Specs.BySubject.Helpers.Sessions.GetSettingSpec-    Specs.BySubject.ReleaseSpec-    Specs.BySubject.SpecHook-    Specs.BySubject.UsageError.AcquisitionTimeoutSpec-    Specs.BySubject.UsageError.SessionSpec-    Specs.BySubject.UseSpec+    Specs.Config.AgingTimeoutSpec+    Specs.Config.IdlenessTimeoutSpec+    Specs.Config.InitSessionSpec+    Specs.Helpers.Sessions.CountConnectionsSpec+    Specs.Helpers.Sessions.GetSettingSpec+    Specs.InterruptionSpec+    Specs.ReleaseSpec+    Specs.SpecHook+    Specs.UsageError.AcquisitionTimeoutSpec+    Specs.UsageError.SessionSpec+    Specs.UseSpec    ghc-options: -threaded   build-tool-depends:@@ -120,7 +124,9 @@     hasql,     hasql-pool,     hspec >=2.6 && <3,-    postgresql-libpq >=0.10 && <0.12,+    pqi >=1.0 && <1.2,+    pqi-ffi ^>=1.0,+    pqi-native ^>=1.0,     random >=1.2 && <2,     rerebase >=1.15 && <2,     testcontainers-postgresql >=0.2 && <0.3,
+ src/integration-tests/Helpers/Adapters.hs view
@@ -0,0 +1,30 @@+module Helpers.Adapters+  ( adapters,+    byAdapter,+    hook,+  )+where++import Pqi qualified+import Pqi.Ffi qualified+import Pqi.Native qualified+import Prelude+import Test.Hspec++adapters :: [Pqi.Adapter]+adapters =+  [ Pqi.Ffi.adapter,+    Pqi.Native.adapter+  ]++-- | Run the given spec-building function once per available Pqi adapter,+-- nesting each run under a @describe@ named after the adapter.+byAdapter :: (Pqi.Adapter -> Spec) -> Spec+byAdapter f =+  for_ adapters \adapter ->+    describe (toList (Pqi.name adapter)) (f adapter)++hook :: SpecWith Pqi.Adapter -> Spec+hook hookedSpec =+  byAdapter \adapter ->+    mapSubject (const adapter) hookedSpec
src/integration-tests/Helpers/Scripts.hs view
@@ -3,20 +3,23 @@ import Hasql.Connection.Settings qualified as Connection.Settings import Hasql.Pool qualified as Pool import Hasql.Pool.Config qualified as Config+import Hasql.Pool.Observation (Observation) import Hasql.Session qualified as Session+import Pqi qualified import Prelude import System.Random.Stateful qualified as Random import TextBuilder qualified  -- | -- Parameters provided by the scope.--- Host and port of a running isolated postgres server.-type ScopeParams = (Text, Word16)+-- Adapter, host and port of a running isolated postgres server.+type ScopeParams = (Pqi.Adapter, Text, Word16)  onTaggedPool :: Int -> DiffTime -> DiffTime -> DiffTime -> Text -> ScopeParams -> (Pool.Pool -> IO ()) -> IO ()-onTaggedPool poolSize acqTimeout maxLifetime maxIdletime appName (host, port) =+onTaggedPool poolSize acqTimeout maxLifetime maxIdletime appName (adapter, host, port) =   bracket     ( Pool.acquire+        adapter         ( Config.settings             [ Config.size poolSize,               Config.acquisitionTimeout acqTimeout,@@ -37,15 +40,46 @@     Pool.release  onAutotaggedPool :: Int -> DiffTime -> DiffTime -> DiffTime -> ScopeParams -> (Text -> Pool.Pool -> IO ()) -> IO ()-onAutotaggedPool poolSize acqTimeout maxLifetime maxIdletime (host, port) cont = do+onAutotaggedPool poolSize acqTimeout maxLifetime maxIdletime scopeParams cont = do   -- Generate app name   appName <- generateName "hasql-pool-test-"-  onTaggedPool poolSize acqTimeout maxLifetime maxIdletime appName (host, port) (cont appName)+  onTaggedPool poolSize acqTimeout maxLifetime maxIdletime appName scopeParams (cont appName) +onTaggedPoolWithObservationHandler :: Int -> DiffTime -> DiffTime -> DiffTime -> (Observation -> IO ()) -> Text -> ScopeParams -> (Pool.Pool -> IO ()) -> IO ()+onTaggedPoolWithObservationHandler poolSize acqTimeout maxLifetime maxIdletime observationHandler appName (adapter, host, port) =+  bracket+    ( Pool.acquire+        adapter+        ( Config.settings+            [ Config.size poolSize,+              Config.acquisitionTimeout acqTimeout,+              Config.agingTimeout maxLifetime,+              Config.idlenessTimeout maxIdletime,+              Config.observationHandler observationHandler,+              Config.staticConnectionSettings+                ( mconcat+                    [ Connection.Settings.hostAndPort host (fromIntegral port),+                      Connection.Settings.user "postgres",+                      Connection.Settings.password "",+                      Connection.Settings.dbname "postgres",+                      Connection.Settings.applicationName appName+                    ]+                )+            ]+        )+    )+    Pool.release++onAutotaggedPoolWithObservationHandler :: Int -> DiffTime -> DiffTime -> DiffTime -> (Observation -> IO ()) -> ScopeParams -> (Text -> Pool.Pool -> IO ()) -> IO ()+onAutotaggedPoolWithObservationHandler poolSize acqTimeout maxLifetime maxIdletime observationHandler scopeParams cont = do+  appName <- generateName "hasql-pool-test-"+  onTaggedPoolWithObservationHandler poolSize acqTimeout maxLifetime maxIdletime observationHandler appName scopeParams (cont appName)+ onTaggedPoolWithInitSession :: Int -> DiffTime -> DiffTime -> DiffTime -> Session.Session () -> Text -> ScopeParams -> (Pool.Pool -> IO ()) -> IO ()-onTaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession appName (host, port) =+onTaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession appName (adapter, host, port) =   bracket     ( Pool.acquire+        adapter         ( Config.settings             [ Config.size poolSize,               Config.acquisitionTimeout acqTimeout,@@ -67,9 +101,39 @@     Pool.release  onAutotaggedPoolWithInitSession :: Int -> DiffTime -> DiffTime -> DiffTime -> Session.Session () -> ScopeParams -> (Text -> Pool.Pool -> IO ()) -> IO ()-onAutotaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession (host, port) cont = do+onAutotaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession (adapter, host, port) cont = do   appName <- generateName "hasql-pool-test-"-  onTaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession appName (host, port) (cont appName)+  onTaggedPoolWithInitSession poolSize acqTimeout maxLifetime maxIdletime initSession appName (adapter, host, port) (cont appName)++onTaggedPoolWithReuseOrder :: Int -> DiffTime -> DiffTime -> DiffTime -> Config.ReuseOrder -> Text -> ScopeParams -> (Pool.Pool -> IO ()) -> IO ()+onTaggedPoolWithReuseOrder poolSize acqTimeout maxLifetime maxIdletime reuseOrder appName (adapter, host, port) =+  bracket+    ( Pool.acquire+        adapter+        ( Config.settings+            [ Config.size poolSize,+              Config.acquisitionTimeout acqTimeout,+              Config.agingTimeout maxLifetime,+              Config.idlenessTimeout maxIdletime,+              Config.reuseOrder reuseOrder,+              Config.staticConnectionSettings+                ( mconcat+                    [ Connection.Settings.hostAndPort host (fromIntegral port),+                      Connection.Settings.user "postgres",+                      Connection.Settings.password "",+                      Connection.Settings.dbname "postgres",+                      Connection.Settings.applicationName appName+                    ]+                )+            ]+        )+    )+    Pool.release++onAutotaggedPoolWithReuseOrder :: Int -> DiffTime -> DiffTime -> DiffTime -> Config.ReuseOrder -> ScopeParams -> (Text -> Pool.Pool -> IO ()) -> IO ()+onAutotaggedPoolWithReuseOrder poolSize acqTimeout maxLifetime maxIdletime reuseOrder scopeParams cont = do+  appName <- generateName "hasql-pool-test-"+  onTaggedPoolWithReuseOrder poolSize acqTimeout maxLifetime maxIdletime reuseOrder appName scopeParams (cont appName)  onDefaultTaggedPool :: ScopeParams -> (Text -> Pool.Pool -> IO ()) -> IO () onDefaultTaggedPool =
src/integration-tests/Helpers/Sessions.hs view
@@ -6,15 +6,16 @@     getSetting,     countConnections,     sleep,+    backendPid,   ) where  import Data.Tuple.All-import Database.PostgreSQL.LibPQ qualified as Pq import Hasql.Decoders qualified as Decoders import Hasql.Encoders qualified as Encoders import Hasql.Session qualified as Session import Hasql.Statement qualified as Statement+import Pqi qualified import Prelude  selectOne :: Session.Session Int64@@ -34,7 +35,7 @@ closeConn :: Session.Session () closeConn =   Session.onLibpqConnection \conn -> do-    Pq.finish conn+    Pqi.finish conn     pure (Right (), conn)  setSetting :: Text -> Text -> Session.Session ()@@ -71,3 +72,10 @@   where     statement = Statement.preparable "SELECT pg_sleep($1)" encoder Decoders.noResult     encoder = Encoders.param (Encoders.nonNullable Encoders.float8)++backendPid :: Session.Session Int32+backendPid =+  Session.statement () statement+  where+    statement = Statement.preparable "SELECT pg_backend_pid()" Encoders.noParams decoder+    decoder = Decoders.singleRow (Decoders.column (Decoders.nonNullable Decoders.int4))
− src/integration-tests/Specs/BySubject/Config/AgingTimeoutSpec.hs 
@@ -1,32 +0,0 @@-module Specs.BySubject.Config.AgingTimeoutSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Actively times out old connections" \scopeParams -> do-    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \_appName1 pool1 -> do-      Scripts.onAutotaggedPool 3 10 0.5 1_800 scopeParams \appName2 pool2 -> do-        res <- use pool2 $ Sessions.selectOne-        res `shouldBe` Right 1-        res2 <- use pool1 $ Sessions.countConnections appName2-        res2 `shouldBe` Right 1-        threadDelay 1_000_000 -- 1s-        res3 <- use pool1 $ Sessions.countConnections appName2-        res3 `shouldBe` Right 0--  it "Passively times out old connections" \scopeParams -> do-    -- 0.5s connection lifetime-    Scripts.onAutotaggedPool 1 10 0.5 1_800 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname-      res <- use pool $ Sessions.setSetting varName "hello world"-      res `shouldBe` Right ()-      res2 <- use pool $ Sessions.getSetting varName-      res2 `shouldBe` Right (Just "hello world")-      threadDelay 1_000_000 -- 1s-      res3 <- use pool $ Sessions.getSetting varName-      res3 `shouldBe` Right Nothing
− src/integration-tests/Specs/BySubject/Config/IdlenessTimeoutSpec.hs 
@@ -1,44 +0,0 @@-module Specs.BySubject.Config.IdlenessTimeoutSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Times out old connections (maxIdletime)" \scopeParams -> do-    -- 0.5s connection idle time-    Scripts.onAutotaggedPool 1 10 1_800 0.5 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname-      res <- use pool $ Sessions.setSetting varName "hello world"-      res `shouldBe` Right ()-      res2 <- use pool $ Sessions.getSetting varName-      res2 `shouldBe` Right (Just "hello world")-      -- busy sleep, to keep connection alive-      forM_ [1 :: Int .. 10] $ \_ -> do-        r <- use pool $ Sessions.selectOne-        r `shouldBe` Right 1-        threadDelay 100_000 -- 0.1s-      res3 <- use pool $ Sessions.getSetting varName-      res3 `shouldBe` Right (Just "hello world")-      -- idle sleep, connection times out-      threadDelay 1_000_000 -- 1s-      res4 <- use pool $ Sessions.getSetting varName-      res4 `shouldBe` Right Nothing--  it "Passively times out idle connections" \scopeParams -> do-    -- 0.5s connection idle time, large lifetime, so only idleness can explain a passive close.-    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \_appName1 pool1 -> do-      Scripts.onAutotaggedPool 3 10 1_800 0.5 scopeParams \appName2 pool2 -> do-        res <- use pool2 $ Sessions.selectOne-        res `shouldBe` Right 1-        res2 <- use pool1 $ Sessions.countConnections appName2-        res2 `shouldBe` Right 1-        -- Give the background reaper (1s tick) a chance to passively evict-        -- the now-idle connection, without ever calling `use pool2` again-        -- (which would trigger the separate active idleness check).-        threadDelay 1_500_000 -- 1.5s-        res3 <- use pool1 $ Sessions.countConnections appName2-        res3 `shouldBe` Right 0
− src/integration-tests/Specs/BySubject/Config/InitSessionSpec.hs 
@@ -1,59 +0,0 @@-module Specs.BySubject.Config.InitSessionSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Persists after exceptions thrown in session" \scopeParams -> do-    Scripts.onAutotaggedPool 1 10 60 60 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname--      res <- use pool do-        Sessions.setSetting varName "1"-        Sessions.getSetting varName-      shouldBe res (Right (Just "1"))--      try @SomeException do-        use pool do-          liftIO do-            throwIO (userError "Intentional error for testing")--      res <- use pool do-        Sessions.getSetting varName-      shouldBe res (Right (Just "1"))--  it "Persists after bad query" \scopeParams -> do-    Scripts.onAutotaggedPool 1 10 60 60 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname--      res <- use pool do-        Sessions.setSetting varName "1"-        Sessions.getSetting varName-      shouldBe res (Right (Just "1"))--      use pool do-        Sessions.badQuery--      res <- use pool do-        Sessions.getSetting varName-      shouldBe res (Right (Just "1"))--  -- https://github.com/nikita-volkov/hasql-pool/issues/56-  it "Does not exhaust the pool capacity when it fails" \scopeParams -> do-    -- Pool of size 1 whose init session always fails, with a short-    -- acquisition timeout so that a leaked capacity slot shows up as-    -- an AcquisitionTimeoutUsageError instead of hanging the test.-    Scripts.onAutotaggedPoolWithInitSession 1 1 60 60 Sessions.badQuery scopeParams \_ pool -> do-      res1 <- use pool Sessions.selectOne-      res1 `shouldSatisfy` \case-        Left (SessionUsageError _) -> True-        _ -> False--      res2 <- use pool Sessions.selectOne-      res2 `shouldSatisfy` \case-        Left (SessionUsageError _) -> True-        _ -> False
− src/integration-tests/Specs/BySubject/Helpers/Sessions/CountConnectionsSpec.hs 
@@ -1,14 +0,0 @@-module Specs.BySubject.Helpers.Sessions.CountConnectionsSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Counts active connections" \scopeParams -> do-    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \appName pool -> do-      res <- use pool $ Sessions.countConnections appName-      res `shouldBe` Right 1
− src/integration-tests/Specs/BySubject/Helpers/Sessions/GetSettingSpec.hs 
@@ -1,36 +0,0 @@-module Specs.BySubject.Helpers.Sessions.GetSettingSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Getting and setting session variables works" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname-      res <- use pool $ Sessions.getSetting varName-      res `shouldBe` Right Nothing-      res <- use pool $ do-        Sessions.setSetting varName "hello world"-        Sessions.getSetting varName-      res `shouldBe` Right (Just "hello world")--  it "Session variables stay set when a connection gets reused" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      varName <- Scripts.generateVarname-      res <- use pool $ Sessions.setSetting varName "hello world"-      res `shouldBe` Right ()-      res2 <- use pool $ Sessions.getSetting varName-      res2 `shouldBe` Right (Just "hello world")--  it "Releasing the pool resets session variables" \scopeParams -> do-    varName <- Scripts.generateVarname-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      res <- use pool $ Sessions.setSetting varName "hello world"-      res `shouldBe` Right ()-      release pool-      res <- use pool $ Sessions.getSetting varName-      res `shouldBe` Right Nothing
− src/integration-tests/Specs/BySubject/ReleaseSpec.hs 
@@ -1,16 +0,0 @@-module Specs.BySubject.ReleaseSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "The pool remains usable after release" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      _ <- use pool $ Sessions.selectOne-      release pool-      res <- use pool $ Sessions.selectOne-      shouldSatisfy res $ isRight
− src/integration-tests/Specs/BySubject/SpecHook.hs 
@@ -1,11 +0,0 @@--- Docs: https://hspec.github.io/hspec-discover.html-module Specs.BySubject.SpecHook where--import Helpers.Hooks qualified as Hooks-import Helpers.Scripts qualified as Scripts-import Prelude-import Test.Hspec--hook :: SpecWith Scripts.ScopeParams -> Spec-hook =-  aroundAll Hooks.postgres17 . parallel
− src/integration-tests/Specs/BySubject/UsageError/AcquisitionTimeoutSpec.hs 
@@ -1,33 +0,0 @@-module Specs.BySubject.UsageError.AcquisitionTimeoutSpec where--import Control.Concurrent.Async (race)-import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Gets produced on timeout" \scopeParams ->-    -- 1ms timeout-    Scripts.onAutotaggedPool 1 0.001 1_800 1_800 scopeParams \_ pool -> do-      sleeping <- newEmptyMVar-      t0 <- getCurrentTime-      res <--        race-          ( use pool-              $ liftIO-              $ do-                putMVar sleeping ()-                -- 1s-                threadDelay 1_000_000-          )-          ( do-              takeMVar sleeping-              use pool $ Sessions.selectOne-          )-      t1 <- getCurrentTime-      res `shouldBe` Right (Left AcquisitionTimeoutUsageError)-      -- 0.5s-      diffUTCTime t1 t0 `shouldSatisfy` (< 0.5)
− src/integration-tests/Specs/BySubject/UsageError/SessionSpec.hs 
@@ -1,16 +0,0 @@-module Specs.BySubject.UsageError.SessionSpec where--import Hasql.Pool-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Bad SQL query triggers error" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      res <- use pool Sessions.badQuery-      shouldSatisfy res $ \case-        Left (SessionUsageError _) -> True-        _ -> False
− src/integration-tests/Specs/BySubject/UseSpec.hs 
@@ -1,133 +0,0 @@-module Specs.BySubject.UseSpec where--import Control.Concurrent.Async (race)-import Data.Text qualified as Text-import Hasql.Decoders qualified as Decoders-import Hasql.Encoders qualified as Encoders-import Hasql.Errors qualified as Errors-import Hasql.Pool-import Hasql.Session qualified as Session-import Hasql.Statement qualified as Statement-import Helpers.Scripts qualified as Scripts-import Helpers.Sessions qualified as Sessions-import Prelude-import Test.Hspec--spec :: SpecWith Scripts.ScopeParams-spec = do-  it "Releases a spot in the pool when there is a query error" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      use pool Sessions.badQuery `shouldNotReturn` (Right ())-      use pool Sessions.selectOne `shouldReturn` (Right 1)--  it "Connection errors cause eviction of connection" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne-      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne-      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne-      res <- use pool $ Sessions.selectOne-      shouldSatisfy res $ isRight--  it "Driver errors cause eviction of connection" \scopeParams -> do-    settingName <- Scripts.generateVarname-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      use pool (Sessions.setSetting settingName "present") `shouldReturn` Right ()-      result <- use pool driverError-      result `shouldSatisfy` \case-        Left (SessionUsageError (Errors.DriverSessionError _)) -> True-        _ -> False-      use pool (Sessions.getSetting settingName) `shouldReturn` Right Nothing--  it "Connection gets returned to the pool after normal use" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      _ <- use pool $ Sessions.selectOne-      _ <- use pool $ Sessions.selectOne-      _ <- use pool $ Sessions.selectOne-      _ <- use pool $ Sessions.selectOne-      res <- use pool $ Sessions.selectOne-      shouldSatisfy res $ isRight--  it "Connection gets returned to the pool after non-connection error" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      _ <- use pool $ Sessions.badQuery-      _ <- use pool $ Sessions.badQuery-      _ <- use pool $ Sessions.badQuery-      _ <- use pool $ Sessions.badQuery-      res <- use pool $ Sessions.selectOne-      shouldSatisfy res $ isRight--  -- https://github.com/nikita-volkov/hasql-pool/issues/38-  ---  -- When a session is interrupted by an asynchronous exception (e.g., a-  -- caller-side timeout racing the query, as simulated here via `race`)-  -- while it is genuinely blocked waiting on the server's response, the-  -- underlying libpq connection is left mid-command: the query was sent,-  -- but its result was never read. `onLiveConn` in Hasql.Pool.use still-  -- unconditionally returns such a connection to the pool (the `Left exc`-  -- branch calls `returnConn` for all exceptions, not just synchronous-  -- ones), so the next `use` call hands out a connection whose protocol-  -- state is desynced from libpq's expectations. This is a plausible root-  -- cause of the "connection pointer is NULL" reports: two independent-  -- consumers of hasql-pool end up driving the same libpq connection state-  -- machine without coordination.-  it "Does not return a connection to the pool when the session is interrupted by an asynchronous exception" \scopeParams ->-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      started <- newEmptyMVar-      _ <--        race-          ( use pool do-              liftIO $ putMVar started ()-              Sessions.sleep 2-          )-          ( do-              takeMVar started-              -- Give the query time to actually reach the server and for-              -- the client to start blocking on the socket read, as-              -- opposed to being cancelled while still sending.-              threadDelay 200_000-          )-      res <- use pool Sessions.selectOne-      res `shouldSatisfy` isRight--  it "Cached type errors cause eviction of connection" \scopeParams -> do-    typeName <- Text.replace "-" "_" <$> Scripts.generateName "cached_type_"-    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do-      use pool (Session.script (createTypeSql typeName)) `shouldReturn` Right ()-      use pool (roundtripEnum typeName "ok") `shouldReturn` Right "ok"-      use pool (Session.script (recreateTypeSql typeName)) `shouldReturn` Right ()-      res <- use pool (roundtripEnum typeName "ok")-      shouldSatisfy res \case-        Left (SessionUsageError _) -> True-        _ -> False-      use pool (roundtripEnum typeName "ok") `shouldReturn` Right "ok"--quoteIdentifier :: Text -> Text-quoteIdentifier identifier =-  "\"" <> Text.replace "\"" "\"\"" identifier <> "\""--createTypeSql :: Text -> Text-createTypeSql typeName =-  "create type " <> quotedTypeName <> " as enum ('sad', 'ok', 'happy')"-  where-    quotedTypeName = quoteIdentifier typeName--recreateTypeSql :: Text -> Text-recreateTypeSql typeName =-  "drop type " <> quotedTypeName <> "; create type " <> quotedTypeName <> " as enum ('sad', 'ok', 'happy')"-  where-    quotedTypeName = quoteIdentifier typeName--roundtripEnum :: Text -> Text -> Session.Session Text-roundtripEnum typeName value =-  Session.statement value statement-  where-    statement =-      Statement.preparable-        ("select $1 :: " <> quoteIdentifier typeName)-        (Encoders.param (Encoders.nonNullable (Encoders.enum Nothing typeName id)))-        (Decoders.singleRow (Decoders.column (Decoders.nonNullable (Decoders.enum Nothing typeName Just))))--driverError :: Session.Session ()-driverError =-  Session.onLibpqConnection \connection ->-    pure (Left (Errors.DriverSessionError "synthetic driver error"), connection)
+ src/integration-tests/Specs/Config/AgingTimeoutSpec.hs view
@@ -0,0 +1,32 @@+module Specs.Config.AgingTimeoutSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Actively times out old connections" \scopeParams -> do+    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \_appName1 pool1 -> do+      Scripts.onAutotaggedPool 3 10 0.5 1_800 scopeParams \appName2 pool2 -> do+        res <- use pool2 $ Sessions.selectOne+        res `shouldBe` Right 1+        res2 <- use pool1 $ Sessions.countConnections appName2+        res2 `shouldBe` Right 1+        threadDelay 1_000_000 -- 1s+        res3 <- use pool1 $ Sessions.countConnections appName2+        res3 `shouldBe` Right 0++  it "Passively times out old connections" \scopeParams -> do+    -- 0.5s connection lifetime+    Scripts.onAutotaggedPool 1 10 0.5 1_800 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname+      res <- use pool $ Sessions.setSetting varName "hello world"+      res `shouldBe` Right ()+      res2 <- use pool $ Sessions.getSetting varName+      res2 `shouldBe` Right (Just "hello world")+      threadDelay 1_000_000 -- 1s+      res3 <- use pool $ Sessions.getSetting varName+      res3 `shouldBe` Right Nothing
+ src/integration-tests/Specs/Config/IdlenessTimeoutSpec.hs view
@@ -0,0 +1,62 @@+module Specs.Config.IdlenessTimeoutSpec where++import Hasql.Pool+import Hasql.Pool.Config qualified as Config+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Times out old connections (maxIdletime)" \scopeParams -> do+    -- 0.5s connection idle time+    Scripts.onAutotaggedPool 1 10 1_800 0.5 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname+      res <- use pool $ Sessions.setSetting varName "hello world"+      res `shouldBe` Right ()+      res2 <- use pool $ Sessions.getSetting varName+      res2 `shouldBe` Right (Just "hello world")+      -- busy sleep, to keep connection alive+      forM_ [1 :: Int .. 10] $ \_ -> do+        r <- use pool $ Sessions.selectOne+        r `shouldBe` Right 1+        threadDelay 100_000 -- 0.1s+      res3 <- use pool $ Sessions.getSetting varName+      res3 `shouldBe` Right (Just "hello world")+      -- idle sleep, connection times out+      threadDelay 1_000_000 -- 1s+      res4 <- use pool $ Sessions.getSetting varName+      res4 `shouldBe` Right Nothing++  it "Passively times out idle connections" \scopeParams -> do+    -- 0.5s connection idle time, large lifetime, so only idleness can explain a passive close.+    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \_appName1 pool1 -> do+      Scripts.onAutotaggedPool 3 10 1_800 0.5 scopeParams \appName2 pool2 -> do+        res <- use pool2 $ Sessions.selectOne+        res `shouldBe` Right 1+        res2 <- use pool1 $ Sessions.countConnections appName2+        res2 `shouldBe` Right 1+        -- Give the background reaper (1s tick) a chance to passively evict+        -- the now-idle connection, without ever calling `use pool2` again+        -- (which would trigger the separate active idleness check).+        threadDelay 1_500_000 -- 1.5s+        res3 <- use pool1 $ Sessions.countConnections appName2+        res3 `shouldBe` Right 0++  it "Times out the connections that aren't needed with LIFO" \scopeParams -> do+    -- 0.5s connection idle time+    Scripts.onAutotaggedPoolWithReuseOrder 2 10 1_800 0.5 Config.LIFO scopeParams \appName pool -> do+      held <- newEmptyMVar+      done <- newEmptyMVar+      -- Establish two connections.+      _ <- forkIO (void (use pool (liftIO (putMVar held () *> takeMVar done))))+      takeMVar held+      use pool Sessions.selectOne `shouldReturn` Right 1+      putMVar done ()+      -- Keep using the pool one pool request at a time, which needs only one+      -- connection, for longer than the idle time and the reaper's 1s tick.+      forM_ [1 :: Int .. 15] \_ -> do+        use pool Sessions.selectOne `shouldReturn` Right 1+        threadDelay 100_000 -- 0.1s+      use pool (Sessions.countConnections appName) `shouldReturn` Right 1
+ src/integration-tests/Specs/Config/InitSessionSpec.hs view
@@ -0,0 +1,59 @@+module Specs.Config.InitSessionSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Persists after exceptions thrown in session" \scopeParams -> do+    Scripts.onAutotaggedPool 1 10 60 60 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname++      res <- use pool do+        Sessions.setSetting varName "1"+        Sessions.getSetting varName+      shouldBe res (Right (Just "1"))++      try @SomeException do+        use pool do+          liftIO do+            throwIO (userError "Intentional error for testing")++      res <- use pool do+        Sessions.getSetting varName+      shouldBe res (Right (Just "1"))++  it "Persists after bad query" \scopeParams -> do+    Scripts.onAutotaggedPool 1 10 60 60 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname++      res <- use pool do+        Sessions.setSetting varName "1"+        Sessions.getSetting varName+      shouldBe res (Right (Just "1"))++      use pool do+        Sessions.badQuery++      res <- use pool do+        Sessions.getSetting varName+      shouldBe res (Right (Just "1"))++  -- https://github.com/nikita-volkov/hasql-pool/issues/56+  it "Does not exhaust the pool capacity when it fails" \scopeParams -> do+    -- Pool of size 1 whose init session always fails, with a short+    -- acquisition timeout so that a leaked capacity slot shows up as+    -- an AcquisitionTimeoutUsageError instead of hanging the test.+    Scripts.onAutotaggedPoolWithInitSession 1 1 60 60 Sessions.badQuery scopeParams \_ pool -> do+      res1 <- use pool Sessions.selectOne+      res1 `shouldSatisfy` \case+        Left (SessionUsageError _) -> True+        _ -> False++      res2 <- use pool Sessions.selectOne+      res2 `shouldSatisfy` \case+        Left (SessionUsageError _) -> True+        _ -> False
+ src/integration-tests/Specs/Helpers/Sessions/CountConnectionsSpec.hs view
@@ -0,0 +1,14 @@+module Specs.Helpers.Sessions.CountConnectionsSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Counts active connections" \scopeParams -> do+    Scripts.onAutotaggedPool 3 10 1_800 1_800 scopeParams \appName pool -> do+      res <- use pool $ Sessions.countConnections appName+      res `shouldBe` Right 1
+ src/integration-tests/Specs/Helpers/Sessions/GetSettingSpec.hs view
@@ -0,0 +1,36 @@+module Specs.Helpers.Sessions.GetSettingSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Getting and setting session variables works" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname+      res <- use pool $ Sessions.getSetting varName+      res `shouldBe` Right Nothing+      res <- use pool $ do+        Sessions.setSetting varName "hello world"+        Sessions.getSetting varName+      res `shouldBe` Right (Just "hello world")++  it "Session variables stay set when a connection gets reused" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      varName <- Scripts.generateVarname+      res <- use pool $ Sessions.setSetting varName "hello world"+      res `shouldBe` Right ()+      res2 <- use pool $ Sessions.getSetting varName+      res2 `shouldBe` Right (Just "hello world")++  it "Releasing the pool resets session variables" \scopeParams -> do+    varName <- Scripts.generateVarname+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      res <- use pool $ Sessions.setSetting varName "hello world"+      res `shouldBe` Right ()+      release pool+      res <- use pool $ Sessions.getSetting varName+      res `shouldBe` Right Nothing
+ src/integration-tests/Specs/InterruptionSpec.hs view
@@ -0,0 +1,163 @@+module Specs.InterruptionSpec where++import Control.Exception (SomeException, try)+import Hasql.Pool+import Hasql.Pool qualified as Pool+import Hasql.Pool.Config qualified as Config+import Hasql.Pool.Observation+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++-- | Regression tests for the pool capacity getting lost when a pool request+-- gets interrupted anywhere between the enrollment and the session+-- (https://github.com/nikita-volkov/hasql-pool/issues/60), and for the pool+-- surviving failing observation handlers.+spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Restores the pool capacity when the pool request is interrupted while observing the connection attempt" \scopeParams ->+    onGatedPool connectingObs 1 10 1_800 1_800 scopeParams \gate pool -> do+      interruptAt gate (\pool -> void (use pool Sessions.selectOne)) pool+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Restores the pool capacity when the pool request is interrupted while observing the idle-eviction" \scopeParams ->+    onGatedPool idleEvictionObs 1 10 1_800 0.3 scopeParams \gate pool -> do+      -- Establish a connection and let it go idle.+      _ <- use pool Sessions.selectOne+      threadDelay 600_000 -- 0.6s+      interruptAt gate (\pool -> void (use pool Sessions.selectOne)) pool+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Preserves the dequeued connection when the pool request is interrupted while observing its use" \scopeParams ->+    onGatedPool inUseObs 1 10 1_800 1_800 scopeParams \gate pool -> do+      -- Establish a connection and return it to the pool.+      _ <- use pool Sessions.selectOne+      interruptAt gate (\pool -> void (use pool Sessions.selectOne)) pool+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Succeeds the session when the observation handler throws synchronously during the connection attempt" \scopeParams ->+    Scripts.onAutotaggedPoolWithObservationHandler 1 10 1_800 1_800 (throwAt connectingObs) scopeParams \_ pool -> do+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Succeeds the session when the observation handler throws synchronously during the idle-eviction" \scopeParams ->+    Scripts.onAutotaggedPoolWithObservationHandler 1 10 1_800 0.3 (throwAt idleEvictionObs) scopeParams \_ pool -> do+      _ <- use pool Sessions.selectOne+      threadDelay 600_000 -- 0.6s+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Succeeds the session when the observation handler throws synchronously while observing the use" \scopeParams ->+    Scripts.onAutotaggedPoolWithObservationHandler 1 10 1_800 1_800 (throwAt inUseObs) scopeParams \_ pool -> do+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "The reaper survives a throwing observation handler and keeps reaping on later ticks" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ counterPool ->+      Scripts.onAutotaggedPoolWithObservationHandler 1 10 1_800 0.3 (throwAt idleEvictionObs) scopeParams \appName pool -> do+        -- Establish a connection and let it go idle past the reaper's tick.+        _ <- use pool Sessions.selectOne+        threadDelay 1_600_000 -- 1.6s+        -- The connection got reaped and the reaper is still alive.+        use counterPool (Sessions.countConnections appName) `shouldReturn` Right 0+        use pool Sessions.selectOne `shouldReturn` Right 1+        -- It keeps reaping on the later ticks.+        threadDelay 1_600_000 -- 1.6s+        use counterPool (Sessions.countConnections appName) `shouldReturn` Right 0++  it "The pool remains usable after the release with a throwing observation handler" \scopeParams ->+    Scripts.onAutotaggedPoolWithObservationHandler 1 10 1_800 1_800 (throwAt releaseObs) scopeParams \_ pool -> do+      _ <- use pool Sessions.selectOne+      release pool+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Resolves the pool requests waiting on a garbage-collected pool" \scopeParams -> do+    (adapter, host, port) <- pure scopeParams+    result <- newEmptyMVar+    -- Inside this block the pool is only reachable from the waiting pool+    -- request. Once collected, the finalizer resolves it, and if it is not+    -- collectible, the acquisition timeout does. Either way it does not wait+    -- forever.+    do+      pool <-+        Pool.acquire+          adapter+          ( Config.settings+              [ -- No capacity: every pool request waits.+                Config.size 0,+                Config.acquisitionTimeout 0.5+              ]+          )+      _ <- forkIO (putMVar result =<< use pool Sessions.selectOne)+      threadDelay 100_000 -- 0.1s, to let the pool request start waiting+      pure ()+    performGC+    performGC+    res <- takeMVar result+    res `shouldBe` Left AcquisitionTimeoutUsageError++-- | Runs the action in a pool request interrupted at the gated observation.+-- The pool request is expected to die with the interruption.+interruptAt :: Gate -> (Pool.Pool -> IO ()) -> Pool.Pool -> IO ()+interruptAt gate action pool = do+  armGate gate+  done <- newEmptyMVar+  thread <- forkIO do+    _ <- try @SomeException (action pool)+    putMVar done ()+  takeMVar (gateEntered gate)+  killThread thread+  disarmGate gate+  takeMVar done++-- | Runs the continuation in a pool with a gated observation handler.+onGatedPool :: (Observation -> Bool) -> Int -> DiffTime -> DiffTime -> DiffTime -> Scripts.ScopeParams -> (Gate -> Pool.Pool -> IO ()) -> IO ()+onGatedPool matches poolSize acqTimeout maxLifetime maxIdletime scopeParams cont = do+  gate <- newGate matches+  Scripts.onAutotaggedPoolWithObservationHandler poolSize acqTimeout maxLifetime maxIdletime (gateHandler gate) scopeParams \appName pool -> cont gate pool++-- | A gate for stopping a pool request at a chosen observation and letting the+-- test interrupt it there. While the gate is armed, the pool request stops at+-- the first matching observation, waiting to be released or interrupted.+data Gate = Gate+  { gateMatches :: Observation -> Bool,+    gateEntered :: MVar (),+    gateProceed :: MVar (),+    gateArmed :: IORef Bool+  }++newGate :: (Observation -> Bool) -> IO Gate+newGate matches = Gate matches <$> newEmptyMVar <*> newEmptyMVar <*> newIORef False++armGate, disarmGate :: Gate -> IO ()+armGate gate = writeIORef (gateArmed gate) True+disarmGate gate = writeIORef (gateArmed gate) False++-- | The observation handler stopping at the gate.+gateHandler :: Gate -> Observation -> IO ()+gateHandler gate observation =+  when (gateMatches gate observation) do+    armed <- readIORef (gateArmed gate)+    when armed do+      putMVar (gateEntered gate) ()+      takeMVar (gateProceed gate)++-- | The observations the tests stop or throw at.+connectingObs, idleEvictionObs, inUseObs, releaseObs :: Observation -> Bool+connectingObs = \case+  ConnectionObservation _ ConnectingConnectionStatus -> True+  _ -> False+idleEvictionObs = \case+  ConnectionObservation _ (TerminatedConnectionStatus IdlenessConnectionTerminationReason) -> True+  _ -> False+inUseObs = \case+  ConnectionObservation _ InUseConnectionStatus -> True+  _ -> False+releaseObs = \case+  ConnectionObservation _ (TerminatedConnectionStatus ReleaseConnectionTerminationReason) -> True+  _ -> False++-- | An observation handler that throws synchronously at the matching+-- observations, and passes all the other observations through.+throwAt :: (Observation -> Bool) -> Observation -> IO ()+throwAt matches observation =+  when (matches observation) do+    error "Synchronous exception from the observation handler"
+ src/integration-tests/Specs/ReleaseSpec.hs view
@@ -0,0 +1,16 @@+module Specs.ReleaseSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "The pool remains usable after release" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      _ <- use pool $ Sessions.selectOne+      release pool+      res <- use pool $ Sessions.selectOne+      shouldSatisfy res $ isRight
+ src/integration-tests/Specs/SpecHook.hs view
@@ -0,0 +1,15 @@+-- Docs: https://hspec.github.io/hspec-discover.html+module Specs.SpecHook where++import Helpers.Adapters qualified as Adapters+import Helpers.Hooks qualified as Hooks+import Helpers.Scripts qualified as Scripts+import Test.Hspec++hook :: SpecWith Scripts.ScopeParams -> Spec+hook hookedSpec =+  Adapters.hook+    ( aroundAllWith+        (\action adapter -> Hooks.postgres17 \(host, port) -> action (adapter, host, port))+        (parallel hookedSpec)+    )
+ src/integration-tests/Specs/UsageError/AcquisitionTimeoutSpec.hs view
@@ -0,0 +1,45 @@+module Specs.UsageError.AcquisitionTimeoutSpec where++import Control.Concurrent.Async (forConcurrently, race)+import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Gets produced on timeout" \scopeParams ->+    -- 1ms timeout+    Scripts.onAutotaggedPool 1 0.001 1_800 1_800 scopeParams \_ pool -> do+      sleeping <- newEmptyMVar+      t0 <- getCurrentTime+      res <-+        race+          ( use pool+              $ liftIO+              $ do+                putMVar sleeping ()+                -- 1s+                threadDelay 1_000_000+          )+          ( do+              takeMVar sleeping+              use pool $ Sessions.selectOne+          )+      t1 <- getCurrentTime+      res `shouldBe` Right (Left AcquisitionTimeoutUsageError)+      -- 0.5s+      diffUTCTime t1 t0 `shouldSatisfy` (< 0.5)++  it "Gets produced for every waiting pool request, and the pool remains usable" \scopeParams ->+    -- 100ms timeout+    Scripts.onAutotaggedPool 1 0.1 1_800 1_800 scopeParams \_ pool -> do+      held <- newEmptyMVar+      done <- newEmptyMVar+      _ <- forkIO (void (use pool (liftIO (putMVar held () *> takeMVar done))))+      takeMVar held+      results <- forConcurrently [1 .. 3 :: Int] \_ -> use pool Sessions.selectOne+      results `shouldBe` replicate 3 (Left AcquisitionTimeoutUsageError)+      putMVar done ()+      use pool Sessions.selectOne `shouldReturn` Right 1
+ src/integration-tests/Specs/UsageError/SessionSpec.hs view
@@ -0,0 +1,16 @@+module Specs.UsageError.SessionSpec where++import Hasql.Pool+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Bad SQL query triggers error" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      res <- use pool Sessions.badQuery+      shouldSatisfy res $ \case+        Left (SessionUsageError _) -> True+        _ -> False
+ src/integration-tests/Specs/UseSpec.hs view
@@ -0,0 +1,252 @@+module Specs.UseSpec where++import Control.Concurrent.Async (race)+import Data.Text qualified as Text+import Hasql.Decoders qualified as Decoders+import Hasql.Encoders qualified as Encoders+import Hasql.Errors qualified as Errors+import Hasql.Pool+import Hasql.Pool.Config qualified as Config+import Hasql.Session qualified as Session+import Hasql.Statement qualified as Statement+import Helpers.Scripts qualified as Scripts+import Helpers.Sessions qualified as Sessions+import Prelude+import Test.Hspec++spec :: SpecWith Scripts.ScopeParams+spec = do+  it "Releases a spot in the pool when there is a query error" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      use pool Sessions.badQuery `shouldNotReturn` (Right ())+      use pool Sessions.selectOne `shouldReturn` (Right 1)++  it "Connection errors cause eviction of connection" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne+      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne+      _ <- use pool $ Sessions.closeConn >> Sessions.selectOne+      res <- use pool $ Sessions.selectOne+      shouldSatisfy res $ isRight++  it "Driver errors cause eviction of connection" \scopeParams -> do+    settingName <- Scripts.generateVarname+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      use pool (Sessions.setSetting settingName "present") `shouldReturn` Right ()+      result <- use pool driverError+      result `shouldSatisfy` \case+        Left (SessionUsageError (Errors.DriverSessionError _)) -> True+        _ -> False+      use pool (Sessions.getSetting settingName) `shouldReturn` Right Nothing++  -- After a server restart or @pg_terminate_backend@ the first statement on+  -- the closed connection can fail with an 'Errors.UnexpectedRowCountStatementError'+  -- instead of a 'Errors.ConnectionSessionError'. The pool must not hand the+  -- connection out again.+  it "Connections closed by the server cause eviction of connection" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \appName pool -> do+      use pool Sessions.selectOne `shouldReturn` Right 1+      Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ adminPool ->+        use adminPool (terminateBackends appName) `shouldReturn` Right [True]+      _ <- use pool Sessions.selectOne+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Unexpected row counts on a healthy connection don't cause eviction of connection" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      Right pid <- use pool backendPid+      result <- use pool selectTwoRowsAsSingleRow+      result `shouldSatisfy` \case+        Left (SessionUsageError (Errors.StatementSessionError _ _ _ _ _ Errors.UnexpectedRowCountStatementError {})) -> True+        _ -> False+      use pool backendPid `shouldReturn` Right pid++  it "Connection gets returned to the pool after normal use" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      _ <- use pool $ Sessions.selectOne+      _ <- use pool $ Sessions.selectOne+      _ <- use pool $ Sessions.selectOne+      _ <- use pool $ Sessions.selectOne+      res <- use pool $ Sessions.selectOne+      shouldSatisfy res $ isRight++  it "Connection gets returned to the pool after non-connection error" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      _ <- use pool $ Sessions.badQuery+      _ <- use pool $ Sessions.badQuery+      _ <- use pool $ Sessions.badQuery+      _ <- use pool $ Sessions.badQuery+      res <- use pool $ Sessions.selectOne+      shouldSatisfy res $ isRight++  -- https://github.com/nikita-volkov/hasql-pool/issues/38+  --+  -- When a session is interrupted by an asynchronous exception (e.g., a+  -- caller-side timeout racing the query, as simulated here via `race`)+  -- while it is genuinely blocked waiting on the server's response, the+  -- underlying libpq connection is left mid-command: the query was sent,+  -- but its result was never read. `onLiveConn` in Hasql.Pool.use still+  -- unconditionally returns such a connection to the pool (the `Left exc`+  -- branch calls `returnConn` for all exceptions, not just synchronous+  -- ones), so the next `use` call hands out a connection whose protocol+  -- state is desynced from libpq's expectations. This is a plausible root+  -- cause of the "connection pointer is NULL" reports: two independent+  -- consumers of hasql-pool end up driving the same libpq connection state+  -- machine without coordination.+  it "Does not return a connection to the pool when the session is interrupted by an asynchronous exception" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      started <- newEmptyMVar+      _ <-+        race+          ( use pool do+              liftIO $ putMVar started ()+              Sessions.sleep 2+          )+          ( do+              takeMVar started+              -- Give the query time to actually reach the server and for+              -- the client to start blocking on the socket read, as+              -- opposed to being cancelled while still sending.+              threadDelay 200_000+          )+      res <- use pool Sessions.selectOne+      res `shouldSatisfy` isRight++  it "Gives a freed connection to a pool request waiting for it rather than to a later one" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      order <- newIORef []+      held <- newEmptyMVar+      done <- newEmptyMVar+      finished <- newEmptyMVar+      let record name = use pool (liftIO (atomicModifyIORef' order \names -> (names <> [name], ())))+      -- Requests a connection again as soon as it returns one, before the+      -- waiting pool request gets to run.+      _ <- forkIO do+        _ <- use pool (liftIO (putMVar held () *> takeMVar done))+        _ <- record "later"+        putMVar finished ()+      takeMVar held+      _ <- forkIO (record "waiting" *> putMVar finished ())+      -- Give the waiting pool request time to start waiting.+      threadDelay 100_000+      putMVar done ()+      replicateM_ 2 (takeMVar finished)+      readIORef order `shouldReturn` ["waiting", "later"]++  it "Loses no capacity when a pool request waiting for a connection is interrupted" \scopeParams ->+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      held <- newEmptyMVar+      done <- newEmptyMVar+      _ <- forkIO (void (use pool (liftIO (putMVar held () *> takeMVar done))))+      takeMVar held+      waiting <- forkIO (void (use pool Sessions.selectOne))+      -- Give the pool request time to start waiting.+      threadDelay 100_000+      killThread waiting+      putMVar done ()+      use pool Sessions.selectOne `shouldReturn` Right 1++  it "Reuses the most recently returned connection with LIFO" \scopeParams ->+    Scripts.onAutotaggedPoolWithReuseOrder 2 10 1_800 1_800 Config.LIFO scopeParams \_ pool -> do+      (first, second) <- returnTwoConnections pool+      first `shouldNotBe` second+      use pool Sessions.backendPid `shouldReturn` Right second++  it "Reuses the least recently returned connection by default" \scopeParams ->+    Scripts.onAutotaggedPool 2 10 1_800 1_800 scopeParams \_ pool -> do+      (first, second) <- returnTwoConnections pool+      first `shouldNotBe` second+      use pool Sessions.backendPid `shouldReturn` Right first++  it "Cached type errors cause eviction of connection" \scopeParams -> do+    typeName <- Text.replace "-" "_" <$> Scripts.generateName "cached_type_"+    Scripts.onAutotaggedPool 1 10 1_800 1_800 scopeParams \_ pool -> do+      use pool (Session.script (createTypeSql typeName)) `shouldReturn` Right ()+      use pool (roundtripEnum typeName "ok") `shouldReturn` Right "ok"+      use pool (Session.script (recreateTypeSql typeName)) `shouldReturn` Right ()+      res <- use pool (roundtripEnum typeName "ok")+      shouldSatisfy res \case+        Left (SessionUsageError _) -> True+        _ -> False+      use pool (roundtripEnum typeName "ok") `shouldReturn` Right "ok"++quoteIdentifier :: Text -> Text+quoteIdentifier identifier =+  "\"" <> Text.replace "\"" "\"\"" identifier <> "\""++createTypeSql :: Text -> Text+createTypeSql typeName =+  "create type " <> quotedTypeName <> " as enum ('sad', 'ok', 'happy')"+  where+    quotedTypeName = quoteIdentifier typeName++recreateTypeSql :: Text -> Text+recreateTypeSql typeName =+  "drop type " <> quotedTypeName <> "; create type " <> quotedTypeName <> " as enum ('sad', 'ok', 'happy')"+  where+    quotedTypeName = quoteIdentifier typeName++roundtripEnum :: Text -> Text -> Session.Session Text+roundtripEnum typeName value =+  Session.statement value statement+  where+    statement =+      Statement.preparable+        ("select $1 :: " <> quoteIdentifier typeName)+        (Encoders.param (Encoders.nonNullable (Encoders.enum Nothing typeName id)))+        (Decoders.singleRow (Decoders.column (Decoders.nonNullable (Decoders.enum Nothing typeName Just))))++terminateBackends :: Text -> Session.Session [Bool]+terminateBackends appName =+  Session.statement appName statement+  where+    statement =+      Statement.unpreparable+        "select pg_terminate_backend(pid, 10000) from pg_stat_activity where application_name = $1"+        (Encoders.param (Encoders.nonNullable Encoders.text))+        (Decoders.rowList (Decoders.column (Decoders.nonNullable Decoders.bool)))++backendPid :: Session.Session Int32+backendPid =+  Session.statement () statement+  where+    statement =+      Statement.preparable+        "select pg_backend_pid()"+        Encoders.noParams+        (Decoders.singleRow (Decoders.column (Decoders.nonNullable Decoders.int4)))++selectTwoRowsAsSingleRow :: Session.Session Int64+selectTwoRowsAsSingleRow =+  Session.statement () statement+  where+    statement =+      Statement.preparable+        "select * from (values (1 :: int8), (2 :: int8)) as t"+        Encoders.noParams+        (Decoders.singleRow (Decoders.column (Decoders.nonNullable Decoders.int8)))++driverError :: Session.Session ()+driverError =+  Session.onLibpqConnection \connection ->+    pure (Left (Errors.DriverSessionError "synthetic driver error"), connection)++-- | Establish two connections, return the first before the second, and give+-- their backend PIDs.+returnTwoConnections :: Pool -> IO (Int32, Int32)+returnTwoConnections pool = do+  held <- newEmptyMVar+  done <- newEmptyMVar+  returned <- newEmptyMVar+  _ <- forkIO do+    res <- use pool (Sessions.backendPid <* liftIO (putMVar held () *> takeMVar done))+    putMVar returned res+  takeMVar held+  res <- use pool do+    second <- Sessions.backendPid+    first <- liftIO do+      putMVar done ()+      takeMVar returned+    pure (first, second)+  case res of+    Right (Right first, second) -> pure (first, second)+    _ -> fail ("Unexpected result: " <> show res)
src/library/Hasql/Pool.hs view
@@ -16,10 +16,12 @@ import Hasql.Connection.Settings qualified as Connection.Settings import Hasql.Errors qualified as Errors import Hasql.Pool.Config.Config qualified as Config+import Hasql.Pool.Config.ReuseOrder (ReuseOrder (..)) import Hasql.Pool.Observation import Hasql.Pool.Prelude import Hasql.Pool.SessionErrorDestructors qualified as ErrorsDestruction import Hasql.Session qualified as Session+import Pqi qualified  -- | A connection tagged with metadata. data Entry = Entry@@ -37,28 +39,63 @@ entryIsIdle maxIdletime now Entry {..} =   now > entryUseTimeNSec + maxIdletime +-- | A pool request waiting for a connection.+data Waiter = Waiter+  { -- | When the pool request times out, in nanoseconds of the monotonic clock.+    waiterDeadline :: Word64,+    -- | What the pool request gets.+    waiterGiven :: TMVar Given,+    -- | Whether the pool request stopped waiting, so that it gets passed over.+    waiterGone :: TVar Bool+  }++-- | What a waiting pool request gets: an idle connection, or the slot of a+-- closed one to establish a connection in, with the reuse flag at the time,+-- or a timeout.+data Given+  = Given (TVar Bool) (Maybe Entry)+  | TimedOut++-- | What a pool request holds after the enrollment transaction commits and+-- has to give back on any failure.+data Holding+  = -- | An entry dequeued from the idle connections.+    EntryHolding (TVar Bool) Entry+  | -- | A capacity unit taken from the pool.+    SlotHolding (TVar Bool)+  | -- | A spot in the waiting queue.+    WaitingHolding Waiter+ -- | Pool of connections to DB. data Pool = Pool   { -- | Pool size.     poolSize :: Int,+    -- | Adapter used to establish connections.+    poolAdapter :: Pqi.Adapter,     -- | Connection settings.     poolFetchConnectionSettings :: IO Connection.Settings.Settings,-    -- | Acquisition timeout, in microseconds.-    poolAcquisitionTimeout :: Int,+    -- | Acquisition timeout, in nanoseconds.+    poolAcquisitionTimeout :: Word64,     -- | Maximal connection lifetime, in nanoseconds.     poolMaxLifetime :: Word64,     -- | Maximal connection idle time, in nanoseconds.     poolMaxIdletime :: Word64,-    -- | Avail connections.+    -- | Avail connections, in the order they get reused.     poolConnectionQueue :: TQueue Entry,+    -- | Which end of the queue returned connections go to.+    poolReuseOrder :: ReuseOrder,     -- | Remaining capacity.     -- The pool size limits the sum of poolCapacity, the length     -- of poolConnectionQueue and the number of in-flight     -- connections.     poolCapacity :: TVar Int,+    -- | Pool requests waiting for a connection, the longest waiting first.+    -- Freed connections and slots go to them before anyone else,+    -- so that only the pool request given one wakes up.+    poolWaiting :: TQueue Waiter,     -- | Whether to return a connection to the pool.     poolReuseVar :: TVar (TVar Bool),-    -- | To stop the manager thread via garbage collection.+    -- | To stop the manager and expirer threads via garbage collection.     poolReaperRef :: IORef (),     -- | Action for reporting the observations.     poolObserver :: Observation -> IO (),@@ -66,18 +103,33 @@     poolInitSession :: Session.Session ()   } +-- | Contain the failures of the user-supplied observation handler. Synchronous+-- exceptions from it are discarded, asynchronous ones are honored, so that+-- neither affects the pool's state or the session result, and the pool's+-- threads stay killable.+containObserver :: (Observation -> IO ()) -> Observation -> IO ()+containObserver observer observation =+  catch @SomeException (observer observation) \exc ->+    case fromException exc of+      Just SomeAsyncException {} -> throwIO exc+      Nothing -> return ()+ -- | Create a connection-pool. -- -- No connections actually get established by this function. It is delegated -- to 'use'. -- -- If you want to ensure that the pool connects fine at the initialization phase, just run 'use' with an empty session (@pure ()@) and check for errors.-acquire :: Config.Config -> IO Pool-acquire config = do+--+-- The 'Pqi.Adapter' determines which connection implementation the pool uses, e.g. an FFI adapter backed by @postgresql-libpq@, or a pure Haskell one. Pick one from an adapter package such as @pqi-ffi@ or @pqi-native@.+acquire :: Pqi.Adapter -> Config.Config -> IO Pool+acquire adapter config = do   connectionQueue <- newTQueueIO   capVar <- newTVarIO (Config.size config)   reuseVar <- newTVarIO =<< newTVarIO True+  waiting <- newTQueueIO   reaperRef <- newIORef ()+  let observer = containObserver (Config.observationHandler config)    managerTid <- forkIOWithUnmask $ \unmask -> unmask $ forever $ do     threadDelay 1000000@@ -88,23 +140,22 @@           (idleEntries, liveEntries) = partition (entryIsIdle maxIdletimeNanos now) unagedEntries       traverse_ (writeTQueue connectionQueue) liveEntries       return $ do-        forM_ agedEntries $ \entry -> do-          Connection.release (entryConnection entry)-          atomically $ modifyTVar' capVar succ-          (Config.observationHandler config) (ConnectionObservation (entryId entry) (TerminatedConnectionStatus AgingConnectionTerminationReason))-        forM_ idleEntries $ \entry -> do-          Connection.release (entryConnection entry)-          atomically $ modifyTVar' capVar succ-          (Config.observationHandler config) (ConnectionObservation (entryId entry) (TerminatedConnectionStatus IdlenessConnectionTerminationReason))+        forM_ agedEntries $ reap observer reuseVar waiting capVar AgingConnectionTerminationReason+        forM_ idleEntries $ reap observer reuseVar waiting capVar IdlenessConnectionTerminationReason +  expirerTid <- forkIOWithUnmask $ \unmask -> unmask $ expire waiting+   void . mkWeakIORef reaperRef $ do-    -- When the pool goes out of scope, stop the manager.+    -- When the pool goes out of scope, resolve the pool requests still+    -- waiting, and stop the manager and the expirer.+    atomically $ drainWaiting waiting     killThread managerTid+    killThread expirerTid -  return $ Pool (Config.size config) (Config.connectionSettingsProvider config) acqTimeoutMicros agingTimeoutNanos maxIdletimeNanos connectionQueue capVar reuseVar reaperRef (Config.observationHandler config) (Config.initSession config)+  return $ Pool (Config.size config) adapter (Config.connectionSettingsProvider config) acqTimeoutNanos agingTimeoutNanos maxIdletimeNanos connectionQueue (Config.reuseOrder config) capVar waiting reuseVar reaperRef observer (Config.initSession config)   where-    acqTimeoutMicros =-      div (fromIntegral (diffTimeToPicoseconds (Config.acquisitionTimeout config))) 1_000_000+    acqTimeoutNanos =+      div (fromIntegral (diffTimeToPicoseconds (Config.acquisitionTimeout config))) 1_000     agingTimeoutNanos =       div (fromIntegral (diffTimeToPicoseconds (Config.agingTimeout config))) 1_000     maxIdletimeNanos =@@ -125,127 +176,327 @@     newReuse <- newTVar True     writeTVar poolReuseVar newReuse     entries <- flushTQueue poolConnectionQueue-    return $ forM_ entries $ \entry -> do-      Connection.release (entryConnection entry)-      atomically $ modifyTVar' poolCapacity succ-      poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus ReleaseConnectionTerminationReason))+    return $ forM_ entries $ \entry ->+      mask \restore ->+        catch @SomeException+          ( do+              restore $ Connection.release (entryConnection entry)+              restore $ poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus ReleaseConnectionTerminationReason))+              atomically $ freeSlot poolReuseVar poolWaiting poolCapacity+          )+          \exc -> do+            atomically $ freeSlot poolReuseVar poolWaiting poolCapacity+            case fromException exc of+              Just SomeAsyncException {} -> throwIO exc+              Nothing -> return ()  -- | Use a connection from the pool to run a session and return the connection -- to the pool, when finished. ----- Session failing with a 'Session.ClientError' gets interpreted as a loss of+-- Session failing with a 'Errors.ConnectionSessionError' or leaving the+-- connection in the 'Pqi.ConnectionBad' state gets interpreted as a loss of -- connection. In such case the connection does not get returned to the pool -- and a slot gets freed up for a new connection to be established the next -- time one is needed. The error still gets returned from this function. -- -- __Warning:__ Due to the mechanism mentioned above you should avoid intercepting this error type from within sessions.-use :: Pool -> Session.Session a -> IO (Either UsageError a)+--+-- When no connection is available, the pool requests wait for one in the+-- order they came, and a later pool request doesn't take a connection while+-- others wait.+use :: forall a. Pool -> Session.Session a -> IO (Either UsageError a) use Pool {..} sess = do-  timeout <- do-    delay <- registerDelay poolAcquisitionTimeout-    return $ readTVar delay-  join . atomically $ do-    reuseVar <- readTVar poolReuseVar-    asum-      [ readTQueue poolConnectionQueue <&> onConn reuseVar,-        do-          capVal <- readTVar poolCapacity-          if capVal > 0-            then do-              writeTVar poolCapacity $! pred capVal-              return $ onNewConn reuseVar-            else retry,-        do-          timedOut <- timeout-          if timedOut-            then return . return . Left $ AcquisitionTimeoutUsageError-            else retry-      ]+  now <- getMonotonicTimeNSec+  mask \unmask -> do+    holding <- atomically $ do+      reuseVar <- readTVar poolReuseVar+      waited <- someoneWaiting poolWaiting+      -- Behind the pool requests already waiting, which get what's freed first.+      if waited+        then enqueue now <&> WaitingHolding+        else+          asum+            [ readTQueue poolConnectionQueue <&> EntryHolding reuseVar,+              do+                capVal <- readTVar poolCapacity+                if capVal > 0+                  then do+                    writeTVar poolCapacity $! pred capVal+                    return $ SlotHolding reuseVar+                  else retry,+              enqueue now <&> WaitingHolding+            ]+    case holding of+      EntryHolding reuseVar entry -> onEntry unmask reuseVar entry+      SlotHolding reuseVar -> onSlot unmask reuseVar+      WaitingHolding waiter -> do+        given <- atomically (takeTMVar (waiterGiven waiter)) `onException` abandon waiter+        case given of+          TimedOut -> return $ Left AcquisitionTimeoutUsageError+          Given reuseVar Nothing -> onSlot unmask reuseVar+          Given reuseVar (Just entry) -> onEntry unmask reuseVar entry   where-    onNewConn reuseVar = do-      settings <- poolFetchConnectionSettings+    enqueue :: Word64 -> STM Waiter+    enqueue now = do+      waiter <- Waiter (now + poolAcquisitionTimeout) <$> newEmptyTMVar <*> newTVar False+      writeTQueue poolWaiting waiter+      return waiter++    abandon :: Waiter -> IO ()+    abandon waiter = do+      given <- atomically $ do+        writeTVar (waiterGone waiter) True+        tryTakeTMVar (waiterGiven waiter)+      forM_ given \case+        Given _ Nothing -> atomically returnSlot+        Given reuseVar (Just entry) -> returnConn reuseVar entry+        TimedOut -> return ()++    returnSlot :: STM ()+    returnSlot = freeSlot poolReuseVar poolWaiting poolCapacity++    -- \| Holding one entry dequeued from the idle connections. If it is still+    -- good, run the session on it; if it expired, replace it with a fresh+    -- connection on the same slot. All the way, the holding is given back on+    -- interruption.+    onEntry :: (forall x. IO x -> IO x) -> TVar Bool -> Entry -> IO (Either UsageError a)+    onEntry unmask reuseVar entry = do       now <- getMonotonicTimeNSec+      if entryIsAged poolMaxLifetime now entry+        then renewEntry unmask reuseVar entry AgingConnectionTerminationReason+        else+          if entryIsIdle poolMaxIdletime now entry+            then renewEntry unmask reuseVar entry IdlenessConnectionTerminationReason+            else onLiveConn unmask reuseVar entry {entryUseTimeNSec = now}++    -- \| Holding an expired entry. Release its connection and establish a+    -- fresh one on the same slot. On interruption the slot gets given back:+    -- the released connection cannot return to the pool.+    renewEntry :: (forall x. IO x -> IO x) -> TVar Bool -> Entry -> ConnectionTerminationReason -> IO (Either UsageError a)+    renewEntry unmask reuseVar entry reason = do+      outcome <-+        onException+          ( do+              Connection.release (entryConnection entry)+              unmask $ poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus reason))+              establish unmask+          )+          (atomically returnSlot)+      case outcome of+        Left err -> return $ Left err+        Right newEntry -> onLiveConn unmask reuseVar newEntry++    -- \| Holding one capacity unit. Establish a connection on it and run the+    -- session. On interruption the slot gets given back.+    onSlot :: (forall x. IO x -> IO x) -> TVar Bool -> IO (Either UsageError a)+    onSlot unmask reuseVar = do+      outcome <- onException (establish unmask) (atomically returnSlot)+      case outcome of+        Left err -> return $ Left err+        Right entry -> onLiveConn unmask reuseVar entry++    -- Run with one capacity unit held: establish the connection and run the+    -- init session on it. On any failure the slot gets given back and the+    -- error gets returned. On interruption the slot gets given back and the+    -- exception gets rethrown.+    establish :: (forall x. IO x -> IO x) -> IO (Either UsageError Entry)+    establish unmask = do+      settings <- unmask poolFetchConnectionSettings+      now <- getMonotonicTimeNSec       id <- Uuid.nextRandom-      poolObserver (ConnectionObservation id ConnectingConnectionStatus)-      Connection.acquire settings >>= \case+      unmask $ poolObserver (ConnectionObservation id ConnectingConnectionStatus)+      unmask (Connection.acquire poolAdapter settings) >>= \case         Left connErr -> do           let connErrText = case connErr of                 Errors.NetworkingConnectionError details -> Just details                 Errors.AuthenticationConnectionError details -> Just details                 Errors.CompatibilityConnectionError details -> Just details                 Errors.OtherConnectionError details -> if details == "" then Nothing else Just details-          poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason connErrText)))-          atomically $ modifyTVar' poolCapacity succ+          unmask $ poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason connErrText)))+          atomically returnSlot           return $ Left $ ConnectionUsageError connErr-        Right connection -> do-          Connection.use connection poolInitSession >>= \case+        Right connection ->+          unmask (Connection.use connection poolInitSession) >>= \case             Left err -> do               Connection.release connection-              atomically $ modifyTVar' poolCapacity succ-              ErrorsDestruction.reset-                ( \details -> do-                    poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (Just details))))-                )-                (poolObserver (ConnectionObservation id (TerminatedConnectionStatus (InitializationErrorTerminationReason err))))-                err+              unmask+                $ ErrorsDestruction.reset+                  (\details -> poolObserver (ConnectionObservation id (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (Just details)))))+                  (poolObserver (ConnectionObservation id (TerminatedConnectionStatus (InitializationErrorTerminationReason err))))+                  err+              atomically returnSlot               return $ Left $ SessionUsageError err             Right () -> do-              poolObserver (ConnectionObservation id (ReadyForUseConnectionStatus EstablishedConnectionReadyForUseReason))-              onLiveConn reuseVar (Entry connection now now id)--    onConn reuseVar entry = do-      now <- getMonotonicTimeNSec-      if entryIsAged poolMaxLifetime now entry-        then do-          Connection.release (entryConnection entry)-          poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus AgingConnectionTerminationReason))-          onNewConn reuseVar-        else-          if entryIsIdle poolMaxIdletime now entry-            then do-              Connection.release (entryConnection entry)-              poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus IdlenessConnectionTerminationReason))-              onNewConn reuseVar-            else do-              onLiveConn reuseVar entry {entryUseTimeNSec = now}+              unmask $ poolObserver (ConnectionObservation id (ReadyForUseConnectionStatus EstablishedConnectionReadyForUseReason))+              return $ Right (Entry connection now now id) -    onLiveConn reuseVar entry = do-      poolObserver (ConnectionObservation (entryId entry) InUseConnectionStatus)-      sessRes <- try @SomeException (Connection.use (entryConnection entry) sess)+    -- \| Holding one entry ready for use. Run the session on it, return the+    -- entry to the pool, and return the session result. Interrupted, the+    -- session exception gets rethrown after the entry is back in the pool.+    onLiveConn :: (forall x. IO x -> IO x) -> TVar Bool -> Entry -> IO (Either UsageError a)+    onLiveConn unmask reuseVar entry = do+      sessRes <-+        onException+          ( unmask $ do+              poolObserver (ConnectionObservation (entryId entry) InUseConnectionStatus)+              try @SomeException (Connection.use (entryConnection entry) sess)+          )+          (returnConn reuseVar entry)        case sessRes of         Left exc -> do-          returnConn+          returnConn reuseVar entry           throwIO exc-        Right (Left err) ->-          if ErrorsDestruction.requiresConnectionDiscard err+        Right (Left err) -> do+          discard <-+            if ErrorsDestruction.requiresConnectionDiscard err+              then return True+              else connectionIsLost (entryConnection entry)+          if discard             then do               Connection.release (entryConnection entry)-              atomically $ modifyTVar' poolCapacity succ-              poolObserver-                ( ConnectionObservation-                    (entryId entry)-                    (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (ErrorsDestruction.discardDetails err)))-                )+              atomically returnSlot+              unmask+                $ poolObserver+                  ( ConnectionObservation+                      (entryId entry)+                      (TerminatedConnectionStatus (NetworkErrorConnectionTerminationReason (Just (Errors.toMessage err))))+                  )               return $ Left $ SessionUsageError err             else do-              returnConn-              poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus (SessionFailedConnectionReadyForUseReason err)))+              returnConn reuseVar entry+              unmask $ poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus (SessionFailedConnectionReadyForUseReason err)))               return $ Left $ SessionUsageError err         Right (Right res) -> do-          returnConn-          poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus SessionSucceededConnectionReadyForUseReason))+          returnConn reuseVar entry+          unmask $ poolObserver (ConnectionObservation (entryId entry) (ReadyForUseConnectionStatus SessionSucceededConnectionReadyForUseReason))           return $ Right res-      where-        returnConn =-          join . atomically $ do-            reuse <- readTVar reuseVar-            if reuse-              then writeTQueue poolConnectionQueue entry $> return ()-              else return $ do-                Connection.release (entryConnection entry)-                atomically $ modifyTVar' poolCapacity succ-                poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus ReleaseConnectionTerminationReason))++    -- Back to the pool request waiting longest or to the idle connections,+    -- unless the pool was released meanwhile.+    returnConn reuseVar entry =+      join . atomically $ do+        reuse <- readTVar reuseVar+        if reuse+          then do+            nextWaiter poolWaiting >>= \case+              Just waiter -> do+                currentReuseVar <- readTVar poolReuseVar+                putTMVar (waiterGiven waiter) (Given currentReuseVar (Just entry))+              Nothing ->+                case poolReuseOrder of+                  LIFO -> unGetTQueue poolConnectionQueue entry+                  FIFO -> writeTQueue poolConnectionQueue entry+            return $ return ()+          else return $ do+            Connection.release (entryConnection entry)+            atomically returnSlot+            poolObserver (ConnectionObservation (entryId entry) (TerminatedConnectionStatus ReleaseConnectionTerminationReason))++-- | Whether the adapter has marked the connection as lost.+--+-- When the server closes an idle connection, e.g. on restart or with+-- @pg_terminate_backend@, the next statement on it can fail with an error+-- that doesn't say so: 'Errors.UnexpectedRowCountStatementError', for the+-- extra result that reports the closed connection. A statement returning more+-- rows than its decoder expects fails the same way on a healthy connection, so+-- the error can't tell the two apart. The connection status can: the adapter+-- has set it to 'Pqi.ConnectionBad' by then.+connectionIsLost :: Connection -> IO Bool+connectionIsLost connection =+  Connection.use connection checkStatus <&> \case+    Left _ -> True+    Right lost -> lost+  where+    checkStatus =+      Session.onLibpqConnection \pqConnection -> do+        status <- Pqi.status pqConnection+        return (Right (status == Pqi.ConnectionBad), pqConnection)++-- | Whether a pool request is waiting. The ones that stopped waiting get+-- dropped.+someoneWaiting :: TQueue Waiter -> STM Bool+someoneWaiting waiting =+  tryPeekTQueue waiting >>= \case+    Nothing -> return False+    Just waiter ->+      readTVar (waiterGone waiter) >>= \case+        True -> readTQueue waiting *> someoneWaiting waiting+        False -> return True++-- | Take the pool request waiting longest, passing over the ones that stopped+-- waiting.+nextWaiter :: TQueue Waiter -> STM (Maybe Waiter)+nextWaiter waiting =+  tryReadTQueue waiting >>= \case+    Nothing -> return Nothing+    Just waiter ->+      readTVar (waiterGone waiter) >>= \case+        True -> nextWaiter waiting+        False -> return (Just waiter)++-- | Give the slot of a closed connection to the pool request waiting longest,+-- or back to the pool if no pool request waits.+freeSlot :: TVar (TVar Bool) -> TQueue Waiter -> TVar Int -> STM ()+freeSlot reuseVarVar waiting capVar =+  nextWaiter waiting >>= \case+    Just waiter -> do+      reuseVar <- readTVar reuseVarVar+      putTMVar (waiterGiven waiter) (Given reuseVar Nothing)+    Nothing -> modifyTVar' capVar succ++-- | Time out the pool requests waiting too long. All wait as long, so the pool+-- request waiting longest times out first: one thread sleeps until its+-- deadline, rather than every waiting pool request registering a timer, which+-- GHC can't cancel.+expire :: TQueue Waiter -> IO ()+expire waiting = forever $ do+  deadline <- atomically $ do+    waited <- someoneWaiting waiting+    if waited then waiterDeadline <$> peekTQueue waiting else retry+  now <- getMonotonicTimeNSec+  -- In microseconds, at most an hour at a time.+  when (deadline > now) $ threadDelay (fromIntegral (min 3_600_000_000 (div (deadline - now) 1_000 + 1)))+  atomically . timeOut =<< getMonotonicTimeNSec+  where+    timeOut now =+      tryPeekTQueue waiting >>= \case+        Just waiter | waiterDeadline waiter <= now -> do+          _ <- readTQueue waiting+          gone <- readTVar (waiterGone waiter)+          unless gone $ putTMVar (waiterGiven waiter) TimedOut+          timeOut now+        _ -> return ()++-- | Resolve the pool requests still waiting: with the pool gone, nothing will+-- ever be given to them.+drainWaiting :: TQueue Waiter -> STM ()+drainWaiting waiting =+  tryReadTQueue waiting >>= \case+    Nothing -> return ()+    Just waiter -> do+      gone <- readTVar (waiterGone waiter)+      unless gone $ void $ tryPutTMVar (waiterGiven waiter) TimedOut+      drainWaiting waiting++-- | Terminate one expired connection on the reaper's tick: release it, report+-- the termination, and give its slot back. The slot gets given back even when+-- the release or the observation fails, so no capacity is lost, and a failing+-- entry neither skips the other entries of the tick nor kills the reaper.+reap :: (Observation -> IO ()) -> TVar (TVar Bool) -> TQueue Waiter -> TVar Int -> ConnectionTerminationReason -> Entry -> IO ()+reap observer reuseVar waiting capVar reason entry =+  mask \restore ->+    catch @SomeException+      ( do+          restore $ Connection.release (entryConnection entry)+          restore $ observer (ConnectionObservation (entryId entry) (TerminatedConnectionStatus reason))+          atomically $ freeSlot reuseVar waiting capVar+      )+      \exc -> do+        atomically $ freeSlot reuseVar waiting capVar+        case fromException exc of+          Just SomeAsyncException {} -> throwIO exc+          Nothing -> return ()  -- | Union over all errors that 'use' can result in. data UsageError
src/library/Hasql/Pool/Config.hs view
@@ -11,10 +11,13 @@     Setting.dynamicConnectionSettings,     Setting.observationHandler,     Setting.initSession,+    Setting.reuseOrder,+    ReuseOrder.ReuseOrder (..),   ) where  import Hasql.Pool.Config.Config qualified as Config+import Hasql.Pool.Config.ReuseOrder qualified as ReuseOrder import Hasql.Pool.Config.Setting qualified as Setting import Hasql.Pool.Prelude
src/library/Hasql/Pool/Config/Config.hs view
@@ -2,6 +2,7 @@  import Hasql.Connection.Settings qualified as Connection.Settings import Hasql.Pool.Config.Defaults qualified as Defaults+import Hasql.Pool.Config.ReuseOrder (ReuseOrder) import Hasql.Pool.Observation (Observation) import Hasql.Pool.Prelude import Hasql.Session qualified as Session@@ -14,7 +15,8 @@     idlenessTimeout :: DiffTime,     connectionSettingsProvider :: IO Connection.Settings.Settings,     observationHandler :: Observation -> IO (),-    initSession :: Session.Session ()+    initSession :: Session.Session (),+    reuseOrder :: ReuseOrder   }  -- | Reasonable defaults, which can be built upon.@@ -27,5 +29,6 @@       idlenessTimeout = Defaults.idlenessTimeout,       connectionSettingsProvider = Defaults.dynamicConnectionSettings,       observationHandler = Defaults.observationHandler,-      initSession = Defaults.initSession+      initSession = Defaults.initSession,+      reuseOrder = Defaults.reuseOrder     }
src/library/Hasql/Pool/Config/Defaults.hs view
@@ -1,6 +1,7 @@ module Hasql.Pool.Config.Defaults where  import Hasql.Connection.Settings qualified as Connection.Settings+import Hasql.Pool.Config.ReuseOrder (ReuseOrder (..)) import Hasql.Pool.Observation (Observation) import Hasql.Pool.Prelude import Hasql.Session qualified as Session@@ -45,3 +46,8 @@ -- > pure () initSession :: Session.Session () initSession = pure ()++-- |+-- The idle connection returned longest ago first.+reuseOrder :: ReuseOrder+reuseOrder = FIFO
+ src/library/Hasql/Pool/Config/ReuseOrder.hs view
@@ -0,0 +1,17 @@+module Hasql.Pool.Config.ReuseOrder where++import Hasql.Pool.Prelude++-- | Which of the idle connections a pool request gets.+data ReuseOrder+  = -- | Last in, first out: the one returned most recently.+    --+    -- The pool keeps reusing the few connections the load needs, so the rest+    -- time out as idle, and the ones in use keep their caches warm.+    LIFO+  | -- | First in, first out: the one returned longest ago.+    --+    -- Pool requests cycle through all the connections, so steady load keeps+    -- every connection open.+    FIFO+  deriving (Show, Eq)
src/library/Hasql/Pool/Config/Setting.hs view
@@ -3,6 +3,7 @@ import Hasql.Connection.Settings qualified as Connection.Settings import Hasql.Pool.Config.Config (Config) import Hasql.Pool.Config.Config qualified as Config+import Hasql.Pool.Config.ReuseOrder (ReuseOrder (..)) import Hasql.Pool.Observation (Observation) import Hasql.Pool.Prelude import Hasql.Session qualified as Session@@ -74,6 +75,8 @@ -- -- Typically it's used for monitoring the state of the pool via metrics and logging. --+-- An observation handler must not throw. Synchronous exceptions from it are discarded; asynchronous exceptions are honored. Its failure never affects the session result or the pool's state.+-- -- If the provided action is not lightweight, it's recommended to use intermediate bufferring via channels like TBQueue to avoid occupying the pool management thread for too long. -- E.g., if the action is @'atomically' . 'writeTBQueue' yourQueue@, then reading from it and processing can be done on a separate thread. --@@ -95,3 +98,14 @@ initSession :: Session.Session () -> Setting initSession x =   Setting (\config -> config {Config.initSession = x})++-- | Which of the idle connections a pool request gets.+--+-- With 'LIFO', the pool shrinks to the connections the load needs: the rest+-- time out as idle (see 'idlenessTimeout'). With 'FIFO', steady load keeps+-- every connection open.+--+-- 'FIFO' by default.+reuseOrder :: ReuseOrder -> Setting+reuseOrder x =+  Setting (\config -> config {Config.reuseOrder = x})
src/library/Hasql/Pool/SessionErrorDestructors.hs view
@@ -19,12 +19,6 @@   -- cleanup after an interruption fails, so it must not be reused by the pool.   Errors.DriverSessionError {} -> True -discardDetails :: Errors.SessionError -> Maybe Text-discardDetails err =-  if requiresConnectionDiscard err-    then Just $ Errors.toMessage err-    else Nothing- statementRequiresConnectionDiscard :: Errors.StatementError -> Bool statementRequiresConnectionDiscard = \case   Errors.ServerStatementError serverError -> isStaleServerError serverError