Do not allocate more resources than the maxTotal

typelevel · Jun 7, 2022 · a872544 · a872544
1 parent 53e30cc
commit a872544
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Showing 5 changed files with 65 additions and 13 deletions.
diff --git a/build.sbt b/build.sbt
@@ -59,8 +59,7 @@ lazy val commonSettings = Seq(
   Test / parallelExecution := false,
   libraryDependencies ++= Seq(
     "org.typelevel" %%% "cats-core"           % catsV,
-    "org.typelevel" %%% "cats-effect-kernel"  % catsEffectV,
-    "org.typelevel" %%% "cats-effect-std"     % catsEffectV      % Test,
+    "org.typelevel" %%% "cats-effect-std"     % catsEffectV,
     "org.scalameta" %%% "munit"               % munitV           % Test,
     "org.typelevel" %%% "munit-cats-effect-3" % munitCatsEffectV % Test
   )

diff --git a/core/src/main/scala/org/typelevel/keypool/KeyPool.scala b/core/src/main/scala/org/typelevel/keypool/KeyPool.scala
@@ -23,6 +23,7 @@ package org.typelevel.keypool
 
 import cats._
 import cats.effect.kernel._
+import cats.effect.std.Semaphore
 import cats.syntax.all._
 import scala.concurrent.duration._
 import org.typelevel.keypool.internal._
@@ -64,6 +65,7 @@ object KeyPool {
       private[keypool] val kpDefaultReuseState: Reusable,
       private[keypool] val kpMaxPerKey: A => Int,
       private[keypool] val kpMaxTotal: Int,
+      private[keypool] val kpMaxTotalSem: Semaphore[F],
       private[keypool] val kpVar: Ref[F, PoolMap[A, (B, F[Unit])]]
   ) extends KeyPool[F, A, B] {
 
@@ -291,6 +293,7 @@ object KeyPool {
       }
 
     for {
+      _ <- kp.kpMaxTotalSem.permit
       optR <- Resource.eval(kp.kpVar.modify(go))
       releasedState <- Resource.eval(Ref[F].of[Reusable](kp.kpDefaultReuseState))
       resource <- Resource.make(optR.fold(kp.kpRes(k).allocated)(r => Applicative[F].pure(r))) {
@@ -360,6 +363,7 @@ object KeyPool {
         kpVar <- Resource.make(
           Ref[F].of[PoolMap[A, (B, F[Unit])]](PoolMap.open(0, Map.empty[A, PoolList[(B, F[Unit])]]))
         )(kpVar => KeyPool.destroy(kpVar))
+        kpMaxTotalSem <- Resource.eval(Semaphore[F](kpMaxTotal))
         _ <- idleTimeAllowedInPool match {
           case fd: FiniteDuration =>
             val nanos = 0.seconds.max(fd)
@@ -374,6 +378,7 @@ object KeyPool {
         kpDefaultReuseState,
         kpMaxPerKey,
         kpMaxTotal,
+        kpMaxTotalSem,
         kpVar
       )
     }

diff --git a/core/src/main/scala/org/typelevel/keypool/KeyPoolBuilder.scala b/core/src/main/scala/org/typelevel/keypool/KeyPoolBuilder.scala
@@ -25,6 +25,7 @@ import internal.{PoolList, PoolMap}
 import cats._
 import cats.syntax.all._
 import cats.effect.kernel._
+import cats.effect.std.Semaphore
 import scala.concurrent.duration._
 
 @deprecated("use KeyPool.Builder", "0.4.7")
@@ -83,6 +84,7 @@ final class KeyPoolBuilder[F[_]: Temporal, A, B] private (
       kpVar <- Resource.make(
         Ref[F].of[PoolMap[A, (B, F[Unit])]](PoolMap.open(0, Map.empty[A, PoolList[(B, F[Unit])]]))
       )(kpVar => KeyPool.destroy(kpVar))
+      kpMaxTotalSem <- Resource.eval(Semaphore[F](kpMaxTotal))
       _ <- idleTimeAllowedInPool match {
         case fd: FiniteDuration =>
           val nanos = 0.seconds.max(fd)
@@ -97,6 +99,7 @@ final class KeyPoolBuilder[F[_]: Temporal, A, B] private (
       kpDefaultReuseState,
       kpMaxPerKey,
       kpMaxTotal,
+      kpMaxTotalSem,
       kpVar
     )
   }

diff --git a/core/src/test/scala/org/typelevel/keypool/KeyPoolSpec.scala b/core/src/test/scala/org/typelevel/keypool/KeyPoolSpec.scala
@@ -23,6 +23,7 @@ package org.typelevel.keypool
 
 import cats.syntax.all._
 import cats.effect._
+import cats.effect.std.CountDownLatch
 import scala.concurrent.duration._
 import munit.CatsEffectSuite
 import scala.concurrent.ExecutionContext
@@ -32,8 +33,6 @@ class KeypoolSpec extends CatsEffectSuite {
   override val munitExecutionContext: ExecutionContext = ExecutionContext.global
 
   test("Keep Resources marked to be kept") {
-    def nothing(ref: Ref[IO, Int]): IO[Unit] =
-      ref.get.void
     KeyPool
       .Builder(
         (i: Int) => Ref.of[IO, Int](i),
@@ -54,8 +53,6 @@ class KeypoolSpec extends CatsEffectSuite {
   }
 
   test("Delete Resources marked to be deleted") {
-    def nothing(ref: Ref[IO, Int]): IO[Unit] =
-      ref.get.void
     KeyPool
       .Builder(
         (i: Int) => Ref.of[IO, Int](i),
@@ -76,8 +73,6 @@ class KeypoolSpec extends CatsEffectSuite {
   }
 
   test("Delete Resource when pool is full") {
-    def nothing(ref: Ref[IO, Int]): IO[Unit] =
-      ref.get.void
     KeyPool
       .Builder(
         (i: Int) => Ref.of[IO, Int](i),
@@ -101,8 +96,6 @@ class KeypoolSpec extends CatsEffectSuite {
   }
 
   test("Used Resource Cleaned Up By Reaper") {
-    def nothing(ref: Ref[IO, Int]): IO[Unit] =
-      ref.get.void
     KeyPool
       .Builder(
         (i: Int) => Ref.of[IO, Int](i),
@@ -128,9 +121,6 @@ class KeypoolSpec extends CatsEffectSuite {
   }
 
   test("Used Resource Not Cleaned Up if Idle Time has not expired") {
-    def nothing(ref: Ref[IO, Int]): IO[Unit] =
-      ref.get.void
-
     KeyPool
       .Builder(
         (i: Int) => Ref.of[IO, Int](i),
@@ -154,4 +144,33 @@ class KeypoolSpec extends CatsEffectSuite {
         } yield assert(init === 1 && later === 1)
       }
   }
+
+  test("Do not allocate more resources than the maxTotal") {
+    val MaxTotal = 10
+
+    KeyPool
+      .Builder(
+        (i: Int) => Ref.of[IO, Int](i),
+        nothing
+      )
+      .withMaxTotal(MaxTotal)
+      .build
+      .use { pool =>
+        for {
+          cdl <- CountDownLatch[IO](MaxTotal)
+          allocated <- IO.parReplicateAN(MaxTotal)(
+            MaxTotal,
+            pool.take(1).use(_ => cdl.release >> IO.never).start
+          )
+          _ <- cdl.await // make sure the pool is exhausted
+          attempt1 <- pool.take(1).use_.timeout(100.millis).attempt
+          _ <- allocated.traverse(_.cancel)
+          attempt2 <- pool.take(1).use_.timeout(100.millis).attempt
+        } yield assert(attempt1.isLeft && attempt2.isRight)
+      }
+  }
+
+  private def nothing(ref: Ref[IO, Int]): IO[Unit] =
+    ref.get.void
+
 }
diff --git a/core/src/test/scala/org/typelevel/keypool/PoolSpec.scala b/core/src/test/scala/org/typelevel/keypool/PoolSpec.scala
@@ -23,6 +23,7 @@ package org.typelevel.keypool
 
 import cats.syntax.all._
 import cats.effect._
+import cats.effect.std.CountDownLatch
 import scala.concurrent.duration._
 import munit.CatsEffectSuite
 import scala.concurrent.ExecutionContext
@@ -136,6 +137,31 @@ class PoolSpec extends CatsEffectSuite {
       }
   }
 
+  test("Do not allocate more resources than the maxTotal") {
+    val MaxTotal = 10
+
+    Pool
+      .Builder(
+        Ref.of[IO, Int](1),
+        nothing
+      )
+      .withMaxTotal(MaxTotal)
+      .build
+      .use { pool =>
+        for {
+          cdl <- CountDownLatch[IO](MaxTotal)
+          allocated <- IO.parReplicateAN(MaxTotal)(
+            MaxTotal,
+            pool.take.use(_ => cdl.release >> IO.never).start
+          )
+          _ <- cdl.await // make sure the pool is exhausted
+          attempt1 <- pool.take.use_.timeout(100.millis).attempt
+          _ <- allocated.traverse(_.cancel)
+          attempt2 <- pool.take.use_.timeout(100.millis).attempt
+        } yield assert(attempt1.isLeft && attempt2.isRight)
+      }
+  }
+
   private def nothing(ref: Ref[IO, Int]): IO[Unit] =
     ref.get.void
 }