Merge pull request #2350 from ChristopherDavenport/semaphoreFix

Fix Cancellation Point in Semaphore
typelevel · Sep 14, 2021 · 4b42b0f · 4b42b0f
2 parents 7dc4aaa + 79c7ae8
commit 4b42b0f
Showing 1 changed file with 11 additions and 8 deletions.
diff --git a/std/shared/src/main/scala/cats/effect/std/Semaphore.scala b/std/shared/src/main/scala/cats/effect/std/Semaphore.scala
@@ -220,14 +220,17 @@ object Semaphore {
 
           if (n == 0) F.unit
           else
-            state.modify {
-              case State(permits, waiting) =>
-                if (waiting.isEmpty) State(permits + n, waiting) -> F.unit
-                else {
-                  val (newN, waitingNow, wakeup) = fulfil(n, waiting, Q())
-                  State(newN, waitingNow) -> wakeup.traverse_(_.complete)
-                }
-            }.flatten
+            state
+              .modify {
+                case State(permits, waiting) =>
+                  if (waiting.isEmpty) State(permits + n, waiting) -> F.unit
+                  else {
+                    val (newN, waitingNow, wakeup) = fulfil(n, waiting, Q())
+                    State(newN, waitingNow) -> wakeup.traverse_(_.complete)
+                  }
+              }
+              .flatten
+              .uncancelable
         }
 
         def available: F[Long] = state.get.map(_.permits)