Do Not Increment Cache Hits For Expired Entries (#163)

* do not increment cache hits for expired entries * format
zio · Oct 19, 2023 · 8a2586f · 8a2586f
1 parent 3ce1022
commit 8a2586f
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/zio-cache/shared/src/main/scala/zio/cache/Cache.scala b/zio-cache/shared/src/main/scala/zio/cache/Cache.scala
@@ -225,11 +225,11 @@ object Cache {
                       promise.await
                     case MapValue.Complete(key, exit, _, timeToLive) =>
                       trackAccess(key)
-                      trackHit()
                       if (hasExpired(timeToLive)) {
                         map.remove(k, value)
                         get(in)
                       } else {
+                        trackHit()
                         ZIO.done(exit)
                       }
                     case MapValue.Refreshing(

diff --git a/zio-cache/shared/src/test/scala/zio/cache/CacheSpec.scala b/zio-cache/shared/src/test/scala/zio/cache/CacheSpec.scala
@@ -1,14 +1,17 @@
 package zio.cache
 
+import zio._
 import zio.test.Assertion._
 import zio.test._
-import zio.{Duration, Ref, Scope, UIO, ZIO, duration2DurationOps}
 
 object CacheSpec extends ZIOSpecDefault {
 
   def hash(x: Int): Int => UIO[Int] =
     y => ZIO.succeed((x ^ y).hashCode)
 
+  val identity: Int => UIO[Int] =
+    ZIO.succeed(_)
+
   def spec: Spec[TestEnvironment with Scope, Any] = suite("CacheSpec")(
     test("cacheStats") {
       check(Gen.int) { salt =>
@@ -142,6 +145,18 @@ object CacheSpec extends ZIOSpecDefault {
           size  <- cache.size
         } yield assertTrue(size == 10)
       }
+    },
+    test("cache hits should not be incremented for expired entries") {
+      for {
+        cache      <- Cache.make(100, 1.second, Lookup(identity))
+        _          <- cache.get(42)
+        _          <- TestClock.adjust(2.seconds)
+        _          <- cache.get(42)
+        cacheStats <- cache.cacheStats
+        hits        = cacheStats.hits
+        misses      = cacheStats.misses
+      } yield assertTrue(hits == 0L) &&
+        assertTrue(misses == 2L)
     }
   )
 }