implement Cache#invalidate (#24)

Author: adamgfraser

zio-cache/shared/src/main/scala/zio/cache/Cache.scala

@@ -50,6 +50,11 @@ trait Cache[-Key, +Error, +Value] {
    */
   def get(key: Key): IO[Error, Value]
 
+  /**
+   * Invalidates the value associated with the specified key.
+   */
+  def invalidate(key: Key): UIO[Unit]
+
   /**
    * Returns the approximate number of values in the cache.
    */
@@ -114,6 +119,24 @@ object Cache {
 
         new Cache[Key, Error, Value] {
 
+          def cacheStats: UIO[CacheStats] =
+            ZIO.succeed(CacheStats(hits.longValue, misses.longValue))
+
+          def contains(k: Key): UIO[Boolean] =
+            ZIO.succeed(map.containsKey(k))
+
+          def entryStats(k: Key): UIO[Option[EntryStats]] =
+            ZIO.succeed {
+              val value = map.get(k)
+              if (value eq null) None
+              else {
+                value match {
+                  case MapValue.Pending(_, _)              => None
+                  case MapValue.Complete(_, _, entryState) => Some(EntryStats(entryState.loaded))
+                }
+              }
+            }
+
           def get(k: Key): IO[Error, Value] =
             ZIO.effectSuspendTotal {
               var key: MapKey[Key]               = null
@@ -160,26 +183,14 @@ object Cache {
 
             }
 
-          def contains(k: Key): UIO[Boolean] =
-            ZIO.succeed(map.containsKey(k))
+          def invalidate(k: Key): UIO[Unit] =
+            ZIO.succeed {
+              map.remove(k)
+              ()
+            }
 
           def size: UIO[Int] =
             ZIO.succeed(map.size)
-
-          def cacheStats: UIO[CacheStats] =
-            ZIO.succeed(CacheStats(hits.longValue, misses.longValue))
-
-          def entryStats(k: Key): UIO[Option[EntryStats]] =
-            ZIO.succeed {
-              val value = map.get(k)
-              if (value eq null) None
-              else {
-                value match {
-                  case MapValue.Pending(_, _)              => None
-                  case MapValue.Complete(_, _, entryState) => Some(EntryStats(entryState.loaded))
-                }
-              }
-            }
         }
       }
     }

zio-cache/shared/src/test/scala/zio/cache/CacheSpec.scala

@@ -21,6 +21,28 @@ object CacheSpec extends DefaultRunnableSpec {
   ] with Has[Clock.Service] with Has[zio.console.Console.Service] with Has[zio.system.System.Service] with Has[
     Random.Service
   ] with Has[Blocking.Service], TestFailure[Any], TestSuccess] = suite("CacheSpec")(
+    testM("cacheStats") {
+      checkM(Gen.anyInt) { salt =>
+        for {
+          cache      <- Cache.make(100, Duration.Infinity, Lookup(hash(salt)))
+          _          <- ZIO.foreachPar((1 to 100).map(_ / 2))(cache.get)
+          cacheStats <- cache.cacheStats
+          hits        = cacheStats.hits
+          misses      = cacheStats.misses
+        } yield assert(hits)(equalTo(49L)) &&
+          assert(misses)(equalTo(51L))
+      }
+    },
+    testM("invalidate") {
+      checkM(Gen.anyInt) { salt =>
+        for {
+          cache    <- Cache.make(100, Duration.Infinity, Lookup(hash(salt)))
+          _        <- ZIO.foreach(1 to 100)(cache.get)
+          _        <- cache.invalidate(42)
+          contains <- cache.contains(42)
+        } yield assert(contains)(isFalse)
+      }
+    },
     suite("lookup")(
       testM("sequential") {
         checkM(Gen.anyInt) { salt =>
@@ -58,18 +80,6 @@ object CacheSpec extends DefaultRunnableSpec {
           size  <- cache.size
         } yield assert(size)(equalTo(10))
       }
-    },
-    testM("cacheStats") {
-      checkM(Gen.anyInt) { salt =>
-        for {
-          cache      <- Cache.make(100, Duration.Infinity, Lookup(hash(salt)))
-          _          <- ZIO.foreachPar((1 to 100).map(_ / 2))(cache.get)
-          cacheStats <- cache.cacheStats
-          hits        = cacheStats.hits
-          misses      = cacheStats.misses
-        } yield assert(hits)(equalTo(49L)) &&
-          assert(misses)(equalTo(51L))
-      }
     }
   )
 }