Add test for cache hits

main/src/main/scala/sbt/internal/Aggregation.scala

@@ -118,7 +118,7 @@ object Aggregation {
       val transform = nodeView(s, str, roots, extra)
       runTask(toRun, s, str, structure.index.triggers, config)(using transform)
     val stop = System.currentTimeMillis
-    val cacheSummary = Def.cacheEventLog.summary
+    val cacheSummary = Def.cacheEventLog.summary.toString()
     Complete(start, stop, result, cacheSummary, newS)
 
   def runTasks[A1](

sbt-app/src/sbt-test/cache/basic/build.sbt

@@ -1,9 +1,10 @@
-import sbt.internal.util.StringVirtualFile1
+import sbt.internal.util.{ CacheEventSummary, StringVirtualFile1 }
 import sjsonnew.BasicJsonProtocol.*
 
 val pure1 = taskKey[Unit]("")
 val map1 = taskKey[String]("")
 val mapN1 = taskKey[Unit]("")
+val checkMapN1 = taskKey[Unit]("")
 
 Global / localCacheDirectory := baseDirectory.value / "diskcache"
 
@@ -29,3 +30,11 @@ mapN1 := (Def.cachedTask {
   Def.declareOutput(output)
   ()
 }).value
+
+checkMapN1 := {
+  val config = Def.cacheConfiguration.value
+  val prev = config.cacheEventLog.previous match
+    case s: CacheEventSummary.Data => s
+    case s                         => sys.error(s"empty event log") 
+  assert(prev.hitCount == 2, s"prev.hitCount = ${prev.hitCount}")
+}

sbt-app/src/sbt-test/cache/basic/test

@@ -16,3 +16,4 @@ $ exists target/out/b2.txt
 $ exists target/out/a.txt
 $ exists target/out/b1.txt
 $ exists target/out/c.txt
+> checkMapN1

sbt-app/src/sbt-test/cache/compiler-plugin/build.sbt

@@ -0,0 +1,21 @@
+import sbt.internal.util.CacheEventSummary
+
+val check = taskKey[Unit]("")
+
+Global / localCacheDirectory := baseDirectory.value / "diskcache"
+
+scalaVersion := "2.13.16"
+
+addCompilerPlugin(("org.typelevel" % "kind-projector" % "0.13.3").cross(CrossVersion.full))
+check := {
+  val config = Def.cacheConfiguration.value
+  val prev = config.cacheEventLog.previous match
+    case s: CacheEventSummary.Data => s
+    case s                         => sys.error(s"empty event log") 
+  assert(prev.hitCount == 1, s"prev.hitCount = ${prev.hitCount}")
+}
+
+lazy val foo = (project in file("foo"))
+  .settings(
+    name := "foo"
+  )

sbt-app/src/sbt-test/cache/compiler-plugin/foo/A.scala

@@ -0,0 +1,5 @@
+package example
+
+class A {
+  def foo = 1
+}

sbt-app/src/sbt-test/cache/compiler-plugin/test

@@ -0,0 +1,4 @@
+> foo/compile
+> clean
+> foo/compile
+> check

util-cache/src/main/scala/sbt/internal/util/CacheEventLog.scala

@@ -13,8 +13,45 @@ end ActionCacheEvent
 
 case class ActionCacheError(outputFiles: Seq[VirtualFileRef])
 
+enum CacheEventSummary:
+  case Empty
+  case Data(
+      hits: Seq[(String, Long)],
+      hitCount: Long,
+      missCount: Long,
+      hitRate: Double,
+      onsiteCount: Option[Long],
+      errorCount: Option[Long]
+  )
+  override def toString(): String = this match
+    case Empty => ""
+    case Data(
+          hits,
+          hitCount,
+          missCount,
+          hitRate,
+          onsiteCount,
+          errorCount
+        ) =>
+      val hitDescs = hits.map {
+        case (id, 1) => s"1 $id cache hit"
+        case (id, v) => s"$v $id cache hits"
+      }.sorted
+      val missDesc = onsiteCount.map:
+        case 1 => s"1 onsite task"
+        case _ => s"$missCount onsite tasks"
+      val errorDesc = errorCount.map:
+        case 1      => s"1 error"
+        case errors => s"$errors errors"
+      val descs = hitDescs ++ missDesc ++ errorDesc
+      val descsSummary = descs.mkString(", ")
+      val hitRateStr = (hitRate * 100.0).floor.toInt
+      s"cache $hitRateStr%, $descsSummary"
+end CacheEventSummary
+
 class CacheEventLog:
   private val acEvents = TrieMap.empty[ActionCacheEvent, Long]
+  private val previousEvents = TrieMap.empty[ActionCacheEvent, Long]
 
   def append(event: ActionCacheEvent): Unit =
     acEvents.updateWith(event) {
@@ -23,31 +60,29 @@ class CacheEventLog:
     }
 
   def clear(): Unit =
+    previousEvents.clear()
+    previousEvents ++= acEvents
     acEvents.clear()
 
-  def summary: String =
-    if acEvents.isEmpty then ""
+  def summary: CacheEventSummary = toSummary(acEvents)
+  def previous: CacheEventSummary = toSummary(previousEvents)
+
+  def toSummary(events: TrieMap[ActionCacheEvent, Long]): CacheEventSummary =
+    if events.isEmpty then CacheEventSummary.Empty
     else
-      val total = acEvents.values.sum
-      val hits = acEvents.view.collect { case (ActionCacheEvent.Found(id), v) => (id, v) }.toMap
+      val total = events.values.sum
+      val hits = events.view.collect { case (ActionCacheEvent.Found(id), v) => (id, v) }.toMap
       val hitCount = hits.values.sum
       val missCount = total - hitCount
-      val hitRate = (hitCount.toDouble / total.toDouble * 100.0).floor.toInt
-      val hitDescs = hits.toSeq.map {
-        case (id, 1) => s"1 $id cache hit"
-        case (id, v) => s"$v $id cache hits"
-      }.sorted
-      val missDesc = acEvents
-        .get(ActionCacheEvent.OnsiteTask)
-        .map:
-          case 1 => s"1 onsite task"
-          case _ => s"$missCount onsite tasks"
-      val errorDesc = acEvents
-        .get(ActionCacheEvent.Error)
-        .map:
-          case 1      => s"1 error"
-          case errors => s"$errors errors"
-      val descs = hitDescs ++ missDesc ++ errorDesc
-      val descsSummary = descs.mkString(", ")
-      s"cache $hitRate%, $descsSummary"
+      val hitRate = (hitCount.toDouble / total.toDouble)
+      val onsiteCount = events.get(ActionCacheEvent.OnsiteTask)
+      val errorCount = events.get(ActionCacheEvent.Error)
+      CacheEventSummary.Data(
+        hits.toSeq,
+        hitCount,
+        missCount,
+        hitRate,
+        onsiteCount,
+        errorCount
+      )
 end CacheEventLog

util-cache/src/test/scala/sbt/util/CacheEventLogTest.scala

@@ -7,14 +7,14 @@ object CacheEventLogTest extends BasicTestSuite:
   test("summary of 0 events") {
     val logger = CacheEventLog()
     val expectedSummary = ""
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk event") {
     val logger = CacheEventLog()
     logger.append(ActionCacheEvent.Found("disk"))
     val expectedSummary = "cache 100%, 1 disk cache hit"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 2 disk events") {
@@ -22,7 +22,7 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.append(ActionCacheEvent.Found("disk"))
     logger.append(ActionCacheEvent.Found("disk"))
     val expectedSummary = "cache 100%, 2 disk cache hits"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk, 1 onsite task") {
@@ -30,7 +30,7 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.append(ActionCacheEvent.Found("disk"))
     logger.append(ActionCacheEvent.OnsiteTask)
     val expectedSummary = "cache 50%, 1 disk cache hit, 1 onsite task"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk, 1 onsite task, 1 error") {
@@ -39,7 +39,7 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.append(ActionCacheEvent.OnsiteTask)
     logger.append(ActionCacheEvent.Error)
     val expectedSummary = "cache 33%, 1 disk cache hit, 1 onsite task, 1 error"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk, 2 errors") {
@@ -48,7 +48,7 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.append(ActionCacheEvent.Error)
     logger.append(ActionCacheEvent.Error)
     val expectedSummary = "cache 33%, 1 disk cache hit, 2 errors"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk, 2 remote, 1 onsite task") {
@@ -58,7 +58,7 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.append(ActionCacheEvent.Found("remote"))
     logger.append(ActionCacheEvent.OnsiteTask)
     val expectedSummary = "cache 75%, 1 disk cache hit, 2 remote cache hits, 1 onsite task"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 
   test("summary of 1 disk event after clear") {
@@ -67,6 +67,6 @@ object CacheEventLogTest extends BasicTestSuite:
     logger.clear()
     logger.append(ActionCacheEvent.Found("disk"))
     val expectedSummary = "cache 100%, 1 disk cache hit"
-    assertEquals(logger.summary, expectedSummary)
+    assertEquals(logger.summary.toString(), expectedSummary)
   }
 end CacheEventLogTest