From d227b6423f897c46c07a895f4cbd923125510675 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Fri, 17 Jul 2020 15:49:36 -0700
Subject: [PATCH] Clear singleton TaskProgress between runs

In db4878c78600f4c80cf81d97ea915c3d5fee17fe, TaskProgress became an
object which mostly made things easier to reason about. The one problem
was that it started leaking tasks with every run because the timings map
would accumulate tasks that weren't cleared. To fix this, we can clear
the timings and activeTasksMap in the TaskProgress object in the
afterAllCompleted callback. Some extra null checks needed to be added
since it's possible for the maps to not contain a previously added key
after reset has been called.
---
 .../main/scala/sbt/internal/AbstractTaskProgress.scala | 10 +++++++++-
 main/src/main/scala/sbt/internal/TaskProgress.scala    |  9 +++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala b/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
index 082c18419..61e93050b 100644
--- a/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/AbstractTaskProgress.scala
@@ -42,7 +42,10 @@ private[sbt] abstract class AbstractTaskExecuteProgress extends ExecuteProgress[
   }
 
   override def afterWork[A](task: Task[A], result: Either[Task[A], Result[A]]): Unit = {
-    timings.get(task).stop()
+    timings.get(task) match {
+      case null =>
+      case t    => t.stop()
+    }
     activeTasksMap.remove(task)
 
     // we need this to infer anonymous task names
@@ -51,6 +54,11 @@ private[sbt] abstract class AbstractTaskExecuteProgress extends ExecuteProgress[
     }
   }
 
+  protected def reset(): Unit = {
+    activeTasksMap.clear()
+    timings.clear()
+  }
+
   private[this] val taskNameCache = TrieMap.empty[Task[_], String]
   protected def taskName(t: Task[_]): String =
     taskNameCache.getOrElseUpdate(t, taskName0(t))
diff --git a/main/src/main/scala/sbt/internal/TaskProgress.scala b/main/src/main/scala/sbt/internal/TaskProgress.scala
index ed74d20b1..494520fcc 100644
--- a/main/src/main/scala/sbt/internal/TaskProgress.scala
+++ b/main/src/main/scala/sbt/internal/TaskProgress.scala
@@ -101,6 +101,7 @@ private[sbt] class TaskProgress private ()
   }
 
   override def afterAllCompleted(results: RMap[Task, Result]): Unit = {
+    reset()
     // send an empty progress report to clear out the previous report
     appendProgress(ProgressEvent("Info", Vector(), Some(lastTaskCount.get), None, None))
   }
@@ -132,8 +133,12 @@ private[sbt] class TaskProgress private ()
     StandardMain.exchange.updateProgress(event)
   private[this] def active: Vector[Task[_]] = activeTasks.toVector.filterNot(Def.isDummy)
   private[this] def activeExceedingThreshold: Vector[(Task[_], Long)] = active.flatMap { task =>
-    val elapsed = timings.get(task).currentElapsedMicros
-    if (elapsed.micros > threshold) Some[(Task[_], Long)](task -> elapsed) else None
+    timings.get(task) match {
+      case null => None
+      case t =>
+        val elapsed = t.currentElapsedMicros
+        if (elapsed.micros > threshold) Some[(Task[_], Long)](task -> elapsed) else None
+    }
   }
   private[this] def report(): Unit = {
     val currentTasks = activeExceedingThreshold