From 5c322510b185e7ee50ec6f75057369c427b9724b Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 25 Oct 2010 13:26:35 +0000
Subject: Now short-circuits reload work items that are s...

Now short-circuits reload work items that are superseded by later ones.
---
 .../tools/nsc/interactive/CompilerControl.scala    | 50 +++++++++++++---------
 .../scala/tools/nsc/util/WorkScheduler.scala       |  3 ++
 2 files changed, 32 insertions(+), 21 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala b/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
index 5258849b8c..87eace3a24 100644
--- a/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
+++ b/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
@@ -13,6 +13,11 @@ trait CompilerControl { self: Global =>
 
   abstract class WorkItem extends (() => Unit)
 
+  case class ReloadItem(sources: List[SourceFile], response: Response[Unit]) extends WorkItem {
+    def apply() = reload(sources, response)
+    override def toString = "reload "+sources
+  }
+
   /** Info given for every member found by completion
    */
   abstract class Member {
@@ -89,54 +94,57 @@ trait CompilerControl { self: Global =>
   }
 
   /** Make sure a set of compilation units is loaded and parsed.
-   *  Return () to syncvar `result` on completion.
+   *  Return () to syncvar `response` on completion.
    */
-  def askReload(sources: List[SourceFile], result: Response[Unit]) =
-    scheduler postWorkItem new WorkItem {
-      def apply() = reload(sources, result)
-      override def toString = "reload "+sources
+  def askReload(sources: List[SourceFile], response: Response[Unit]) = {
+    val superseeded = scheduler.dequeueAll {
+      case ri: ReloadItem if ri.sources == sources => Some(ri)
+      case _ => None
     }
+    superseeded foreach (_.response.set())
+    scheduler postWorkItem new ReloadItem(sources, response)
+  }
 
-  /** Set sync var `result` to the smallest fully attributed tree that encloses position `pos`.
+  /** Set sync var `response` to the smallest fully attributed tree that encloses position `pos`.
    */
-  def askTypeAt(pos: Position, result: Response[Tree]) =
+  def askTypeAt(pos: Position, response: Response[Tree]) =
     scheduler postWorkItem new WorkItem {
-      def apply() = self.getTypedTreeAt(pos, result)
+      def apply() = self.getTypedTreeAt(pos, response)
       override def toString = "typeat "+pos.source+" "+pos.show
     }
 
-  /** Set sync var `result` to the fully attributed & typechecked tree contained in `source`.
+  /** Set sync var `response` to the fully attributed & typechecked tree contained in `source`.
    */
-  def askType(source: SourceFile, forceReload: Boolean, result: Response[Tree]) =
+  def askType(source: SourceFile, forceReload: Boolean, response: Response[Tree]) =
     scheduler postWorkItem new WorkItem {
-      def apply() = self.getTypedTree(source, forceReload, result)
+      def apply() = self.getTypedTree(source, forceReload, response)
       override def toString = "typecheck"
   }
 
-  /** Set sync var `result` to the last fully attributed & typechecked tree produced from `source`.
-   *  If no such tree exists yet, do a normal askType(source, false, result)
+  /** Set sync var `response` to the last fully attributed & typechecked tree produced from `source`.
+   *  If no such tree exists yet, do a normal askType(source, false, response)
    */
-  def askLastType(source: SourceFile, result: Response[Tree]) =
+  def askLastType(source: SourceFile, response: Response[Tree]) =
     scheduler postWorkItem new WorkItem {
-      def apply() = self.getLastTypedTree(source, result)
+      def apply() = self.getLastTypedTree(source, response)
       override def toString = "reconcile"
   }
 
-  /** Set sync var `result' to list of members that are visible
+  /** Set sync var `response' to list of members that are visible
    *  as members of the tree enclosing `pos`, possibly reachable by an implicit.
    */
-  def askTypeCompletion(pos: Position, result: Response[List[Member]]) =
+  def askTypeCompletion(pos: Position, response: Response[List[Member]]) =
     scheduler postWorkItem new WorkItem {
-      def apply() = self.getTypeCompletion(pos, result)
+      def apply() = self.getTypeCompletion(pos, response)
       override def toString = "type completion "+pos.source+" "+pos.show
     }
 
-  /** Set sync var `result' to list of members that are visible
+  /** Set sync var `response' to list of members that are visible
    *  as members of the scope enclosing `pos`.
    */
-  def askScopeCompletion(pos: Position, result: Response[List[Member]]) =
+  def askScopeCompletion(pos: Position, response: Response[List[Member]]) =
     scheduler postWorkItem new WorkItem {
-      def apply() = self.getScopeCompletion(pos, result)
+      def apply() = self.getScopeCompletion(pos, response)
       override def toString = "scope completion "+pos.source+" "+pos.show
     }
 
diff --git a/src/compiler/scala/tools/nsc/util/WorkScheduler.scala b/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
index f520aec8bc..509efca8e5 100644
--- a/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
+++ b/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
@@ -26,6 +26,9 @@ class WorkScheduler {
     if (todo.isEmpty) None else Some(todo.dequeue())
   }
 
+  def dequeueAll[T](f: Action => Option[T]): Seq[T] =
+    todo.dequeueAll(a => f(a).isDefined).map(a => f(a).get)
+
   /** Called from server: return optional exception posted by client
    *  Reset to no exception.
    */
-- 
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