Added `ask` method to compiler control to do fa...

Added `ask` method to compiler control to do fast trunaround
computations on presentation compiler thread.

3 files changed, 34 insertions, 9 deletions

diff --git a/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala b/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
index 26f7fb1115..c6106a9865 100644
--- a/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
+++ b/src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
@@ -134,6 +134,9 @@ trait CompilerControl { self: Global =>
   /** Tell the compile server to shutdown, and do not restart again */
   def askShutdown() = scheduler raise ShutdownReq
 
+  /** Ask for a computation to be done quickly on the presentation compiler thread */
+  def ask[A](op: () => A): A = scheduler doQuickly op
+
   // ---------------- Interpreted exceptions -------------------
 
   object CancelActionReq extends ControlThrowable
diff --git a/src/compiler/scala/tools/nsc/interactive/Global.scala b/src/compiler/scala/tools/nsc/interactive/Global.scala
index 2c174860e4..cb2f4a0340 100644
--- a/src/compiler/scala/tools/nsc/interactive/Global.scala
+++ b/src/compiler/scala/tools/nsc/interactive/Global.scala
@@ -110,10 +110,16 @@ self =>
   // ----------------- Polling ---------------------------------------
 
   /** Called from runner thread and signalDone:
-   *  Poll for exceptions.
-   *  Poll for work reload/typedTreeAt/doFirst commands during background checking.
+   *  Poll for interrupts and execute them immediately.
+   *  Then, poll for exceptions and execute them.
+   *  Then, poll for work reload/typedTreeAt/doFirst commands during background checking.
    */
   def pollForWork() {
+    scheduler.pollInterrupt() match {
+      case Some(ir) =>
+        ir.execute(); pollForWork()
+      case _ =>
+    }
     scheduler.pollThrowable() match {
       case Some(ex @ CancelActionReq) => if (acting) throw ex
       case Some(ex @ FreshRunReq) =>
diff --git a/src/compiler/scala/tools/nsc/util/WorkScheduler.scala b/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
index e309b19b76..5f33ea4aaa 100644
--- a/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
+++ b/src/compiler/scala/tools/nsc/util/WorkScheduler.scala
@@ -9,22 +9,21 @@ class WorkScheduler {
 
   private var todo = new Queue[Action]
   private var throwables = new Queue[Throwable]
+  private var interruptReqs = new Queue[InterruptReq]
 
-  /** Called from server: block until todo list is nonempty */
+  /** Called from server: block until one of todo list, throwables or interruptReqs is nonempty */
   def waitForMoreWork() = synchronized {
-    while (todo.isEmpty) { wait() }
+    while (todo.isEmpty && throwables.isEmpty && interruptReqs.isEmpty) { wait() }
   }
 
-  /** called from Server: test whether todo list is nonempty */
+  /** called from Server: test whether one of todo list, throwables, or InterruptReqs is nonempty */
   def moreWork(): Boolean = synchronized {
-    todo.nonEmpty
+    todo.nonEmpty || throwables.nonEmpty || interruptReqs.nonEmpty
   }
 
   /** Called from server: get first action in todo list, and pop it off */
   def nextWorkItem(): Option[Action] = synchronized {
-    if (!todo.isEmpty) {
-      Some(todo.dequeue())
-    } else None
+    if (todo.isEmpty) None else Some(todo.dequeue())
   }
 
   /** Called from server: return optional exception posted by client
@@ -41,6 +40,22 @@ class WorkScheduler {
     }
   }
 
+  def pollInterrupt(): Option[InterruptReq] = synchronized {
+    if (interruptReqs.isEmpty) None else Some(interruptReqs.dequeue())
+  }
+
+  /** Called from client: have interrupt executed by server and return result */
+  def doQuickly[A](op: () => A): A = {
+    val ir = new InterruptReq {
+      type R = A
+      val todo = op
+    }
+    synchronized {
+      interruptReqs enqueue ir
+    }
+    ir.getResult()
+  }
+
   /** Called from client: have action executed by server */
   def postWorkItem(action: Action) = synchronized {
     todo enqueue action
@@ -60,3 +75,4 @@ class WorkScheduler {
     postWorkItem { () => }
   }
 }
+