From 797b2aeda3786b4d38ad389380ee5f24fff1c9d6 Mon Sep 17 00:00:00 2001
From: Hubert Plociniczak <hubert.plociniczak@epfl.ch>
Date: Thu, 26 Nov 2009 12:05:45 +0000
Subject: Closes #2562

---
 .../nsc/interactive/RefinedBuildManager.scala      | 54 +++++++++++++++++-----
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/interactive/RefinedBuildManager.scala b/src/compiler/scala/tools/nsc/interactive/RefinedBuildManager.scala
index 6af23f8fde..893ed7b0e9 100644
--- a/src/compiler/scala/tools/nsc/interactive/RefinedBuildManager.scala
+++ b/src/compiler/scala/tools/nsc/interactive/RefinedBuildManager.scala
@@ -87,7 +87,10 @@ class RefinedBuildManager(val settings: Settings) extends Changes with BuildMana
    *  of the dependency analysis.
    */
   private def update(files: Set[AbstractFile]) = {
-    def update0(files: Set[AbstractFile], updated: Set[AbstractFile]): Unit = if (!files.isEmpty) {
+    val coll: mutable.Map[AbstractFile, immutable.Set[AbstractFile]] =
+        mutable.HashMap[AbstractFile, immutable.Set[AbstractFile]]()
+
+    def update0(files: Set[AbstractFile]): Unit = if (!files.isEmpty) {
       deleteClassfiles(files)
       val run = compiler.newRun()
       compiler.inform("compiling " + files)
@@ -105,8 +108,8 @@ class RefinedBuildManager(val settings: Settings) extends Changes with BuildMana
       val defs = compiler.dependencyAnalysis.definitions
       for (src <- files) {
         if (definitions(src).isEmpty)
-    	  additionalDefs ++= compiler.dependencyAnalysis.
-    	                     dependencies.dependentFiles(1, mutable.Set(src))
+          additionalDefs ++= compiler.dependencyAnalysis.
+                             dependencies.dependentFiles(1, mutable.Set(src))
         else {
           val syms = defs(src)
           for (sym <- syms) {
@@ -130,29 +133,56 @@ class RefinedBuildManager(val settings: Settings) extends Changes with BuildMana
       }
       println("Changes: " + changesOf)
       updateDefinitions(files)
-      val compiled = updated ++ files
-      val invalid = invalidated(files, changesOf, additionalDefs.clone() ++= compiled)
-      update0(invalid -- compiled, compiled)
+      val invalid = invalidated(files, changesOf, additionalDefs)
+      update0(checkCycles(invalid, files, coll))
     }
 
-    update0(files, immutable.Set())
+    update0(files)
   }
 
+  // Attempt to break the cycling reference deps as soon as possible and reduce
+  // the number of compilations to minimum without having too coarse grained rules
+  private def checkCycles(files: Set[AbstractFile], initial: Set[AbstractFile],
+                          collect: mutable.Map[AbstractFile, immutable.Set[AbstractFile]]):
+    Set[AbstractFile] = {
+      def followChain(set: Set[AbstractFile], rest: immutable.Set[AbstractFile]):
+        immutable.Set[AbstractFile] = {
+        val deps:Set[AbstractFile] = set.flatMap(
+              s => collect.get(s) match {
+                     case Some(x) => x
+                     case _ => Set[AbstractFile]()
+              })
+          val newDeps = deps -- rest
+          if (newDeps.isEmpty) rest else followChain(newDeps, rest ++ newDeps)
+      }
+      var res:Set[AbstractFile] = mutable.Set()
+      files.foreach( f =>
+        if (collect contains f) {
+          val chain = followChain(Set(f), immutable.Set()) ++ files
+          chain.foreach((fc: AbstractFile) => collect += fc -> chain)
+          res ++= chain
+        } else
+          res += f
+       )
+
+      initial.foreach((f: AbstractFile) => collect += (f -> (collect.getOrElse(f, immutable.Set()) ++ res)))
+      if (res.subsetOf(initial)) Set() else res
+  }
 
   /** Return the set of source files that are invalidated by the given changes. */
   def invalidated(files: Set[AbstractFile], changesOf: collection.Map[Symbol, List[Change]],
-		          processed: Set[AbstractFile] = Set.empty): Set[AbstractFile] = {
+                  processed: Set[AbstractFile] = Set.empty):
+    Set[AbstractFile] = {
     val buf = new mutable.HashSet[AbstractFile]
     val newChangesOf = new mutable.HashMap[Symbol, List[Change]]
     var directDeps =
       compiler.dependencyAnalysis.dependencies.dependentFiles(1, files)
-    directDeps --= processed
 
     def invalidate(file: AbstractFile, reason: String, change: Change) = {
       println("invalidate " + file + " because " + reason + " [" + change + "]")
       buf += file
       directDeps -= file
-      for (sym <- definitions(file))
+      for (sym <- definitions(file))     // fixes #2557
         newChangesOf(sym) = List(change)
       break
     }
@@ -160,7 +190,7 @@ class RefinedBuildManager(val settings: Settings) extends Changes with BuildMana
     for ((oldSym, changes) <- changesOf; change <- changes) {
       def checkParents(cls: Symbol, file: AbstractFile) {
         val parentChange = cls.info.parents.exists(_.typeSymbol.fullNameString == oldSym.fullNameString)
-//          println("checkParents " + cls + " oldSym: " + oldSym + " parentChange: " + parentChange + " " + cls.info.parents)
+          // println("checkParents " + cls + " oldSym: " + oldSym + " parentChange: " + parentChange + " " + cls.info.parents)
         change match {
           case Changed(Class(_)) if parentChange =>
             invalidate(file, "parents have changed", change)
@@ -192,7 +222,7 @@ class RefinedBuildManager(val settings: Settings) extends Changes with BuildMana
       }
 
       def checkReferences(file: AbstractFile) {
-//        println(file + ":" + references(file))
+        // println(file + ":" + references(file))
         val refs = references(file)
         if (refs.isEmpty)
           invalidate(file, "it is a direct dependency and we don't yet have finer-grained dependency information", change)
-- 
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