Create possibility to skip flat classpath caching

There's added -YdisableFlatCpCaching option to ScalaSettings which
allows user to disable caching of flat representation of classpath
elements.

2 files changed, 10 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala b/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala
index 6d8c4880d5..dba3c60b0f 100644
--- a/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala
+++ b/src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala
@@ -11,7 +11,7 @@ import scala.tools.nsc.Settings
 import FileUtils._
 
 /**
- * A trait providing a cache for classpath entries obtained from zip and jar files.
+ * A trait providing an optional cache for classpath entries obtained from zip and jar files.
  * It's possible to create such a cache assuming that entries in such files won't change (at
  * least will be the same each time we'll load classpath during the lifetime of JVM process)
  * - unlike class and source files in directories, which can be modified and recompiled.
@@ -22,7 +22,14 @@ trait ZipAndJarFileLookupFactory {
 
   private val cache = collection.mutable.Map.empty[AbstractFile, FlatClassPath]
 
-  def create(zipFile: AbstractFile, settings: Settings): FlatClassPath = cache.synchronized {
+  def create(zipFile: AbstractFile, settings: Settings): FlatClassPath = {
+    if (settings.YdisableFlatCpCaching) createForZipFile(zipFile)
+    else createUsingCache(zipFile, settings)
+  }
+
+  protected def createForZipFile(zipFile: AbstractFile): FlatClassPath
+
+  private def createUsingCache(zipFile: AbstractFile, settings: Settings): FlatClassPath = cache.synchronized {
     def newClassPathInstance = {
       if (settings.verbose || settings.Ylogcp)
         println(s"$zipFile is not yet in the classpath cache")
@@ -30,8 +37,6 @@ trait ZipAndJarFileLookupFactory {
     }
     cache.getOrElseUpdate(zipFile, newClassPathInstance)
   }
-
-  protected def createForZipFile(zipFile: AbstractFile): FlatClassPath
 }
 
 /**
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index e259c543cf..18e639b81c 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -203,6 +203,7 @@ trait ScalaSettings extends AbsScalaSettings
   val etaExpandKeepsStar = BooleanSetting ("-Yeta-expand-keeps-star", "Eta-expand varargs methods to T* rather than Seq[T].  This is a temporary option to ease transition.").withDeprecationMessage(removalIn212)
   val inferByName     = BooleanSetting    ("-Yinfer-by-name", "Allow inference of by-name types. This is a temporary option to ease transition. See SI-7899.").withDeprecationMessage(removalIn212)
   val YclasspathImpl  = ChoiceSetting     ("-YclasspathImpl", "implementation", "Choose classpath scanning method.", List(ClassPathRepresentationType.Recursive, ClassPathRepresentationType.Flat), ClassPathRepresentationType.Recursive)
+  val YdisableFlatCpCaching  = BooleanSetting    ("-YdisableFlatCpCaching", "Do not cache flat classpath representation of classpath elements from jars across compiler instances.")
 
   val YvirtClasses    = false // too embryonic to even expose as a -Y //BooleanSetting    ("-Yvirtual-classes", "Support virtual classes")
   val YdisableUnreachablePrevention = BooleanSetting("-Ydisable-unreachable-prevention", "Disable the prevention of unreachable blocks in code generation.")