Add an "always" cache policy for classloaders

Author: retronym

src/compiler/scala/tools/nsc/PipelineMain.scala

@@ -296,8 +296,8 @@ class PipelineMainClass(label: String, parallelism: Int, strategy: BuildStrategy
       dependency.outlineDone.future
 
 
-    command.settings.YcacheMacroClassLoader.value = "last-modified"
-    command.settings.YcachePluginClassLoader.value = "last-modified"
+    command.settings.YcacheMacroClassLoader.value = "always"
+    command.settings.YcachePluginClassLoader.value = "always"
 
     val groups: List[Group] = {
       val isScalaLibrary = files.exists(_.endsWith("Predef.scala"))

src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala

@@ -39,7 +39,7 @@ sealed trait ZipAndJarFileLookupFactory {
       closeableRegistry.registerClosable(result)
       result
     } else {
-      cache.getOrCreate(List(zipFile.file.toPath), () => createForZipFile(zipFile, settings.releaseValue), closeableRegistry)
+      cache.getOrCreate(List(zipFile.file.toPath), () => createForZipFile(zipFile, settings.releaseValue), closeableRegistry, checkStamps = true)
     }
   }
 
@@ -213,7 +213,7 @@ final class FileBasedCache[T] {
   }
   private val cache = collection.mutable.Map.empty[Seq[Path], Entry]
 
-  def getOrCreate(paths: Seq[Path], create: () => T, closeableRegistry: CloseableRegistry): T = cache.synchronized {
+  def getOrCreate(paths: Seq[Path], create: () => T, closeableRegistry: CloseableRegistry, checkStamps: Boolean): T = cache.synchronized {
     val stamps = paths.map { path =>
       val attrs = Files.readAttributes(path, classOf[BasicFileAttributes])
       val lastModified = attrs.lastModifiedTime()
@@ -224,7 +224,7 @@ final class FileBasedCache[T] {
 
     cache.get(paths) match {
       case Some(e@Entry(cachedStamps, cached)) =>
-        if (cachedStamps == stamps) {
+        if (!checkStamps || cachedStamps == stamps) {
           // Cache hit
           e.referenceCount.incrementAndGet()
           closeableRegistry.registerClosable(e.referenceCountDecrementer)

src/compiler/scala/tools/nsc/plugins/Plugins.scala

@@ -69,7 +69,8 @@ trait Plugins { global: Global =>
     * @return
     */
   protected def findPluginClassLoader(classpath: Seq[Path]): ClassLoader = {
-    val disableCache = settings.YcachePluginClassLoader.value == settings.CachePolicy.None.name
+    val policy = settings.YcachePluginClassLoader.value
+    val disableCache = policy == settings.CachePolicy.None.name
     def newLoader = () => {
       val compilerLoader = classOf[Plugin].getClassLoader
       val urls = classpath map (_.toURL)
@@ -88,7 +89,7 @@ trait Plugins { global: Global =>
       val loader = newLoader()
       closeableRegistry.registerClosable(loader)
       loader
-    } else pluginClassLoadersCache.getOrCreate(classpath.map(_.jfile.toPath()), newLoader, closeableRegistry)
+    } else pluginClassLoadersCache.getOrCreate(classpath.map(_.jfile.toPath()), newLoader, closeableRegistry, policy == settings.CachePolicy.LastModified.name)
   }
 
   protected lazy val roughPluginsList: List[Plugin] = loadRoughPluginsList()
@@ -181,7 +182,8 @@ trait Plugins { global: Global =>
       ScalaClassLoader.fromURLs(classpath, getClass.getClassLoader)
     }
 
-    val disableCache = settings.YcacheMacroClassLoader.value == settings.CachePolicy.None.name
+    val policy = settings.YcacheMacroClassLoader.value
+    val disableCache = policy == settings.CachePolicy.None.name
     if (disableCache) newLoader()
     else {
       import scala.tools.nsc.io.Jar
@@ -196,7 +198,7 @@ trait Plugins { global: Global =>
         perRunCaches.recordClassloader(newLoader())
       } else {
         val locations = urlsAndFiles.map(t => Path(t._2.file))
-        Macros.macroClassLoadersCache.getOrCreate(locations.map(_.jfile.toPath()), newLoader, closeableRegistry)
+        Macros.macroClassLoadersCache.getOrCreate(locations.map(_.jfile.toPath()), newLoader, closeableRegistry, checkStamps = policy == settings.CachePolicy.LastModified.name)
       }
     }
   }

src/compiler/scala/tools/nsc/settings/ScalaSettings.scala

@@ -260,9 +260,10 @@ trait ScalaSettings extends AbsScalaSettings
     def setting(style: String, styleLong: String) = ChoiceSetting(s"-Ycache-$style-class-loader", "policy", s"Policy for caching class loaders for $styleLong that are dynamically loaded.", values.map(_.name), None.name, values.map(_.help))
     object None extends CachePolicy("none", "Don't cache class loader")
     object LastModified extends CachePolicy("last-modified", "Cache class loader, using file last-modified time to invalidate")
+    object Always extends CachePolicy("always", "Cache class loader with no invalidation")
     // TODO Jorge to add new policy. Think about whether there is a benefit to the user on offering this as a separate policy or unifying with the previous one.
     // object ZipMetadata extends CachePolicy("zip-metadata", "Cache classloade, using file last-modified time, then ZIP file metadata to invalidate")
-    def values: List[CachePolicy] = List(None, LastModified)
+    def values: List[CachePolicy] = List(None, LastModified, Always)
   }
 
   object optChoices extends MultiChoiceEnumeration {