Merge pull request #14261 from dwijnand/trim-runner

Trim RichClassLoader and ScalaClassLoader

Author: nicolasstucki

compiler/src/dotty/tools/runner/ScalaClassLoader.scala

@@ -1,103 +1,47 @@
 package dotty.tools
 package runner
 
-import java.lang.invoke.{MethodHandles, MethodType}
-
 import scala.language.implicitConversions
-import java.lang.{ClassLoader => JClassLoader}
+
+import java.lang.ClassLoader
+import java.lang.invoke.{MethodHandles, MethodType}
 import java.lang.reflect.Modifier
-import java.net.{URLClassLoader => JURLClassLoader}
-import java.net.URL
+import java.net.{ URL, URLClassLoader }
+import java.lang.reflect.{ InvocationTargetException, UndeclaredThrowableException }
 
+import scala.annotation.internal.sharable
 import scala.annotation.tailrec
 import scala.util.control.Exception.catching
-import scala.reflect.{ClassTag, classTag}
-import java.lang.reflect.InvocationTargetException
-import java.lang.reflect.UndeclaredThrowableException
-import dotty.tools.repl.AbstractFileClassLoader
-import dotty.tools.io.AbstractFile
-import dotty.tools.io.Streamable
-import scala.annotation.internal.sharable
 
-trait HasClassPath {
-  def classPathURLs: Seq[URL]
-}
-
-final class RichClassLoader(private val self: JClassLoader) extends AnyVal {
+final class RichClassLoader(private val self: ClassLoader) extends AnyVal {
   /** Executing an action with this classloader as context classloader */
-  def asContext[T](action: => T): T = {
+  private def asContext[T](action: => T): T = {
     val saved = Thread.currentThread.getContextClassLoader
     try { ScalaClassLoader.setContext(self) ; action }
     finally ScalaClassLoader.setContext(saved)
   }
 
   /** Load and link a class with this classloader */
   def tryToLoadClass[T <: AnyRef](path: String): Option[Class[T]] = tryClass(path, initialize = false)
+
   /** Load, link and initialize a class with this classloader */
   def tryToInitializeClass[T <: AnyRef](path: String): Option[Class[T]] = tryClass(path, initialize = true)
 
   private def tryClass[T <: AnyRef](path: String, initialize: Boolean): Option[Class[T]] =
     catching(classOf[ClassNotFoundException], classOf[SecurityException]) opt
       Class.forName(path, initialize, self).asInstanceOf[Class[T]]
 
-  /** Create an instance of a class with this classloader */
-  def create(path: String): AnyRef =
-    tryToInitializeClass[AnyRef](path).map(_.getConstructor().newInstance()).orNull
-
-  /** Create an instance with ctor args, or invoke errorFn before throwing. */
-  def create[T <: AnyRef : ClassTag](path: String, errorFn: String => Unit)(args: AnyRef*): T = {
-    def fail(msg: String) = error(msg, new IllegalArgumentException(msg))
-    def error(msg: String, e: Throwable) = { errorFn(msg) ; throw e }
-    try {
-      val clazz = Class.forName(path, /*initialize =*/ true, /*loader =*/ self)
-      if (classTag[T].runtimeClass isAssignableFrom clazz) {
-        val ctor = {
-          val maybes = clazz.getConstructors filter (c => c.getParameterCount == args.size &&
-            (c.getParameterTypes zip args).forall { case (k, a) => k isAssignableFrom a.getClass })
-          if (maybes.size == 1) maybes.head
-          else fail(s"Constructor must accept arg list (${args map (_.getClass.getName) mkString ", "}): ${path}")
-        }
-        (ctor.newInstance(args: _*)).asInstanceOf[T]
-      } else {
-        errorFn(s"""Loader for ${classTag[T]}:   [${show(classTag[T].runtimeClass.getClassLoader)}]
-                    |Loader for ${clazz.getName}: [${show(clazz.getClassLoader)}]""".stripMargin)
-        fail(s"Not a ${classTag[T]}: ${path}")
-      }
-    } catch {
-      case e: ClassNotFoundException =>
-        error(s"Class not found: ${path}", e)
-      case e @ (_: LinkageError | _: ReflectiveOperationException) =>
-        error(s"Unable to create instance: ${path}: ${e.toString}", e)
-    }
-  }
-
-  /** The actual bytes for a class file, or an empty array if it can't be found. */
-  def classBytes(className: String): Array[Byte] = classAsStream(className) match {
-    case null   => Array()
-    case stream => Streamable.bytes(stream)
-  }
-
-  /** An InputStream representing the given class name, or null if not found. */
-  def classAsStream(className: String) = self.getResourceAsStream {
-    if (className endsWith ".class") className
-    else s"${className.replace('.', '/')}.class"  // classNameToPath
-  }
-
   /** Run the main method of a class to be loaded by this classloader */
   def run(objectName: String, arguments: Seq[String]): Unit = {
-    val clsToRun = tryToInitializeClass(objectName) getOrElse (
-      throw new ClassNotFoundException(objectName)
-    )
+    val clsToRun = tryToInitializeClass(objectName).getOrElse(throw new ClassNotFoundException(objectName))
     val method = clsToRun.getMethod("main", classOf[Array[String]])
-    if (!Modifier.isStatic(method.getModifiers))
-      throw new NoSuchMethodException(objectName + ".main is not static")
-
-    try asContext(method.invoke(null, Array(arguments.toArray: AnyRef): _*)) // !!! : AnyRef shouldn't be necessary
+    if !Modifier.isStatic(method.getModifiers) then
+      throw new NoSuchMethodException(s"$objectName.main is not static")
+    try asContext(method.invoke(null, Array(arguments.toArray: AnyRef): _*))
     catch unwrapHandler({ case ex => throw ex })
   }
 
-  @tailrec
-  def unwrapThrowable(x: Throwable): Throwable = x match {
+  @tailrec private def unwrapThrowable(x: Throwable): Throwable = x match {
     case  _: InvocationTargetException |      // thrown by reflectively invoked method or constructor
           _: ExceptionInInitializerError |    // thrown when running a static initializer (e.g. a scala module constructor)
           _: UndeclaredThrowableException |   // invocation on a proxy instance if its invocation handler's `invoke` throws an exception
@@ -107,136 +51,27 @@ final class RichClassLoader(private val self: JClassLoader) extends AnyVal {
               unwrapThrowable(x.getCause)
     case _ => x
   }
+
   // Transforms an exception handler into one which will only receive the unwrapped
   // exceptions (for the values of wrap covered in unwrapThrowable.)
-  def unwrapHandler[T](pf: PartialFunction[Throwable, T]): PartialFunction[Throwable, T] =
+  private def unwrapHandler[T](pf: PartialFunction[Throwable, T]): PartialFunction[Throwable, T] =
     pf.compose({ case ex => unwrapThrowable(ex) })
-
-  def show(cl: ClassLoader): String = {
-    import scala.reflect.Selectable.reflectiveSelectable
-
-    @tailrec
-    def isAbstractFileClassLoader(clazz: Class[_]): Boolean = {
-      if (clazz == null) return false
-      if (clazz == classOf[AbstractFileClassLoader]) return true
-      isAbstractFileClassLoader(clazz.getSuperclass)
-    }
-    def inferClasspath(cl: ClassLoader): String = cl match {
-      case cl: java.net.URLClassLoader if cl.getURLs != null =>
-        (cl.getURLs mkString ",")
-      case cl if cl != null && isAbstractFileClassLoader(cl.getClass) =>
-        cl.asInstanceOf[{val root: AbstractFile}].root.canonicalPath
-      case null =>
-        val loadBootCp = (flavor: String) => scala.util.Properties.propOrNone(flavor + ".boot.class.path")
-        loadBootCp("sun") orElse loadBootCp("java") getOrElse "<unknown>"
-      case _ =>
-        "<unknown>"
-    }
-    cl match {
-      case null => s"primordial classloader with boot classpath [${inferClasspath(cl)}]"
-      case _    => s"$cl of type ${cl.getClass} with classpath [${inferClasspath(cl)}] and parent being ${show(cl.getParent)}"
-    }
-  }
 }
 
 object RichClassLoader {
   implicit def wrapClassLoader(loader: ClassLoader): RichClassLoader = new RichClassLoader(loader)
 }
 
-/** A wrapper around java.lang.ClassLoader to lower the annoyance
- *  of java reflection.
- */
-trait ScalaClassLoader extends JClassLoader {
-  private def wrap = new RichClassLoader(this)
-  /** Executing an action with this classloader as context classloader */
-  def asContext[T](action: => T): T = wrap.asContext(action)
-
-  /** Load and link a class with this classloader */
-  def tryToLoadClass[T <: AnyRef](path: String): Option[Class[T]] = wrap.tryToLoadClass[T](path)
-  /** Load, link and initialize a class with this classloader */
-  def tryToInitializeClass[T <: AnyRef](path: String): Option[Class[T]] = wrap.tryToInitializeClass(path)
-
-  /** Create an instance of a class with this classloader */
-  def create(path: String): AnyRef = wrap.create(path)
-
-  /** Create an instance with ctor args, or invoke errorFn before throwing. */
-  def create[T <: AnyRef : ClassTag](path: String, errorFn: String => Unit)(args: AnyRef*): T =
-    wrap.create[T](path, errorFn)(args: _*)
-
-  /** The actual bytes for a class file, or an empty array if it can't be found. */
-  def classBytes(className: String): Array[Byte] = wrap.classBytes(className)
-
-  /** An InputStream representing the given class name, or null if not found. */
-  def classAsStream(className: String) = wrap.classAsStream(className)
-
-  /** Run the main method of a class to be loaded by this classloader */
-  def run(objectName: String, arguments: Seq[String]): Unit = wrap.run(objectName, arguments)
-}
-
-
-/** Methods for obtaining various classloaders.
- *      appLoader: the application classloader.  (Also called the java system classloader.)
- *      extLoader: the extension classloader.
- *     bootLoader: the boot classloader.
- *  contextLoader: the context classloader.
- */
 object ScalaClassLoader {
-  /** Returns loaders which are already ScalaClassLoaders unaltered,
-   *  and translates java.net.URLClassLoaders into scala URLClassLoaders.
-   *  Otherwise creates a new wrapper.
-   */
-  implicit def apply(cl: JClassLoader): ScalaClassLoader = cl match {
-    case cl: ScalaClassLoader => cl
-    case cl: JURLClassLoader  => new URLClassLoader(cl.getURLs.toSeq, cl.getParent)
-    case _                    => new JClassLoader(cl) with ScalaClassLoader
-  }
-  def contextLoader = apply(Thread.currentThread.getContextClassLoader)
-  def appLoader     = apply(JClassLoader.getSystemClassLoader)
-  def setContext(cl: JClassLoader) = Thread.currentThread.setContextClassLoader(cl)
-
-  class URLClassLoader(urls: Seq[URL], parent: JClassLoader)
-      extends JURLClassLoader(urls.toArray, parent)
-         with ScalaClassLoader
-         with HasClassPath {
-    private[this] var classloaderURLs: Seq[URL] = urls
-    def classPathURLs: Seq[URL] = classloaderURLs
+  def setContext(cl: ClassLoader) = Thread.currentThread.setContextClassLoader(cl)
 
-    /** Override to widen to public */
-    override def addURL(url: URL) = {
-      classloaderURLs :+= url
-      super.addURL(url)
-    }
-    override def close(): Unit = {
-      super.close()
-      classloaderURLs = null
-    }
-  }
-
-  def fromURLs(urls: Seq[URL], parent: ClassLoader = null): URLClassLoader = {
-    new URLClassLoader(urls, if (parent == null) bootClassLoader else parent)
-  }
+  def fromURLsParallelCapable(urls: Seq[URL], parent: ClassLoader = null): URLClassLoader =
+    new URLClassLoader(urls.toArray, if parent == null then bootClassLoader else parent)
 
-  def fromURLsParallelCapable(urls: Seq[URL], parent: ClassLoader = null): JURLClassLoader = {
-    new JURLClassLoader(urls.toArray, if (parent == null) bootClassLoader else parent)
-  }
-
-  /** True if supplied class exists in supplied path */
-  def classExists(urls: Seq[URL], name: String): Boolean =
-    (fromURLs(urls) tryToLoadClass name).isDefined
-
-  /** Finding what jar a clazz or instance came from */
-  def originOfClass(x: Class[_]): Option[URL] =
-    Option(x.getProtectionDomain.getCodeSource) flatMap (x => Option(x.getLocation))
-
-  @sharable private[this] val bootClassLoader: ClassLoader = {
-    if (!scala.util.Properties.isJavaAtLeast("9")) null
-    else {
-      try {
+  @sharable private[this] val bootClassLoader: ClassLoader =
+    if scala.util.Properties.isJavaAtLeast("9") then
+      try
         MethodHandles.lookup().findStatic(classOf[ClassLoader], "getPlatformClassLoader", MethodType.methodType(classOf[ClassLoader])).invoke().asInstanceOf[ClassLoader]
-      } catch {
-        case _: Throwable =>
-          null
-      }
-    }
-  }
+      catch case _: Throwable => null
+    else null
 }