git: rebase and squash from parent branch

Signed-off-by: Iltotore <rafbodaha@gmail.com>

Author: Iltotore

library/src/dotty/runtime/RuntimeHandleReceptacle.scala

@@ -0,0 +1,43 @@
+package dotty.runtime
+
+import java.lang.invoke.MethodHandles
+
+import scala.reflect.ClassTag
+
+/**
+ * sun.misc.Unsafe and java.lang.invoke.VarHandle receptacle.
+ * It allows Java 8-9+ compatibility without using 9-deprecated Unsafe class.
+ */
+
+trait RuntimeHandleReceptacle {
+
+
+  def get[U <: AnyRef : ClassTag](ref: Object, clazz: Class[_], varName: String)(implicit tag: ClassTag[U]): U
+
+  def getLongVolatile(ref: Object, clazz: Class[_], varName: String): Long
+
+  def put[U <: AnyRef : ClassTag](ref: Object, clazz: Class[_], varName: String, value: U)(implicit tag: ClassTag[U]): Unit
+
+  def compareAndSwapLong(ref: Object, clazz: Class[_], varName: String, expected: Long, value: Long): Boolean
+}
+
+object RuntimeHandleReceptacle {
+
+  private val lookup = MethodHandles.lookup()
+  private val reference: RuntimeHandleReceptacle = {
+    try {
+      //Java 9+
+      Class.forName("java.lang.invoke.VarHandle")
+      new VarHandlerReceptacle(lookup)
+    } catch {
+      //Java 8
+      case e: ClassNotFoundException =>
+        val unsafeClass = Class.forName("sun.misc.Unsafe")
+        var unsafeReference: sun.misc.Unsafe = null
+        for (field <- unsafeClass.getDeclaredFields) if (field.getType.isAssignableFrom(unsafeClass)) unsafeReference = field.get(null).asInstanceOf[sun.misc.Unsafe]
+        new UnsafeReceptacle(unsafeReference)
+    }
+  }
+
+  def apply(): RuntimeHandleReceptacle = reference
+}

library/src/dotty/runtime/UnsafeReceptacle.scala

@@ -0,0 +1,20 @@
+package dotty.runtime
+
+import sun.misc.Unsafe
+
+import scala.reflect.ClassTag
+
+
+class UnsafeReceptacle(runtimeReference: Unsafe) extends RuntimeHandleReceptacle {
+
+  override def get[U <: AnyRef : ClassTag](ref: Object, clazz: Class[_], varName: String)(implicit tag: ClassTag[U]): U = runtimeReference.getObject(ref, getOffset(clazz, varName)).asInstanceOf[U]
+  override def getLongVolatile(ref: Object, clazz: Class[_], varName: String): Long = runtimeReference.getLongVolatile(ref, getOffset(clazz, varName))
+
+  override def put[U : ClassTag](ref: Object, clazz: Class[_], varName: String, value: U)(implicit tag: ClassTag[U]): Unit = runtimeReference.putObject(ref, getOffset(clazz, varName), value)
+
+  override def compareAndSwapLong(ref: Object, clazz: Class[_], varName: String, expected: Long, value: Long): Boolean = runtimeReference.compareAndSwapLong(ref, getOffset(clazz, varName), expected, value)
+
+  private def getOffset(clazz: Class[_], varName: String): Long = runtimeReference.objectFieldOffset(clazz.getDeclaredField(varName))
+
+
+}

library/src/dotty/runtime/VarHandlerReceptacle.scala

@@ -0,0 +1,16 @@
+package dotty.runtime
+
+import java.lang.invoke.MethodHandles
+
+import scala.reflect.ClassTag
+
+class VarHandlerReceptacle(lookup: MethodHandles.Lookup) extends RuntimeHandleReceptacle {
+
+  override def get[U <: AnyRef : ClassTag](ref: Object, clazz: Class[_], varName: String)(implicit tag: ClassTag[U]): U  = lookup.findVarHandle(clazz, varName, tag.runtimeClass).get(ref.asInstanceOf[Object]).asInstanceOf[U]
+
+  override def put[U <: AnyRef : ClassTag](ref: Object, clazz: Class[_], varName: String, value: U)(implicit tag: ClassTag[U]): Unit = lookup.findVarHandle(clazz, varName, tag.runtimeClass).set(ref.asInstanceOf[Object], value.asInstanceOf[Object]).asInstanceOf[U]
+
+  override def compareAndSwapLong(ref: Object, clazz: Class[_], varName: String, expected: Long, value: Long): Boolean =  lookup.findVarHandle(clazz, varName, classOf[Long]).compareAndSet(ref, Long.box(expected), Long.box(value))
+
+  override def getLongVolatile(ref: Object, clazz: Class[_], varName: String): Long = ???
+}