= util add Throwables helper to help fatal checking of Throwable for Java,alias with Scala's Nonfatal pattern matching. (#24661)

akka-actor-tests/src/test/java/akka/japi/ThrowablesTest.java

@@ -0,0 +1,26 @@
+/**
+ * Copyright (C) 2014-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+package akka.japi;
+
+import org.junit.Assert;
+import org.junit.Test;
+import scala.util.control.ControlThrowable;
+
+public class ThrowablesTest {
+    @Test
+    public void testIsNonFatal(){
+        Assert.assertTrue(Throwables.isNonFatal(new IllegalArgumentException("isNonFatal")));
+    }
+
+    private static class ControlThrowableImpl extends Throwable implements ControlThrowable{}
+
+    @Test
+    public void testIsFatal(){
+        Assert.assertTrue(Throwables.isFatal(new StackOverflowError("fatal")));
+        Assert.assertTrue(Throwables.isFatal(new ThreadDeath()));
+        Assert.assertTrue(Throwables.isFatal(new InterruptedException("fatal")));
+        Assert.assertTrue(Throwables.isFatal(new LinkageError("fatal")));
+        Assert.assertTrue(Throwables.isFatal(new ControlThrowableImpl()));
+    }
+}

akka-actor/src/main/scala/akka/japi/Throwables.scala

@@ -0,0 +1,41 @@
+/**
+ * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+package akka.japi
+
+import scala.util.control.NonFatal
+
+/**
+ * Helper class for determining whether a `Throwable` is fatal or not.
+ * User should only catch the non-fatal one,and keep rethrow the fatal one.
+ *
+ * Fatal errors are errors like `VirtualMachineError`
+ * (for example, `OutOfMemoryError` and `StackOverflowError`, subclasses of `VirtualMachineError`), `ThreadDeath`,
+ * `LinkageError`, `InterruptedException`, `ControlThrowable`.
+ *
+ * Note. this helper keep the same semantic with `NonFatal` in Scala.
+ * For example, all harmless `Throwable`s can be caught by:
+ * {{{
+ *   try {
+ *     // dangerous stuff
+ *   } catch(Throwable e) {
+ *     if (Throwables.isNonFatal(e)){
+ *       log.error(e, "Something not that bad.");
+ *     } else {
+ *       throw e;
+ *     }
+ * }}}
+ */
+object Throwables {
+  /**
+   * Returns true if the provided `Throwable` is to be considered non-fatal,
+   * or false if it is to be considered fatal
+   */
+  def isNonFatal(throwable: Throwable): Boolean = NonFatal(throwable)
+
+  /**
+   * Returns true if the provided `Throwable` is to be considered fatal,
+   * or false if it is to be considered non-fatal
+   */
+  def isFatal(throwable: Throwable): Boolean = !isNonFatal(throwable)
+}