Merge branch '1.3.x'

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/SilentExitExceptionHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,11 +17,13 @@
 package org.springframework.boot.devtools.restart;
 
 import java.lang.Thread.UncaughtExceptionHandler;
+import java.util.Arrays;
 
 /**
  * {@link UncaughtExceptionHandler} decorator that allows a thread to exit silently.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 class SilentExitExceptionHandler implements UncaughtExceptionHandler {
 
@@ -34,6 +36,9 @@ class SilentExitExceptionHandler implements UncaughtExceptionHandler {
 	@Override
 	public void uncaughtException(Thread thread, Throwable exception) {
 		if (exception instanceof SilentExitException) {
+			if (jvmWillExit(thread)) {
+				preventNonZeroExitCode();
+			}
 			return;
 		}
 		if (this.delegate != null) {
@@ -53,6 +58,41 @@ class SilentExitExceptionHandler implements UncaughtExceptionHandler {
 		throw new SilentExitException();
 	}
 
+	private boolean jvmWillExit(Thread exceptionThread) {
+		for (Thread thread : getAllThreads()) {
+			if (thread != exceptionThread && thread.isAlive() && !thread.isDaemon()) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+	protected void preventNonZeroExitCode() {
+		System.exit(0);
+	}
+
+	protected Thread[] getAllThreads() {
+		ThreadGroup rootThreadGroup = getRootThreadGroup();
+		int size = 32;
+		int threadCount;
+		Thread[] threads;
+		do {
+			size *= 2;
+			threads = new Thread[size];
+			threadCount = rootThreadGroup.enumerate(threads);
+		}
+		while (threadCount == threads.length);
+		return Arrays.copyOf(threads, threadCount);
+	}
+
+	private ThreadGroup getRootThreadGroup() {
+		ThreadGroup candidate = Thread.currentThread().getThreadGroup();
+		while (candidate.getParent() != null) {
+			candidate = candidate.getParent();
+		}
+		return candidate;
+	}
+
 	private static class SilentExitException extends RuntimeException {
 
 	}

spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/SilentExitExceptionHandlerTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.devtools.restart;
 
+import java.util.concurrent.CountDownLatch;
+
 import org.junit.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -55,6 +57,24 @@ public class SilentExitExceptionHandlerTests {
 		assertThat(testThread.getThrown().getMessage()).isEqualTo("Expected");
 	}
 
+	@Test
+	public void preventsNonZeroExitCodeWhenAllOtherThreadsAreDaemonThreads() {
+		try {
+			SilentExitExceptionHandler.exitCurrentThread();
+		}
+		catch (Exception ex) {
+			TestSilentExitExceptionHandler silentExitExceptionHandler = new TestSilentExitExceptionHandler();
+			silentExitExceptionHandler.uncaughtException(Thread.currentThread(), ex);
+			try {
+				assertThat(silentExitExceptionHandler.nonZeroExitCodePrevented).isTrue();
+			}
+			finally {
+				silentExitExceptionHandler.cleanUp();
+			}
+		}
+
+	}
+
 	private static abstract class TestThread extends Thread {
 
 		private Throwable thrown;
@@ -79,4 +99,58 @@ public class SilentExitExceptionHandlerTests {
 
 	}
 
+	private static class TestSilentExitExceptionHandler
+			extends SilentExitExceptionHandler {
+
+		private boolean nonZeroExitCodePrevented;
+
+		private final Object monitor = new Object();
+
+		TestSilentExitExceptionHandler() {
+			super(null);
+		}
+
+		@Override
+		protected void preventNonZeroExitCode() {
+			this.nonZeroExitCodePrevented = true;
+		}
+
+		@Override
+		protected Thread[] getAllThreads() {
+			final CountDownLatch threadRunning = new CountDownLatch(1);
+			Thread daemonThread = new Thread(new Runnable() {
+
+				@Override
+				public void run() {
+					synchronized (TestSilentExitExceptionHandler.this.monitor) {
+						threadRunning.countDown();
+						try {
+							TestSilentExitExceptionHandler.this.monitor.wait();
+						}
+						catch (InterruptedException ex) {
+							Thread.currentThread().interrupt();
+						}
+					}
+				}
+
+			});
+			daemonThread.setDaemon(true);
+			daemonThread.start();
+			try {
+				threadRunning.await();
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+			return new Thread[] { Thread.currentThread(), daemonThread };
+		}
+
+		private void cleanUp() {
+			synchronized (this.monitor) {
+				this.monitor.notifyAll();
+			}
+		}
+
+	}
+
 }