Add RestartScope and Restart attributes

Add a "restart" Spring `Scope` that remains between application
restarts. Allows beans such as the livereload server to remain active
during restarts and not disconnect clients.

See gh-3085

spring-boot-developer-tools/src/main/java/org/springframework/boot/developertools/restart/RestartScope.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.developertools.restart;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.context.annotation.Scope;
+
+/**
+ * Restart {@code @Scope} Annotation used to indicate that a bean shoul remain beteen
+ * restarts.
+ *
+ * @author Phillip Webb
+ * @since 1.3.0
+ * @see RestartScopeInitializer
+ */
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Scope("restart")
+public @interface RestartScope {
+
+}

spring-boot-developer-tools/src/main/java/org/springframework/boot/developertools/restart/RestartScopeInitializer.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2012-2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.developertools.restart;
+
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.beans.factory.config.Scope;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+
+/**
+ * Support for a 'restart' {@link Scope} that allows beans to remain between restarts.
+ *
+ * @author Phillip Webb
+ * @since 1.3.0
+ */
+public class RestartScopeInitializer implements
+		ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+	@Override
+	public void initialize(ConfigurableApplicationContext applicationContext) {
+		applicationContext.getBeanFactory().registerScope("restart", new RestartScope());
+	}
+
+	/**
+	 * {@link Scope} that stores beans as {@link Restarter} attributes.
+	 */
+	private static class RestartScope implements Scope {
+
+		@Override
+		public Object get(String name, ObjectFactory<?> objectFactory) {
+			return Restarter.getInstance().getOrAddAttribute(name, objectFactory);
+		}
+
+		@Override
+		public Object remove(String name) {
+			return Restarter.getInstance().removeAttribute(name);
+		}
+
+		@Override
+		public void registerDestructionCallback(String name, Runnable callback) {
+		}
+
+		@Override
+		public Object resolveContextualObject(String key) {
+			return null;
+		}
+
+		@Override
+		public String getConversationId() {
+			return null;
+		}
+	}
+
+}

spring-boot-developer-tools/src/main/java/org/springframework/boot/developertools/restart/Restarter.java

@@ -22,6 +22,7 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.net.URL;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.Iterator;
 import java.util.LinkedList;
@@ -38,6 +39,7 @@ import java.util.concurrent.locks.ReentrantLock;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.CachedIntrospectionResults;
+import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.developertools.restart.classloader.RestartClassLoader;
 import org.springframework.boot.logging.DeferredLog;
@@ -89,6 +91,8 @@ public class Restarter {
 
 	private final UncaughtExceptionHandler exceptionHandler;
 
+	private final Map<String, Object> attributes = new HashMap<String, Object>();
+
 	private final BlockingDeque<LeakSafeThread> leakSafeThreads = new LinkedBlockingDeque<LeakSafeThread>();
 
 	private boolean finished = false;
@@ -344,6 +348,22 @@ public class Restarter {
 		}
 	}
 
+	public Object getOrAddAttribute(final String name,
+			final ObjectFactory<?> objectFactory) {
+		synchronized (this.attributes) {
+			if (!this.attributes.containsKey(name)) {
+				this.attributes.put(name, objectFactory.getObject());
+			}
+			return this.attributes.get(name);
+		}
+	}
+
+	public Object removeAttribute(String name) {
+		synchronized (this.attributes) {
+			return this.attributes.remove(name);
+		}
+	}
+
 	/**
 	 * Return the initial set of URLs as configured by the {@link RestartInitializer}.
 	 * @return the initial URLs or {@code null}

spring-boot-developer-tools/src/main/resources/META-INF/spring.factories

@@ -1,3 +1,7 @@
+# Application Initializers
+org.springframework.context.ApplicationContextInitializer=\
+org.springframework.boot.developertools.restart.RestartScopeInitializer
+
 # Application Listeners
 org.springframework.context.ApplicationListener=\
 org.springframework.boot.developertools.restart.RestartApplicationListener

spring-boot-developer-tools/src/test/java/org/springframework/boot/developertools/restart/MockRestarter.java

@@ -24,8 +24,13 @@ import java.util.concurrent.ThreadFactory;
 import org.junit.rules.TestRule;
 import org.junit.runner.Description;
 import org.junit.runners.model.Statement;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+import org.springframework.beans.factory.ObjectFactory;
 
 import static org.mockito.BDDMockito.given;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyString;
 import static org.mockito.Mockito.mock;
 
 /**
@@ -53,9 +58,26 @@ public class MockRestarter implements TestRule {
 		};
 	}
 
+	@SuppressWarnings("rawtypes")
 	private void setup() {
 		Restarter.setInstance(this.mock);
 		given(this.mock.getInitialUrls()).willReturn(new URL[] {});
+		given(this.mock.getOrAddAttribute(anyString(), (ObjectFactory) any()))
+				.willAnswer(new Answer<Object>() {
+
+					@Override
+					public Object answer(InvocationOnMock invocation) throws Throwable {
+						String name = (String) invocation.getArguments()[0];
+						ObjectFactory factory = (ObjectFactory) invocation.getArguments()[1];
+						Object attribute = MockRestarter.this.attributes.get(name);
+						if (attribute == null) {
+							attribute = factory.getObject();
+							MockRestarter.this.attributes.put(name, attribute);
+						}
+						return attribute;
+					}
+
+				});
 		given(this.mock.getThreadFactory()).willReturn(new ThreadFactory() {
 
 			@Override

spring-boot-developer-tools/src/test/java/org/springframework/boot/developertools/restart/RestartScopeInitializerTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2012-2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.developertools.restart;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.Test;
+import org.springframework.boot.SpringApplication;
+import org.springframework.context.ApplicationListener;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.event.ContextRefreshedEvent;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link RestartScopeInitializer}.
+ *
+ * @author Phillip Webb
+ */
+public class RestartScopeInitializerTests {
+
+	private static AtomicInteger createCount;
+
+	private static AtomicInteger refreshCount;
+
+	@Test
+	public void restartScope() throws Exception {
+		createCount = new AtomicInteger();
+		refreshCount = new AtomicInteger();
+		ConfigurableApplicationContext context = runApplication();
+		context.close();
+		context = runApplication();
+		context.close();
+		assertThat(createCount.get(), equalTo(1));
+		assertThat(refreshCount.get(), equalTo(2));
+	}
+
+	private ConfigurableApplicationContext runApplication() {
+		SpringApplication application = new SpringApplication(Config.class);
+		application.setWebEnvironment(false);
+		return application.run();
+	}
+
+	@Configuration
+	public static class Config {
+
+		@Bean
+		@RestartScope
+		public ScopeTestBean scopeTestBean() {
+			return new ScopeTestBean();
+		}
+
+	}
+
+	public static class ScopeTestBean implements
+			ApplicationListener<ContextRefreshedEvent> {
+
+		public ScopeTestBean() {
+			createCount.incrementAndGet();
+		}
+
+		@Override
+		public void onApplicationEvent(ContextRefreshedEvent event) {
+			refreshCount.incrementAndGet();
+		}
+
+	}
+
+}

spring-boot-developer-tools/src/test/java/org/springframework/boot/developertools/restart/RestarterTests.java

@@ -25,6 +25,8 @@ import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.boot.test.OutputCapture;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.scheduling.annotation.EnableScheduling;
@@ -38,6 +40,7 @@ import static org.junit.Assert.assertThat;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyZeroInteractions;
 
 /**
  * Tests for {@link Restarter}.
@@ -88,6 +91,30 @@ public class RestarterTests {
 		assertThat(StringUtils.countOccurrencesOf(output, "Tick 1"), greaterThan(2));
 	}
 
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void getOrAddAttributeWithNewAttribute() throws Exception {
+		ObjectFactory objectFactory = mock(ObjectFactory.class);
+		given(objectFactory.getObject()).willReturn("abc");
+		Object attribute = Restarter.getInstance().getOrAddAttribute("x", objectFactory);
+		assertThat(attribute, equalTo((Object) "abc"));
+	}
+
+	@Test
+	@SuppressWarnings("rawtypes")
+	public void getOrAddAttributeWithExistingAttribute() throws Exception {
+		Restarter.getInstance().getOrAddAttribute("x", new ObjectFactory<String>() {
+			@Override
+			public String getObject() throws BeansException {
+				return "abc";
+			}
+		});
+		ObjectFactory objectFactory = mock(ObjectFactory.class);
+		Object attribute = Restarter.getInstance().getOrAddAttribute("x", objectFactory);
+		assertThat(attribute, equalTo((Object) "abc"));
+		verifyZeroInteractions(objectFactory);
+	}
+
 	@Test
 	public void getThreadFactory() throws Exception {
 		final ClassLoader parentLoader = Thread.currentThread().getContextClassLoader();