INT-3064 Change MessageHeaders.Id Strategy

Use `com.eaio.uuid` by default and document how to replace
the default strategy.

Provide JDK and a simple incrementing incrementing implementation.

Add code to detect multiple contexts in the same classloaded using
the same strategy.

Add code to detect multiple IdGenerator beans and emit a WARN
instead of DEBUG, which is the case for no beans.

build.gradle

@@ -27,6 +27,7 @@ allprojects {
 	repositories {
 		maven { url 'http://repo.springsource.org/libs-milestone' }
 		maven { url 'http://repo.springsource.org/plugins-release' }
+		mavenCentral()
 	}
 }
 
@@ -55,6 +56,7 @@ subprojects { subproject ->
 		junitVersion = '4.11'
 		log4jVersion = '1.2.12'
 		mockitoVersion = '1.9.5'
+		eaioUUIDVersion = '3.2'
 
 		springVersionDefault = '3.1.4.RELEASE'
 		springVersion = project.hasProperty('springVersion') ? getProperty('springVersion') : springVersionDefault
@@ -180,6 +182,7 @@ project('spring-integration-core') {
 		compile "org.springframework:spring-context:$springVersion"
 		compile "org.springframework:spring-tx:$springVersion"
 		compile "org.springframework.retry:spring-retry:$springRetryVersion"
+		compile "com.eaio.uuid:uuid:$eaioUUIDVersion"
 		compile("org.codehaus.jackson:jackson-mapper-asl:$jacksonVersion", optional)
 		compile("com.fasterxml.jackson.core:jackson-databind:$jackson2Version", optional)
 		testCompile "org.aspectj:aspectjweaver:$aspectjVersion"

spring-integration-core/src/main/java/org/springframework/integration/MessageHeaders.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -28,10 +28,13 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
+import java.util.concurrent.atomic.AtomicLong;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import com.eaio.uuid.UUIDGen;
+
 /**
  * The headers for a {@link Message}.<br>
  * IMPORTANT: MessageHeaders are immutable. Any mutating operation (e.g., put(..), putAll(..) etc.)
@@ -97,8 +100,9 @@ public final class MessageHeaders implements Map<String, Object>, Serializable {
 
 	public MessageHeaders(Map<String, Object> headers) {
 		this.headers = (headers != null) ? new HashMap<String, Object>(headers) : new HashMap<String, Object>();
-		if (MessageHeaders.idGenerator == null){
-			this.headers.put(ID, UUID.randomUUID());
+		if (MessageHeaders.idGenerator == null) {
+			UUID uuid = new UUID(UUIDGen.newTime(), UUIDGen.getClockSeqAndNode());
+			this.headers.put(ID, uuid);
 		}
 		else {
 			this.headers.put(ID, MessageHeaders.idGenerator.generateId());
@@ -271,4 +275,31 @@ public final class MessageHeaders implements Map<String, Object>, Serializable {
 	public static interface IdGenerator {
 		UUID generateId();
 	}
+
+	public static class JdkIdGenerator implements IdGenerator {
+
+		@Override
+		public UUID generateId() {
+			return UUID.randomUUID();
+		}
+
+	}
+
+	public static class SimpleIncrementingIdGenerator implements IdGenerator {
+
+		private final AtomicLong topBits = new AtomicLong();
+
+		private final AtomicLong bottomBits = new AtomicLong();
+
+		@Override
+		public UUID generateId() {
+			long bottomBits = this.bottomBits.incrementAndGet();
+			if (bottomBits == 0) {
+				this.topBits.incrementAndGet();
+			}
+			return new UUID(this.topBits.get(), bottomBits);
+		}
+
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/config/IdGeneratorConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -17,6 +17,8 @@
 package org.springframework.integration.config;
 
 import java.lang.reflect.Field;
+import java.util.HashSet;
+import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -35,30 +37,35 @@ import org.springframework.util.ReflectionUtils;
 /**
  * @author Oleg Zhurakousky
  * @author Mark Fisher
+ * @author Gary Russell
  * @since 2.0.4
  */
 public final class IdGeneratorConfigurer implements ApplicationListener<ApplicationContextEvent> {
 
-	private static volatile String generatorContextId;
+	private static final Set<String> generatorContextId = new HashSet<String>();
+
+	private static volatile IdGenerator theIdGenerator;
 
 	private final Log logger = LogFactory.getLog(getClass());
 
-	public void onApplicationEvent(ApplicationContextEvent event) {
+	public synchronized void onApplicationEvent(ApplicationContextEvent event) {
 		ApplicationContext context = event.getApplicationContext();
 		if (event instanceof ContextRefreshedEvent) {
 			boolean contextHasIdGenerator = context.getBeanNamesForType(IdGenerator.class).length > 0;
 			if (contextHasIdGenerator) {
 				if (this.setIdGenerator(context)) {
-					IdGeneratorConfigurer.generatorContextId = context.getId();
+					IdGeneratorConfigurer.generatorContextId.add(context.getId());
 				}
 			}
 		}
 		else if (event instanceof ContextClosedEvent) {
-			if (context.getId().equals(IdGeneratorConfigurer.generatorContextId)) {
-				this.unsetIdGenerator();
-				IdGeneratorConfigurer.generatorContextId = null;
+			if (IdGeneratorConfigurer.generatorContextId.contains(context.getId())) {
+				if (IdGeneratorConfigurer.generatorContextId.size() == 1) {
+					this.unsetIdGenerator();
+				}
+				IdGeneratorConfigurer.generatorContextId.remove(context.getId());
 			}
-		}	
+		}
 	}
 
 	private boolean setIdGenerator(ApplicationContext context) {
@@ -76,19 +83,34 @@ public final class IdGeneratorConfigurer implements ApplicationListener<Applicat
 					return false;
 				}
 				else {
-					// different instance has been set, not legal
-					throw new BeanDefinitionStoreException("'MessageHeaders.idGenerator' has already been set and can not be set again");
+					if (IdGeneratorConfigurer.theIdGenerator.getClass() == idGeneratorBean.getClass()) {
+						if (logger.isWarnEnabled()) {
+							logger.warn("Another instance of " + idGeneratorBean.getClass() +
+									" has already been established; ignoring");
+						}
+						return true;
+					}
+					else {
+						// different instance has been set, not legal
+						throw new BeanDefinitionStoreException("'MessageHeaders.idGenerator' has already been set and can not be set again");
+					}
 				}
 			}
 			if (logger.isInfoEnabled()) {
 				logger.info("Message IDs will be generated using custom IdGenerator [" + idGeneratorBean.getClass() + "]");
 			}
 			ReflectionUtils.setField(idGeneratorField, null, idGeneratorBean);
+			IdGeneratorConfigurer.theIdGenerator = idGeneratorBean;
 		}
 		catch (NoSuchBeanDefinitionException e) {
 			// No custom IdGenerator. We will use the default.
-			if (logger.isDebugEnabled()) {
-				logger.debug("Unable to locate MessageHeaders.IdGenerator. Will use default: UUID.randomUUID()");
+			int idBeans = context.getBeansOfType(IdGenerator.class).size();
+			if (idBeans > 1 && logger.isWarnEnabled()) {
+				logger.warn("Found too many 'IdGenerator' beans (" + idBeans + ") " +
+						"Will use the existing UUID strategy.");
+			}
+			else if (logger.isDebugEnabled()) {
+				logger.debug("Unable to locate MessageHeaders.IdGenerator. Will use the existing UUID strategy.");
 			}
 			return false;
 		}
@@ -96,7 +118,7 @@ public final class IdGeneratorConfigurer implements ApplicationListener<Applicat
 			// thrown from ReflectionUtils
 			if (logger.isWarnEnabled()) {
 				logger.warn("Unexpected exception occurred while accessing idGenerator of MessageHeaders." +
-						" Will use default: UUID.randomUUID()", e);
+						" Will use the existing UUID strategy.", e);
 			}
 			return false;
 		}
@@ -108,6 +130,7 @@ public final class IdGeneratorConfigurer implements ApplicationListener<Applicat
 			Field idGeneratorField = ReflectionUtils.findField(MessageHeaders.class, "idGenerator");
 			ReflectionUtils.makeAccessible(idGeneratorField);
 			idGeneratorField.set(null, null);
+			IdGeneratorConfigurer.theIdGenerator = null;
 		}
 		catch (Exception e) {
 			if (logger.isWarnEnabled()) {

spring-integration-core/src/test/java/org/springframework/integration/config/xml/IdGeneratorConfigurerTests.java

@@ -0,0 +1,221 @@
+/*
+ * Copyright 2002-2013 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.integration.config.xml;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.fail;
+
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.junit.Test;
+
+import org.springframework.beans.factory.BeanDefinitionStoreException;
+import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.integration.MessageHeaders;
+import org.springframework.integration.MessageHeaders.IdGenerator;
+import org.springframework.integration.MessageHeaders.JdkIdGenerator;
+import org.springframework.integration.MessageHeaders.SimpleIncrementingIdGenerator;
+import org.springframework.integration.test.util.TestUtils;
+
+/**
+ * @author Gary Russell
+ * @since 3.0
+ *
+ */
+public class IdGeneratorConfigurerTests {
+
+	@Test
+	public void testOneBean() {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context.refresh();
+		MessageHeaders headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+		context.destroy();
+		headers = new MessageHeaders(null);
+		assertNotEquals(1, headers.getId().getMostSignificantBits());
+		assertNotEquals(2, headers.getId().getLeastSignificantBits());
+		assertNull(TestUtils.getPropertyValue(headers, "idGenerator"));
+	}
+
+	@Test
+	public void testTwoBeans() throws Exception {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(JdkIdGenerator.class));
+		context.registerBeanDefinition("bar", new RootBeanDefinition(SimpleIncrementingIdGenerator.class));
+		context.refresh();
+
+		// multiple beans are ignored with warning
+		MessageHeaders headers = new MessageHeaders(null);
+		assertNull(TestUtils.getPropertyValue(headers, "idGenerator"));
+
+		context.destroy();
+	}
+
+	@Test
+	public void testNoBeans() throws Exception {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.refresh();
+
+		MessageHeaders headers = new MessageHeaders(null);
+		assertNull(TestUtils.getPropertyValue(headers, "idGenerator"));
+
+		context.destroy();
+	}
+
+	@Test
+	public void testTwoContextsSameClass() throws Exception {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context.refresh();
+		MessageHeaders headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+
+		GenericApplicationContext context2 = new GenericApplicationContext();
+		context2.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context2.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context2.refresh();
+
+		context.destroy();
+		context2.destroy();
+
+		headers = new MessageHeaders(null);
+		assertNotEquals(1, headers.getId().getMostSignificantBits());
+		assertNotEquals(2, headers.getId().getLeastSignificantBits());
+
+		assertNull(TestUtils.getPropertyValue(headers, "idGenerator"));
+	}
+
+	@Test
+	public void testTwoContextsSameClassFirstDestroyed() throws Exception {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context.refresh();
+		MessageHeaders headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+
+		GenericApplicationContext context2 = new GenericApplicationContext();
+		context2.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context2.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context2.refresh();
+
+		context.destroy();
+		// we should still use the custom strategy
+		headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+
+		context2.destroy();
+		// back to default
+		headers = new MessageHeaders(null);
+		assertNotEquals(1, headers.getId().getMostSignificantBits());
+		assertNotEquals(2, headers.getId().getLeastSignificantBits());
+
+		assertNull(TestUtils.getPropertyValue(headers, "idGenerator"));
+	}
+
+	@Test
+	public void testTwoContextDifferentClass() {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator.class));
+		context.refresh();
+		MessageHeaders headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+
+		GenericApplicationContext context2 = new GenericApplicationContext();
+		context2.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context2.registerBeanDefinition("foo", new RootBeanDefinition(MyIdGenerator2.class));
+		try {
+			context2.refresh();
+			fail("Expected exception");
+		}
+		catch (BeanDefinitionStoreException e) {
+			assertEquals("'MessageHeaders.idGenerator' has already been set and can not be set again",
+					e.getMessage());
+		}
+
+		context.destroy();
+		context2.destroy();
+	}
+
+	@Test
+	public void testJdk() {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(JdkIdGenerator.class));
+		context.refresh();
+		MessageHeaders headers = new MessageHeaders(null);
+		assertSame(context.getBean(IdGenerator.class), TestUtils.getPropertyValue(headers, "idGenerator"));
+
+		context.destroy();
+	}
+
+	@Test
+	public void testIncrementing() {
+		GenericApplicationContext context = new GenericApplicationContext();
+		context.registerBeanDefinition("bfpp", new RootBeanDefinition(DefaultConfiguringBeanFactoryPostProcessor.class));
+		context.registerBeanDefinition("foo", new RootBeanDefinition(SimpleIncrementingIdGenerator.class));
+		context.refresh();
+		IdGenerator idGenerator = context.getBean(IdGenerator.class);
+		MessageHeaders headers = new MessageHeaders(null);
+		assertEquals(0, headers.getId().getMostSignificantBits());
+		assertEquals(1, headers.getId().getLeastSignificantBits());
+		headers = new MessageHeaders(null);
+		assertEquals(0, headers.getId().getMostSignificantBits());
+		assertEquals(2, headers.getId().getLeastSignificantBits());
+		AtomicLong bottomBits = TestUtils.getPropertyValue(idGenerator, "bottomBits", AtomicLong.class);
+		bottomBits.set(0xffffffff);
+		headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(0, headers.getId().getLeastSignificantBits());
+		headers = new MessageHeaders(null);
+		assertEquals(1, headers.getId().getMostSignificantBits());
+		assertEquals(1, headers.getId().getLeastSignificantBits());
+
+		context.destroy();
+	}
+
+	public static class MyIdGenerator implements IdGenerator {
+
+		@Override
+		public UUID generateId() {
+			return new UUID(1, 2);
+		}
+	};
+
+	public static class MyIdGenerator2 implements IdGenerator {
+
+		@Override
+		public UUID generateId() {
+			return new UUID(3, 4);
+		}
+	};
+}

src/reference/docbook/message.xml

@@ -116,6 +116,43 @@
       Many inbound and outbound adapter implementations will also provide and/or expect certain headers, and additional
       user-defined headers can also be configured.
     </para>
+    <section id="message-id-generation">
+        <title>Message ID Generation</title>
+        <para>
+          When a message transitions through an application, each time it is
+          mutated (e.g. by a transformer) a new message id is assigned. The message id is
+          a <code>UUID</code>. Beginning with Spring Integration 3.0, the default strategy
+          used for id generation is to use the <code>com.eaio.uuid</code> package to
+          generate Type 1 UUIDs. This is much more efficient than the previous
+          <code>java.util.UUID.randomUUID()</code> implementation.
+        </para>
+        <para>
+          A different UUID generation strategy can be selected by declaring a bean that implements
+          <interfacename>MessageHeaders.IdGenerator</interfacename> in the application context.
+        </para>
+        <important>
+          Only one UUID generation strategy can be used in a classloader. This means that if
+          two or more application contexts are running in the same classloader, they will share
+          the same strategy. If one of the contexts changes the strategy, it will be used by
+          all contexts. If two or more contexts in the same classloader declare a bean of type
+          <interfacename>MessageHeaders.IdGenerator</interfacename>, they must all be an instance
+          of the same class, otherwise the context attempting to replace a custom strategy will
+          fail to initialize. If the strategy is the same, but parameterized, the strategy in the
+          first context to initialize will be used.
+        </important>
+        <para>
+          In addition to the default strategy, two additional <interfacename>IdGenerators</interfacename>
+          are provided; <classname>MessageHeaders.JdkIdGenerator</classname> uses the previous
+          <code>UUID.randomUUID()</code> mechanism; <classname>MessageHeaders.SimpleIncrementingIdGenerator</classname>
+          can be used in cases where a UUID is not really needed and a simple incrementing
+          value is sufficient.
+        </para>
+        <important>
+          The default strategy of creating Type 1 UUIDs may present security concerns for some users
+          because the UUID contains the MAC address of a network interface on the platform. For these
+          users, an alternate strategy should be selected.
+        </important>
+    </section>
   </section>
 
   <section id="message-implementations">

src/reference/docbook/whats-new.xml

@@ -234,5 +234,15 @@
 				<classname>ImapIdleExceptionEvent</classname> or one of its super classes.
 			</para>
 		</section>
+		<section id="3.0-message-id">
+			<title>Message ID Generation</title>
+			<para>
+				Previously, message ids were generated using the JDK <code>UUID.randomUUID()</code> method. With this
+				release, the default mechanism has been changed to use the <code>com.eaio.uuid</code> package which
+				generates Type 1 UUIDs, and is significantly faster. In addition, the ability to change
+				the strategy used to generate message ids has been added.
+				For more information see <xref linkend="message-id-generation"/>.
+			</para>
+		</section>
 	</section>
 </chapter>