INT-4353: Let to set id for DefaultLockRepository

JIRA: https://jira.spring.io/browse/INT-4353

Updated based on code review

* Polishing according PR comments

**Cherry-pick to 4.3.x**

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/DefaultLockRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 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.
@@ -41,6 +41,8 @@ import org.springframework.util.Assert;
  *
  * @author Dave Syer
  * @author Artem Bilan
+ * @author Glenn Renfro
+ *
  * @since 4.3
  */
 @Repository
@@ -57,7 +59,7 @@ public class DefaultLockRepository implements LockRepository, InitializingBean {
 	 */
 	public static final int DEFAULT_TTL = 10000;
 
-	private final String id = UUID.randomUUID().toString();
+	private final String id;
 
 	private final JdbcTemplate template;
 
@@ -79,10 +81,27 @@ public class DefaultLockRepository implements LockRepository, InitializingBean {
 
 	private String countQuery = "SELECT COUNT(REGION) FROM %SLOCK WHERE REGION=? AND LOCK_KEY=? AND CLIENT_ID=? AND CREATED_DATE>=?";
 
-
+	/**
+	 * Constructor that initializes the client id that will be associated for
+	 * all the locks persisted by the store instance to a random {@link UUID}.
+	 * @param dataSource the {@link DataSource} used to maintain the lock repository.
+	 */
 	@Autowired
 	public DefaultLockRepository(DataSource dataSource) {
+		this(dataSource, UUID.randomUUID().toString());
+	}
+
+	/**
+	 * Constructor that allows the user to specify a client id that will
+	 * be associated for all the locks persisted by the store instance.
+	 * @param dataSource the {@link DataSource} used to maintain the lock repository.
+	 * @param id the client id to be associated with locks handled by the repository.
+	 * @since 4.3.13
+	 */
+	public DefaultLockRepository(DataSource dataSource, String id) {
+		Assert.hasText(id, "id must not be null nor empty");
 		this.template = new JdbcTemplate(dataSource);
+		this.id = id;
 	}
 
 	/**

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/lock/JdbcLockRegistryDifferentClientTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 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.
@@ -53,11 +53,13 @@ import org.springframework.util.StopWatch;
 /**
  * @author Dave Syer
  * @author Artem Bilan
+ * @author Glenn Renfro
+ *
  * @since 4.3
  */
 @ContextConfiguration("JdbcLockRegistryTests-context.xml")
 @RunWith(SpringJUnit4ClassRunner.class)
-@DirtiesContext // close at the end after class
+@DirtiesContext
 public class JdbcLockRegistryDifferentClientTests {
 
 	private static Log logger = LogFactory.getLog(JdbcLockRegistryDifferentClientTests.class);
@@ -194,7 +196,11 @@ public class JdbcLockRegistryDifferentClientTests {
 
 	@Test
 	public void testOnlyOneLock() throws Exception {
+		testOnlyOneLock(null);
+		testOnlyOneLock("AABBCCDD");
+	}
 
+	private void testOnlyOneLock(String id) throws Exception {
 		for (int i = 0; i < 100; i++) {
 
 			final List<String> locked = new ArrayList<String>();
@@ -202,7 +208,9 @@ public class JdbcLockRegistryDifferentClientTests {
 			ExecutorService pool = Executors.newFixedThreadPool(6);
 			ArrayList<Callable<Boolean>> tasks = new ArrayList<Callable<Boolean>>();
 			for (int j = 0; j < 20; j++) {
-				final DefaultLockRepository client = new DefaultLockRepository(this.dataSource);
+				final DefaultLockRepository client = (id == null) ?
+						new DefaultLockRepository(this.dataSource) :
+						new DefaultLockRepository(this.dataSource, id);
 				client.afterPropertiesSet();
 				this.context.getAutowireCapableBeanFactory().autowireBean(client);
 				Callable<Boolean> task = () -> {

src/reference/asciidoc/jdbc.adoc

@@ -995,6 +995,8 @@ Therefore `prefix` property must be used on the `DefaultLockRepository` bean def
 Sometimes it happens that one application has moved to the state when it can't release distributed lock - remove the particular record in the data base.
 For this purpose such dead locks can be expired by the other application on the next locking invocation.
 The `timeToLive` (TTL) option on the `DefaultLockRepository` is provided for this purpose.
+The user may also want to specify `CLIENT_ID` for the locks stored for a given `DefaultLockRepository` instance.
+In this case you can specify the `id` to be associated with the `DefaultLockRepository` as a constructor parameter.
 
 [[jdbc-metadata-store]]
 === JDBC Metadata Store