Fix Zookeeper Issues

- `tryLock()` didn't throw `InterruptedException`
- `putIfAbsent()` use `get()` for current value

Author: garyrussell

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/lock/ZookeeperLockRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2016 the original author or authors.
+ * Copyright 2015-2019 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.
@@ -307,9 +307,15 @@ public Boolean call() throws Exception {
 				}
 			}
 			catch (TimeoutException e) {
-				future.cancel(true);
+				if (future != null) {
+					future.cancel(true);
+				}
 				return false;
 			}
+			catch (InterruptedException e) {
+				Thread.currentThread().interrupt();
+				throw e;
+			}
 			catch (Exception e) {
 				throw new MessagingException("Failed to acquire mutex at " + this.path, e);
 			}

spring-integration-zookeeper/src/main/java/org/springframework/integration/zookeeper/metadata/ZookeeperMetadataStore.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2019 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.
@@ -122,13 +122,7 @@ public String putIfAbsent(String key, String value) {
 			}
 			catch (KeeperException.NodeExistsException e) {
 				// so the data actually exists, we can read it
-				try {
-					byte[] bytes = this.client.getData().forPath(getPath(key));
-					return IntegrationUtils.bytesToString(bytes, this.encoding);
-				}
-				catch (Exception exceptionDuringGet) {
-					throw new ZookeeperMetadataStoreException("Exception while reading node with key '" + key + "':", e);
-				}
+				return get(key);
 			}
 			catch (Exception e) {
 				throw new ZookeeperMetadataStoreException("Error while trying to set '" + key + "':", e);

spring-integration-zookeeper/src/test/java/org/springframework/integration/zookeeper/metadata/ZookeeperMetadataStoreTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2019 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.
@@ -308,6 +308,7 @@ public void testListenerInvokedOnRemoteChanges() throws Exception {
 
 		CuratorFramework otherClient = createNewClient();
 		ZookeeperMetadataStore otherMetadataStore = new ZookeeperMetadataStore(otherClient);
+		otherMetadataStore.start();
 
 		// register listeners
 		final List<List<String>> notifiedChanges = new ArrayList<List<String>>();