Prevent a task from starting if an inst with the same name is running.

resolves #81

Using LockRegistryLeaderInitiator to do leadership election.

When task is started and singleInstanceEnabled isset to true then we use leader election
to determine if a task needs to be started.

Error Event Name had to be updated

spring-cloud-task-core/src/test/java/org/springframework/cloud/task/SimpleSingleTaskAutoConfigurationTests.java

@@ -0,0 +1,62 @@
+/*
+ *  Copyright 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.
+ *  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.cloud.task;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cloud.task.configuration.SingleTaskConfiguration;
+import org.springframework.cloud.task.configuration.SimpleTaskConfiguration;
+import org.springframework.cloud.task.configuration.SingleInstanceTaskListener;
+import org.springframework.cloud.task.configuration.TaskProperties;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Verifies that the beans created by the SimpleSingleTaskAutoConfigurationConfiguration
+ * specifically that PassThruRegistry was selected.
+ *
+ * @author Glenn Renfro
+ * @since 2.0.0
+ */
+@RunWith(SpringRunner.class)
+@ContextConfiguration(classes = {TaskProperties.class, SimpleTaskConfiguration.class, SingleTaskConfiguration.class})
+@TestPropertySource(properties = {
+		"spring.cloud.task.singleInstanceEnabled=true",
+})
+public class SimpleSingleTaskAutoConfigurationTests {
+	@Autowired
+	private ConfigurableApplicationContext context;
+
+	@Test
+	public void testConfiguration() throws Exception {
+
+		SingleInstanceTaskListener singleInstanceTaskListener = this.context.getBean(SingleInstanceTaskListener.class);
+
+		assertNotNull("singleInstanceTaskListener should not be null", singleInstanceTaskListener);
+
+		assertEquals(singleInstanceTaskListener.getClass(), SingleInstanceTaskListener.class);
+
+	}
+
+}

spring-cloud-task-core/src/test/java/org/springframework/cloud/task/SimpleSingleTaskAutoConfigurationWithDataSourceTests.java

@@ -0,0 +1,63 @@
+/*
+ *  Copyright 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.
+ *  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.cloud.task;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.jdbc.EmbeddedDataSourceConfiguration;
+import org.springframework.cloud.task.configuration.SingleTaskConfiguration;
+import org.springframework.cloud.task.configuration.SimpleTaskConfiguration;
+import org.springframework.cloud.task.configuration.SingleInstanceTaskListener;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Verifies that the beans created by the SimpleSingleTaskAutoConfigurationConfiguration
+ * specifically that the JdbcLockRegistry was selected.
+ *
+ * @author Glenn Renfro
+ * @since 2.0.0
+ */
+@RunWith(SpringRunner.class)
+@ContextConfiguration(classes = {SimpleTaskConfiguration.class,
+		SingleTaskConfiguration.class,
+		EmbeddedDataSourceConfiguration.class})
+@TestPropertySource(properties = {
+		"spring.cloud.task.singleInstanceEnabled=true",
+})
+public class SimpleSingleTaskAutoConfigurationWithDataSourceTests {
+
+	@Autowired
+	private ConfigurableApplicationContext context;
+
+	@Test
+	public void testConfiguration() throws Exception {
+
+		SingleInstanceTaskListener singleInstanceTaskListener = this.context.getBean(SingleInstanceTaskListener.class);
+
+		assertNotNull("singleInstanceTaskListener should not be null", singleInstanceTaskListener);
+
+		assertEquals(singleInstanceTaskListener.getClass(), SingleInstanceTaskListener.class);
+	}
+}

spring-cloud-task-core/src/test/java/org/springframework/cloud/task/listener/TaskLifecycleListenerTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.task.listener;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -76,6 +77,10 @@ public class TaskLifecycleListenerTests {
 		context = new AnnotationConfigApplicationContext();
 		context.setId("testTask");
 		context.register(TestDefaultConfiguration.class, PropertyPlaceholderAutoConfiguration.class);
+		TestListener.getStartupOrderList().clear();
+		TestListener.getFailOrderList().clear();
+		TestListener.getEndOrderList().clear();
+
 	}
 
 	@After
@@ -125,6 +130,9 @@ public class TaskLifecycleListenerTests {
 	@Test
 	public void testTaskFailedWithExitCodeEvent() {
 		final int exitCode = 10;
+		context.register(TestListener.class);
+		context.register(TestListener2.class);
+
 		context.refresh();
 		RuntimeException exception = new RuntimeException("This was expected");
 		SpringApplication application = new SpringApplication();
@@ -134,6 +142,18 @@ public class TaskLifecycleListenerTests {
 		context.publishEvent(new ApplicationReadyEvent(application, new String[0], context));
 
 		verifyTaskExecution(0, true, exitCode, exception, null);
+		assertEquals(2, TestListener.getStartupOrderList().size());
+		assertEquals(Integer.valueOf(2), TestListener.getStartupOrderList().get(0));
+		assertEquals(Integer.valueOf(1), TestListener.getStartupOrderList().get(1));
+
+		assertEquals(2, TestListener.getEndOrderList().size());
+		assertEquals(Integer.valueOf(1), TestListener.getEndOrderList().get(0));
+		assertEquals(Integer.valueOf(2), TestListener.getEndOrderList().get(1));
+
+		assertEquals(2, TestListener.getFailOrderList().size());
+		assertEquals(Integer.valueOf(1), TestListener.getFailOrderList().get(0));
+		assertEquals(Integer.valueOf(2), TestListener.getFailOrderList().get(1));
+
 	}
 
 	@Test
@@ -300,4 +320,53 @@ public class TaskLifecycleListenerTests {
 			throw new UnsupportedOperationException("Not supported at this time.");
 		}
 	}
+
+	private static class TestListener2 extends TestListener {
+
+	}
+
+	private static class TestListener implements TaskExecutionListener {
+
+		private static int currentCount = 0;
+
+		private int id = 0;
+
+		static List<Integer> startupOrderList = new ArrayList<>();
+
+		static List<Integer> endOrderList = new ArrayList<>();
+
+		static List<Integer> failOrderList = new ArrayList<>();
+
+		public TestListener() {
+			currentCount++;
+			id = currentCount;
+		}
+
+		@Override
+		public void onTaskStartup(TaskExecution taskExecution) {
+			startupOrderList.add(id);
+		}
+
+		@Override
+		public void onTaskEnd(TaskExecution taskExecution) {
+			endOrderList.add(id);
+		}
+
+		@Override
+		public void onTaskFailed(TaskExecution taskExecution, Throwable throwable) {
+			failOrderList.add(id);
+		}
+
+		public static List<Integer> getStartupOrderList() {
+			return startupOrderList;
+		}
+
+		public static List<Integer> getEndOrderList() {
+			return endOrderList;
+		}
+
+		public static List<Integer> getFailOrderList() {
+			return failOrderList;
+		}
+	}
 }