Merge "Add ServiceManager class"

6 files changed, 591 insertions, 8 deletions

diff --git a/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManager.java b/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManager.java
new file mode 100644
index 00000000..8bf89d56
--- /dev/null
+++ b/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManager.java
@@ -0,0 +1,190 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP PAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.LinkedList;
+import org.onap.policy.common.capabilities.Startable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Manages a series of services. The services are started in order, and stopped in reverse
+ * order.
+ */
+public class ServiceManager {
+    private static final Logger logger = LoggerFactory.getLogger(ServiceManager.class);
+
+    /**
+     * Services to be started/stopped.
+     */
+    private final Deque<Service> items = new LinkedList<>();
+
+    /**
+     * {@code True} if the services are currently running, {@code false} otherwise.
+     */
+    private boolean running;
+
+    /**
+     * Adds a pair of service actions to the manager.
+     *
+     * @param stepName name to be logged when the service is started/stopped
+     * @param starter function to start the service
+     * @param stopper function to stop the service
+     * @return this manager
+     */
+    public synchronized ServiceManager addAction(String stepName, RunnableWithEx starter, RunnableWithEx stopper) {
+        if (running) {
+            throw new IllegalStateException("services are already running; cannot add " + stepName);
+        }
+
+        items.add(new Service(stepName, starter, stopper));
+        return this;
+    }
+
+    /**
+     * Adds a service to the manager. The manager will invoke the service's
+     * {@link Startable#start()} and {@link Startable#stop()} methods.
+     *
+     * @param stepName name to be logged when the service is started/stopped
+     * @param service object to be started/stopped
+     * @return this manager
+     */
+    public synchronized ServiceManager addService(String stepName, Startable service) {
+        if (running) {
+            throw new IllegalStateException("services are already running; cannot add " + stepName);
+        }
+
+        items.add(new Service(stepName, () -> service.start(), () -> service.stop()));
+        return this;
+    }
+
+    /**
+     * Starts each service, in order. If a service throws an exception, then the
+     * previously started services are stopped, in reverse order.
+     *
+     * @throws ServiceManagerException if a service fails to start
+     */
+    public synchronized void start() throws ServiceManagerException {
+        if (running) {
+            throw new IllegalStateException("services are already running");
+        }
+
+        // tracks the services that have been started so far
+        Deque<Service> started = new LinkedList<>();
+        Exception ex = null;
+
+        for (Service item : items) {
+            try {
+                logger.info("starting {}", item.stepName);
+                item.starter.run();
+                started.add(item);
+
+            } catch (Exception e) {
+                logger.error("failed to start {}; rewinding steps", item.stepName);
+                ex = e;
+                break;
+            }
+        }
+
+        if (ex == null) {
+            running = true;
+            return;
+        }
+
+        // one of the services failed to start - rewind those we've previously started
+        try {
+            rewind(started);
+
+        } catch (ServiceManagerException e) {
+            logger.error("rewind failed", e);
+        }
+
+        throw new ServiceManagerException(ex);
+    }
+
+    /**
+     * Stops the services, in reverse order from which they were started. Stops all of the
+     * services, even if one of the "stop" functions throws an exception. Assumes that
+     * {@link #start()} has completed successfully.
+     *
+     * @throws ServiceManagerException if a service fails to stop
+     */
+    public synchronized void stop() throws ServiceManagerException {
+        if (!running) {
+            throw new IllegalStateException("services are not running");
+        }
+
+        running = false;
+        rewind(items);
+    }
+
+    /**
+     * Rewinds a list of services, stopping them in reverse order. Stops all of the
+     * services, even if one of the "stop" functions throws an exception.
+     *
+     * @param running services that are running, in the order they were started
+     * @throws ServiceManagerException if a service fails to stop
+     */
+    private void rewind(Deque<Service> running) throws ServiceManagerException {
+        Exception ex = null;
+
+        // stop everything, in reverse order
+        Iterator<Service> it = running.descendingIterator();
+        while (it.hasNext()) {
+            Service item = it.next();
+            try {
+                logger.info("stopping {}", item.stepName);
+                item.stopper.run();
+            } catch (Exception e) {
+                logger.error("failed to stop {}", item.stepName);
+                ex = e;
+
+                // do NOT break or re-throw, as we must stop ALL remaining items
+            }
+        }
+
+        if (ex != null) {
+            throw new ServiceManagerException(ex);
+        }
+    }
+
+    /**
+     * Service information.
+     */
+    private static class Service {
+        private String stepName;
+        private RunnableWithEx starter;
+        private RunnableWithEx stopper;
+
+        public Service(String stepName, RunnableWithEx starter, RunnableWithEx stopper) {
+            this.stepName = stepName;
+            this.starter = starter;
+            this.stopper = stopper;
+        }
+    }
+
+    @FunctionalInterface
+    public static interface RunnableWithEx {
+        public void run() throws Exception;
+    }
+}
diff --git a/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManagerException.java b/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManagerException.java
new file mode 100644
index 00000000..3daa441a
--- /dev/null
+++ b/utils/src/main/java/org/onap/policy/common/utils/services/ServiceManagerException.java
@@ -0,0 +1,44 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP PAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+/**
+ * Exceptions thrown by the ServiceManager.
+ */
+public class ServiceManagerException extends Exception {
+    private static final long serialVersionUID = 1L;
+
+    public ServiceManagerException() {
+        super();
+    }
+
+    public ServiceManagerException(String message) {
+        super(message);
+    }
+
+    public ServiceManagerException(Throwable cause) {
+        super(cause);
+    }
+
+    public ServiceManagerException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}
diff --git a/utils/src/test/java/org/onap/policy/common/utils/resources/ResourceUtilsTest.java b/utils/src/test/java/org/onap/policy/common/utils/resources/ResourceUtilsTest.java
index d1aa59d5..eb918d35 100644
--- a/utils/src/test/java/org/onap/policy/common/utils/resources/ResourceUtilsTest.java
+++ b/utils/src/test/java/org/onap/policy/common/utils/resources/ResourceUtilsTest.java
@@ -5,15 +5,15 @@
  * 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.
- * 
+ *
  * SPDX-License-Identifier: Apache-2.0
  * ============LICENSE_END=========================================================
  */
@@ -158,10 +158,10 @@ public class ResourceUtilsTest {
 
         theUrl = ResourceUtils.getLocalFile("file:///");
         assertNotNull(theUrl);
-        
+
         theUrl = ResourceUtils.getLocalFile("file:///testdir/testfile.xml");
         assertNull(theUrl);
-        
+
         theUrl = ResourceUtils.getLocalFile(null);
         assertNull(theUrl);
     }
@@ -185,7 +185,7 @@ public class ResourceUtilsTest {
 
         theStream = ResourceUtils.getResourceAsStream(jarFileResource);
         assertNotNull(theStream);
-        
+
         theStream = ResourceUtils.getResourceAsStream(pathDirResource);
         assertNotNull(theStream);
 
@@ -250,7 +250,7 @@ public class ResourceUtilsTest {
         assertNull(theString);
 
         theString = ResourceUtils.getResourceAsString("");
-        assertEquals("org\ntestdir\n", theString);
+        assertEquals("logback-test.xml\norg\ntestdir\n", theString);
     }
 
     @Test
@@ -295,7 +295,7 @@ public class ResourceUtilsTest {
         assertEquals("/something/else", ResourceUtils.getFilePath4Resource("/something/else"));
         assertTrue(ResourceUtils.getFilePath4Resource("xml/example.xml").endsWith("xml/example.xml"));
     }
-    
+
     /**
      * Cleandown resource utils test.
      */
diff --git a/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerExceptionTest.java b/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerExceptionTest.java
new file mode 100644
index 00000000..5fe321e8
--- /dev/null
+++ b/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerExceptionTest.java
@@ -0,0 +1,63 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+
+import org.junit.Test;
+
+public class ServiceManagerExceptionTest {
+    private ServiceManagerException sme;
+
+    @Test
+    public void testServiceManagerException() {
+        sme = new ServiceManagerException();
+        assertNull(sme.getMessage());
+        assertNull(sme.getCause());
+    }
+
+    @Test
+    public void testServiceManagerExceptionString() {
+        sme = new ServiceManagerException("hello");
+        assertEquals("hello", sme.getMessage());
+        assertNull(sme.getCause());
+    }
+
+    @Test
+    public void testServiceManagerExceptionThrowable() {
+        Throwable thrown = new Throwable("expected exception");
+        sme = new ServiceManagerException(thrown);
+        assertNotNull(sme.getMessage());
+        assertSame(thrown, sme.getCause());
+    }
+
+    @Test
+    public void testServiceManagerExceptionStringThrowable() {
+        Throwable thrown = new Throwable("another expected exception");
+        sme = new ServiceManagerException("world", thrown);
+        assertEquals("world", sme.getMessage());
+        assertSame(thrown, sme.getCause());
+    }
+
+}
diff --git a/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerTest.java b/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerTest.java
new file mode 100644
index 00000000..49c0599b
--- /dev/null
+++ b/utils/src/test/java/org/onap/policy/common/utils/services/ServiceManagerTest.java
@@ -0,0 +1,249 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.services;
+
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.common.capabilities.Startable;
+import org.onap.policy.common.utils.services.ServiceManager.RunnableWithEx;
+
+public class ServiceManagerTest {
+    private static final String ALREADY_RUNNING = "services are already running";
+    private static final String EXPECTED_EXCEPTION = "expected exception";
+
+    private ServiceManager svcmgr;
+
+    /**
+     * Initializes {@link #svcmgr}.
+     */
+    @Before
+    public void setUp() {
+        svcmgr = new ServiceManager();
+    }
+
+    @Test
+    public void testAddAction() throws Exception {
+        RunnableWithEx start1 = mock(RunnableWithEx.class);
+        RunnableWithEx stop1 = mock(RunnableWithEx.class);
+        svcmgr.addAction("first action", start1, stop1);
+
+        RunnableWithEx start2 = mock(RunnableWithEx.class);
+        RunnableWithEx stop2 = mock(RunnableWithEx.class);
+        svcmgr.addAction("second action", start2, stop2);
+
+        svcmgr.start();
+        verify(start1).run();
+        verify(start2).run();
+        verify(stop1, never()).run();
+        verify(stop2, never()).run();
+
+        // cannot add while running
+        assertThatIllegalStateException().isThrownBy(() -> svcmgr.addAction("fail action", start1, stop1))
+                        .withMessage(ALREADY_RUNNING + "; cannot add fail action");
+
+        svcmgr.stop();
+        verify(start1).run();
+        verify(start2).run();
+        verify(stop1).run();
+        verify(stop2).run();
+    }
+
+    @Test
+    public void testAddStartable() throws Exception {
+        Startable start1 = mock(Startable.class);
+        svcmgr.addService("first startable", start1);
+
+        Startable start2 = mock(Startable.class);
+        svcmgr.addService("second startable", start2);
+
+        svcmgr.start();
+        verify(start1).start();
+        verify(start1, never()).stop();
+        verify(start2).start();
+        verify(start2, never()).stop();
+
+        // cannot add while running
+        assertThatIllegalStateException().isThrownBy(() -> svcmgr.addService("fail startable", start1))
+                        .withMessage(ALREADY_RUNNING + "; cannot add fail startable");
+
+        svcmgr.stop();
+        verify(start1).start();
+        verify(start1).stop();
+        verify(start2).start();
+        verify(start2).stop();
+    }
+
+    @Test
+    public void testStart() throws Exception {
+        Startable start1 = mock(Startable.class);
+        svcmgr.addService("test start", start1);
+
+        svcmgr.start();
+        verify(start1).start();
+        verify(start1, never()).stop();
+
+        // cannot re-start
+        assertThatIllegalStateException().isThrownBy(() -> svcmgr.start())
+                        .withMessage(ALREADY_RUNNING);
+
+        // verify that it didn't try to start the service again
+        verify(start1).start();
+    }
+
+    @Test
+    public void testStart_Ex() {
+        Startable start1 = mock(Startable.class);
+        svcmgr.addService("test start ex", start1);
+
+        Startable start2 = mock(Startable.class);
+        svcmgr.addService("second test start ex", start2);
+
+        // this one will throw an exception
+        Startable start3 = mock(Startable.class);
+        RuntimeException exception = new RuntimeException(EXPECTED_EXCEPTION);
+        when(start3.start()).thenThrow(exception);
+        svcmgr.addService("third test start ex", start3);
+
+        Startable start4 = mock(Startable.class);
+        svcmgr.addService("fourth test start ex", start4);
+
+        Startable start5 = mock(Startable.class);
+        svcmgr.addService("fifth test start ex", start5);
+
+        assertThatThrownBy(() -> svcmgr.start()).isInstanceOf(ServiceManagerException.class).hasCause(exception);
+
+        verify(start1).start();
+        verify(start2).start();
+        verify(start3).start();
+        verify(start4, never()).start();
+        verify(start5, never()).start();
+
+        verify(start1).stop();
+        verify(start2).stop();
+        verify(start3, never()).stop();
+        verify(start4, never()).stop();
+        verify(start5, never()).stop();
+    }
+
+    @Test
+    public void testStart_RewindEx() {
+        Startable start1 = mock(Startable.class);
+        svcmgr.addService("test start rewind", start1);
+
+        // this one will throw an exception during rewind
+        Startable start2 = mock(Startable.class);
+        RuntimeException exception2 = new RuntimeException(EXPECTED_EXCEPTION);
+        when(start2.stop()).thenThrow(exception2);
+        svcmgr.addService("second test start rewind", start2);
+
+        // this one will throw an exception
+        Startable start3 = mock(Startable.class);
+        RuntimeException exception = new RuntimeException(EXPECTED_EXCEPTION);
+        when(start3.start()).thenThrow(exception);
+        svcmgr.addService("third test start rewind", start3);
+
+        Startable start4 = mock(Startable.class);
+        svcmgr.addService("fourth test start rewind", start4);
+
+        Startable start5 = mock(Startable.class);
+        svcmgr.addService("fifth test start rewind", start5);
+
+        assertThatThrownBy(() -> svcmgr.start()).isInstanceOf(ServiceManagerException.class).hasCause(exception);
+    }
+
+    @Test
+    public void testStop() throws Exception {
+        Startable start1 = mock(Startable.class);
+        svcmgr.addService("first stop", start1);
+
+        // cannot stop until started
+        assertThatIllegalStateException().isThrownBy(() -> svcmgr.stop())
+                        .withMessage("services are not running");
+
+        // verify that it didn't try to stop the service
+        verify(start1, never()).stop();
+
+        // start it
+        svcmgr.start();
+
+        svcmgr.stop();
+        verify(start1).stop();
+    }
+
+    @Test
+    public void testStop_Ex() throws Exception {
+        RunnableWithEx start1 = mock(RunnableWithEx.class);
+        RunnableWithEx stop1 = mock(RunnableWithEx.class);
+        svcmgr.addAction("first stop ex", start1, stop1);
+
+        Startable start2 = mock(Startable.class);
+        svcmgr.addService("second stop ex", start2);
+
+        svcmgr.start();
+        verify(start1).run();
+        verify(stop1, never()).run();
+        verify(start2).start();
+        verify(start2, never()).stop();
+
+        svcmgr.stop();
+        verify(start1).run();
+        verify(stop1).run();
+        verify(start2).start();
+        verify(start2).stop();
+    }
+
+    @Test
+    public void testRewind() throws Exception {
+        RunnableWithEx starter = mock(RunnableWithEx.class);
+        LinkedList<String> lst = new LinkedList<>();
+
+        svcmgr.addAction("first rewind", starter, () -> lst.add("rewind1"));
+        svcmgr.addAction("second rewind", starter, () -> lst.add("rewind2"));
+
+        // this one will throw an exception during rewind
+        RuntimeException exception = new RuntimeException(EXPECTED_EXCEPTION);
+        svcmgr.addAction("third rewind", starter, () -> {
+            lst.add("rewind3");
+            throw exception;
+        });
+
+        svcmgr.addAction("fourth rewind", starter, () -> lst.add("rewind4"));
+        svcmgr.addAction("fifth rewind", starter, () -> lst.add("rewind5"));
+
+        svcmgr.start();
+
+        assertThatThrownBy(() -> svcmgr.stop()).isInstanceOf(ServiceManagerException.class).hasCause(exception);
+
+        // all of them should have been stopped, in reverse order
+        assertEquals(Arrays.asList("rewind5", "rewind4", "rewind3", "rewind2", "rewind1").toString(), lst.toString());
+    }
+
+}
diff --git a/utils/src/test/resources/logback-test.xml b/utils/src/test/resources/logback-test.xml
new file mode 100644
index 00000000..01d5c861
--- /dev/null
+++ b/utils/src/test/resources/logback-test.xml
@@ -0,0 +1,37 @@
+<!--
+  ============LICENSE_START=======================================================
+  ONAP - Common Modules
+  ================================================================================
+  Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+  ================================================================================
+  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.
+  ============LICENSE_END=========================================================
+  -->
+
+<!-- Controls the output of logs for JUnit tests -->
+
+<configuration>
+
+ <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+  <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
+   <Pattern>
+    %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36}.%M\(%line\) - %msg%n
+   </Pattern>
+  </encoder>
+ </appender>
+
+ <root level="debug">
+  <appender-ref ref="STDOUT" />
+ </root>
+
+</configuration>