MAPREDUCE-3970 ServiceOperations class
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1300901 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Steve Loughran
parent
27dc31c103
commit
8e5862e342
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/**
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.hadoop.yarn.service;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.apache.hadoop.conf.Configuration;
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/**
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* This class contains a set of methods to work with services, especially
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* to walk them through their lifecycle.
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*/
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public final class ServiceOperations {
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private static final Log LOG = LogFactory.getLog(AbstractService.class);
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private ServiceOperations() {
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}
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/**
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* Verify that that a service is in a given state.
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* @param state the actual state a service is in
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* @param expectedState the desired state
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* @throws IllegalStateException if the service state is different from
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* the desired state
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*/
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public static void ensureCurrentState(Service.STATE state,
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Service.STATE expectedState) {
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if (state != expectedState) {
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throw new IllegalStateException("For this operation, the " +
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"current service state must be "
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+ expectedState
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+ " instead of " + state);
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}
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}
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/**
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* Initialize a service.
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* <p/>
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* The service state is checked <i>before</i> the operation begins.
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* This process is <i>not</i> thread safe.
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* @param service a service that must be in the state
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* {@link Service.STATE#NOTINITED}
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* @param configuration the configuration to initialize the service with
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* @throws RuntimeException on a state change failure
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* @throws IllegalStateException if the service is in the wrong state
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*/
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public static void init(Service service, Configuration configuration) {
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Service.STATE state = service.getServiceState();
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ensureCurrentState(state, Service.STATE.NOTINITED);
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service.init(configuration);
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}
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/**
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* Start a service.
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* <p/>
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* The service state is checked <i>before</i> the operation begins.
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* This process is <i>not</i> thread safe.
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* @param service a service that must be in the state
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* {@link Service.STATE#INITED}
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* @throws RuntimeException on a state change failure
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* @throws IllegalStateException if the service is in the wrong state
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*/
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public static void start(Service service) {
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Service.STATE state = service.getServiceState();
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ensureCurrentState(state, Service.STATE.INITED);
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service.start();
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}
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/**
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* Initialize then start a service.
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* <p/>
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* The service state is checked <i>before</i> the operation begins.
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* This process is <i>not</i> thread safe.
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* @param service a service that must be in the state
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* {@link Service.STATE#NOTINITED}
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* @param configuration the configuration to initialize the service with
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* @throws RuntimeException on a state change failure
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* @throws IllegalStateException if the service is in the wrong state
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*/
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public static void deploy(Service service, Configuration configuration) {
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init(service, configuration);
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start(service);
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}
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/**
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* Stop a service.
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* <p/>Do nothing if the service is null or not
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* in a state in which it can be/needs to be stopped.
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* <p/>
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* The service state is checked <i>before</i> the operation begins.
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* This process is <i>not</i> thread safe.
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* @param service a service or null
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*/
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public static void stop(Service service) {
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if (service != null) {
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Service.STATE state = service.getServiceState();
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if (state == Service.STATE.STARTED) {
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service.stop();
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}
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}
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}
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/**
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* Stop a service; if it is null do nothing. Exceptions are caught and
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* logged at warn level. (but not Throwables). This operation is intended to
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* be used in cleanup operations
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*
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* @param service a service; may be null
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* @return any exception that was caught; null if none was.
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*/
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public static Exception stopQuietly(Service service) {
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try {
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stop(service);
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} catch (Exception e) {
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LOG.warn("When stopping the service " + service.getName()
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+ " : " + e,
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e);
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return e;
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}
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return null;
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}
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}
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@ -0,0 +1,312 @@
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/**
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.hadoop.yarn.service;
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import org.apache.hadoop.conf.Configuration;
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import org.junit.Test;
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/**
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* These tests verify that the {@link ServiceOperations} methods
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* do a best-effort attempt to make the service state change operations
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* idempotent. That is still best effort -there is no thread safety, and
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* a failure during a state change does not prevent the operation
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* being called again.
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*/
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public class TestServiceOperations extends ServiceAssert {
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@Test
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public void testWalkthrough() throws Throwable {
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BreakableService svc = new BreakableService();
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assertServiceStateCreated(svc);
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Configuration conf = new Configuration();
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conf.set("test.walkthrough","t");
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ServiceOperations.init(svc, conf);
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assertServiceStateInited(svc);
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assertStateCount(svc, Service.STATE.INITED, 1);
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//check the configuration made it all the way through.
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assertServiceConfigurationContains(svc, "test.walkthrough");
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ServiceOperations.start(svc);
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assertServiceStateStarted(svc);
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assertStateCount(svc, Service.STATE.STARTED, 1);
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ServiceOperations.stop(svc);
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assertServiceStateStopped(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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}
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/**
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* Call init twice -expect a failure, and expect the count
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* of initialization attempts to still be 1: the state
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* check was made before the subclass method was called.
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* @throws Throwable if need be
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*/
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@Test
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public void testInitTwice() throws Throwable {
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BreakableService svc = new BreakableService();
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Configuration conf = new Configuration();
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conf.set("test.init", "t");
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ServiceOperations.init(svc, conf);
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try {
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ServiceOperations.init(svc, new Configuration());
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fail("Expected a failure, got " + svc);
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} catch (IllegalStateException e) {
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//expected
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}
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assertStateCount(svc, Service.STATE.INITED, 1);
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assertServiceConfigurationContains(svc, "test.init");
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}
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/**
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* call start twice; expect failures and the start invoke count to
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* be exactly 1.
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* @throws Throwable if necessary
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*/
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@Test
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public void testStartTwice() throws Throwable {
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BreakableService svc = new BreakableService();
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ServiceOperations.init(svc, new Configuration());
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ServiceOperations.start(svc);
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try {
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ServiceOperations.start(svc);
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fail("Expected a failure, got " + svc);
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} catch (IllegalStateException e) {
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//expected
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}
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assertStateCount(svc, Service.STATE.STARTED, 1);
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}
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/**
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* Test that the deploy operation pushes a service into its started state
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* @throws Throwable on any failure.
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*/
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@Test
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public void testDeploy() throws Throwable {
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BreakableService svc = new BreakableService();
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assertServiceStateCreated(svc);
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ServiceOperations.deploy(svc, new Configuration());
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assertServiceStateStarted(svc);
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assertStateCount(svc, Service.STATE.INITED, 1);
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assertStateCount(svc, Service.STATE.STARTED, 1);
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ServiceOperations.stop(svc);
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assertServiceStateStopped(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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}
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/**
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* Demonstrate that the deploy operation fails when invoked twice,
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* but the service method call counts are unchanged after the second call.
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* @throws Throwable on any failure.
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*/
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@Test
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public void testDeployNotIdempotent() throws Throwable {
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BreakableService svc = new BreakableService();
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assertServiceStateCreated(svc);
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ServiceOperations.deploy(svc, new Configuration());
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try {
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ServiceOperations.deploy(svc, new Configuration());
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fail("Expected a failure, got " + svc);
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} catch (IllegalStateException e) {
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//expected
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}
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//verify state and values are unchanged
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assertServiceStateStarted(svc);
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assertStateCount(svc, Service.STATE.INITED, 1);
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assertStateCount(svc, Service.STATE.STARTED, 1);
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ServiceOperations.stop(svc);
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}
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/**
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* Test that the deploy operation can fail part way through, in which
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* case the service is in the state that it was in before the failing
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* state method was called.
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* @throws Throwable on any failure.
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*/
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@Test
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public void testDeployNotAtomic() throws Throwable {
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//this instance is set to fail in the start() call.
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BreakableService svc = new BreakableService(false, true, false);
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try {
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ServiceOperations.deploy(svc, new Configuration());
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fail("Expected a failure, got " + svc);
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} catch (BreakableService.BrokenLifecycleEvent expected) {
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//expected
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}
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//now in the inited state
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assertServiceStateInited(svc);
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assertStateCount(svc, Service.STATE.INITED, 1);
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assertStateCount(svc, Service.STATE.STARTED, 1);
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//try again -expect a failure as the service is now inited.
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try {
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ServiceOperations.deploy(svc, new Configuration());
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fail("Expected a failure, got " + svc);
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} catch (IllegalStateException e) {
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//expected
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}
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}
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/**
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* verify that when a service is stopped more than once, no exception
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* is thrown, and the counter is not incremented
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* this is because the state change operations happen after the counter in
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* the subclass is incremented, even though stop is meant to be a no-op
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* @throws Throwable on a failure
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*/
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@Test
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public void testStopTwice() throws Throwable {
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BreakableService svc = new BreakableService();
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ServiceOperations.deploy(svc, new Configuration());
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ServiceOperations.stop(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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assertServiceStateStopped(svc);
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ServiceOperations.stop(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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}
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/**
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* verify that when a service that is not started is stopped, it's counter
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* is not incremented -the stop() method was not invoked.
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* @throws Throwable on a failure
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*/
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@Test
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public void testStopInit() throws Throwable {
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BreakableService svc = new BreakableService();
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ServiceOperations.stop(svc);
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assertServiceStateCreated(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 0);
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ServiceOperations.stop(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 0);
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}
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/**
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* Show that if the service failed during an init
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* operation, it stays in the created state, even after stopping it
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* @throws Throwable
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*/
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@Test
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public void testStopFailedInit() throws Throwable {
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BreakableService svc = new BreakableService(true, false, false);
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assertServiceStateCreated(svc);
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try {
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ServiceOperations.init(svc, new Configuration());
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fail("Expected a failure, got " + svc);
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} catch (BreakableService.BrokenLifecycleEvent e) {
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//expected
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}
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//the service state wasn't passed
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assertServiceStateCreated(svc);
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//the init state got invoked once
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assertStateCount(svc, Service.STATE.INITED, 1);
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//now try to stop
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ServiceOperations.stop(svc);
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//even after the stop operation, we haven't entered the state
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assertServiceStateCreated(svc);
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}
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/**
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* Show that if the service failed during an init
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* operation, it stays in the created state, even after stopping it
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* @throws Throwable
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*/
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@Test
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public void testStopFailedStart() throws Throwable {
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BreakableService svc = new BreakableService(false, true, false);
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ServiceOperations.init(svc, new Configuration());
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assertServiceStateInited(svc);
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try {
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ServiceOperations.start(svc);
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fail("Expected a failure, got " + svc);
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} catch (BreakableService.BrokenLifecycleEvent e) {
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//expected
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}
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//the service state wasn't passed
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assertServiceStateInited(svc);
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assertStateCount(svc, Service.STATE.INITED, 1);
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//now try to stop
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ServiceOperations.stop(svc);
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//even after the stop operation, we haven't entered the state
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assertServiceStateInited(svc);
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}
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/**
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* verify that when a service is stopped more than once, no exception
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* is thrown, and the counter is incremented
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* this is because the state change operations happen after the counter in
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* the subclass is incremented, even though stop is meant to be a no-op.
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*
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* The {@link ServiceOperations#stop(Service)} operation does not prevent
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* this from happening
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* @throws Throwable
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*/
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@Test
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public void testFailingStop() throws Throwable {
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BreakableService svc = new BreakableService(false, false, true);
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ServiceOperations.deploy(svc, new Configuration());
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try {
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ServiceOperations.stop(svc);
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fail("Expected a failure, got " + svc);
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} catch (BreakableService.BrokenLifecycleEvent e) {
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//expected
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}
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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//now try to stop, this time doing it quietly
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Exception exception = ServiceOperations.stopQuietly(svc);
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assertTrue("Wrong exception type : " + exception,
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exception instanceof BreakableService.BrokenLifecycleEvent);
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assertStateCount(svc, Service.STATE.STOPPED, 2);
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}
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/**
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* verify that when a service that is not started is stopped, its counter
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* of stop calls is still incremented-and the service remains in its
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* original state..
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* @throws Throwable on a failure
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*/
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@Test
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public void testStopUnstarted() throws Throwable {
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BreakableService svc = new BreakableService();
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//invocation in NOTINITED state should be no-op
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ServiceOperations.stop(svc);
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assertServiceStateCreated(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 0);
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//stop failed, now it can be initialised
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ServiceOperations.init(svc, new Configuration());
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//again, no-op
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ServiceOperations.stop(svc);
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assertServiceStateInited(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 0);
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//once started, the service can be stopped reliably
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ServiceOperations.start(svc);
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ServiceOperations.stop(svc);
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assertServiceStateStopped(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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//now stop one more time
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ServiceOperations.stop(svc);
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assertStateCount(svc, Service.STATE.STOPPED, 1);
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}
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}
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