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Diffstat (limited to 'sql/hive-thriftserver/src/main/java/org/apache/hive/service/AbstractService.java')
-rw-r--r-- | sql/hive-thriftserver/src/main/java/org/apache/hive/service/AbstractService.java | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/AbstractService.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/AbstractService.java new file mode 100644 index 0000000000..c2a2b2d478 --- /dev/null +++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/AbstractService.java @@ -0,0 +1,184 @@ +/** + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.hive.service; + +import java.util.ArrayList; +import java.util.List; + +import org.apache.commons.logging.Log; +import org.apache.commons.logging.LogFactory; +import org.apache.hadoop.hive.conf.HiveConf; + +/** + * AbstractService. + * + */ +public abstract class AbstractService implements Service { + + private static final Log LOG = LogFactory.getLog(AbstractService.class); + + /** + * Service state: initially {@link STATE#NOTINITED}. + */ + private STATE state = STATE.NOTINITED; + + /** + * Service name. + */ + private final String name; + /** + * Service start time. Will be zero until the service is started. + */ + private long startTime; + + /** + * The configuration. Will be null until the service is initialized. + */ + private HiveConf hiveConf; + + /** + * List of state change listeners; it is final to ensure + * that it will never be null. + */ + private final List<ServiceStateChangeListener> listeners = + new ArrayList<ServiceStateChangeListener>(); + + /** + * Construct the service. + * + * @param name + * service name + */ + public AbstractService(String name) { + this.name = name; + } + + @Override + public synchronized STATE getServiceState() { + return state; + } + + /** + * {@inheritDoc} + * + * @throws IllegalStateException + * if the current service state does not permit + * this action + */ + @Override + public synchronized void init(HiveConf hiveConf) { + ensureCurrentState(STATE.NOTINITED); + this.hiveConf = hiveConf; + changeState(STATE.INITED); + LOG.info("Service:" + getName() + " is inited."); + } + + /** + * {@inheritDoc} + * + * @throws IllegalStateException + * if the current service state does not permit + * this action + */ + @Override + public synchronized void start() { + startTime = System.currentTimeMillis(); + ensureCurrentState(STATE.INITED); + changeState(STATE.STARTED); + LOG.info("Service:" + getName() + " is started."); + } + + /** + * {@inheritDoc} + * + * @throws IllegalStateException + * if the current service state does not permit + * this action + */ + @Override + public synchronized void stop() { + if (state == STATE.STOPPED || + state == STATE.INITED || + state == STATE.NOTINITED) { + // already stopped, or else it was never + // started (eg another service failing canceled startup) + return; + } + ensureCurrentState(STATE.STARTED); + changeState(STATE.STOPPED); + LOG.info("Service:" + getName() + " is stopped."); + } + + @Override + public synchronized void register(ServiceStateChangeListener l) { + listeners.add(l); + } + + @Override + public synchronized void unregister(ServiceStateChangeListener l) { + listeners.remove(l); + } + + @Override + public String getName() { + return name; + } + + @Override + public synchronized HiveConf getHiveConf() { + return hiveConf; + } + + @Override + public long getStartTime() { + return startTime; + } + + /** + * Verify that that a service is in a given state. + * + * @param currentState + * the desired state + * @throws IllegalStateException + * if the service state is different from + * the desired state + */ + private void ensureCurrentState(STATE currentState) { + ServiceOperations.ensureCurrentState(state, currentState); + } + + /** + * Change to a new state and notify all listeners. + * This is a private method that is only invoked from synchronized methods, + * which avoid having to clone the listener list. It does imply that + * the state change listener methods should be short lived, as they + * will delay the state transition. + * + * @param newState + * new service state + */ + private void changeState(STATE newState) { + state = newState; + // notify listeners + for (ServiceStateChangeListener l : listeners) { + l.stateChanged(this); + } + } + +} |