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/*
* ============LICENSE_START=======================================================
* feature-distributed-locking
* ================================================================================
* Copyright (C) 2018 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.distributed.locking;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.UUID;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import org.onap.policy.common.utils.properties.exception.PropertyException;
import org.onap.policy.drools.core.lock.LockRequestFuture;
import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureAPI;
import org.onap.policy.drools.features.PolicyEngineFeatureAPI;
import org.onap.policy.drools.persistence.SystemPersistence;
import org.onap.policy.drools.system.PolicyEngine;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class DistributedLockingFeature implements PolicyEngineFeatureAPI, PolicyResourceLockFeatureAPI {
/**
* Logger instance
*/
private static final Logger logger = LoggerFactory.getLogger(DistributedLockingFeature.class);
/**
* Properties Configuration Name
*/
public static final String CONFIGURATION_PROPERTIES_NAME = "feature-distributed-locking";
/**
* Properties for locking feature
*/
private DistributedLockingProperties lockProps;
/**
*ScheduledExecutorService for LockHeartbeat
*/
private ScheduledExecutorService scheduledExecutorService;
/**
* UUID
*/
private static final UUID uuid = UUID.randomUUID();
/**
* Reference to Heartbeat
*/
private static Heartbeat heartbeat = null;
@Override
public int getSequenceNumber() {
return 1000;
}
@Override
public Future<Boolean> beforeLock(String resourceId, String owner, Callback callback) {
TargetLock tLock = new TargetLock(resourceId, this.uuid, owner, lockProps);
return new LockRequestFuture(resourceId, owner, tLock.lock());
}
@Override
public Boolean beforeUnlock(String resourceId, String owner) {
TargetLock tLock = new TargetLock(resourceId, this.uuid, owner, lockProps);
return tLock.unlock();
}
@Override
public Boolean beforeIsLockedBy(String resourceId, String owner) {
TargetLock tLock = new TargetLock(resourceId, this.uuid, owner, lockProps);
return tLock.isActive();
}
@Override
public Boolean beforeIsLocked(String resourceId) {
TargetLock tLock = new TargetLock(resourceId, this.uuid, "dummyOwner", lockProps);
return tLock.isLocked();
}
@Override
public boolean afterStart(PolicyEngine engine) {
try {
this.lockProps = new DistributedLockingProperties(SystemPersistence.manager.getProperties(DistributedLockingFeature.CONFIGURATION_PROPERTIES_NAME));
} catch (PropertyException e) {
logger.error("DistributedLockingFeature feature properies have not been loaded", e);
throw new DistributedLockingFeatureException(e);
}
long heartbeatInterval = this.lockProps.getHeartBeatIntervalProperty();
cleanLockTable();
heartbeat = new Heartbeat(this.uuid, lockProps);
this.scheduledExecutorService = Executors.newScheduledThreadPool(1);
this.scheduledExecutorService.scheduleAtFixedRate(heartbeat, heartbeatInterval, heartbeatInterval, TimeUnit.MILLISECONDS);
return false;
}
/**
* This method kills the heartbeat thread and calls refreshLockTable which removes
* any records from the db where the current host is the owner.
*/
@Override
public boolean beforeShutdown(PolicyEngine engine) {
scheduledExecutorService.shutdown();
cleanLockTable();
return false;
}
/**
* This method removes all records owned by the current host from the db.
*/
private void cleanLockTable() {
try (Connection conn = DriverManager.getConnection(lockProps.getDbUrl(),
lockProps.getDbUser(),
lockProps.getDbPwd());
PreparedStatement statement = conn.prepareStatement("DELETE FROM pooling.locks WHERE host = ? OR expirationTime < ?");
){
statement.setString(1, this.uuid.toString());
statement.setLong(2, System.currentTimeMillis());
statement.executeUpdate();
} catch (SQLException e) {
logger.error("error in refreshLockTable()", e);
}
}
public static Heartbeat getHeartbeat() {
return heartbeat;
}
}
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