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/**
* 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.activemq.store.jdbc;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.Date;
import java.util.concurrent.TimeUnit;
import org.apache.activemq.util.IOExceptionSupport;
import org.apache.activemq.util.ServiceStopper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Represents an exclusive lease on a database to avoid multiple brokers running
* against the same logical database.
*
* @org.apache.xbean.XBean element="lease-database-locker"
*
*/
public class LeaseDatabaseLocker extends AbstractJDBCLocker {
private static final Logger LOG = LoggerFactory.getLogger(LeaseDatabaseLocker.class);
protected int maxAllowableDiffFromDBTime = 0;
protected long diffFromCurrentTime = Long.MAX_VALUE;
protected String leaseHolderId;
protected boolean handleStartException;
public void doStart() throws Exception {
if (lockAcquireSleepInterval < lockable.getLockKeepAlivePeriod()) {
LOG.warn("LockableService keep alive period: " + lockable.getLockKeepAlivePeriod()
+ ", which renews the lease, is less than lockAcquireSleepInterval: " + lockAcquireSleepInterval
+ ", the lease duration. These values will allow the lease to expire.");
}
LOG.info(getLeaseHolderId() + " attempting to acquire exclusive lease to become the master");
String sql = getStatements().getLeaseObtainStatement();
LOG.debug(getLeaseHolderId() + " locking Query is "+sql);
long now = 0l;
while (!isStopping()) {
Connection connection = null;
PreparedStatement statement = null;
try {
connection = getConnection();
initTimeDiff(connection);
statement = connection.prepareStatement(sql);
setQueryTimeout(statement);
now = System.currentTimeMillis() + diffFromCurrentTime;
statement.setString(1, getLeaseHolderId());
statement.setLong(2, now + lockAcquireSleepInterval);
statement.setLong(3, now);
int result = statement.executeUpdate();
if (result == 1) {
// we got the lease, verify we still have it
if (keepAlive()) {
break;
}
}
reportLeasOwnerShipAndDuration(connection);
} catch (Exception e) {
LOG.debug(getLeaseHolderId() + " lease acquire failure: "+ e, e);
if (isStopping()) {
throw new Exception(
"Cannot start broker as being asked to shut down. "
+ "Interrupted attempt to acquire lock: "
+ e, e);
}
if (handleStartException) {
lockable.getBrokerService().handleIOException(IOExceptionSupport.create(e));
}
} finally {
close(statement);
close(connection);
}
LOG.info(getLeaseHolderId() + " failed to acquire lease. Sleeping for " + lockAcquireSleepInterval + " milli(s) before trying again...");
TimeUnit.MILLISECONDS.sleep(lockAcquireSleepInterval);
}
if (isStopping()) {
throw new RuntimeException(getLeaseHolderId() + " failing lease acquire due to stop");
}
LOG.info(getLeaseHolderId() + ", becoming master with lease expiry " + new Date(now + lockAcquireSleepInterval) + " on dataSource: " + dataSource);
}
private void reportLeasOwnerShipAndDuration(Connection connection) throws SQLException {
PreparedStatement statement = null;
try {
statement = connection.prepareStatement(getStatements().getLeaseOwnerStatement());
ResultSet resultSet = statement.executeQuery();
while (resultSet.next()) {
LOG.info(getLeaseHolderId() + " Lease held by " + resultSet.getString(1) + " till " + new Date(resultSet.getLong(2)));
}
} finally {
close(statement);
}
}
protected long initTimeDiff(Connection connection) throws SQLException {
if (Long.MAX_VALUE == diffFromCurrentTime) {
if (maxAllowableDiffFromDBTime > 0) {
diffFromCurrentTime = determineTimeDifference(connection);
} else {
diffFromCurrentTime = 0l;
}
}
return diffFromCurrentTime;
}
protected long determineTimeDifference(Connection connection) throws SQLException {
PreparedStatement statement = connection.prepareStatement(getStatements().getCurrentDateTime());
ResultSet resultSet = statement.executeQuery();
long result = 0l;
if (resultSet.next()) {
Timestamp timestamp = resultSet.getTimestamp(1);
long diff = System.currentTimeMillis() - timestamp.getTime();
if (Math.abs(diff) > maxAllowableDiffFromDBTime) {
// off by more than maxAllowableDiffFromDBTime so lets adjust
result = (-diff);
}
LOG.info(getLeaseHolderId() + " diff adjust from db: " + result + ", db time: " + timestamp);
}
return result;
}
public void doStop(ServiceStopper stopper) throws Exception {
if (lockable.getBrokerService() != null && lockable.getBrokerService().isRestartRequested()) {
// keep our lease for restart
return;
}
releaseLease();
}
private void releaseLease() {
Connection connection = null;
PreparedStatement statement = null;
try {
connection = getConnection();
statement = connection.prepareStatement(getStatements().getLeaseUpdateStatement());
statement.setString(1, null);
statement.setLong(2, 0l);
statement.setString(3, getLeaseHolderId());
if (statement.executeUpdate() == 1) {
LOG.info(getLeaseHolderId() + ", released lease");
}
} catch (Exception e) {
LOG.error(getLeaseHolderId() + " failed to release lease: " + e, e);
} finally {
close(statement);
close(connection);
}
}
@Override
public boolean keepAlive() throws IOException {
boolean result = false;
final String sql = getStatements().getLeaseUpdateStatement();
LOG.debug(getLeaseHolderId() + ", lease keepAlive Query is " + sql);
Connection connection = null;
PreparedStatement statement = null;
try {
connection = getConnection();
initTimeDiff(connection);
statement = connection.prepareStatement(sql);
setQueryTimeout(statement);
final long now = System.currentTimeMillis() + diffFromCurrentTime;
statement.setString(1, getLeaseHolderId());
statement.setLong(2, now + lockAcquireSleepInterval);
statement.setString(3, getLeaseHolderId());
result = (statement.executeUpdate() == 1);
if (!result) {
reportLeasOwnerShipAndDuration(connection);
}
} catch (Exception e) {
LOG.warn(getLeaseHolderId() + ", failed to update lease: " + e, e);
IOException ioe = IOExceptionSupport.create(e);
lockable.getBrokerService().handleIOException(ioe);
throw ioe;
} finally {
close(statement);
close(connection);
}
return result;
}
public String getLeaseHolderId() {
if (leaseHolderId == null) {
if (lockable.getBrokerService() != null) {
leaseHolderId = lockable.getBrokerService().getBrokerName();
}
}
return leaseHolderId;
}
public void setLeaseHolderId(String leaseHolderId) {
this.leaseHolderId = leaseHolderId;
}
public int getMaxAllowableDiffFromDBTime() {
return maxAllowableDiffFromDBTime;
}
public void setMaxAllowableDiffFromDBTime(int maxAllowableDiffFromDBTime) {
this.maxAllowableDiffFromDBTime = maxAllowableDiffFromDBTime;
}
public boolean isHandleStartException() {
return handleStartException;
}
public void setHandleStartException(boolean handleStartException) {
this.handleStartException = handleStartException;
}
@Override
public String toString() {
return "LeaseDatabaseLocker owner:" + leaseHolderId + ",duration:" + lockAcquireSleepInterval + ",renew:" + lockAcquireSleepInterval;
}
}