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/*-
* ============LICENSE_START=======================================================
* openECOMP : APP-C
* ================================================================================
* Copyright (C) 2017 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.openecomp.appc.lockmanager.impl.sql.optimistic;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.openecomp.appc.lockmanager.api.LockException;
import org.openecomp.appc.lockmanager.api.LockRuntimeException;
import org.openecomp.appc.lockmanager.impl.sql.JdbcLockManager;
import org.openecomp.appc.lockmanager.impl.sql.Messages;
abstract class SqlLockManager extends JdbcLockManager {
private static final String SQL_LOAD_LOCK_RECORD = "SELECT * FROM %s WHERE RESOURCE_ID=?";
private static final String SQL_INSERT_LOCK_RECORD = "INSERT INTO %s (RESOURCE_ID, OWNER_ID, UPDATED, TIMEOUT, VER) VALUES (?, ?, ?, ?, ?)";
private static final String SQL_UPDATE_LOCK_RECORD = "UPDATE %s SET OWNER_ID=?, UPDATED=?, TIMEOUT=?, VER=? WHERE RESOURCE_ID=? AND VER=?";
// private static final String SQL_DELETE_LOCK_RECORD = "DELETE FROM %s WHERE RESOURCE_ID=? AND VER=?";
private static final String SQL_CURRENT_TIMESTAMP = "SELECT CURRENT_TIMESTAMP()";
private String sqlLoadLockRecord;
private String sqlInsertLockRecord;
private String sqlUpdateLockRecord;
// private String sqlDeleteLockRecord;
@Override
public boolean acquireLock(String resource, String owner) throws LockException {
return acquireLock(resource, owner, 0);
}
@Override
public boolean acquireLock(String resource, String owner, long timeout) throws LockException {
if(owner == null) {
throw new LockRuntimeException(Messages.ERR_NULL_LOCK_OWNER.format(resource));
}
boolean res = false;
Connection connection = openDbConnection();
try {
res = lockResource(connection, resource, owner, timeout);
} finally {
closeDbConnection(connection);
}
return res;
}
@Override
public void releaseLock(String resource, String owner) throws LockException {
Connection connection = openDbConnection();
try {
unlockResource(connection, resource, owner);
} finally {
closeDbConnection(connection);
}
}
@Override
public boolean isLocked(String resource) {
Connection connection=openDbConnection();
try {
LockRecord lockRecord=loadLockRecord(connection,resource);
if(lockRecord==null){
return false;
}else{
if(lockRecord.getOwner()==null){
return false;
}else if(isLockExpired(lockRecord, connection)){
return false;
}else{
return true;
}
}
} catch (SQLException e) {
throw new LockRuntimeException(Messages.EXP_LOCK.format(resource));
}finally {
closeDbConnection(connection);
}
}
private boolean lockResource(Connection connection, String resource, String owner, long timeout) throws LockException {
try {
boolean res = false;
LockRecord lockRecord = loadLockRecord(connection, resource);
if(lockRecord != null) {
// lock record already exists
String currentOwner = lockRecord.getOwner();
if(currentOwner != null) {
if(isLockExpired(lockRecord, connection)) {
currentOwner = null;
} else if(!owner.equals(currentOwner)) {
throw new LockException(Messages.ERR_LOCK_LOCKED_BY_OTHER.format(resource, owner, currentOwner));
}
}
// set new owner on the resource lock record
if(!updateLockRecord(connection, resource, owner, timeout, lockRecord.getVer())) {
// try again - maybe same owner updated the record
lockResource(connection, resource, owner, timeout);
}
if(currentOwner == null) {
// no one locked the resource before
res = true;
}
} else {
// resource record does not exist in lock table => create new record
try {
addLockRecord(connection, resource, owner, timeout);
res = true;
} catch(SQLException e) {
if(isDuplicatePkError(e)) {
// try again - maybe same owner inserted the record
lockResource(connection, resource, owner, timeout);
} else {
throw e;
}
}
}
return res;
} catch(SQLException e) {
throw new LockRuntimeException(Messages.EXP_LOCK.format(resource), e);
}
}
protected boolean isDuplicatePkError(SQLException e) {
return e.getSQLState().startsWith("23");
}
private void unlockResource(Connection connection, String resource, String owner) throws LockException {
try {
LockRecord lockRecord = loadLockRecord(connection, resource);
if(lockRecord != null) {
// check if expired
if(isLockExpired(lockRecord, connection)) {
// lock is expired => no lock
lockRecord = null;
}
}
if((lockRecord == null) || (lockRecord.getOwner() == null)) {
// resource is not locked
throw new LockException(Messages.ERR_UNLOCK_NOT_LOCKED.format(resource));
}
String currentOwner = lockRecord.getOwner();
if(!owner.equals(currentOwner)) {
throw new LockException(Messages.ERR_UNLOCK_LOCKED_BY_OTHER.format(resource, owner, currentOwner));
}
if (!updateLockRecord(connection, resource, null, 0, lockRecord.getVer())) {
unlockResource(connection, resource, owner);
}
// TODO delete record from table on lock release?
// deleteLockRecord(connection, resource, lockRecord.getVer());
} catch(SQLException e) {
throw new LockRuntimeException(Messages.EXP_UNLOCK.format(resource), e);
}
}
protected LockRecord loadLockRecord(Connection connection, String resource) throws SQLException {
LockRecord res = null;
if(sqlLoadLockRecord == null) {
sqlLoadLockRecord = String.format(SQL_LOAD_LOCK_RECORD, tableName);
}
try(PreparedStatement statement = connection.prepareStatement(sqlLoadLockRecord)) {
statement.setString(1, resource);
try(ResultSet resultSet = statement.executeQuery()) {
if(resultSet.next()) {
res = new LockRecord(resource);
res.setOwner(resultSet.getString(2));
res.setUpdated(resultSet.getLong(3));
res.setTimeout(resultSet.getLong(4));
res.setVer(resultSet.getLong(5));
}
}
}
return res;
}
protected void addLockRecord(Connection connection, String resource, String owner, long timeout) throws SQLException {
if(sqlInsertLockRecord == null) {
sqlInsertLockRecord = String.format(SQL_INSERT_LOCK_RECORD, tableName);
}
try(PreparedStatement statement = connection.prepareStatement(sqlInsertLockRecord)) {
statement.setString(1, resource);
statement.setString(2, owner);
statement.setLong(3, getCurrentTime(connection));
statement.setLong(4, timeout);
statement.setLong(5, 1);
statement.executeUpdate();
}
}
protected boolean updateLockRecord(Connection connection, String resource, String owner, long timeout, long ver) throws SQLException {
if(sqlUpdateLockRecord == null) {
sqlUpdateLockRecord = String.format(SQL_UPDATE_LOCK_RECORD, tableName);
}
try(PreparedStatement statement = connection.prepareStatement(sqlUpdateLockRecord)) {
long newVer = (ver >= Long.MAX_VALUE) ? 1 : (ver + 1);
statement.setString(1, owner);
statement.setLong(2, getCurrentTime(connection));
statement.setLong(3, timeout);
statement.setLong(4, newVer);
statement.setString(5, resource);
statement.setLong(6, ver);
return (statement.executeUpdate() != 0);
}
}
// protected void deleteLockRecord(Connection connection, String resource, long ver) throws SQLException {
// if(sqlDeleteLockRecord == null) {
// sqlDeleteLockRecord = String.format(SQL_DELETE_LOCK_RECORD, tableName);
// }
// try(PreparedStatement statement = connection.prepareStatement(sqlDeleteLockRecord)) {
// statement.setString(1, resource);
// statement.setLong(2, ver);
// statement.executeUpdate();
// }
// }
private boolean isLockExpired(LockRecord lockRecord, Connection connection) throws SQLException {
long timeout = lockRecord.getTimeout();
if(timeout == 0) {
return false;
}
long updated = lockRecord.getUpdated();
long now = getCurrentTime(connection);
long expiration = updated + timeout;
return (now > expiration);
}
private long getCurrentTime(Connection connection) throws SQLException {
long res = -1;
if(connection != null) {
try(PreparedStatement statement = connection.prepareStatement(SQL_CURRENT_TIMESTAMP)) {
try(ResultSet resultSet = statement.executeQuery()) {
if(resultSet.next()) {
res = resultSet.getTimestamp(1).getTime();
}
}
}
}
if(res == -1) {
res = System.currentTimeMillis();
}
return res;
}
}
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