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/*
* Copyright 2006-2012 Amazon Technologies, Inc. or its affiliates.
* Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
* of Amazon Technologies, Inc. or its affiliates. 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.
*/
package com.amazon.carbonado.repo.jdbc;
import java.util.ArrayList;
import java.util.List;
import java.sql.Connection;
import java.sql.Savepoint;
import java.sql.SQLException;
import com.amazon.carbonado.IsolationLevel;
/**
* JDBCTransaction is just a wrapper around a connection and (optionally) a
* savepoint.
*
* @author Brian S O'Neill
*/
class JDBCTransaction {
// Use this magic value to indicate that the isolation level need not be
// changed when the transaction ends. This is a little optimization to
// avoid a round trip call to the remote database.
private static final int LEVEL_NOT_CHANGED = -1;
private final boolean mIsNested;
private final Connection mConnection;
private final int mOriginalLevel;
private boolean mReady = true;
private Savepoint mSavepoint;
private List<JDBCLob> mRegisteredLobs;
JDBCTransaction(Connection con) {
mIsNested = false;
mConnection = con;
// Don't change level upon abort.
mOriginalLevel = LEVEL_NOT_CHANGED;
}
/**
* Construct a nested transaction.
*/
JDBCTransaction(JDBCTransaction parent, IsolationLevel level) throws SQLException {
mIsNested = true;
mConnection = parent.mConnection;
if (level == null) {
// Don't change level upon abort.
mOriginalLevel = LEVEL_NOT_CHANGED;
} else {
int newLevel = JDBCRepository.mapIsolationLevelToJdbc(level);
int originalLevel = mConnection.getTransactionIsolation();
if (newLevel == originalLevel) {
// Don't change level upon abort.
mOriginalLevel = LEVEL_NOT_CHANGED;
} else {
// Do change level upon abort.
mOriginalLevel = originalLevel;
if (originalLevel == Connection.TRANSACTION_NONE) {
mConnection.setAutoCommit(false);
}
mConnection.setTransactionIsolation(newLevel);
}
}
mSavepoint = mConnection.setSavepoint();
}
Connection getConnection() {
return mConnection;
}
void reuse() throws SQLException {
if (mIsNested && mSavepoint == null) {
mSavepoint = mConnection.setSavepoint();
}
mReady = true;
}
void commit() throws SQLException {
if (mIsNested) {
mSavepoint = null;
} else {
mConnection.commit();
}
mReady = false;
}
/**
* @return true if the connection should be closed after the transaction is aborted.
*/
boolean shouldCloseConnection() {
return !mIsNested;
}
/**
* Note: The caller should close the connection after aborting if
* shouldCloseConnection() returns true.
*/
void abort() throws SQLException {
if (mRegisteredLobs != null) {
for (JDBCLob lob : mRegisteredLobs) {
lob.close();
}
mRegisteredLobs = null;
}
if (mIsNested) {
if (mReady) {
if (mSavepoint != null) {
mConnection.rollback(mSavepoint);
mSavepoint = null;
}
mReady = false;
}
if (mOriginalLevel != LEVEL_NOT_CHANGED) {
if (mOriginalLevel == Connection.TRANSACTION_NONE) {
mConnection.setAutoCommit(true);
} else {
mConnection.setTransactionIsolation(mOriginalLevel);
}
}
} else {
if (mReady) {
mConnection.rollback();
mReady = false;
}
}
}
void register(JDBCLob lob) {
if (mRegisteredLobs == null) {
mRegisteredLobs = new ArrayList<JDBCLob>(4);
}
mRegisteredLobs.add(lob);
}
}
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