/*
 * Copyright 2006 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;

/**
 * An OptimisticLockException is thrown if the {@link Repository} is using
 * optimistic locking for concurrency control, and lock aquisition failed.
 * This exception may also be thrown if multiversion concurrency control (MVCC)
 * is being used and the commit fails.
 *
 * @author Brian S O'Neill
 */
public class OptimisticLockException extends PersistException {

    private static final long serialVersionUID = 4081788711829580886L;

    public OptimisticLockException() {
        super();
    }

    public OptimisticLockException(String message) {
        super(message);
    }

    public OptimisticLockException(String message, Throwable cause) {
        super(message, cause);
    }

    public OptimisticLockException(Throwable cause) {
        super(cause);
    }

    /**
     * @param expectedVersion version number that was expected for persistent
     * record when update was executed
     */
    public OptimisticLockException(long expectedVersion) {
        this((Long) expectedVersion);
    }

    /**
     * @param expectedVersion version number that was expected for persistent
     * record when update was executed
     */
    public OptimisticLockException(Object expectedVersion) {
        this(expectedVersion, null);
    }

    /**
     * @param expectedVersion version number that was expected for persistent
     * record when update was executed
     * @param savedVersion actual persistent version number of storable
     */
    public OptimisticLockException(Object expectedVersion, Object savedVersion) {
        super(makeMessage(expectedVersion, savedVersion));
    }

    private static String makeMessage(Object expectedVersion, Object savedVersion) {
        if (expectedVersion == null) {
            if (savedVersion == null) {
                return null;
            }
            return "Failed to update because saved version is " + savedVersion;
        }
        if (savedVersion == null) {
            return "Failed to update for expected version " + expectedVersion;
        }
        return "Failed to update for expected version " + expectedVersion +
            " because saved version is " + savedVersion;
    }
}