net.javacrumbs.shedlock.provider.jdbc.JdbcLockProvider Maven / Gradle / Ivy

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/**
 * Copyright 2009 the original author or authors.
 *
 * 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 net.javacrumbs.shedlock.provider.jdbc;

import javax.sql.DataSource;
import net.javacrumbs.shedlock.support.StorageBasedLockProvider;
import net.javacrumbs.shedlock.support.annotation.NonNull;

/**
 * Lock provided by plain JDBC. It uses a table that contains lock_name and
 * locked_until.
 *
 * 

 * Attempts to insert a new lock record. Since lock name is a primary key,
 * it fails if the record already exists. As an optimization, we keep in-memory
 * track of created lock records.
 * 
If the insert succeeds (1 inserted row) we have the lock.
 * 
If the insert failed due to duplicate key or we have skipped the
 * insertion, we will try to update lock record using UPDATE tableName SET
 * lock_until = :lockUntil WHERE name = :lockName AND lock_until <= :now
 * 
If the update succeeded (1 updated row), we have the lock. If the update
 * failed (0 updated rows) somebody else holds the lock
 * 
When unlocking, lock_until is set to now.
 * 
 */
public class JdbcLockProvider extends StorageBasedLockProvider {
    public JdbcLockProvider(@NonNull DataSource datasource) {
        this(datasource, "shedlock");
    }

    public JdbcLockProvider(@NonNull DataSource datasource, @NonNull String tableName) {
        super(new JdbcStorageAccessor(datasource, tableName));
    }
}