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Utility classes developed at Adrian Smith Software (A.S.S.)

There is a newer version: 21.0.1

package com.databasesandlife.util.jdbc;

import java.util.HashMap;

/** 
 * Maintains a table full of mutexes as described
 * here
 *    
 * To use this, create this table:
 * 
 *   CREATE TABLE mutex (name VARCHAR(100)) ENGINE=InnoDB;
 *  
 *
 * @author This source is copyright Adrian Smith and licensed under the LGPL 3.
 * @see Project on GitHub
 */
@SuppressWarnings("serial")
public class DbMutex {
    
    public String name;
    
    public DbMutex(String name) { this.name = name; }
    
    public void acquire(DbTransaction tx) {
        tx.insertIgnoringUniqueConstraintViolations("mutex", new HashMap() {{ put("name", name); }});
        tx.query("SELECT * FROM mutex WHERE name=? FOR UPDATE", name);
    }

}