DbEnvState.java

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2002-2006
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: DbEnvState.java,v 1.1 2006/05/06 09:00:24 ckaestne Exp $
 */

package com.sleepycat.je.dbi;

import com.sleepycat.je.DatabaseException;

/**
 * DbEnvState implements a typesafe enumeration of environment states
 * and does state change validation.
 */
class DbEnvState {
    private static final boolean DEBUG = false;

    private String name;

    /* Valid environment states. */
    public static final DbEnvState INIT = new DbEnvState("initialized");
    public static final DbEnvState OPEN = new DbEnvState("open");
    public static final DbEnvState CLOSED = new DbEnvState("closed");
    public static final DbEnvState INVALID = new DbEnvState("invalid");

    /* Valid previous states, for state transition checking. */
    public static final DbEnvState[] VALID_FOR_OPEN =   {INIT, CLOSED};
    public static final DbEnvState[] VALID_FOR_CLOSE =  {INIT, OPEN, INVALID};
    public static final DbEnvState[] VALID_FOR_REMOVE = {INIT, CLOSED};
    
    DbEnvState(String name) {
        this.name = name;
    }
    
    public String toString() {
        return name;
    }
    
    /* Check for valid state transitions. */
    void checkState(DbEnvState [] validPrevStates,
                    DbEnvState newState)
        throws DatabaseException {

        if (DEBUG) {
            System.out.println("newState = " + newState +
                               " currentState = " + name);
        }
        boolean transitionOk = false;
        for (int i = 0; i < validPrevStates.length; i++) {
            if (this == validPrevStates[i]) {
                transitionOk = true;
                break;
            }
        }
        if (!transitionOk) {
            throw new DatabaseException("Can't go from environment state " +
					toString() + 
					" to " +
					newState.toString());
        }
    }
}