server/src/main/java/org/apache/asyncweb/server/session/BasicSession.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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 org.apache.asyncweb.server.session;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.apache.asyncweb.server.HttpSession;
import org.apache.asyncweb.server.util.TimedPermit;

/**
 * A basic <code>Session</code> implementation which holds session values
 * in memory
 *
 */
class BasicSession implements HttpSession
{

    private TimedPermit permit;

    private boolean isAttached;

    private boolean isDestroyed;

    private Object lock = new Object();

    private BasicSessionStore owner;

    private String id;

    private Map<String, Object> values = Collections
            .synchronizedMap(new HashMap<String, Object>());

    /**
     * @param owner  The owner of this session
     */
    BasicSession(String id, BasicSessionStore owner) {
        this.owner = owner;
        this.id = id;
    }

    public Object getValue(String key) {
        return values.get(key);
    }

    public void setValue(String key, Object value) {
        values.put(key, value);
    }

    public Object removeValue(String key) {
        return values.remove(key);
    }

    public boolean isAttached() {
        return isAttached;
    }

    public boolean isValid() {
        synchronized (lock) {
            return !isDestroyed;
        }
    }

    /**
     * Destroys this session if it is not already destroyed.
     * If destruction takes place, notifications are fired.
     */
    public void destroy() {
        if (destroyIfActive()) {
            owner.sessionDestroyed(this);
        }
    }

    /**
     * @return  The id of this session
     */
    public String getId() {
        return id;
    }

    /**
     * Instructs this session to expire.
     * If this session is not already expired, expiration notifications
     * are fired
     */
    void expire() {
        if (destroyIfActive()) {
            owner.sessionExpired(this);
        }
    }

    /**
     * Sets the permit associated with this session
     *
     * @param permit  This sessions access permit
     */
    void setPermit(TimedPermit permit) {
        this.permit = permit;
    }

    /**
     * Invoked when this session is referenced by a client request.
     * The permit associated with this session is renewed, and subsequent calls
     * to <code>isAttached</code> will return <code>true</code>
     */
    void access() {
        permit.renew();
        isAttached = true;
    }

    /**
     * Destroys this session if it is not destroyed already.
     *
     * @return  <code>true</code> if this session is successfully
     */
    private boolean destroyIfActive() {
        synchronized (lock) {
            if (isDestroyed) {
                return false;
            }
            isDestroyed = true;
        }
        permit.cancel();
        return true;
    }

}