/*

 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.security.pkcs11;

import java.lang.ref.*;

import java.util.*;

import java.util.concurrent.atomic.AtomicInteger;

import java.security.*;

import sun.security.pkcs11.wrapper.*;

/**

 * A session object. Sessions are obtained via the SessionManager,

 * see there for details. Most code will only ever need one method in

 * this class, the id() method to obtain the session id.

 *

 * @author  Andreas Sterbenz

 * @since   1.5

 */

final class Session implements Comparable<Session> {

    // time after which to close idle sessions, in milliseconds (3 minutes)

    private final static long MAX_IDLE_TIME = 3 * 60 * 1000;

    // token instance

    final Token token;

    // session id

    private final long id;

    // number of objects created within this session

    private final AtomicInteger createdObjects;

    // time this session was last used

    // not synchronized/volatile for performance, so may be unreliable

    // this could lead to idle sessions being closed early, but that is harmless

    private long lastAccess;

    private final SessionRef sessionRef;

    Session(Token token, long id) {

        this.token = token;

        this.id = id;

        createdObjects = new AtomicInteger();

        id();

        sessionRef = new SessionRef(this, id, token);

    }

    public int compareTo(Session other) {

        if (this.lastAccess == other.lastAccess) {

            return 0;

        } else {

            return (this.lastAccess < other.lastAccess) ? -1 : 1;

        }

    }

    boolean isLive(long currentTime) {

        return currentTime - lastAccess < MAX_IDLE_TIME;

    }

    long idInternal() {

        return id;

    }

    long id() {

        if (token.isPresent(this.id) == false) {

            throw new ProviderException("Token has been removed");

        }

        lastAccess = System.currentTimeMillis();

        return id;

    }

    void addObject() {

        int n = createdObjects.incrementAndGet();

        // XXX update statistics in session manager if n == 1

    }

    void removeObject() {

        int n = createdObjects.decrementAndGet();

        if (n == 0) {

            token.sessionManager.demoteObjSession(this);

        } else if (n < 0) {

            throw new ProviderException("Internal error: objects created " + n);

        }

    }

    boolean hasObjects() {

        return createdObjects.get() != 0;

    }

    void close() {

        if (hasObjects()) {

            throw new ProviderException(

                "Internal error: close session with active objects");

        }

        sessionRef.dispose();

    }

}

/*

 * NOTE: Use PhantomReference here and not WeakReference

 * otherwise the sessions maybe closed before other objects

 * which are still being finalized.

 */

final class SessionRef extends PhantomReference<Session>

        implements Comparable<SessionRef> {

    private static ReferenceQueue<Session> refQueue =

        new ReferenceQueue<Session>();

    private static Set<SessionRef> refList =

        Collections.synchronizedSortedSet(new TreeSet<SessionRef>());

    static ReferenceQueue<Session> referenceQueue() {

        return refQueue;

    }

    static int totalCount() {

        return refList.size();

    }

    private static void drainRefQueueBounded() {

        while (true) {

            SessionRef next = (SessionRef) refQueue.poll();

            if (next == null) break;

            next.dispose();

        }

    }

    // handle to the native session

    private long id;

    private Token token;

    SessionRef(Session session, long id, Token token) {

        super(session, refQueue);

        this.id = id;

        this.token = token;

        refList.add(this);

        // TBD: run at some interval and not every time?

        drainRefQueueBounded();

    }

    void dispose() {

        refList.remove(this);

        try {

            if (token.isPresent(id)) {

                token.p11.C_CloseSession(id);

            }

        } catch (PKCS11Exception e1) {

            // ignore

        } catch (ProviderException e2) {

            // ignore

        } finally {

            this.clear();

        }

    }

    public int compareTo(SessionRef other) {

        if (this.id == other.id) {

            return 0;

        } else {

            return (this.id < other.id) ? -1 : 1;

        }

    }

}