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	/*
	* Copyright (c) 2002, 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 com.sun.jndi.ldap.pool;

	/**
	* Represents a description of PooledConnection in Connections.
	* Contains a PooledConnection, its state (busy, idle, expired), and idle time.
	*
	* Any access or update to a descriptor's state is synchronized.
	*
	* @author Rosanna Lee
	*/
	final class ConnectionDesc {
	private final static boolean debug = Pool.debug;

	// Package private because used by Pool.showStats()
	static final byte BUSY = (byte)0;
	static final byte IDLE = (byte)1;
	static final byte EXPIRED = (byte)2;

	final private PooledConnection conn;

	private byte state = IDLE; // initial state
	private long idleSince;
	private long useCount = 0; // for stats & debugging only

	ConnectionDesc(PooledConnection conn) {
	this.conn = conn;
	}

	ConnectionDesc(PooledConnection conn, boolean use) {
	this.conn = conn;
	if (use) {
	state = BUSY;
	++useCount;
	}
	}

	/**
	* Two desc are equal if their PooledConnections are the same.
	* This is useful when searching for a ConnectionDesc using only its
	* PooledConnection.
	*/
	public boolean equals(Object obj) {
	return obj != null
	&& obj instanceof ConnectionDesc
	&& ((ConnectionDesc)obj).conn == conn;
	}

	/**
	* Hashcode is that of PooledConnection to facilitate
	* searching for a ConnectionDesc using only its PooledConnection.
	*/
	public int hashCode() {
	return conn.hashCode();
	}

	/**
	* Changes the state of a ConnectionDesc from BUSY to IDLE and
	* records the current time so that we will know how long it has been idle.
	* @return true if state change occurred.
	*/
	synchronized boolean release() {
	d("release()");
	if (state == BUSY) {
	state = IDLE;

	idleSince = System.currentTimeMillis();
	return true; // Connection released, ready for reuse
	} else {
	return false; // Connection wasn't busy to begin with
	}
	}

	/**
	* If ConnectionDesc is IDLE, change its state to BUSY and return
	* its connection.
	*
	* @return ConnectionDesc's PooledConnection if it was idle; null otherwise.
	*/
	synchronized PooledConnection tryUse() {
	d("tryUse()");

	if (state == IDLE) {
	state = BUSY;
	++useCount;
	return conn;
	}

	return null;
	}

	/**
	* If ConnectionDesc is IDLE and has expired, close the corresponding
	* PooledConnection.
	*
	* @param threshold a connection that has been idle before this time
	* have expired.
	*
	* @return true if entry is idle and has expired; false otherwise.
	*/
	synchronized boolean expire(long threshold) {
	if (state == IDLE && idleSince < threshold) {

	d("expire(): expired");

	state = EXPIRED;
	conn.closeConnection(); // Close real connection

	return true; // Expiration successful
	} else {
	d("expire(): not expired");
	return false; // Expiration did not occur
	}
	}

	public String toString() {
	return conn.toString() + " " +
	(state == BUSY ? "busy" : (state == IDLE ? "idle" : "expired"));
	}

	// Used by Pool.showStats()
	int getState() {
	return state;
	}

	// Used by Pool.showStats()
	long getUseCount() {
	return useCount;
	}

	private void d(String msg) {
	if (debug) {
	System.err.println("ConnectionDesc." + msg + " " + toString());
	}
	}
	}

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