1/* 2 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package com.sun.jndi.ldap.pool; 27 28import java.lang.ref.WeakReference; 29import java.lang.ref.ReferenceQueue; 30 31/* 32 * This class defines a WeakReference to the ConnectionRef (the referent). 33 * 34 * The ConnectionRef enables to break the reference 35 * cycle between Connection, LdapClient, Connections and ConnectionDesc, 36 * shown in the figure below. 37 * 38 * -------> Connections -----> ConnectionDesc 39 * | ^ | 40 * | | | 41 * | | | 42 * ConnectionsRef LdapClient <------------ 43 * ^ | ^ 44 * : | | 45 * : v | 46 * ConnectionsWeakRef Connection 47 * 48 * The ConnectionsRef is for cleaning up the resources held by the 49 * Connection thread by making them available to the GC. The pool 50 * uses ConnectionRef to hold the pooled resources. 51 * 52 * This class in turn holds a WeakReference with a ReferenceQueue to the 53 * ConnectionRef to track when the ConnectionRef becomes ready 54 * for getting GC'ed. It extends from WeakReference in order to hold a 55 * reference to Connections used for closing (which in turn terminates 56 * the Connection thread) it by monitoring the ReferenceQueue. 57 */ 58class ConnectionsWeakRef extends WeakReference<ConnectionsRef> { 59 60 private final Connections conns; 61 62 ConnectionsWeakRef (ConnectionsRef connsRef, 63 ReferenceQueue<? super ConnectionsRef> queue) { 64 super(connsRef, queue); 65 this.conns = connsRef.getConnections(); 66 } 67 68 Connections getConnections() { 69 return conns; 70 } 71} 72