| /* |
| * Copyright (c) 1996, 2013, 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 java.rmi.dgc; |
| |
| import java.rmi.server.UID; |
| import java.security.SecureRandom; |
| |
| /** |
| * A VMID is a identifier that is unique across all Java virtual |
| * machines. VMIDs are used by the distributed garbage collector |
| * to identify client VMs. |
| * |
| * @author Ann Wollrath |
| * @author Peter Jones |
| */ |
| public final class VMID implements java.io.Serializable { |
| /** Array of bytes uniquely identifying this host */ |
| private static final byte[] randomBytes; |
| |
| /** |
| * @serial array of bytes uniquely identifying host created on |
| */ |
| private byte[] addr; |
| |
| /** |
| * @serial unique identifier with respect to host created on |
| */ |
| private UID uid; |
| |
| /** indicate compatibility with JDK 1.1.x version of class */ |
| private static final long serialVersionUID = -538642295484486218L; |
| |
| static { |
| // Generate 8 bytes of random data. |
| SecureRandom secureRandom = new SecureRandom(); |
| byte bytes[] = new byte[8]; |
| secureRandom.nextBytes(bytes); |
| randomBytes = bytes; |
| } |
| |
| /** |
| * Create a new VMID. Each new VMID returned from this constructor |
| * is unique for all Java virtual machines under the following |
| * conditions: a) the conditions for uniqueness for objects of |
| * the class <code>java.rmi.server.UID</code> are satisfied, and b) an |
| * address can be obtained for this host that is unique and constant |
| * for the lifetime of this object. |
| */ |
| public VMID() { |
| addr = randomBytes; |
| uid = new UID(); |
| } |
| |
| /** |
| * Return true if an accurate address can be determined for this |
| * host. If false, reliable VMID cannot be generated from this host |
| * @return true if host address can be determined, false otherwise |
| * @deprecated |
| */ |
| @Deprecated |
| public static boolean isUnique() { |
| return true; |
| } |
| |
| /** |
| * Compute hash code for this VMID. |
| */ |
| public int hashCode() { |
| return uid.hashCode(); |
| } |
| |
| /** |
| * Compare this VMID to another, and return true if they are the |
| * same identifier. |
| */ |
| public boolean equals(Object obj) { |
| if (obj instanceof VMID) { |
| VMID vmid = (VMID) obj; |
| if (!uid.equals(vmid.uid)) |
| return false; |
| if ((addr == null) ^ (vmid.addr == null)) |
| return false; |
| if (addr != null) { |
| if (addr.length != vmid.addr.length) |
| return false; |
| for (int i = 0; i < addr.length; ++ i) |
| if (addr[i] != vmid.addr[i]) |
| return false; |
| } |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| /** |
| * Return string representation of this VMID. |
| */ |
| public String toString() { |
| StringBuilder sb = new StringBuilder(); |
| if (addr != null) |
| for (int i = 0; i < addr.length; ++ i) { |
| int x = addr[i] & 0xFF; |
| sb.append((x < 0x10 ? "0" : "") + |
| Integer.toString(x, 16)); |
| } |
| sb.append(':'); |
| sb.append(uid.toString()); |
| return sb.toString(); |
| } |
| } |