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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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,      Peter Jones/**
 * 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 /** Array of bytes uniquely identifying this host */
    private static final byte[] randomBytes;

    
@serial
array of bytes uniquely identifying host created on/**
     * @serial array of bytes uniquely identifying host created on
     */
    private byte[] addr;

    
@serial
unique identifier with respect to host created on/**
     * @serial unique identifier with respect to host created on
     */
    private UID uid;

    
indicate compatibility with JDK 1.1.x version of class /** 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 java.rmi.server.UID are satisfied, and b) an
address can be obtained for this host that is unique and constant
for the lifetime of this object.
/**
     * 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
Returns:
true if host address can be determined, false otherwise
Deprecated:
/**
     * 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.
/**
     * 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.
/**
     * 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.
/**
     * Return string representation of this VMID.
     */
    public String toString() {
        StringBuffer result = new StringBuffer();
        if (addr != null)
            for (int i = 0; i < addr.length; ++ i) {
                int x = addr[i] & 0xFF;
                result.append((x < 0x10 ? "0" : "") +
                              Integer.toString(x, 16));
            }
        result.append(':');
        result.append(uid.toString());
        return result.toString();
    }
}