J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package com.sun.tools.attach; |
| 27 | |
| 28 | import com.sun.tools.attach.spi.AttachProvider; |
| 29 | |
| 30 | /** |
| 31 | * Describes a Java virtual machine. |
| 32 | * |
| 33 | * <p> A <code>VirtualMachineDescriptor</code> is a container class used to |
| 34 | * describe a Java virtual machine. It encapsulates an identifier that identifies |
| 35 | * a target virtual machine, and a reference to the {@link |
| 36 | * com.sun.tools.attach.spi.AttachProvider AttachProvider} that should be used |
| 37 | * when attempting to attach to the virtual machine. The identifier is |
| 38 | * implementation-dependent but is typically the process identifier (or pid) |
| 39 | * environments where each Java virtual machine runs in its own operating system |
| 40 | * process. </p> |
| 41 | * |
| 42 | * <p> A <code>VirtualMachineDescriptor</code> also has a {@link #displayName() displayName}. |
| 43 | * The display name is typically a human readable string that a tool might |
| 44 | * display to a user. For example, a tool that shows a list of Java |
| 45 | * virtual machines running on a system might use the display name rather |
| 46 | * than the identifier. A <code>VirtualMachineDescriptor</code> may be |
| 47 | * created without a <i>display name</i>. In that case the identifier is |
| 48 | * used as the <i>display name</i>. |
| 49 | * |
| 50 | * <p> <code>VirtualMachineDescriptor</code> instances are typically created by |
| 51 | * invoking the {@link com.sun.tools.attach.VirtualMachine#list VirtualMachine.list()} |
| 52 | * method. This returns the complete list of descriptors to describe the |
| 53 | * Java virtual machines known to all installed {@link |
| 54 | * com.sun.tools.attach.spi.AttachProvider attach providers}. |
| 55 | * |
| 56 | * @since 1.6 |
| 57 | */ |
| 58 | public class VirtualMachineDescriptor { |
| 59 | |
| 60 | private AttachProvider provider; |
| 61 | private String id; |
| 62 | private String displayName; |
| 63 | |
| 64 | private volatile int hash; // 0 => not computed |
| 65 | |
| 66 | /** |
| 67 | * Creates a virtual machine descriptor from the given components. |
| 68 | * |
| 69 | * @param provider The AttachProvider to attach to the Java virtual machine. |
| 70 | * @param id The virtual machine identifier. |
| 71 | * @param displayName The display name. |
| 72 | * |
| 73 | * @throws NullPointerException |
| 74 | * If any of the arguments are <code>null</code> |
| 75 | */ |
| 76 | public VirtualMachineDescriptor(AttachProvider provider, String id, String displayName) { |
| 77 | if (provider == null) { |
| 78 | throw new NullPointerException("provider cannot be null"); |
| 79 | } |
| 80 | if (id == null) { |
| 81 | throw new NullPointerException("identifier cannot be null"); |
| 82 | } |
| 83 | if (displayName == null) { |
| 84 | throw new NullPointerException("display name cannot be null"); |
| 85 | } |
| 86 | this.provider = provider; |
| 87 | this.id = id; |
| 88 | this.displayName = displayName; |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * Creates a virtual machine descriptor from the given components. |
| 93 | * |
| 94 | * <p> This convenience constructor works as if by invoking the |
| 95 | * three-argument constructor as follows: |
| 96 | * |
| 97 | * <blockquote><tt> |
| 98 | * new {@link #VirtualMachineDescriptor(AttachProvider, String, String) |
| 99 | * VirtualMachineDescriptor}(provider, id, id); |
| 100 | * </tt></blockquote> |
| 101 | * |
| 102 | * <p> That is, it creates a virtual machine descriptor such that |
| 103 | * the <i>display name</i> is the same as the virtual machine |
| 104 | * identifier. |
| 105 | * |
| 106 | * @param provider The AttachProvider to attach to the Java virtual machine. |
| 107 | * @param id The virtual machine identifier. |
| 108 | * |
| 109 | * @throws NullPointerException |
| 110 | * If <tt>provider</tt> or <tt>id</tt> is <tt>null</tt>. |
| 111 | */ |
| 112 | public VirtualMachineDescriptor(AttachProvider provider, String id) { |
| 113 | this(provider, id, id); |
| 114 | } |
| 115 | |
| 116 | /** |
| 117 | * Return the <code>AttachProvider</code> that this descriptor references. |
| 118 | * |
| 119 | * @return The <code>AttachProvider</code> that this descriptor references. |
| 120 | */ |
| 121 | public AttachProvider provider() { |
| 122 | return provider; |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Return the identifier component of this descriptor. |
| 127 | * |
| 128 | * @return The identifier component of this descriptor. |
| 129 | */ |
| 130 | public String id() { |
| 131 | return id; |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Return the <i>display name</i> component of this descriptor. |
| 136 | * |
| 137 | * @return The display name component of this descriptor. |
| 138 | */ |
| 139 | public String displayName() { |
| 140 | return displayName; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * Returns a hash-code value for this VirtualMachineDescriptor. The hash |
| 145 | * code is based upon the descriptor's components, and satifies |
| 146 | * the general contract of the {@link java.lang.Object#hashCode() |
| 147 | * Object.hashCode} method. |
| 148 | * |
| 149 | * @return A hash-code value for this descriptor. |
| 150 | */ |
| 151 | public int hashCode() { |
| 152 | if (hash != 0) { |
| 153 | return hash; |
| 154 | } |
| 155 | hash = provider.hashCode() * 127 + id.hashCode(); |
| 156 | return hash; |
| 157 | } |
| 158 | |
| 159 | /** |
| 160 | * Tests this VirtualMachineDescriptor for equality with another object. |
| 161 | * |
| 162 | * <p> If the given object is not a VirtualMachineDescriptor then this |
| 163 | * method returns <tt>false</tt>. For two VirtualMachineDescriptors to |
| 164 | * be considered equal requires that they both reference the same |
| 165 | * provider, and their {@link #id() identifiers} are equal. </p> |
| 166 | * |
| 167 | * <p> This method satisfies the general contract of the {@link |
| 168 | * java.lang.Object#equals(Object) Object.equals} method. </p> |
| 169 | * |
| 170 | * @param ob The object to which this object is to be compared |
| 171 | * |
| 172 | * @return <tt>true</tt> if, and only if, the given object is |
| 173 | * a VirtualMachineDescriptor that is equal to this |
| 174 | * VirtualMachineDescriptor. |
| 175 | */ |
| 176 | public boolean equals(Object ob) { |
| 177 | if (ob == this) |
| 178 | return true; |
| 179 | if (!(ob instanceof VirtualMachineDescriptor)) |
| 180 | return false; |
| 181 | VirtualMachineDescriptor other = (VirtualMachineDescriptor)ob; |
| 182 | if (other.provider() != this.provider()) { |
| 183 | return false; |
| 184 | } |
| 185 | if (!other.id().equals(this.id())) { |
| 186 | return false; |
| 187 | } |
| 188 | return true; |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * Returns the string representation of the <code>VirtualMachineDescriptor</code>. |
| 193 | */ |
| 194 | public String toString() { |
| 195 | String s = provider.toString() + ": " + id; |
| 196 | if (displayName != id) { |
| 197 | s += " " + displayName; |
| 198 | } |
| 199 | return s; |
| 200 | } |
| 201 | |
| 202 | |
| 203 | } |