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/* * Copyright (c) 2005, 2006, 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.tools.attach; import com.sun.tools.attach.spi.AttachProvider;import java.util.ArrayList;import java.util.List;import java.util.Properties;import java.io.IOException;  /** * A Java virtual machine. * * <p> A <code>VirtualMachine</code> represents a Java virtual machine to which this * Java virtual machine has attached. The Java virtual machine to which it is * attached is sometimes called the <i>target virtual machine</i>, or <i>target VM</i>. * An application (typically a tool such as a managemet console or profiler) uses a * VirtualMachine to load an agent into the target VM. For example, a profiler tool * written in the Java Language might attach to a running application and load its * profiler agent to profile the running application. </p> * * <p> A VirtualMachine is obtained by invoking the {@link #attach(String) attach} method * with an identifier that identifies the target virtual machine. The identifier is * implementation-dependent but is typically the process identifier (or pid) in * environments where each Java virtual machine runs in its own operating system process. * Alternatively, a <code>VirtualMachine</code> instance is obtained by invoking the * {@link #attach(VirtualMachineDescriptor) attach} method with a {@link * com.sun.tools.attach.VirtualMachineDescriptor VirtualMachineDescriptor} obtained * from the list of virtual machine descriptors returned by the {@link #list list} method. * Once a reference to a virtual machine is obtained, the {@link #loadAgent loadAgent}, * {@link #loadAgentLibrary loadAgentLibrary}, and {@link #loadAgentPath loadAgentPath} * methods are used to load agents into target virtual machine. The {@link * #loadAgent loadAgent} method is used to load agents that are written in the Java * Language and deployed in a {@link java.util.jar.JarFile JAR file}. (See * {@link java.lang.instrument} for a detailed description on how these agents * are loaded and started). The {@link #loadAgentLibrary loadAgentLibrary} and * {@link #loadAgentPath loadAgentPath} methods are used to load agents that * are deployed in a dynamic library and make use of the <a * href="../../../../../../../../technotes/guides/jvmti/index.html">JVM Tools * Interface</a>. </p> * * <p> In addition to loading agents a VirtualMachine provides read access to the * {@link java.lang.System#getProperties() system properties} in the target VM. * This can be useful in some environments where properties such as * <code>java.home</code>, <code>os.name</code>, or <code>os.arch</code> are * used to construct the path to agent that will be loaded into the target VM. * * <p> The following example demonstrates how VirtualMachine may be used:</p> * * <pre> * *      // attach to target VM *      VirtualMachine vm = VirtualMachine.attach("2177"); * *      // get system properties in target VM *      Properties props = vm.getSystemProperties(); * *      // construct path to management agent *      String home = props.getProperty("java.home"); *      String agent = home + File.separator + "lib" + File.separator *          + "management-agent.jar"; * *      // load agent into target VM *      vm.loadAgent(agent, "com.sun.management.jmxremote.port=5000"); * *      // detach *      vm.detach(); * * </pre> * * <p> In this example we attach to a Java virtual machine that is identified by * the process identifier <code>2177</code>. The system properties from the target * VM are then used to construct the path to a <i>management agent</i> which is then * loaded into the target VM. Once loaded the client detaches from the target VM. </p> * * <p> A VirtualMachine is safe for use by multiple concurrent threads. </p> * * @since 1.6 */ public abstract class VirtualMachine {    private AttachProvider provider;    private String id;    private volatile int hash;        // 0 => not computed     /**     * Initializes a new instance of this class.     *     * @param   provider     *          The attach provider creating this class.     * @param   id     *          The abstract identifier that identifies the Java virtual machine.     *     * @throws  NullPointerException     *          If <code>provider</code> or <code>id</code> is <code>null</code>.     */    protected VirtualMachine(AttachProvider provider, String id) {        if (provider == null) {            throw new NullPointerException("provider cannot be null");        }        if (id == null) {            throw new NullPointerException("id cannot be null");        }        this.provider = provider;        this.id = id;    }     /**     * Return a list of Java virtual machines.     *     * <p> This method returns a list of Java {@link     * com.sun.tools.attach.VirtualMachineDescriptor} elements.     * The list is an aggregation of the virtual machine     * descriptor lists obtained by invoking the {@link     * com.sun.tools.attach.spi.AttachProvider#listVirtualMachines     * listVirtualMachines} method of all installed     * {@link com.sun.tools.attach.spi.AttachProvider attach providers}.     * If there are no Java virtual machines known to any provider     * then an empty list is returned.     *     * @return  The list of virtual machine descriptors.     */    public static List<VirtualMachineDescriptor> list() {        ArrayList<VirtualMachineDescriptor> l =            new ArrayList<VirtualMachineDescriptor>();        List<AttachProvider> providers = AttachProvider.providers();        for (AttachProvider provider: providers) {            l.addAll(provider.listVirtualMachines());        }        return l;    }     /**     * Attaches to a Java virtual machine.     *     * <p> This method obtains the list of attach providers by invoking the     * {@link com.sun.tools.attach.spi.AttachProvider#providers()     * AttachProvider.providers()} method. It then iterates overs the list     * and invokes each provider's {@link     * com.sun.tools.attach.spi.AttachProvider#attachVirtualMachine(java.lang.String)     * attachVirtualMachine} method in turn. If a provider successfully     * attaches then the iteration terminates, and the VirtualMachine created     * by the provider that successfully attached is returned by this method.     * If the <code>attachVirtualMachine</code> method of all providers throws     * {@link com.sun.tools.attach.AttachNotSupportedException AttachNotSupportedException}     * then this method also throws <code>AttachNotSupportedException</code>.     * This means that <code>AttachNotSupportedException</code> is thrown when     * the identifier provided to this method is invalid, or the identifier     * corresponds to a Java virtual machine that does not exist, or none     * of the providers can attach to it. This exception is also thrown if     * {@link com.sun.tools.attach.spi.AttachProvider#providers()     * AttachProvider.providers()} returns an empty list. </p>     *     * @param   id     *          The abstract identifier that identifies the Java virtual machine.     *     * @return  A VirtualMachine representing the target VM.     *     * @throws  SecurityException     *          If a security manager has been installed and it denies     *          {@link com.sun.tools.attach.AttachPermission AttachPermission}     *          <tt>("attachVirtualMachine")</tt>, or another permission     *          required by the implementation.     *     * @throws  AttachNotSupportedException     *          If the <code>attachVirtualmachine</code> method of all installed     *          providers throws <code>AttachNotSupportedException</code>, or     *          there aren't any providers installed.     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>id</code> is <code>null</code>.     */    public static VirtualMachine attach(String id)        throws AttachNotSupportedException, IOException    {        if (id == null) {            throw new NullPointerException("id cannot be null");        }        List<AttachProvider> providers = AttachProvider.providers();        if (providers.size() == 0) {            throw new AttachNotSupportedException("no providers installed");        }        AttachNotSupportedException lastExc = null;        for (AttachProvider provider: providers) {            try {                return provider.attachVirtualMachine(id);            } catch (AttachNotSupportedException x) {                lastExc = x;            }        }        throw lastExc;    }     /**     * Attaches to a Java virtual machine.     *     * <p> This method first invokes the {@link     * com.sun.tools.attach.VirtualMachineDescriptor#provider() provider()} method     * of the given virtual machine descriptor to obtain the attach provider. It     * then invokes the attach provider's {@link     * com.sun.tools.attach.spi.AttachProvider#attachVirtualMachine(VirtualMachineDescriptor)     * attachVirtualMachine} to attach to the target VM.     *     * @param   vmd     *          The virtual machine descriptor.     *     * @return  A VirtualMachine representing the target VM.     *     * @throws  SecurityException     *          If a security manager has been installed and it denies     *          {@link com.sun.tools.attach.AttachPermission AttachPermission}     *          <tt>("attachVirtualMachine")</tt>, or another permission     *          required by the implementation.     *     * @throws  AttachNotSupportedException     *          If the attach provider's <code>attachVirtualmachine</code>     *          throws <code>AttachNotSupportedException</code>.     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>vmd</code> is <code>null</code>.     */    public static VirtualMachine attach(VirtualMachineDescriptor vmd)        throws AttachNotSupportedException, IOException    {        return vmd.provider().attachVirtualMachine(vmd);    }     /**     * Detach from the virtual machine.     *     * <p> After detaching from the virtual machine, any further attempt to invoke     * operations on that virtual machine will cause an {@link java.io.IOException     * IOException} to be thrown. If an operation (such as {@link #loadAgent     * loadAgent} for example) is in progress when this method is invoked then     * the behaviour is implementation dependent. In other words, it is     * implementation specific if the operation completes or throws     * <tt>IOException</tt>.     *     * <p> If already detached from the virtual machine then invoking this     * method has no effect. </p>     *     * @throws  IOException     *          If an I/O error occurs     */    public abstract void detach() throws IOException;     /**     * Returns the provider that created this virtual machine.     *     * @return  The provider that created this virtual machine.     */    public final AttachProvider provider() {        return provider;    }     /**     * Returns the identifier for this Java virtual machine.     *     * @return  The identifier for this Java virtual machine.     */    public final String id() {        return id;    }     /**     * Loads an agent library.     *     * <p> A <a href="../../../../../../../../technotes/guides/jvmti/index.html">JVM     * TI</a> client is called an <i>agent</i>. It is developed in a native language.     * A JVM TI agent is deployed in a platform specific manner but it is typically the     * platform equivalent of a dynamic library. This method causes the given agent     * library to be loaded into the target VM (if not already loaded).     * It then causes the target VM to invoke the <code>Agent_OnAttach</code> function     * as specified in the     * <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools     * Interface</a> specification. Note that the <code>Agent_OnAttach</code>     * function is invoked even if the agent library was loaded prior to invoking     * this method.     *     * <p> The agent library provided is the name of the agent library. It is interpreted     * in the target virtual machine in an implementation-dependent manner. Typically an     * implementation will expand the library name into an operating system specific file     * name. For example, on UNIX systems, the name <tt>foo</tt> might be expanded to     * <tt>libfoo.so</tt>, and located using the search path specified by the     * <tt>LD_LIBRARY_PATH</tt> environment variable.</p>     *     * <p> If the <code>Agent_OnAttach</code> function in the agent library returns     * an error then an {@link com.sun.tools.attach.AgentInitializationException} is     * thrown. The return value from the <code>Agent_OnAttach</code> can then be     * obtained by invoking the {@link     * com.sun.tools.attach.AgentInitializationException#returnValue() returnValue}     * method on the exception. </p>     *     * @param   agentLibrary     *          The name of the agent library.     *     * @param   options     *          The options to provide to the <code>Agent_OnAttach</code>     *          function (can be <code>null</code>).     *     * @throws  AgentLoadException     *          If the agent library does not exist, or cannot be loaded for     *          another reason.     *     * @throws  AgentInitializationException     *          If the <code>Agent_OnAttach</code> function returns an error     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>agentLibrary</code> is <code>null</code>.     *     * @see     com.sun.tools.attach.AgentInitializationException#returnValue()     */    public abstract void loadAgentLibrary(String agentLibrary, String options)        throws AgentLoadException, AgentInitializationException, IOException;     /**     * Loads an agent library.     *     * <p> This convenience method works as if by invoking:     *     * <blockquote><tt>     * {@link #loadAgentLibrary(String, String) loadAgentLibrary}(agentLibrary,&nbsp;null);     * </tt></blockquote>     *     * @param   agentLibrary     *          The name of the agent library.     *     * @throws  AgentLoadException     *          If the agent library does not exist, or cannot be loaded for     *          another reason.     *     * @throws  AgentInitializationException     *          If the <code>Agent_OnAttach</code> function returns an error     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>agentLibrary</code> is <code>null</code>.     */    public void loadAgentLibrary(String agentLibrary)        throws AgentLoadException, AgentInitializationException, IOException    {        loadAgentLibrary(agentLibrary, null);    }     /**     * Load a native agent library by full pathname.     *     * <p> A <a href="../../../../../../../../technotes/guides/jvmti/index.html">JVM     * TI</a> client is called an <i>agent</i>. It is developed in a native language.     * A JVM TI agent is deployed in a platform specific manner but it is typically the     * platform equivalent of a dynamic library. This method causes the given agent     * library to be loaded into the target VM (if not already loaded).     * It then causes the target VM to invoke the <code>Agent_OnAttach</code> function     * as specified in the     * <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools     * Interface</a> specification. Note that the <code>Agent_OnAttach</code>     * function is invoked even if the agent library was loaded prior to invoking     * this method.     *     * <p> The agent library provided is the absolute path from which to load the     * agent library. Unlike {@link #loadAgentLibrary loadAgentLibrary}, the library name     * is not expanded in the target virtual machine. </p>     *     * <p> If the <code>Agent_OnAttach</code> function in the agent library returns     * an error then an {@link com.sun.tools.attach.AgentInitializationException} is     * thrown. The return value from the <code>Agent_OnAttach</code> can then be     * obtained by invoking the {@link     * com.sun.tools.attach.AgentInitializationException#returnValue() returnValue}     * method on the exception. </p>     *     * @param   agentPath     *          The full path of the agent library.     *     * @param   options     *          The options to provide to the <code>Agent_OnAttach</code>     *          function (can be <code>null</code>).     *     * @throws  AgentLoadException     *          If the agent library does not exist, or cannot be loaded for     *          another reason.     *     * @throws  AgentInitializationException     *          If the <code>Agent_OnAttach</code> function returns an error     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>agentPath</code> is <code>null</code>.     *     * @see     com.sun.tools.attach.AgentInitializationException#returnValue()     */    public abstract void loadAgentPath(String agentPath, String options)        throws AgentLoadException, AgentInitializationException, IOException;     /**     * Load a native agent library by full pathname.     *     * <p> This convenience method works as if by invoking:     *     * <blockquote><tt>     * {@link #loadAgentPath(String, String) loadAgentPath}(agentLibrary,&nbsp;null);     * </tt></blockquote>     *     * @param   agentPath     *          The full path to the agent library.     *     * @throws  AgentLoadException     *          If the agent library does not exist, or cannot be loaded for     *          another reason.     *     * @throws  AgentInitializationException     *          If the <code>Agent_OnAttach</code> function returns an error     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>agentPath</code> is <code>null</code>.     */    public void loadAgentPath(String agentPath)       throws AgentLoadException, AgentInitializationException, IOException    {        loadAgentPath(agentPath, null);    }     /**     * Loads an agent.     *     * <p> The agent provided to this method is a path name to a JAR file on the file     * system of the target virtual machine. This path is passed to the target virtual     * machine where it is interpreted. The target virtual machine attempts to start     * the agent as specified by the {@link java.lang.instrument} specification.     * That is, the specified JAR file is added to the system class path (of the target     * virtual machine), and the <code>agentmain</code> method of the agent class, specified     * by the <code>Agent-Class</code> attribute in the JAR manifest, is invoked. This     * method completes when the <code>agentmain</code> method completes.     *     * @param   agent     *          Path to the JAR file containing the agent.     *     * @param   options     *          The options to provide to the agent's <code>agentmain</code>     *          method (can be <code>null</code>).     *     * @throws  AgentLoadException     *          If the agent does not exist, or cannot be started in the manner     *          specified in the {@link java.lang.instrument} specification.     *     * @throws  AgentInitializationException     *          If the <code>agentmain</code> throws an exception     *     * @throws  IOException     *          If an I/O error occurs     *     * @throws  NullPointerException     *          If <code>agent</code> is <code>null</code>.     */    public abstract void loadAgent(String agent, String options)        throws AgentLoadException, AgentInitializationException, IOException;     /**     * Loads an agent.     *

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