JDK8/Java8源码在线阅读
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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 either in a dynamic library or statically linked into the VM 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");
*
* // start management agent
* Properties props = new Properties();
* props.put("com.sun.management.jmxremote.port", "5000");
* vm.startManagementAgent(props);
*
* // 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>. Then the JMX management agent is
* started in the target process using the supplied arguments. Finally, the
* client detaches from the target VM. </p>
*
* <p> A VirtualMachine is safe for use by multiple concurrent threads. </p>
*
* @since 1.6
*/
@jdk.Exported
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. Alternatively, it may be statically linked into the VM.
* This method causes the given agent library to be loaded into the target
* VM (if not already loaded or if not statically linked into the VM).
* It then causes the target VM to invoke the <code>Agent_OnAttach</code> function
* or, for a statically linked agent named 'L', the <code>Agent_OnAttach_L</code> function
* as specified in the
* <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools
* Interface</a> specification. Note that the <code>Agent_OnAttach[_L]</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>L</tt> might be expanded to
* <tt>libL.so</tt>, and located using the search path specified by the
* <tt>LD_LIBRARY_PATH</tt> environment variable. If the agent named 'L' is
* statically linked into the VM then the VM must export a function named
* <code>Agent_OnAttach_L</code>.</p>
*
* <p> If the <code>Agent_OnAttach[_L]</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[_L]</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[_L]</code>
* function (can be <code>null</code>).
*
* @throws AgentLoadException
* If the agent library does not exist, the agent library is not
* statically linked with the VM, or the agent library cannot be
* loaded for another reason.
*
* @throws AgentInitializationException
* If the <code>Agent_OnAttach[_L]</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, null);
* </tt></blockquote>
*
* @param agentLibrary
* The name of the agent library.
*
* @throws AgentLoadException
* If the agent library does not exist, the agent library is not
* statically linked with the VM, or the agent library cannot be
* loaded for another reason.
*
* @throws AgentInitializationException
* If the <code>Agent_OnAttach[_L]</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. Alternatively, the native
* library specified by the agentPath parameter may be statically
* linked with the VM. The parsing of the agentPath parameter into
* a statically linked library name is done in a platform
* specific manner in the VM. For example, in UNIX, an agentPath parameter
* of <code>/a/b/libL.so</code> would name a library 'L'.
*
* See the JVM TI Specification for more details.
*
* This method causes the given agent library to be loaded into the target
* VM (if not already loaded or if not statically linked into the VM).
* It then causes the target VM to invoke the <code>Agent_OnAttach</code>
* function or, for a statically linked agent named 'L', the
* <code>Agent_OnAttach_L</code> function as specified in the
* <a href="../../../../../../../../technotes/guides/jvmti/index.html"> JVM Tools
* Interface</a> specification.
* Note that the <code>Agent_OnAttach[_L]</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[_L]</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[_L]</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[_L]</code>
* function (can be <code>null</code>).
*
* @throws AgentLoadException
* If the agent library does not exist, the agent library is not
* statically linked with the VM, or the agent library cannot be
* loaded for another reason.
*
* @throws AgentInitializationException
* If the <code>Agent_OnAttach[_L]</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, null);
* </tt></blockquote>
*
* @param agentPath
* The full path to the agent library.
*
* @throws AgentLoadException
* If the agent library does not exist, the agent library is not
* statically linked with the VM, or the agent library cannot be
* loaded for another reason.
*
* @throws AgentInitializationException
* If the <code>Agent_OnAttach[_L]</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.
*
* <p> This convenience method works as if by invoking:
*
* <blockquote><tt>
* {@link #loadAgent(String, String) loadAgent}(agent, null);
* </tt></blockquote>
*
* @param agent
* Path to the JAR file containing the agent.
*
* @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 void loadAgent(String agent)
throws AgentLoadException, AgentInitializationException, IOException
{
loadAgent(agent, null);
}
/**
* Returns the current system properties in the target virtual machine.
*
* <p> This method returns the system properties in the target virtual
* machine. Properties whose key or value is not a <tt>String</tt> are
* omitted. The method is approximately equivalent to the invocation of the
* method {@link java.lang.System#getProperties System.getProperties}
* in the target virtual machine except that properties with a key or
* value that is not a <tt>String</tt> are not included.
*
* <p> This method is typically used to decide which agent to load into
* the target virtual machine with {@link #loadAgent loadAgent}, or
* {@link #loadAgentLibrary loadAgentLibrary}. For example, the
* <code>java.home</code> or <code>user.dir</code> properties might be
* use to create the path to the agent library or JAR file.
*
* @return The system properties
*
* @throws AttachOperationFailedException
* If the target virtual machine is unable to complete the
* attach operation. A more specific error message will be
* given by {@link AttachOperationFailedException#getMessage()}.
*
* @throws IOException
* If an I/O error occurs, a communication error for example,
* that cannot be identified as an error to indicate that the
* operation failed in the target VM.
*
* @see java.lang.System#getProperties
* @see #loadAgentLibrary
* @see #loadAgent
*/
public abstract Properties getSystemProperties() throws IOException;
/**
* Returns the current <i>agent properties</i> in the target virtual
* machine.
*
* <p> The target virtual machine can maintain a list of properties on
* behalf of agents. The manner in which this is done, the names of the
* properties, and the types of values that are allowed, is implementation
* specific. Agent properties are typically used to store communication
* end-points and other agent configuration details. For example, a debugger
* agent might create an agent property for its transport address.
*
* <p> This method returns the agent properties whose key and value is a
* <tt>String</tt>. Properties whose key or value is not a <tt>String</tt>
* are omitted. If there are no agent properties maintained in the target
* virtual machine then an empty property list is returned.
*
* @return The agent properties
*
* @throws AttachOperationFailedException
* If the target virtual machine is unable to complete the
* attach operation. A more specific error message will be
* given by {@link AttachOperationFailedException#getMessage()}.
*
* @throws IOException
* If an I/O error occurs, a communication error for example,
* that cannot be identified as an error to indicate that the
* operation failed in the target VM.
*/
public abstract Properties getAgentProperties() throws IOException;
/**
* Starts the JMX management agent in the target virtual machine.
*
* <p> The configuration properties are the same as those specified on
* the command line when starting the JMX management agent. In the same
* way as on the command line, you need to specify at least the
* {@code com.sun.management.jmxremote.port} property.
*
* <p> See the online documentation for <a
* href="../../../../../../../../technotes/guides/management/agent.html">
* Monitoring and Management Using JMX Technology</a> for further details.
*
* @param agentProperties
* A Properties object containing the configuration properties
* for the agent.
*
* @throws AttachOperationFailedException
* If the target virtual machine is unable to complete the
* attach operation. A more specific error message will be
* given by {@link AttachOperationFailedException#getMessage()}.
*
* @throws IOException
* If an I/O error occurs, a communication error for example,
* that cannot be identified as an error to indicate that the
* operation failed in the target VM.
*
* @throws IllegalArgumentException
* If keys or values in agentProperties are invalid.
*
* @throws NullPointerException
* If agentProperties is null.
*
* @since 1.8
*/
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