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package sun.jvmstat.perfdata.monitor;

import sun.jvmstat.monitor.*;
import java.util.*;
import java.io.*;
import java.lang.reflect.*;
import java.nio.ByteBuffer;


Abstraction for the HotSpot PerfData instrumentation buffer. This class
is responsible for acquiring access to the instrumentation buffer for
a target HotSpot Java Virtual Machine and providing method level access
to its contents.

Author:Brian Doherty
Since:1.5
/**
 * Abstraction for the HotSpot PerfData instrumentation buffer. This class
 * is responsible for acquiring access to the instrumentation buffer for
 * a target HotSpot Java Virtual Machine and providing method level access
 * to its contents.
 *
 * @author Brian Doherty
 * @since 1.5
 */
public abstract class AbstractPerfDataBuffer {

    
Reference to the concrete instance created by the createPerfDataBuffer method. 
/**
     * Reference to the concrete instance created by the
     * {@link #createPerfDataBuffer} method.
     */
    protected PerfDataBufferImpl impl;

    
Get the Local Java Virtual Machine Identifier, or lvmid
for the target JVM associated with this instrumentation buffer.

Returns:int - the lvmid
/**
     * Get the Local Java Virtual Machine Identifier, or <em>lvmid</em>
     * for the target JVM associated with this instrumentation buffer.
     *
     * @return int - the lvmid
     */
    public int getLocalVmId() {
        return impl.getLocalVmId();
    }

    
Get a copy of the raw instrumentation data.
This method is used to get a copy of the current bytes in the
instrumentation buffer. It is generally used for transporting
those bytes over the network.

Returns:byte[] - a copy of the bytes in the instrumentation buffer.
/**
     * Get a copy of the raw instrumentation data.
     * This method is used to get a copy of the current bytes in the
     * instrumentation buffer. It is generally used for transporting
     * those bytes over the network.
     *
     * @return byte[] - a copy of the bytes in the instrumentation buffer.
     */
    public byte[] getBytes() {
        return impl.getBytes();
    }

    
Get the capacity of the instrumentation buffer.

Returns:int - the capacity, or size, of the instrumentation buffer.
/**
     * Get the capacity of the instrumentation buffer.
     *
     * @return int - the capacity, or size, of the instrumentation buffer.
     */
    public int getCapacity() {
        return impl.getCapacity();
    }

    
Find a named Instrumentation object. This method will look for the named instrumentation object in the instrumentation exported by this Java Virtual Machine. If an instrumentation object with the given name exists, a Monitor interface to that object will be return. Otherwise, the method returns null. 
Params:
  • name – the name of the Instrumentation object to find.
Throws:
  • MonitorException – Thrown if an error occurs while communicating
                         with the target Java Virtual Machine.
Returns:Monitor - the Monitor object that can be used to monitor the named instrumentation object, or null if the named object doesn't exist.
/**
     * Find a named Instrumentation object.
     *
     * This method will look for the named instrumentation object in the
     * instrumentation exported by this Java Virtual Machine. If an
     * instrumentation object with the given name exists, a Monitor interface
     * to that object will be return. Otherwise, the method returns
     * {@code null}.
     *
     * @param name the name of the Instrumentation object to find.
     * @return Monitor - the {@link Monitor} object that can be used to
     *                   monitor the named instrumentation object, or
     *                   {@code null} if the named object doesn't exist.
     * @throws MonitorException Thrown if an error occurs while communicating
     *                          with the target Java Virtual Machine.
     */
    public Monitor findByName(String name) throws MonitorException {
        return impl.findByName(name);
    }

    
Find all Instrumentation objects with names matching the given pattern. This method returns a List of Monitor objects such that the name of each object matches the given pattern. 
Params:
  • patternString –  a string containing a pattern as described in Pattern.
Throws:
  • MonitorException – Thrown if an error occurs while communicating
                         with the target Java Virtual Machine.
See Also:
Returns:List<Monitor> - a List of Monitor objects that can be used to monitor the instrumentation objects whose names match the given pattern. If no instrumentation objects have` names matching the given pattern, then an empty List is returned.
/**
     * Find all Instrumentation objects with names matching the given pattern.
     *
     * This method returns a {@link List} of Monitor objects such that
     * the name of each object matches the given pattern.
     *
     * @param patternString  a string containing a pattern as described in
     *                       {@link java.util.regex.Pattern}.
     * @return {@code List<Monitor>} - a List of {@link Monitor}
     *                objects that can be used to
     *                monitor the instrumentation objects whose names match
     *                the given pattern. If no instrumentation objects have`
     *                names matching the given pattern, then an empty List
     *                is returned.
     * @throws MonitorException Thrown if an error occurs while communicating
     *                          with the target Java Virtual Machine.
     * @see java.util.regex.Pattern
     */
    public List<Monitor> findByPattern(String patternString) throws MonitorException {
        return impl.findByPattern(patternString);
    }

    
Get a list of the inserted and removed monitors since last called.

Throws:
  • MonitorException – Thrown if communications errors occur
                         while communicating with the target.
Returns:MonitorStatus - the status of available Monitors for the
                        target Java Virtual Machine.
/**
     * Get a list of the inserted and removed monitors since last called.
     *
     * @return MonitorStatus - the status of available Monitors for the
     *                         target Java Virtual Machine.
     * @throws MonitorException Thrown if communications errors occur
     *                          while communicating with the target.
     */
    public MonitorStatus getMonitorStatus() throws MonitorException {
        return impl.getMonitorStatus();
    }

    
Get the ByteBuffer containing the instrumentation data.

Returns:ByteBuffer - a ByteBuffer object that refers to the
                     instrumentation data.
/**
     * Get the ByteBuffer containing the instrumentation data.
     *
     * @return ByteBuffer - a ByteBuffer object that refers to the
     *                      instrumentation data.
     */
    public ByteBuffer getByteBuffer() {
        return impl.getByteBuffer();
    }

    
Create the perfdata instrumentation buffer for the given lvmid
using the given ByteBuffer object as the source of the instrumentation
data. This method parses the instrumentation buffer header to determine
key characteristics of the instrumentation buffer and then dynamically
loads the appropriate class to handle the particular instrumentation
version.

Params:
  • bb – the ByteBuffer that references the instrumentation data.
  • lvmid – the Local Java Virtual Machine identifier for this
             instrumentation buffer.
Throws:
/**
     * Create the perfdata instrumentation buffer for the given lvmid
     * using the given ByteBuffer object as the source of the instrumentation
     * data. This method parses the instrumentation buffer header to determine
     * key characteristics of the instrumentation buffer and then dynamically
     * loads the appropriate class to handle the particular instrumentation
     * version.
     *
     * @param bb the ByteBuffer that references the instrumentation data.
     * @param lvmid the Local Java Virtual Machine identifier for this
     *              instrumentation buffer.
     *
     * @throws MonitorException
     */
    protected void createPerfDataBuffer(ByteBuffer bb, int lvmid)
                   throws MonitorException {
        int majorVersion = AbstractPerfDataBufferPrologue.getMajorVersion(bb);
        int minorVersion = AbstractPerfDataBufferPrologue.getMinorVersion(bb);

        // instantiate the version specific class
        String classname = "sun.jvmstat.perfdata.monitor.v"
                           + majorVersion + "_" + minorVersion
                           + ".PerfDataBuffer";

        try {
            Class<?> implClass = Class.forName(classname);
            Constructor<?> cons = implClass.getConstructor(new Class<?>[] {
                    Class.forName("java.nio.ByteBuffer"),
                    Integer.TYPE
            });

            impl = (PerfDataBufferImpl)cons.newInstance(new Object[] {
                     bb, lvmid
            });

        } catch (ClassNotFoundException e) {
            // from Class.forName();
            throw new IllegalArgumentException(
                    "Could not find " + classname + ": " + e.getMessage(), e);

        } catch (NoSuchMethodException e) {
            // from Class.getConstructor();
            throw new IllegalArgumentException(
                    "Expected constructor missing in " + classname + ": "
                    + e.getMessage(), e);

        } catch (IllegalAccessException e) {
            // from Constructor.newInstance()
            throw new IllegalArgumentException(
                   "Unexpected constructor access in " + classname + ": "
                   + e.getMessage(), e);

        } catch (InstantiationException e) {
            throw new IllegalArgumentException(
                    classname + "is abstract: " + e.getMessage(), e);

        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof MonitorException) {
                throw (MonitorException)cause;
            }
            throw new RuntimeException("Unexpected exception: "
                                       + e.getMessage() , e);
        }
    }
}