sun.jvmstat.perfdata.monitor.v2_0

Class PerfDataBuffer

java.lang.Object

sun.jvmstat.perfdata.monitor.PerfDataBufferImpl

sun.jvmstat.perfdata.monitor.v2_0.PerfDataBuffer

public class PerfDataBuffer
extends PerfDataBufferImpl

The concrete implementation of version 2.0 of the HotSpot PerfData Instrumentation buffer. This class is responsible for parsing the instrumentation memory and constructing the necessary objects to represent and access the instrumentation objects contained in the memory buffer.

The structure of the 2.0 entry is defined in struct PerfDataEnry as decsribed in perfMemory.hpp. This structure looks like:

 typedef struct {
   jint entry_length;         // entry length in bytes
   jint name_offset;          // offset to entry name, relative to start
                              // of entry
   jint vector_length;        // length of the vector. If 0, then scalar.
   jbyte data_type;           // JNI field descriptor type
   jbyte flags;               // miscellaneous attribute flags
                              // 0x01 - supported
   jbyte data_units;          // unit of measure attribute
   jbyte data_variability;    // variability attribute
   jbyte data_offset;         // offset to data item, relative to start
                              // of entry.
 } PerfDataEntry;
 

Since:

1.5

Author:

Brian Doherty

See Also:

AbstractPerfDataBuffer

Field Summary

Fields inherited from class sun.jvmstat.perfdata.monitor.PerfDataBufferImpl

aliasCache, aliasMap, buffer, lvmid, monitors

Constructor Summary

Constructors

Constructor and Description
PerfDataBuffer(ByteBuffer buffer, int lvmid) Construct a PerfDataBuffer instance.

Method Summary

Modifier and Type	Method and Description
protected void	buildMonitorMap(Map<String,Monitor> map) build the map of Monitor objects.
protected void	buildPseudoMonitors(Map<String,Monitor> map) Build the pseudo monitors used to map the prolog data into counters.
protected MonitorStatus	getMonitorStatus(Map<String,Monitor> map) get the list of inserted and removed monitors since last called.
protected void	getNewMonitors(Map<String,Monitor> map) get the new Monitor objects from the Map of Monitor objects.
protected Monitor	getNextMonitorEntry() method to extract the next monitor entry from the instrumentation memory.
protected void	synchWithTarget() Method that waits until the target jvm indicates that its shared memory is safe to access.

Methods inherited from class sun.jvmstat.perfdata.monitor.PerfDataBufferImpl

findByAlias, findByName, findByPattern, getBytes, getCapacity, getLocalVmId, getMonitorStatus

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PerfDataBuffer

public PerfDataBuffer(ByteBuffer buffer,
                      int lvmid)
               throws MonitorException

Construct a PerfDataBuffer instance.

This class is dynamically loaded by AbstractPerfDataBuffer.createPerfDataBuffer(java.nio.ByteBuffer, int), and this constructor is called to instantiate the instance.

Parameters:

buffer - the buffer containing the instrumentation data

lvmid - the Local Java Virtual Machine Identifier for this instrumentation buffer.

Throws:

MonitorException

Method Detail

buildMonitorMap

protected void buildMonitorMap(Map<String,Monitor> map)
                        throws MonitorException

build the map of Monitor objects.

Specified by:

buildMonitorMap in class PerfDataBufferImpl

Parameters:

map - the map of Monitors.

Throws:

MonitorException - Thrown if communications errors occur while communicating with the target.

getNewMonitors

protected void getNewMonitors(Map<String,Monitor> map)
                       throws MonitorException

get the new Monitor objects from the Map of Monitor objects.

Specified by:

getNewMonitors in class PerfDataBufferImpl

Parameters:

map - the map of Monitors.

Throws:

MonitorException - Thrown if communications errors occur while communicating with the target.

getMonitorStatus

protected MonitorStatus getMonitorStatus(Map<String,Monitor> map)
                                  throws MonitorException

get the list of inserted and removed monitors since last called.

Specified by:

getMonitorStatus in class PerfDataBufferImpl

Parameters:

map - the map of Monitors.

Throws:

MonitorException - Thrown if communications errors occur while communicating with the target.

buildPseudoMonitors

protected void buildPseudoMonitors(Map<String,Monitor> map)

Build the pseudo monitors used to map the prolog data into counters.

synchWithTarget

protected void synchWithTarget()
                        throws MonitorException

Method that waits until the target jvm indicates that its shared memory is safe to access.

Throws:

MonitorException

getNextMonitorEntry

protected Monitor getNextMonitorEntry()
                               throws MonitorException

method to extract the next monitor entry from the instrumentation memory. assumes that nextEntry is the offset into the byte array at which to start the search for the next entry. method leaves next entry pointing to the next entry or to the end of data.

Throws:

MonitorException