sun.jvmstat.perfdata.monitor.v2_0

Class PerfDataBufferPrologue

java.lang.Object

sun.jvmstat.perfdata.monitor.AbstractPerfDataBufferPrologue

sun.jvmstat.perfdata.monitor.v2_0.PerfDataBufferPrologue

public class PerfDataBufferPrologue
extends AbstractPerfDataBufferPrologue

Class representing the 2.0 version of the HotSpot PerfData instrumentation buffer header.

The PerfDataBufferPrologue class supports parsing of the version specific portions of the PerfDataPrologue C structure:

 typedef struct {
   ...                      // handled by superclass
   jint used;               // number of PerfData memory bytes used
   jint overflow;           // number of bytes of overflow
   jlong mod_time_stamp;    // time stamp of the last structural modification
   jint entry_offset;       // offset of the first PerfDataEntry
   jint num_entries;        // number of allocated PerfData entries
 } PerfDataPrologue
 

Since:

1.5

Author:

Brian Doherty

Field Summary

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

byteBuffer, PERFDATA_MAJOR_NAME, PERFDATA_MINOR_NAME

Constructor Summary

Constructors

Constructor and Description
PerfDataBufferPrologue(ByteBuffer byteBuffer) Create an instance of PerfDataBufferPrologue from the given ByteBuffer object.

Method Summary

Modifier and Type	Method and Description
int	getBufferSize() Get the size of the instrumentation memory buffer.
int	getEntryOffset() Get the offset of the first PerfDataEntry.
long	getModificationTimeStamp() Get the time of last modification for the instrumentation memory buffer.
int	getNumEntries() Get the offset of the first PerfDataEntry.
int	getOverflow() Get the buffer overflow amount.
int	getSize() Get the size of the header portion of the instrumentation buffer.
int	getUsed() Get the utilization of the instrumentation memory buffer.
boolean	isAccessible() Get the accessible flag.
boolean	supportsAccessible() Test if the accessible flag is supported by this version of the PerfDataBufferPrologue.

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

getByteOrder, getByteOrder, getMagic, getMagic, getMajorVersion, getMajorVersion, getMinorVersion, getMinorVersion, majorVersionBuffer, minorVersionBuffer

Methods inherited from class java.lang.Object

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

Constructor Detail

PerfDataBufferPrologue

public PerfDataBufferPrologue(ByteBuffer byteBuffer)
                       throws MonitorException

Create an instance of PerfDataBufferPrologue from the given ByteBuffer object.

Parameters:

byteBuffer - the buffer containing the binary header data

Throws:

MonitorException

Method Detail

supportsAccessible

public boolean supportsAccessible()

Test if the accessible flag is supported by this version of the PerfDataBufferPrologue. Although not an abstract method, this method should be overridden by version specific subclasses.

Specified by:

supportsAccessible in class AbstractPerfDataBufferPrologue

Returns:

boolean - the initialized flag support status.

See Also:

AbstractPerfDataBufferPrologue.isAccessible()

isAccessible

public boolean isAccessible()

Get the accessible flag. If supported, it indicates that the shared memory region is sufficiently initialized for client acccess.

Specified by:

isAccessible in class AbstractPerfDataBufferPrologue

Returns:

boolean - the initialized status

See Also:

AbstractPerfDataBufferPrologue.supportsAccessible()

getUsed

public int getUsed()

Get the utilization of the instrumentation memory buffer.

Returns:

int - the utilization of the buffer

getBufferSize

public int getBufferSize()

Get the size of the instrumentation memory buffer.

Returns:

int - the size of the buffer

getOverflow

public int getOverflow()

Get the buffer overflow amount. This value is non-zero if the HotSpot JVM has overflowed the instrumentation memory buffer. The target JVM can be restarted with -XX:PerfDataMemSize=X to create a larger memory buffer.

Returns:

int - the size of the buffer

getModificationTimeStamp

public long getModificationTimeStamp()

Get the time of last modification for the instrumentation memory buffer. This method returns the time, as ticks since the start of the target JVM, of the last structural modification to the instrumentation buffer. Structural modifications correspond to the addition or deletion of instrumentation objects. Updates to counter values are not structural modifications.

getEntryOffset

public int getEntryOffset()

Get the offset of the first PerfDataEntry.

getNumEntries

public int getNumEntries()

Get the offset of the first PerfDataEntry.

getSize

public int getSize()

Get the size of the header portion of the instrumentation buffer.

Overrides:

getSize in class AbstractPerfDataBufferPrologue

Returns:

int - the size of the header