org.jikesrvm.adaptive.measurements.listeners

Class EdgeListener

java.lang.Object

org.jikesrvm.adaptive.measurements.listeners.Listener

org.jikesrvm.adaptive.measurements.listeners.ContextListener

org.jikesrvm.adaptive.measurements.listeners.EdgeListener

public class EdgeListener
extends ContextListener

A EdgeListener defines a listener that computes a call graph edge from the call stack. After a parameterized number of edges are collected, it notifies its organizer that the threshold is reached.

Defines update's interface.

EdgeListener communicates with an organizer through a integer array, buffer. Each time this listener is called, it places a triple of integers in buffer that correspond to the callee, caller, and machine code offset of the call site

Field Summary

Fields

Modifier and Type	Field and Description
private int[]	buffer buffer provides the communication channel between the listener and the organizer.
protected static boolean	DEBUG
private int	desiredSamples Number of samples to be taken before issuing callback to controller
protected int	samplesTaken Number of samples taken so far
protected int	updateCalled Number of times update is called

Constructor Summary

Constructors

Constructor and Description
EdgeListener() Constructor

Method Summary

Modifier and Type	Method and Description
(package private) int	getTimesUpdateCalled()
void	report() No-op.
void	reset() Reset the listeners data structures in preparation of a new sampling window.
private void	resetBuffer() Reset the buffer
void	setBuffer(int[] buffer) Setup buffer and buffer size.
void	update(Address sfp, int whereFrom) This method is called when a call stack edge needs to be sampled.

Methods inherited from class org.jikesrvm.adaptive.measurements.listeners.Listener

activate, activateOrganizer, isActive, passivate, setOrganizer

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

protected static final boolean DEBUG

See Also:

Constant Field Values

buffer

private int[] buffer

buffer provides the communication channel between the listener and the organizer. The buffer contains an array of triples <callee, caller, address> where the caller and callee are CompiledMethodID's. Initially, buffer contains zeros. The listener adds triples. When the listener hits the end of the buffer, notify the organizer.

desiredSamples

private int desiredSamples

Number of samples to be taken before issuing callback to controller

samplesTaken

protected int samplesTaken

Number of samples taken so far

updateCalled

protected int updateCalled

Number of times update is called

Constructor Detail

EdgeListener

public EdgeListener()

Constructor

Method Detail

getTimesUpdateCalled

int getTimesUpdateCalled()

Returns:

the number of times that update has been called

setBuffer

public void setBuffer(int[] buffer)

Setup buffer and buffer size. This method must be called before any data can be written to the buffer.

Parameters:

buffer - the allocated buffer to contain the samples, size should be a muliple of 3

update

public final void update(Address sfp,
                         int whereFrom)

This method is called when a call stack edge needs to be sampled. Expect the sfp argument to point to the stack frame that contains the target of the edge to be sampled.

NOTE: This method is uninterruptible, therefore we don't need to disable thread switching during stackframe inspection.

Specified by:

update in class ContextListener

Parameters:

sfp - a pointer to the stack frame that corresponds to the callee of the call graph edge that is to be sampled.

whereFrom - Was this a yieldpoint in a PROLOGUE, BACKEDGE, or EPILOGUE?

report

public final void report()

No-op.

Specified by:

report in class Listener

reset

public void reset()

Description copied from class: Listener

Reset the listeners data structures in preparation of a new sampling window. This is called by the organizer after processing the samples from the old sampling window.

Specified by:

reset in class Listener

resetBuffer

private void resetBuffer()

Reset the buffer