com.google.apphosting.runtime.timer

Class CpuRatioTimer

java.lang.Object

com.google.apphosting.runtime.timer.CpuRatioTimer

All Implemented Interfaces:

Timer

public class CpuRatioTimer
extends Object
implements Timer

CpuRatioTimer is a composite Timer that is backed by two other Timer objects -- e.g. one that measures CPU time and one that measures wallclock time. When started or stopped, it will start and stop both underlying Timer objects. It also exposes additional methods to calculate a CPU usage ratio and cycle count (calculated from the CPU time and a CpuSpeedExtractor).

Constructor Summary

Constructors

Constructor and Description
CpuRatioTimer(Timer cpuUsageTimer, Timer wallclockTimer, CpuSpeedExtractor cpuSpeedExtractor, Timer[] extraTimers) Create a new CpuRatioTimer.

Method Summary

Modifier and Type	Method and Description
double	getCpuRatio() Returns a ratio (between 0 and 1) that represents the percentage of elapsed wallclock time which was spent executing CPU instructions.
Timer	getCpuUsageTimer() Returns the underlying CPU usage Timer.
long	getCycleCount() Convert the number of CPU seconds elapsed into a CPU cycle count using the CPU speed reported by the CpuSpeedExtractor.
long	getNanoseconds() Returns the number of CPU-nanoseconds used by the current request, plus a fraction of any background work (e.g.
Timer	getWallclockTimer() Returns the underlying wallclock Timer.
void	start() Start both timers.
void	stop() Stop both timers.
String	toString()
void	update() Update any internal state.

Methods inherited from class java.lang.Object

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

Constructor Detail

CpuRatioTimer

public CpuRatioTimer(Timer cpuUsageTimer,
                     Timer wallclockTimer,
                     CpuSpeedExtractor cpuSpeedExtractor,
                     Timer[] extraTimers)

Create a new CpuRatioTimer.

Parameters:

cpuUsageTimer - Tracks the CPU time used by the request.

wallclockTimer - Tracks the total elapsed time of the request.

cpuSpeedExtractor - converts CPU time to CPU cycles

extraTimers - includes timers for background work that is added to the total return value of this timer (but do not affect the CPU ratio).

Method Detail

start

public void start()

Start both timers.

Specified by:

start in interface Timer

stop

public void stop()

Stop both timers.

Specified by:

stop in interface Timer

update

public void update()

Description copied from interface: Timer

Update any internal state. For example, some Timer implementations may take snapshots of data that may be unavailable in the future. Clients should call this method periodically to qensure that any state is being updated. For an example, see JmxThreadGroupCpuTimer.update().

Specified by:

update in interface Timer

getCpuUsageTimer

public Timer getCpuUsageTimer()

Returns the underlying CPU usage Timer.

getWallclockTimer

public Timer getWallclockTimer()

Returns the underlying wallclock Timer.

getCpuRatio

public double getCpuRatio()

Returns a ratio (between 0 and 1) that represents the percentage of elapsed wallclock time which was spent executing CPU instructions.

getCycleCount

public long getCycleCount()

Convert the number of CPU seconds elapsed into a CPU cycle count using the CPU speed reported by the CpuSpeedExtractor. This value also includes a fraction of hotspot and GC times.

getNanoseconds

public long getNanoseconds()

Returns the number of CPU-nanoseconds used by the current request, plus a fraction of any background work (e.g. hotspot, GC) done by the JVM while this request was executing.

Specified by:

getNanoseconds in interface Timer

toString

public String toString()

Overrides:

toString in class Object