org.apache.bookkeeper.stats.codahale

Class FastTimer

java.lang.Object

com.codahale.metrics.Timer

org.apache.bookkeeper.stats.codahale.FastTimer

All Implemented Interfaces:

com.codahale.metrics.Counting, com.codahale.metrics.Metered, com.codahale.metrics.Metric, com.codahale.metrics.Sampling

public class FastTimer
extends com.codahale.metrics.Timer

A fast and (nearly) garbage-free Rate and Response Times Timer. FastTimer uses circular arrays which are allocated upfront. Timer updates or queries never allocate new objects and thus never create garbage. A small number of new objects are allocated for snapshots when calling getSnapshot().

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FastTimer.Buckets Defines the response time buckets to use.

Nested classes/interfaces inherited from class com.codahale.metrics.Timer

com.codahale.metrics.Timer.Context

Constructor Summary

Constructors

Constructor and Description
FastTimer() Constructs a new timer with default time window (60 seconds) and default time buckets (fine).
FastTimer(int timeWindowSeconds, FastTimer.Buckets buckets) Constructs a new timer.

Method Summary

Modifier and Type	Method and Description
int	getBucket(long duration) Figure out which percentile bucket an event of a given duration belongs into.
long	getBucketBound(int b) Returns the upper bucket bound (inclusive) of a given bucket.
long	getBucketValue(int b) Returns the average value of a given bucket (the mean between its lower and upper bound).
long	getCount() Returns the all-time count of events this timer has seen.
double	getFifteenMinuteRate()
double	getFiveMinuteRate()
double	getMeanRate()
int	getNumberOfBuckets() Returns the number of response time buckets used by this timer.
double	getOneMinuteRate()
double	getRate(int seconds) Returns the average per-second rate of events this timer has seen.
com.codahale.metrics.Snapshot	getSnapshot() Returns a snapshot of this timer.
protected int	getTime() Returns the current absolute time (in seconds).
void	update(long duration, java.util.concurrent.TimeUnit unit) Add an event to this timer.

Methods inherited from class com.codahale.metrics.Timer

time, time

Methods inherited from class java.lang.Object

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

Constructor Detail

FastTimer

public FastTimer()

Constructs a new timer with default time window (60 seconds) and default time buckets (fine).

FastTimer

public FastTimer(int timeWindowSeconds,
                 FastTimer.Buckets buckets)

Constructs a new timer.

Parameters:

timeWindowSeconds - the time window (in seconds) for this timer

buckets - the type of buckets to use for response times

Method Detail

getNumberOfBuckets

public int getNumberOfBuckets()

Returns the number of response time buckets used by this timer.

Returns:

the number of response time buckets

getBucket

public int getBucket(long duration)

Figure out which percentile bucket an event of a given duration belongs into.

Parameters:

duration - the duration (in nanoseconds)

Returns:

the bucket

getBucketBound

public long getBucketBound(int b)

Returns the upper bucket bound (inclusive) of a given bucket.

Parameters:

b - the bucket

Returns:

the bound (in nanoseconds)

getBucketValue

public long getBucketValue(int b)

Returns the average value of a given bucket (the mean between its lower and upper bound).

Parameters:

b - the bucket

Returns:

the average value (in nanoseconds)

getTime

protected int getTime()

Returns the current absolute time (in seconds).

Returns:

the current absolute time (in seconds)

getRate

public double getRate(int seconds)

Returns the average per-second rate of events this timer has seen. The computed rate is calculated for past seconds (not including the current second, which is still being updated). If the specified time exceeds the time window of this timer, the only rate of the configured time window is reported.

Parameters:

seconds - the number of seconds over which to calculate the average rate

Returns:

the average rate (per second).

getCount

public long getCount()

Returns the all-time count of events this timer has seen.

Specified by:

getCount in interface com.codahale.metrics.Counting

Specified by:

getCount in interface com.codahale.metrics.Metered

Overrides:

getCount in class com.codahale.metrics.Timer

Returns:

the all-time count of events

getFifteenMinuteRate

public double getFifteenMinuteRate()

Specified by:

getFifteenMinuteRate in interface com.codahale.metrics.Metered

Overrides:

getFifteenMinuteRate in class com.codahale.metrics.Timer

getFiveMinuteRate

public double getFiveMinuteRate()

Specified by:

getFiveMinuteRate in interface com.codahale.metrics.Metered

Overrides:

getFiveMinuteRate in class com.codahale.metrics.Timer

getMeanRate

public double getMeanRate()

Specified by:

getMeanRate in interface com.codahale.metrics.Metered

Overrides:

getMeanRate in class com.codahale.metrics.Timer

getOneMinuteRate

public double getOneMinuteRate()

Specified by:

getOneMinuteRate in interface com.codahale.metrics.Metered

Overrides:

getOneMinuteRate in class com.codahale.metrics.Timer

getSnapshot

public com.codahale.metrics.Snapshot getSnapshot()

Returns a snapshot of this timer. The computed snapshot is calculated over the complete time interval supported by this timer.

Specified by:

getSnapshot in interface com.codahale.metrics.Sampling

Overrides:

getSnapshot in class com.codahale.metrics.Timer

Returns:

a snapshot of this timer

update

public void update(long duration,
                   java.util.concurrent.TimeUnit unit)

Add an event to this timer.

Overrides:

update in class com.codahale.metrics.Timer

Parameters:

duration - the time duration of the event

unit - the unit of time duration