HdrHistogram 2.1.12 · org.HdrHistogram.SingleWriterDoubleRecorder

Records floating point values, and provides stable interval DoubleHistogram samples from live recorded data without interrupting or stalling active recording of values. Each interval histogram provided contains all value counts accumulated since the previous interval histogram was taken.

This pattern is commonly used in logging interval histogram information while recording is ongoing.

SingleWriterDoubleRecorder expects only a single thread (the "single writer") to call SingleWriterDoubleRecorder#recordValue or SingleWriterDoubleRecorder#recordValueWithExpectedInterval at any point in time. It DOES NOT support concurrent recording calls. Recording calls are wait-free on architectures that support atomic increment operations, and are lock-free on architectures that do not.

A common pattern for using a SingleWriterDoubleRecorder looks like this:


SingleWriterDoubleRecorder recorder = new SingleWriterDoubleRecorder(2); // Two decimal point accuracy
DoubleHistogram intervalHistogram = null;
...
[start of some loop construct that periodically wants to grab an interval histogram]
  ...
  // Get interval histogram, recycling previous interval histogram:
  intervalHistogram = recorder.getIntervalHistogram(intervalHistogram);
  histogramLogWriter.outputIntervalHistogram(intervalHistogram);
  ...
[end of loop construct]

Nested and Inner Type Summary

Modifier and Type	Class and Description
private class	SingleWriterDoubleRecorder.InternalDoubleHistogram
private class	SingleWriterDoubleRecorder.PackedInternalDoubleHistogram

Field Summary

Modifier and Type	Field and Description
private volatile DoubleHistogram	activeHistogram
private DoubleHistogram	inactiveHistogram
private final long	instanceId
private static AtomicLong	instanceIdSequencer
private final WriterReaderPhaser	recordingPhaser

Constructor Summary

Access	Constructor and Description
public	SingleWriterDoubleRecorder(final int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5. numberOfSignificantValueDigits, final boolean Specifies whether the recorder will uses a packed internal representation or not. packed) Construct an auto-resizing `SingleWriterDoubleRecorder` using a precision stated as a number of significant decimal digits.
public	SingleWriterDoubleRecorder(final int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5. numberOfSignificantValueDigits) Construct an auto-resizing `SingleWriterDoubleRecorder` using a precision stated as a number of significant decimal digits.
public	SingleWriterDoubleRecorder(final long specifies the dynamic range to use (as a ratio) highestToLowestValueRatio, final int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5. numberOfSignificantValueDigits) Construct a `SingleWriterDoubleRecorder` dynamic range of values to cover and a number of significant decimal digits.

Method Summary

Modifier and Type	Method and Description
public synchronized DoubleHistogram	Returns: a histogram containing the value counts accumulated since the last interval histogram was taken. getIntervalHistogram() Get a new instance of an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
public synchronized DoubleHistogram	Returns: a histogram containing the value counts accumulated since the last interval histogram was taken. getIntervalHistogram(DoubleHistogram a previously returned interval histogram (from this instance of `SingleWriterDoubleRecorder`) that may be recycled to avoid allocation and copy operations. histogramToRecycle) Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
public synchronized DoubleHistogram	Returns: a histogram containing the value counts accumulated since the last interval histogram was taken. getIntervalHistogram(DoubleHistogram a previously returned interval histogram that may be recycled to avoid allocation and copy operations. histogramToRecycle, boolean if true, will only allow recycling of histograms previously returned from this instance of `SingleWriterDoubleRecorder`. If false, will allow recycling histograms previously returned by other instances of `SingleWriterDoubleRecorder`. enforeContainingInstance) Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.
public synchronized void	getIntervalHistogramInto(DoubleHistogram the histogram into which the interval histogram's data should be copied targetHistogram) Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) into `targetHistogram`.
private void	performIntervalSample()
public void	recordValue(final double the value to record value) Implements org.HdrHistogram.DoubleValueRecorder.recordValue. Record a value
public void	recordValueWithCount(final double The value to be recorded value, final long The number of occurrences of this value to record count) Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithCount. Record a value in the histogram (adding to the value's current count)
public void	recordValueWithExpectedInterval(final double The value to record value, final double If expectedIntervalBetweenValueSamples is larger than 0, add auto-generated value records as appropriate if value is larger than expectedIntervalBetweenValueSamples expectedIntervalBetweenValueSamples) Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithExpectedInterval. Record a value To compensate for the loss of sampled values when a recorded value is larger than the expected interval between value samples, Histogram will auto-generate an additional series of decreasingly-smaller (down to the expectedIntervalBetweenValueSamples) value records.
public synchronized void	reset() Implements org.HdrHistogram.DoubleValueRecorder.reset. Reset any value counts accumulated thus far.
private void	validateFitAsReplacementHistogram(DoubleHistogram replacementHistogram, boolean enforeContainingInstance)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

activeHistogram	back to summary
private volatile DoubleHistogram activeHistogram

inactiveHistogram	back to summary
private DoubleHistogram inactiveHistogram

instanceId	back to summary
private final long instanceId

instanceIdSequencer	back to summary
private static AtomicLong instanceIdSequencer

recordingPhaser	back to summary
private final WriterReaderPhaser recordingPhaser

Constructor Detail

SingleWriterDoubleRecorder back to summary

SingleWriterDoubleRecorder	back to summary
public SingleWriterDoubleRecorder(final int numberOfSignificantValueDigits, final boolean packed) Construct an auto-resizing `SingleWriterDoubleRecorder` using a precision stated as a number of significant decimal digits. Depending on the valuer of the `packed` parameter `SingleWriterDoubleRecorder` can be configuired to track value counts in a packed internal representation optimized for typical histogram recoded values are sparse in the value range and tend to be incremented in small unit counts. This packed representation tends to require significantly smaller amounts of stoarge when compared to unpacked representations, but can incur additional recording cost due to resizing and repacking operations that may occur as previously unrecorded values are encountered. Parameters numberOfSignificantValueDigits:int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5. packed:boolean Specifies whether the recorder will uses a packed internal representation or not.

public SingleWriterDoubleRecorder(final int numberOfSignificantValueDigits, final boolean packed)

Construct an auto-resizing SingleWriterDoubleRecorder using a precision stated as a number of significant decimal digits.

Depending on the valuer of the packed parameter SingleWriterDoubleRecorder can be configuired to track value counts in a packed internal representation optimized for typical histogram recoded values are sparse in the value range and tend to be incremented in small unit counts. This packed representation tends to require significantly smaller amounts of stoarge when compared to unpacked representations, but can incur additional recording cost due to resizing and repacking operations that may occur as previously unrecorded values are encountered.

Parameters

numberOfSignificantValueDigits:int: Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.
packed:boolean: Specifies whether the recorder will uses a packed internal representation or not.

SingleWriterDoubleRecorder back to summary

SingleWriterDoubleRecorder	back to summary
public SingleWriterDoubleRecorder(final int numberOfSignificantValueDigits) Construct an auto-resizing `SingleWriterDoubleRecorder` using a precision stated as a number of significant decimal digits. Parameters numberOfSignificantValueDigits:int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.

public SingleWriterDoubleRecorder(final int numberOfSignificantValueDigits)

Construct an auto-resizing SingleWriterDoubleRecorder using a precision stated as a number of significant decimal digits.

Parameters

numberOfSignificantValueDigits:int: Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.

SingleWriterDoubleRecorder back to summary

SingleWriterDoubleRecorder	back to summary
public SingleWriterDoubleRecorder(final long highestToLowestValueRatio, final int numberOfSignificantValueDigits) Construct a `SingleWriterDoubleRecorder` dynamic range of values to cover and a number of significant decimal digits. Parameters highestToLowestValueRatio:long specifies the dynamic range to use (as a ratio) numberOfSignificantValueDigits:int Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.

public SingleWriterDoubleRecorder(final long highestToLowestValueRatio, final int numberOfSignificantValueDigits)

Construct a SingleWriterDoubleRecorder dynamic range of values to cover and a number of significant decimal digits.

Parameters

highestToLowestValueRatio:long: specifies the dynamic range to use (as a ratio)
numberOfSignificantValueDigits:int: Specifies the precision to use. This is the number of significant decimal digits to which the histogram will maintain value resolution and separation. Must be a non-negative integer between 0 and 5.

Method Detail

getIntervalHistogram back to summary

getIntervalHistogram	back to summary
public synchronized DoubleHistogram getIntervalHistogram() Get a new instance of an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken. Calling `getIntervalHistogram()` will reset the value counts, and start accumulating value counts for the next interval. Returns:DoubleHistogram a histogram containing the value counts accumulated since the last interval histogram was taken.

public synchronized DoubleHistogram getIntervalHistogram()

Get a new instance of an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.

Calling getIntervalHistogram() will reset the value counts, and start accumulating value counts for the next interval.

Returns:DoubleHistogram: a histogram containing the value counts accumulated since the last interval histogram was taken.

getIntervalHistogram back to summary

getIntervalHistogram	back to summary
public synchronized DoubleHistogram getIntervalHistogram(DoubleHistogram histogramToRecycle) Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken. `getIntervalHistogram(histogramToRecycle)` accepts a previously returned interval histogram that can be recycled internally to avoid allocation and content copying operations, and is therefore significantly more efficient for repeated use than `SingleWriterDoubleRecorder#getIntervalHistogram()` and `getIntervalHistogramInto()`. The provided `histogramToRecycle` must be either be null or an interval histogram returned by a previous call to `getIntervalHistogram(histogramToRecycle)` or `SingleWriterDoubleRecorder#getIntervalHistogram()`. Note The caller is responsible for not recycling the same returned interval histogram more than once. If the same interval histogram instance is recycled more than once, behavior is undefined. Calling `getIntervalHistogram(histogramToRecycle)` will reset the value counts, and start accumulating value counts for the next interval Parameters histogramToRecycle:DoubleHistogram a previously returned interval histogram (from this instance of `SingleWriterDoubleRecorder`) that may be recycled to avoid allocation and copy operations. Returns:DoubleHistogram a histogram containing the value counts accumulated since the last interval histogram was taken.

public synchronized DoubleHistogram getIntervalHistogram(DoubleHistogram histogramToRecycle)

Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.

getIntervalHistogram(histogramToRecycle) accepts a previously returned interval histogram that can be recycled internally to avoid allocation and content copying operations, and is therefore significantly more efficient for repeated use than SingleWriterDoubleRecorder#getIntervalHistogram() and getIntervalHistogramInto(). The provided histogramToRecycle must be either be null or an interval histogram returned by a previous call to getIntervalHistogram(histogramToRecycle) or SingleWriterDoubleRecorder#getIntervalHistogram().

Note

The caller is responsible for not recycling the same returned interval histogram more than once. If the same interval histogram instance is recycled more than once, behavior is undefined.

Calling getIntervalHistogram(histogramToRecycle) will reset the value counts, and start accumulating value counts for the next interval

Parameters

histogramToRecycle:DoubleHistogram: a previously returned interval histogram (from this instance of SingleWriterDoubleRecorder) that may be recycled to avoid allocation and copy operations.

Returns:DoubleHistogram

a histogram containing the value counts accumulated since the last interval histogram was taken.

getIntervalHistogram back to summary

getIntervalHistogram	back to summary
public synchronized DoubleHistogram getIntervalHistogram(DoubleHistogram histogramToRecycle, boolean enforeContainingInstance) Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken. `getIntervalHistogram(histogramToRecycle)` accepts a previously returned interval histogram that can be recycled internally to avoid allocation and content copying operations, and is therefore significantly more efficient for repeated use than `SingleWriterDoubleRecorder#getIntervalHistogram()` and `getIntervalHistogramInto()`. The provided `histogramToRecycle` must be either be null or an interval histogram returned by a previous call to `getIntervalHistogram(histogramToRecycle)` or `SingleWriterDoubleRecorder#getIntervalHistogram()`. Note The caller is responsible for not recycling the same returned interval histogram more than once. If the same interval histogram instance is recycled more than once, behavior is undefined. Calling `getIntervalHistogram(histogramToRecycle)` will reset the value counts, and start accumulating value counts for the next interval Parameters histogramToRecycle:DoubleHistogram a previously returned interval histogram that may be recycled to avoid allocation and copy operations. enforeContainingInstance:boolean if true, will only allow recycling of histograms previously returned from this instance of `SingleWriterDoubleRecorder`. If false, will allow recycling histograms previously returned by other instances of `SingleWriterDoubleRecorder`. Returns:DoubleHistogram a histogram containing the value counts accumulated since the last interval histogram was taken.

public synchronized DoubleHistogram getIntervalHistogram(DoubleHistogram histogramToRecycle, boolean enforeContainingInstance)

Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.

Note

The caller is responsible for not recycling the same returned interval histogram more than once. If the same interval histogram instance is recycled more than once, behavior is undefined.

Calling getIntervalHistogram(histogramToRecycle) will reset the value counts, and start accumulating value counts for the next interval

Parameters

histogramToRecycle:DoubleHistogram: a previously returned interval histogram that may be recycled to avoid allocation and copy operations.
enforeContainingInstance:boolean: if true, will only allow recycling of histograms previously returned from this instance of SingleWriterDoubleRecorder. If false, will allow recycling histograms previously returned by other instances of SingleWriterDoubleRecorder.

Returns:DoubleHistogram

a histogram containing the value counts accumulated since the last interval histogram was taken.

getIntervalHistogramInto back to summary

getIntervalHistogramInto	back to summary
public synchronized void getIntervalHistogramInto(DoubleHistogram targetHistogram) Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) into `targetHistogram`. Calling `getIntervalHistogramInto(targetHistogram)` will reset the value counts, and start accumulating value counts for the next interval. Parameters targetHistogram:DoubleHistogram the histogram into which the interval histogram's data should be copied

public synchronized void getIntervalHistogramInto(DoubleHistogram targetHistogram)

Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) into targetHistogram. Calling getIntervalHistogramInto(targetHistogram) will reset the value counts, and start accumulating value counts for the next interval.

Parameters

targetHistogram:DoubleHistogram: the histogram into which the interval histogram's data should be copied

performIntervalSample	back to summary
private void performIntervalSample()

recordValue	back to summary
public void recordValue(final double value) Implements org.HdrHistogram.DoubleValueRecorder.recordValue. Record a value Parameters value:double the value to record Exceptions ArrayIndexOutOfBoundsException: (may throw) if value is exceeds highestTrackableValue

recordValue

back to summary

public void recordValue(final double value)

Implements org.HdrHistogram.DoubleValueRecorder.recordValue.

Record a value

Parameters

value:double: the value to record

Exceptions

ArrayIndexOutOfBoundsException:: (may throw) if value is exceeds highestTrackableValue

recordValueWithCount	back to summary
public void recordValueWithCount(final double value, final long count) throws ArrayIndexOutOfBoundsException Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithCount. Record a value in the histogram (adding to the value's current count) Parameters value:double The value to be recorded count:long The number of occurrences of this value to record Exceptions ArrayIndexOutOfBoundsException: (may throw) if value is exceeds highestTrackableValue

recordValueWithCount

back to summary

public void recordValueWithCount(final double value, final long count) throws ArrayIndexOutOfBoundsException

Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithCount.

Record a value in the histogram (adding to the value's current count)

Parameters

value:double: The value to be recorded
count:long: The number of occurrences of this value to record

Exceptions

ArrayIndexOutOfBoundsException:: (may throw) if value is exceeds highestTrackableValue

recordValueWithExpectedInterval back to summary

recordValueWithExpectedInterval	back to summary
public void recordValueWithExpectedInterval(final double value, final double expectedIntervalBetweenValueSamples) throws ArrayIndexOutOfBoundsException Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithExpectedInterval. Record a value To compensate for the loss of sampled values when a recorded value is larger than the expected interval between value samples, Histogram will auto-generate an additional series of decreasingly-smaller (down to the expectedIntervalBetweenValueSamples) value records. See related notes `org.HdrHistogram.DoubleHistogram#recordValueWithExpectedInterval(double, double)` for more explanations about coordinated omission and expected interval correction. * Parameters value:double The value to record expectedIntervalBetweenValueSamples:double If expectedIntervalBetweenValueSamples is larger than 0, add auto-generated value records as appropriate if value is larger than expectedIntervalBetweenValueSamples Exceptions ArrayIndexOutOfBoundsException: (may throw) if value is exceeds highestTrackableValue

public void recordValueWithExpectedInterval(final double value, final double expectedIntervalBetweenValueSamples) throws ArrayIndexOutOfBoundsException

Implements org.HdrHistogram.DoubleValueRecorder.recordValueWithExpectedInterval.

Record a value

To compensate for the loss of sampled values when a recorded value is larger than the expected interval between value samples, Histogram will auto-generate an additional series of decreasingly-smaller (down to the expectedIntervalBetweenValueSamples) value records.

See related notes org.HdrHistogram.DoubleHistogram#recordValueWithExpectedInterval(double, double) for more explanations about coordinated omission and expected interval correction. *

Parameters

value:double: The value to record
expectedIntervalBetweenValueSamples:double: If expectedIntervalBetweenValueSamples is larger than 0, add auto-generated value records as appropriate if value is larger than expectedIntervalBetweenValueSamples

Exceptions

ArrayIndexOutOfBoundsException:: (may throw) if value is exceeds highestTrackableValue

reset	back to summary
public synchronized void reset() Implements org.HdrHistogram.DoubleValueRecorder.reset. Reset any value counts accumulated thus far.

reset

back to summary

public synchronized void reset()

Implements org.HdrHistogram.DoubleValueRecorder.reset.

Reset any value counts accumulated thus far.

validateFitAsReplacementHistogram	back to summary
private void validateFitAsReplacementHistogram(DoubleHistogram replacementHistogram, boolean enforeContainingInstance)

public Class SingleWriterDoubleRecorder

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class SingleWriterDoubleRecorder.InternalDoubleHistogram

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

private Class SingleWriterDoubleRecorder.PackedInternalDoubleHistogram

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Access	Constructor and Description
private	InternalDoubleHistogram(long id, int numberOfSignificantValueDigits)
private	InternalDoubleHistogram(long id, long highestToLowestValueRatio, int numberOfSignificantValueDigits)
private	InternalDoubleHistogram(SingleWriterDoubleRecorder.InternalDoubleHistogram source)