Class SingleWriterRecorder
- java.lang.Object
-
- org.HdrHistogram.SingleWriterRecorder
-
- All Implemented Interfaces:
ValueRecorder
public class SingleWriterRecorder extends java.lang.Object implements ValueRecorder
Records integer values, and provides stable intervalHistogram
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.
SingleWriterRecorder
expects only a single thread (the "single writer") to callrecordValue(long)
orrecordValueWithExpectedInterval(long, long)
at any point in time. It DOES NOT safely support concurrent recording calls. Recording calls are wait-free on architectures that support atomic increment operations, and re lock-free on architectures that do not. *A common pattern for using a
SingleWriterRecorder
looks like this:SingleWriterRecorder recorder = new SingleWriterRecorder(2); // Two decimal point accuracy Histogram 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 Class Summary
Nested Classes Modifier and Type Class Description private static class
SingleWriterRecorder.InternalHistogram
private static class
SingleWriterRecorder.PackedInternalHistogram
-
Field Summary
Fields Modifier and Type Field Description private Histogram
activeHistogram
private Histogram
inactiveHistogram
private long
instanceId
private static java.util.concurrent.atomic.AtomicLong
instanceIdSequencer
private WriterReaderPhaser
recordingPhaser
-
Constructor Summary
Constructors Constructor Description SingleWriterRecorder(int numberOfSignificantValueDigits)
Construct an auto-resizingSingleWriterRecorder
with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue.SingleWriterRecorder(int numberOfSignificantValueDigits, boolean packed)
Construct an auto-resizingSingleWriterRecorder
with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue.SingleWriterRecorder(long highestTrackableValue, int numberOfSignificantValueDigits)
Construct aSingleWriterRecorder
given the highest value to be tracked and a number of significant decimal digits.SingleWriterRecorder(long lowestDiscernibleValue, long highestTrackableValue, int numberOfSignificantValueDigits)
Construct aSingleWriterRecorder
given the Lowest and highest values to be tracked and a number of significant decimal digits.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Histogram
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.Histogram
getIntervalHistogram(Histogram histogramToRecycle)
Get an interval histogram, which will include a stable, consistent view of all value counts accumulated since the last interval histogram was taken.Histogram
getIntervalHistogram(Histogram 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.void
getIntervalHistogramInto(Histogram targetHistogram)
Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) intotargetHistogram
.private void
performIntervalSample()
void
recordValue(long value)
Record a valuevoid
recordValueWithCount(long value, long count)
Record a value in the histogram (adding to the value's current count)void
recordValueWithExpectedInterval(long value, long expectedIntervalBetweenValueSamples)
Record a valuevoid
reset()
Reset any value counts accumulated thus far.private void
validateFitAsReplacementHistogram(Histogram replacementHistogram, boolean enforeContainingInstance)
-
-
-
Field Detail
-
instanceIdSequencer
private static java.util.concurrent.atomic.AtomicLong instanceIdSequencer
-
instanceId
private final long instanceId
-
recordingPhaser
private final WriterReaderPhaser recordingPhaser
-
activeHistogram
private volatile Histogram activeHistogram
-
inactiveHistogram
private Histogram inactiveHistogram
-
-
Constructor Detail
-
SingleWriterRecorder
public SingleWriterRecorder(int numberOfSignificantValueDigits, boolean packed)
Construct an auto-resizingSingleWriterRecorder
with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue. Can auto-resize up to track values up to (Long.MAX_VALUE / 2).Depending on the valuer of the
packed
parameterSingleWriterRecorder
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
- 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
- Specifies whether the recorder will uses a packed internal representation or not.
-
SingleWriterRecorder
public SingleWriterRecorder(int numberOfSignificantValueDigits)
Construct an auto-resizingSingleWriterRecorder
with a lowest discernible value of 1 and an auto-adjusting highestTrackableValue. Can auto-resize up to track values up to (Long.MAX_VALUE / 2).- Parameters:
numberOfSignificantValueDigits
- 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.
-
SingleWriterRecorder
public SingleWriterRecorder(long highestTrackableValue, int numberOfSignificantValueDigits)
Construct aSingleWriterRecorder
given the highest value to be tracked and a number of significant decimal digits. The histogram will be constructed to implicitly track (distinguish from 0) values as low as 1.- Parameters:
highestTrackableValue
- The highest value to be tracked by the histogram. Must be a positive integer that is >= 2.numberOfSignificantValueDigits
- 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.
-
SingleWriterRecorder
public SingleWriterRecorder(long lowestDiscernibleValue, long highestTrackableValue, int numberOfSignificantValueDigits)
Construct aSingleWriterRecorder
given the Lowest and highest values to be tracked and a number of significant decimal digits. Providing a lowestDiscernibleValue is useful is situations where the units used for the histogram's values are much smaller that the minimal accuracy required. E.g. when tracking time values stated in nanosecond units, where the minimal accuracy required is a microsecond, the proper value for lowestDiscernibleValue would be 1000.- Parameters:
lowestDiscernibleValue
- The lowest value that can be tracked (distinguished from 0) by the histogram. Must be a positive integer that is >= 1. May be internally rounded down to nearest power of 2.highestTrackableValue
- The highest value to be tracked by the histogram. Must be a positive integer that is >= (2 * lowestDiscernibleValue).numberOfSignificantValueDigits
- 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
-
recordValue
public void recordValue(long value)
Record a value- Specified by:
recordValue
in interfaceValueRecorder
- Parameters:
value
- the value to record- Throws:
java.lang.ArrayIndexOutOfBoundsException
- (may throw) if value is exceeds highestTrackableValue
-
recordValueWithCount
public void recordValueWithCount(long value, long count) throws java.lang.ArrayIndexOutOfBoundsException
Record a value in the histogram (adding to the value's current count)- Specified by:
recordValueWithCount
in interfaceValueRecorder
- Parameters:
value
- The value to be recordedcount
- The number of occurrences of this value to record- Throws:
java.lang.ArrayIndexOutOfBoundsException
- (may throw) if value is exceeds highestTrackableValue
-
recordValueWithExpectedInterval
public void recordValueWithExpectedInterval(long value, long expectedIntervalBetweenValueSamples) throws java.lang.ArrayIndexOutOfBoundsException
Record a valueTo 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
AbstractHistogram.recordValueWithExpectedInterval(long, long)
for more explanations about coordinated omission and expected interval correction. *- Specified by:
recordValueWithExpectedInterval
in interfaceValueRecorder
- Parameters:
value
- The value to recordexpectedIntervalBetweenValueSamples
- If expectedIntervalBetweenValueSamples is larger than 0, add auto-generated value records as appropriate if value is larger than expectedIntervalBetweenValueSamples- Throws:
java.lang.ArrayIndexOutOfBoundsException
- (may throw) if value is exceeds highestTrackableValue
-
getIntervalHistogram
public Histogram 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:
- a histogram containing the value counts accumulated since the last interval histogram was taken.
-
getIntervalHistogram
public Histogram getIntervalHistogram(Histogram 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 thangetIntervalHistogram()
andgetIntervalHistogramInto()
. The providedhistogramToRecycle
must be either be null or an interval histogram returned by a previous call togetIntervalHistogram(histogramToRecycle)
orgetIntervalHistogram()
.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
- a previously returned interval histogram (from this instance ofSingleWriterRecorder
) that may be recycled to avoid allocation and copy operations.- Returns:
- a histogram containing the value counts accumulated since the last interval histogram was taken.
-
getIntervalHistogram
public Histogram getIntervalHistogram(Histogram 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 thangetIntervalHistogram()
andgetIntervalHistogramInto()
. The providedhistogramToRecycle
must be either be null or an interval histogram returned by a previous call togetIntervalHistogram(histogramToRecycle)
orgetIntervalHistogram()
.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
- a previously returned interval histogram that may be recycled to avoid allocation and copy operations.enforeContainingInstance
- if true, will only allow recycling of histograms previously returned from this instance ofSingleWriterRecorder
. If false, will allow recycling histograms previously returned by other instances ofSingleWriterRecorder
.- Returns:
- a histogram containing the value counts accumulated since the last interval histogram was taken.
-
getIntervalHistogramInto
public void getIntervalHistogramInto(Histogram targetHistogram)
Place a copy of the value counts accumulated since accumulated (since the last interval histogram was taken) intotargetHistogram
. CallinggetIntervalHistogramInto(targetHistogram)
will reset the value counts, and start accumulating value counts for the next interval.- Parameters:
targetHistogram
- the histogram into which the interval histogram's data should be copied
-
reset
public void reset()
Reset any value counts accumulated thus far.- Specified by:
reset
in interfaceValueRecorder
-
performIntervalSample
private void performIntervalSample()
-
validateFitAsReplacementHistogram
private void validateFitAsReplacementHistogram(Histogram replacementHistogram, boolean enforeContainingInstance)
-
-