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/**
* Written by Gil Tene of Azul Systems, and released to the public domain,
* as explained at http://creativecommons.org/publicdomain/zero/1.0/
*
* @author Gil Tene
*/
package org.glowroot.shaded.HdrHistogram;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.nio.ByteBuffer;
import java.nio.LongBuffer;
import java.util.Arrays;
import java.util.zip.DataFormatException;
/**
* An integer values High Dynamic Range (HDR) Histogram that is synchronized as a whole
*
* A {@link SynchronizedHistogram} is a variant of {@link Histogram} that is
* synchronized as a whole, such that queries, copying, and addition operations are atomic with relation to
* modification on the {@link SynchronizedHistogram}, and such that external accessors (e.g. iterations on the
* histogram data) that synchronize on the {@link SynchronizedHistogram} instance can safely assume that no
* modifications to the histogram data occur within their synchronized block.
*
* It is important to note that synchronization can result in blocking recoding calls. If non-blocking recoding
* operations are required, consider using {@link ConcurrentHistogram}, {@link AtomicHistogram}, or (recommended)
* {@link Recorder} or {@link org.glowroot.shaded.HdrHistogram.SingleWriterRecorder} which were intended for concurrent operations.
*
* See package description for {@link org.glowroot.shaded.HdrHistogram} and {@link org.glowroot.shaded.HdrHistogram.Histogram} for more details.
*/
public class SynchronizedHistogram extends Histogram {
@Override
synchronized long getCountAtIndex(final int index) {
return counts[normalizeIndex(index, normalizingIndexOffset, countsArrayLength)];
}
@Override
synchronized long getCountAtNormalizedIndex(final int index) {
return counts[index];
}
@Override
synchronized void incrementCountAtIndex(final int index) {
counts[normalizeIndex(index, normalizingIndexOffset, countsArrayLength)]++;
}
@Override
synchronized void addToCountAtIndex(final int index, final long value) {
counts[normalizeIndex(index, normalizingIndexOffset, countsArrayLength)] += value;
}
@Override
synchronized void setCountAtIndex(int index, long value) {
counts[normalizeIndex(index, normalizingIndexOffset, countsArrayLength)] = value;
}
@Override
synchronized void setCountAtNormalizedIndex(int index, long value) {
counts[index] = value;
}
@Override
synchronized int getNormalizingIndexOffset() {
return normalizingIndexOffset;
}
@Override
synchronized void setNormalizingIndexOffset(int normalizingIndexOffset) {
this.normalizingIndexOffset = normalizingIndexOffset;
}
@Override
synchronized void shiftNormalizingIndexByOffset(int offsetToAdd, boolean lowestHalfBucketPopulated) {
nonConcurrentNormalizingIndexShift(offsetToAdd, lowestHalfBucketPopulated);
}
@Override
synchronized void clearCounts() {
java.util.Arrays.fill(counts, 0);
totalCount = 0;
}
@Override
public void add(final AbstractHistogram otherHistogram) {
// Synchronize add(). Avoid deadlocks by synchronizing in order of construction identity count.
if (identity < otherHistogram.identity) {
synchronized (this) {
synchronized (otherHistogram) {
super.add(otherHistogram);
}
}
} else {
synchronized (otherHistogram) {
synchronized (this) {
super.add(otherHistogram);
}
}
}
}
@Override
public synchronized void shiftValuesLeft(final int numberOfBinaryOrdersOfMagnitude) {
super.shiftValuesLeft(numberOfBinaryOrdersOfMagnitude);
}
@Override
public synchronized void shiftValuesRight(final int numberOfBinaryOrdersOfMagnitude) {
super.shiftValuesRight(numberOfBinaryOrdersOfMagnitude);
}
@Override
public SynchronizedHistogram copy() {
SynchronizedHistogram copy;
synchronized (this) {
copy = new SynchronizedHistogram(this);
}
copy.add(this);
return copy;
}
@Override
public SynchronizedHistogram copyCorrectedForCoordinatedOmission(final long expectedIntervalBetweenValueSamples) {
synchronized (this) {
SynchronizedHistogram toHistogram = new SynchronizedHistogram(this);
toHistogram.addWhileCorrectingForCoordinatedOmission(this, expectedIntervalBetweenValueSamples);
return toHistogram;
}
}
@Override
public long getTotalCount() {
return totalCount;
}
@Override
synchronized void setTotalCount(final long totalCount) {
this.totalCount = totalCount;
}
@Override
synchronized void incrementTotalCount() {
totalCount++;
}
@Override
synchronized void addToTotalCount(long value) {
totalCount += value;
}
@Override
synchronized void updatedMaxValue(long maxValue) {
if (maxValue > getMaxValue()) {
super.updatedMaxValue(maxValue);
}
}
@Override
synchronized void updateMinNonZeroValue(long minNonZeroValue) {
if (minNonZeroValue < getMinNonZeroValue()) {
super.updateMinNonZeroValue(minNonZeroValue);
}
}
@Override
synchronized int _getEstimatedFootprintInBytes() {
return (512 + (8 * counts.length));
}
@Override
synchronized void resize(long newHighestTrackableValue) {
int oldNormalizedZeroIndex = normalizeIndex(0, normalizingIndexOffset, countsArrayLength);
establishSize(newHighestTrackableValue);
int countsDelta = countsArrayLength - counts.length;
counts = Arrays.copyOf(counts, countsArrayLength);
if (oldNormalizedZeroIndex != 0) {
// We need to shift the stuff from the zero index and up to the end of the array:
int newNormalizedZeroIndex = oldNormalizedZeroIndex + countsDelta;
int lengthToCopy = (countsArrayLength - countsDelta) - oldNormalizedZeroIndex;
System.arraycopy(counts, oldNormalizedZeroIndex, counts, newNormalizedZeroIndex, lengthToCopy);
}
}
/**
* Construct an auto-resizing SynchronizedHistogram 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).
*
* @param 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.
*/
public SynchronizedHistogram(final int numberOfSignificantValueDigits) {
this(1, 2, numberOfSignificantValueDigits);
setAutoResize(true);
}
/**
* Construct a SynchronizedHistogram 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.
*
* @param highestTrackableValue The highest value to be tracked by the histogram. Must be a positive
* integer that is {@literal >=} 2.
* @param 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.
*/
public SynchronizedHistogram(final long highestTrackableValue, final int numberOfSignificantValueDigits) {
this(1, highestTrackableValue, numberOfSignificantValueDigits);
}
/**
* Construct a SynchronizedHistogram 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.
*
* @param lowestDiscernibleValue The lowest value that can be tracked (distinguished from 0) by the histogram.
* Must be a positive integer that is {@literal >=} 1. May be internally rounded
* down to nearest power of 2.
* @param highestTrackableValue The highest value to be tracked by the histogram. Must be a positive
* integer that is {@literal >=} (2 * lowestDiscernibleValue).
* @param 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.
*/
public SynchronizedHistogram(final long lowestDiscernibleValue, final long highestTrackableValue, final int numberOfSignificantValueDigits) {
super(lowestDiscernibleValue, highestTrackableValue, numberOfSignificantValueDigits);
}
/**
* Construct a histogram with the same range settings as a given source histogram,
* duplicating the source's start/end timestamps (but NOT it's contents)
* @param source The source histogram to duplicate
*/
public SynchronizedHistogram(final AbstractHistogram source) {
super(source);
}
/**
* Construct a new histogram by decoding it from a ByteBuffer.
* @param buffer The buffer to decode from
* @param minBarForHighestTrackableValue Force highestTrackableValue to be set at least this high
* @return The newly constructed histogram
*/
public static SynchronizedHistogram decodeFromByteBuffer(final ByteBuffer buffer,
final long minBarForHighestTrackableValue) {
return (SynchronizedHistogram) decodeFromByteBuffer(buffer, SynchronizedHistogram.class,
minBarForHighestTrackableValue);
}
/**
* Construct a new histogram by decoding it from a compressed form in a ByteBuffer.
* @param buffer The buffer to decode from
* @param minBarForHighestTrackableValue Force highestTrackableValue to be set at least this high
* @return The newly constructed histogram
* @throws DataFormatException on error parsing/decompressing the buffer
*/
public static SynchronizedHistogram decodeFromCompressedByteBuffer(final ByteBuffer buffer,
final long minBarForHighestTrackableValue) throws DataFormatException {
return (SynchronizedHistogram) decodeFromCompressedByteBuffer(buffer, SynchronizedHistogram.class,
minBarForHighestTrackableValue);
}
private void readObject(final ObjectInputStream o)
throws IOException, ClassNotFoundException {
o.defaultReadObject();
}
@Override
synchronized void fillCountsArrayFromBuffer(final ByteBuffer buffer, final int length) {
buffer.asLongBuffer().get(counts, 0, length);
}
// We try to cache the LongBuffer used in output cases, as repeated
// output form the same histogram using the same buffer is likely:
private LongBuffer cachedDstLongBuffer = null;
private ByteBuffer cachedDstByteBuffer = null;
private int cachedDstByteBufferPosition = 0;
@Override
synchronized void fillBufferFromCountsArray(final ByteBuffer buffer, final int length) {
if ((cachedDstLongBuffer == null) ||
(buffer != cachedDstByteBuffer) ||
(buffer.position() != cachedDstByteBufferPosition)) {
cachedDstByteBuffer = buffer;
cachedDstByteBufferPosition = buffer.position();
cachedDstLongBuffer = buffer.asLongBuffer();
}
cachedDstLongBuffer.rewind();
int zeroIndex = normalizeIndex(0, getNormalizingIndexOffset(), countsArrayLength);
int lengthFromZeroIndexToEnd = Math.min(length, (countsArrayLength - zeroIndex));
int remainingLengthFromNormalizedZeroIndex = length - lengthFromZeroIndexToEnd;
cachedDstLongBuffer.put(counts, zeroIndex, lengthFromZeroIndexToEnd);
cachedDstLongBuffer.put(counts, 0, remainingLengthFromNormalizedZeroIndex);
}
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