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/*
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package org.glassfish.jersey.server.internal.monitoring;
import java.util.LinkedList;
import java.util.Queue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import org.glassfish.jersey.server.monitoring.TimeWindowStatistics;
/**
* {@link TimeWindowStatistics Time window statistics} implementation.
*
* @author Miroslav Fuksa (miroslav.fuksa at oracle.com)
*/
final class TimeWindowStatisticsImpl implements TimeWindowStatistics {
/**
* Builder of time window statistics.
*/
static class Builder {
private static final int DEFAULT_UNITS_PER_INTERVAL = 100;
private static final int MINIMUM_UNIT_SIZE = 1000;
/**
* Total interval for which these statistics are calculated (eg. last 15 seconds, last one minute) converted to ms
*/
private final long interval;
/**
* size of one unit in ms.
*/
private final long unit;
/**
* How many units are in one interval.
*/
private final int unitsPerInterval;
/**
* Start time of measuring statistics.
*/
private final long startTime;
private final Queue unitQueue;
/**
* Total request count measured in the interval window.
* Summary of {@code count} all units in {@code unitQueue}.
*/
private long totalCount;
/**
* Summary of all request duration in the time window.
*/
private long totalDuration;
/**
* Same meaning as {@code interval} but is calculated including rounding error.
* It is equal to {@code unit} * {@code unitsPerInterval}.
*/
private final long intervalWithRoundError;
// last unit = newest unit. Following statistics are not in the queue yet (no Unit yest)
private long lastUnitEnd;
private long lastUnitCount;
private long lastUnitMin = -1;
private long lastUnitMax = -1;
private long lastUnitDuration = 0;
/**
* Oldest unit that is in the queue (first that will be removed).
*/
private Unit oldestUnit;
private static class Unit {
private final long count;
private final long minimumDuration;
private final long maximumDuration;
private final long duration;
private Unit(final long count, final long minimumDuration, final long maximumDuration, final long duration) {
this.count = count;
this.minimumDuration = minimumDuration;
this.maximumDuration = maximumDuration;
this.duration = duration;
}
private static Unit EMPTY_UNIT = new Unit(0, -1, -1, 0);
}
/**
* Create a new builder instance.
*
* @param timeWindowSize Size of time window.
* @param timeUnit Time units of {@code timeWindowSize}.
*/
Builder(final long timeWindowSize, final TimeUnit timeUnit) {
this(timeWindowSize, timeUnit, System.currentTimeMillis());
}
/**
* Create a new builder instance. A constructor is used mainly for testing purposes.
*
* @param timeWindowSize Size of time window.
* @param timeUnit Time units of {@code timeWindowSize}.
* @param now Current time.
*/
Builder(final long timeWindowSize, final TimeUnit timeUnit, final long now) {
startTime = now;
this.interval = timeUnit.toMillis(timeWindowSize);
if (interval == 0) {
// unlimited timeWindowSize
unit = 0;
unitsPerInterval = 0;
intervalWithRoundError = 0;
unitQueue = null;
} else {
int n = DEFAULT_UNITS_PER_INTERVAL;
long u = interval / n;
if (u < 1000) {
n = (int) interval / 1000;
u = interval / n;
}
this.unit = u;
this.unitsPerInterval = n;
intervalWithRoundError = unit * unitsPerInterval;
// TODO change to array
this.unitQueue = new LinkedList<>();
lastUnitEnd = startTime + unit;
}
}
/**
* Add request execution.
*
* @param requestTime Time of execution.
* @param duration Duration of request processing.
*/
void addRequest(final long requestTime, final long duration) {
closeLastUnitIfNeeded(requestTime);
lastUnitCount++;
lastUnitDuration += duration;
if (duration < lastUnitMin || lastUnitMin == -1) {
lastUnitMin = duration;
}
if (duration > lastUnitMax || lastUnitMax == -1) {
lastUnitMax = duration;
}
}
private void closeLastUnitIfNeeded(final long requestTime) {
if (interval != 0) {
if ((requestTime - lastUnitEnd) > interval + unit) {
resetQueue(requestTime);
}
if (lastUnitEnd < requestTime) {
// close the old unit
if (lastUnitCount > 0) {
add(new Unit(lastUnitCount, lastUnitMin, lastUnitMax, lastUnitDuration));
} else {
add(Unit.EMPTY_UNIT);
}
lastUnitEnd += unit;
resetLastUnit();
while (lastUnitEnd < requestTime) {
add(Unit.EMPTY_UNIT);
lastUnitEnd += unit;
}
}
}
}
private void resetLastUnit() {
lastUnitCount = 0;
lastUnitMin = -1;
lastUnitMax = -1;
lastUnitDuration = 0;
}
private void add(final Unit unit) {
unitQueue.add(unit);
// fill with empty until units
if (unitQueue.size() > unitsPerInterval) {
final Unit removedUnit = unitQueue.remove();
totalCount -= removedUnit.count;
totalDuration -= removedUnit.duration;
}
this.oldestUnit = unitQueue.element();
totalCount += lastUnitCount;
totalDuration += lastUnitDuration;
}
private void resetQueue(final long requestTime) {
this.unitQueue.clear();
lastUnitEnd = requestTime + unit;
resetLastUnit();
// fill with empty unit to keep result consistent
for (int i = 0; i < unitsPerInterval; i++) {
unitQueue.add(Unit.EMPTY_UNIT);
}
}
/**
* Build the time window statistics instance.
*
* @return New instance of statistics.
*/
TimeWindowStatisticsImpl build() {
return build(System.currentTimeMillis());
}
/**
* Build the time window statistics instance.
*
* @param currentTime Current time as a reference to which the statistics should be built.
* @return New instance of statistics.
*/
TimeWindowStatisticsImpl build(final long currentTime) {
final long diff = currentTime - startTime;
if (interval == 0) {
if (diff < MINIMUM_UNIT_SIZE) {
return TimeWindowStatisticsImpl.EMPTY.get(0l);
} else {
final double requestsPerSecond = (double) (1000 * lastUnitCount) / diff;
final long avg = lastUnitCount == 0 ? -1 : lastUnitDuration / lastUnitCount;
return lastUnitCount == 0 ?
TimeWindowStatisticsImpl.EMPTY.get(0l) :
new TimeWindowStatisticsImpl(0, requestsPerSecond, lastUnitMin, lastUnitMax, avg, lastUnitCount);
}
}
closeLastUnitIfNeeded(currentTime);
long min = -1;
long max = -1;
final double requestsPerSecond;
for (final Unit u : this.unitQueue) {
min = getMin(min, u.minimumDuration);
max = getMax(max, u.maximumDuration);
}
min = getMin(min, lastUnitMin);
max = getMax(max, lastUnitMax);
long adjustedTotalCount = totalCount + lastUnitCount;
long adjustedTotalDuration = totalDuration + lastUnitDuration;
final int size = unitQueue.size();
if (size >= unitsPerInterval) {
final double ratio = (currentTime - (lastUnitEnd - unit)) / ((double) unit);
if (oldestUnit != null) {
adjustedTotalCount -= (long) (oldestUnit.count * ratio);
adjustedTotalDuration -= (long) (oldestUnit.duration * ratio);
}
// intervalWithRoundError is used instead of size * unit for performance reasons
requestsPerSecond = (double) (1000 * adjustedTotalCount) / intervalWithRoundError;
} else {
requestsPerSecond = diff == 0 ? 0 : (double) (1000 * adjustedTotalCount) / (double) diff;
}
if (adjustedTotalCount == 0) {
return getOrCreateEmptyStats(interval);
} else {
final long avg = adjustedTotalDuration / adjustedTotalCount;
return new TimeWindowStatisticsImpl(interval, requestsPerSecond, min, max, avg, adjustedTotalCount);
}
}
private TimeWindowStatisticsImpl getOrCreateEmptyStats(final long interval) {
if (!EMPTY.containsKey(interval)) {
EMPTY.putIfAbsent(interval, new TimeWindowStatisticsImpl(interval, 0, -1, -1, -1, 0));
}
return EMPTY.get(interval);
}
private long getMax(long globalMax, final long unitMax) {
if ((unitMax > globalMax && unitMax != -1) || globalMax == -1) {
globalMax = unitMax;
}
return globalMax;
}
private long getMin(long globalMin, final long unitMin) {
if ((unitMin < globalMin && unitMin != -1) || globalMin == -1) {
globalMin = unitMin;
}
return globalMin;
}
public long getInterval() {
return interval;
}
}
private final static ConcurrentHashMap EMPTY = new ConcurrentHashMap<>(6);
static {
EMPTY.putIfAbsent(0l, new TimeWindowStatisticsImpl(0, 0, 0, 0, 0, 0));
}
private final long interval;
private final long minimumDuration;
private final long maximumDuration;
private final long averageDuration;
private final long totalCount;
private final double requestsPerSecond;
private TimeWindowStatisticsImpl(final long interval, final double requestsPerSecond, final long minimumDuration,
final long maximumDuration, final long averageDuration, final long totalCount) {
this.interval = interval;
this.requestsPerSecond = requestsPerSecond;
this.minimumDuration = minimumDuration;
this.maximumDuration = maximumDuration;
this.averageDuration = averageDuration;
this.totalCount = totalCount;
}
@Override
public long getTimeWindow() {
return interval;
}
@Override
public double getRequestsPerSecond() {
return requestsPerSecond;
}
@Override
public long getMinimumDuration() {
return minimumDuration;
}
@Override
public long getMaximumDuration() {
return maximumDuration;
}
@Override
public long getRequestCount() {
return totalCount;
}
@Override
public TimeWindowStatistics snapshot() {
// snapshot functionality not yet implemented
return this;
}
@Override
public long getAverageDuration() {
return averageDuration;
}
}
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