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/*
* Copyright 2018, OpenCensus Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.opencensus.implcore.metrics;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.AtomicDouble;
import io.opencensus.common.Clock;
import io.opencensus.implcore.internal.Utils;
import io.opencensus.metrics.DoubleGauge;
import io.opencensus.metrics.LabelKey;
import io.opencensus.metrics.LabelValue;
import io.opencensus.metrics.export.Metric;
import io.opencensus.metrics.export.MetricDescriptor;
import io.opencensus.metrics.export.MetricDescriptor.Type;
import io.opencensus.metrics.export.Point;
import io.opencensus.metrics.export.TimeSeries;
import io.opencensus.metrics.export.Value;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
/** Implementation of {@link DoubleGauge}. */
public final class DoubleGaugeImpl extends DoubleGauge implements Meter {
@VisibleForTesting static final LabelValue UNSET_VALUE = LabelValue.create(null);
private final MetricDescriptor metricDescriptor;
private volatile Map<List<LabelValue>, PointImpl> registeredPoints = Collections.emptyMap();
private final int labelKeysSize;
private final List<LabelValue> defaultLabelValues;
DoubleGaugeImpl(String name, String description, String unit, List<LabelKey> labelKeys) {
labelKeysSize = labelKeys.size();
this.metricDescriptor =
MetricDescriptor.create(name, description, unit, Type.GAUGE_DOUBLE, labelKeys);
// initialize defaultLabelValues
defaultLabelValues = new ArrayList<LabelValue>(labelKeysSize);
for (int i = 0; i < labelKeysSize; i++) {
defaultLabelValues.add(UNSET_VALUE);
}
}
@Override
public DoublePoint getOrCreateTimeSeries(List<LabelValue> labelValues) {
// lock free point retrieval, if it is present
PointImpl existingPoint = registeredPoints.get(labelValues);
if (existingPoint != null) {
return existingPoint;
}
List<LabelValue> labelValuesCopy =
Collections.unmodifiableList(
new ArrayList<LabelValue>(checkNotNull(labelValues, "labelValues")));
return registerTimeSeries(labelValuesCopy);
}
@Override
public DoublePoint getDefaultTimeSeries() {
// lock free default point retrieval, if it is present
PointImpl existingPoint = registeredPoints.get(defaultLabelValues);
if (existingPoint != null) {
return existingPoint;
}
return registerTimeSeries(Collections.unmodifiableList(defaultLabelValues));
}
@Override
public synchronized void removeTimeSeries(List<LabelValue> labelValues) {
checkNotNull(labelValues, "labelValues");
Map<List<LabelValue>, PointImpl> registeredPointsCopy =
new LinkedHashMap<List<LabelValue>, PointImpl>(registeredPoints);
if (registeredPointsCopy.remove(labelValues) == null) {
// The element not present, no need to update the current map of points.
return;
}
registeredPoints = Collections.unmodifiableMap(registeredPointsCopy);
}
@Override
public synchronized void clear() {
registeredPoints = Collections.emptyMap();
}
private synchronized DoublePoint registerTimeSeries(List<LabelValue> labelValues) {
PointImpl existingPoint = registeredPoints.get(labelValues);
if (existingPoint != null) {
// Return a Point that are already registered. This can happen if a multiple threads
// concurrently try to register the same {@code TimeSeries}.
return existingPoint;
}
checkArgument(labelKeysSize == labelValues.size(), "Incorrect number of labels.");
Utils.checkListElementNotNull(labelValues, "labelValue element should not be null.");
PointImpl newPoint = new PointImpl(labelValues);
// Updating the map of points happens under a lock to avoid multiple add operations
// to happen in the same time.
Map<List<LabelValue>, PointImpl> registeredPointsCopy =
new LinkedHashMap<List<LabelValue>, PointImpl>(registeredPoints);
registeredPointsCopy.put(labelValues, newPoint);
registeredPoints = Collections.unmodifiableMap(registeredPointsCopy);
return newPoint;
}
@Nullable
@Override
public Metric getMetric(Clock clock) {
Map<List<LabelValue>, PointImpl> currentRegisteredPoints = registeredPoints;
if (currentRegisteredPoints.isEmpty()) {
return null;
}
if (currentRegisteredPoints.size() == 1) {
PointImpl point = currentRegisteredPoints.values().iterator().next();
return Metric.createWithOneTimeSeries(metricDescriptor, point.getTimeSeries(clock));
}
List<TimeSeries> timeSeriesList = new ArrayList<TimeSeries>(currentRegisteredPoints.size());
for (Map.Entry<List<LabelValue>, PointImpl> entry : currentRegisteredPoints.entrySet()) {
timeSeriesList.add(entry.getValue().getTimeSeries(clock));
}
return Metric.create(metricDescriptor, timeSeriesList);
}
/** Implementation of {@link DoubleGauge.DoublePoint}. */
public static final class PointImpl extends DoublePoint {
// TODO(mayurkale): Consider to use DoubleAdder here, once we upgrade to Java8.
private final AtomicDouble value = new AtomicDouble(0);
private final List<LabelValue> labelValues;
PointImpl(List<LabelValue> labelValues) {
this.labelValues = labelValues;
}
@Override
public void add(double amt) {
value.addAndGet(amt);
}
@Override
public void set(double val) {
value.set(val);
}
private TimeSeries getTimeSeries(Clock clock) {
return TimeSeries.createWithOnePoint(
labelValues, Point.create(Value.doubleValue(value.get()), clock.now()), null);
}
}
}
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