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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.metrics;
import io.opencensus.internal.Utils;
import java.util.List;
import javax.annotation.concurrent.ThreadSafe;
/**
* Long Gauge metric, to report instantaneous measurement of an int64 value. Gauges can go both up
* and down. The gauges values can be negative.
*
* <p>Example 1: Create a Gauge with default labels.
*
* <pre>{@code
* class YourClass {
*
* private static final MetricRegistry metricRegistry = Metrics.getMetricRegistry();
*
* List<LabelKey> labelKeys = Arrays.asList(LabelKey.create("Name", "desc"));
*
* LongGauge gauge = metricRegistry.addLongGauge("queue_size", "Pending jobs", "1", labelKeys);
*
* // It is recommended to keep a reference of a point for manual operations.
* LongPoint defaultPoint = gauge.getDefaultTimeSeries();
*
* void doWork() {
* // Your code here.
* defaultPoint.add(10);
* }
*
* }
* }</pre>
*
* <p>Example 2: You can also use labels(keys and values) to track different types of metric.
*
* <pre>{@code
* class YourClass {
*
* private static final MetricRegistry metricRegistry = Metrics.getMetricRegistry();
*
* List<LabelKey> labelKeys = Arrays.asList(LabelKey.create("Name", "desc"));
* List<LabelValue> labelValues = Arrays.asList(LabelValue.create("Inbound"));
*
* LongGauge gauge = metricRegistry.addLongGauge("queue_size", "Pending jobs", "1", labelKeys);
*
* // It is recommended to keep a reference of a point for manual operations.
* LongPoint inboundPoint = gauge.getOrCreateTimeSeries(labelValues);
*
* void doSomeWork() {
* // Your code here.
* inboundPoint.set(15);
* }
*
* }
* }</pre>
*
* @since 0.17
*/
@ThreadSafe
public abstract class LongGauge {
/**
* Creates a {@code TimeSeries} and returns a {@code LongPoint} if the specified {@code
* labelValues} is not already associated with this gauge, else returns an existing {@code
* LongPoint}.
*
* <p>It is recommended to keep a reference to the LongPoint instead of always calling this method
* for manual operations.
*
* @param labelValues the list of label values. The number of label values must be the same to
* that of the label keys passed to {@link MetricRegistry#addLongGauge}.
* @return a {@code LongPoint} the value of single gauge.
* @throws NullPointerException if {@code labelValues} is null OR any element of {@code
* labelValues} is null.
* @throws IllegalArgumentException if number of {@code labelValues}s are not equal to the label
* keys passed to {@link MetricRegistry#addLongGauge}.
* @since 0.17
*/
public abstract LongPoint getOrCreateTimeSeries(List<LabelValue> labelValues);
/**
* Returns a {@code LongPoint} for a gauge with all labels not set, or default labels.
*
* @return a {@code LongPoint} for a gauge with all labels not set, or default labels.
* @since 0.17
*/
public abstract LongPoint getDefaultTimeSeries();
/**
* Removes the {@code TimeSeries} from the gauge metric, if it is present. i.e. references to
* previous {@code LongPoint} objects are invalid (not part of the metric).
*
* @param labelValues the list of label values.
* @throws NullPointerException if {@code labelValues} is null.
* @since 0.17
*/
public abstract void removeTimeSeries(List<LabelValue> labelValues);
/**
* Removes all {@code TimeSeries} from the gauge metric. i.e. references to all previous {@code
* LongPoint} objects are invalid (not part of the metric).
*
* @since 0.17
*/
public abstract void clear();
/**
* Returns the no-op implementation of the {@code LongGauge}.
*
* @return the no-op implementation of the {@code LongGauge}.
* @since 0.17
*/
static LongGauge newNoopLongGauge(
String name, String description, String unit, List<LabelKey> labelKeys) {
return NoopLongGauge.create(name, description, unit, labelKeys);
}
/**
* The value of a single point in the Gauge.TimeSeries.
*
* @since 0.17
*/
public abstract static class LongPoint {
/**
* Adds the given value to the current value. The values can be negative.
*
* @param amt the value to add
* @since 0.17
*/
public abstract void add(long amt);
/**
* Sets the given value.
*
* @param val the new value.
* @since 0.17
*/
public abstract void set(long val);
}
/** No-op implementations of LongGauge class. */
private static final class NoopLongGauge extends LongGauge {
private final int labelKeysSize;
static NoopLongGauge create(
String name, String description, String unit, List<LabelKey> labelKeys) {
return new NoopLongGauge(name, description, unit, labelKeys);
}
/** Creates a new {@code NoopLongPoint}. */
NoopLongGauge(String name, String description, String unit, List<LabelKey> labelKeys) {
labelKeysSize = labelKeys.size();
}
@Override
public NoopLongPoint getOrCreateTimeSeries(List<LabelValue> labelValues) {
Utils.checkListElementNotNull(
Utils.checkNotNull(labelValues, "labelValues"), "labelValue element should not be null.");
Utils.checkArgument(labelKeysSize == labelValues.size(), "Incorrect number of labels.");
return NoopLongPoint.INSTANCE;
}
@Override
public NoopLongPoint getDefaultTimeSeries() {
return NoopLongPoint.INSTANCE;
}
@Override
public void removeTimeSeries(List<LabelValue> labelValues) {
Utils.checkNotNull(labelValues, "labelValues");
}
@Override
public void clear() {}
/** No-op implementations of LongPoint class. */
private static final class NoopLongPoint extends LongPoint {
private static final NoopLongPoint INSTANCE = new NoopLongPoint();
private NoopLongPoint() {}
@Override
public void add(long amt) {}
@Override
public void set(long val) {}
}
}
}
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