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LongValueObserver.java
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LongValueObserver.java
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/*
* Copyright 2019, OpenTelemetry 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.opentelemetry.metrics;
import io.opentelemetry.common.Labels;
import io.opentelemetry.metrics.AsynchronousInstrument.LongResult;
import javax.annotation.concurrent.ThreadSafe;
/**
* {@code ValueObserver} is the asynchronous instrument corresponding to ValueRecorder, used to
* capture values that are treated as individual observations, recorded with the observe(value)
* method.
*
* <p>A {@code ValueObserver} is a good choice in situations where a measurement is expensive to
* compute, such that it would be wasteful to compute on every request.
*
* <p>Example:
*
* <pre>{@code
* class YourClass {
*
* private static final Meter meter = OpenTelemetry.getMeterRegistry().get("my_library_name");
* private static final LongValueObserver cpuObserver =
* meter.
* .longValueObserverBuilder("cpu_fan_speed")
* .setDescription("System CPU fan speed")
* .setUnit("ms")
* .build();
*
* void init() {
* cpuObserver.setCallback(
* new LongValueObserver.Callback<LongResult>() {
* {@literal @}Override
* public void update(LongResult result) {
* // Get system cpu fan speed
* result.observe(cpuFanSpeed);
* }
* });
* }
* }
* }</pre>
*
* @since 0.5.0
*/
@ThreadSafe
public interface LongValueObserver extends AsynchronousInstrument<LongResult> {
@Override
void setCallback(Callback<LongResult> callback);
/** Builder class for {@link LongValueObserver}. */
interface Builder extends AsynchronousInstrument.Builder {
@Override
Builder setDescription(String description);
@Override
Builder setUnit(String unit);
@Override
Builder setConstantLabels(Labels constantLabels);
@Override
LongValueObserver build();
}
}