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/*
* Copyright 2016-17, 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.stats;
import io.opencensus.internal.DefaultVisibilityForTesting;
import io.opencensus.internal.Provider;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
/**
* Class for accessing the default {@link StatsComponent}.
*
* @since 0.8
*/
public final class Stats {
private static final Logger logger = Logger.getLogger(Stats.class.getName());
private static final StatsComponent statsComponent =
loadStatsComponent(StatsComponent.class.getClassLoader());
/**
* Returns the default {@link StatsRecorder}.
*
* @since 0.8
*/
public static StatsRecorder getStatsRecorder() {
return statsComponent.getStatsRecorder();
}
/**
* Returns the default {@link ViewManager}.
*
* @since 0.8
*/
public static ViewManager getViewManager() {
return statsComponent.getViewManager();
}
/**
* Returns the current {@code StatsCollectionState}.
*
* <p>When no implementation is available, {@code getState} always returns {@link
* StatsCollectionState#DISABLED}.
*
* <p>Once {@link #getState()} is called, subsequent calls to {@link
* #setState(StatsCollectionState)} will throw an {@code IllegalStateException}.
*
* @return the current {@code StatsCollectionState}.
* @since 0.8
*/
public static StatsCollectionState getState() {
return statsComponent.getState();
}
/**
* Sets the current {@code StatsCollectionState}.
*
* <p>When no implementation is available, {@code setState} does not change the state.
*
* <p>If state is set to {@link StatsCollectionState#DISABLED}, all stats that are previously
* recorded will be cleared.
*
* @param state the new {@code StatsCollectionState}.
* @throws IllegalStateException if {@link #getState()} was previously called.
* @deprecated This method is deprecated because other libraries could cache the result of {@link
* #getState()}, use a stale value, and behave incorrectly. It is only safe to call early in
* initialization. This method throws {@link IllegalStateException} after {@code getState()}
* has been called, in order to limit changes to the result of {@code getState()}.
* @since 0.8
*/
@Deprecated
public static void setState(StatsCollectionState state) {
statsComponent.setState(state);
}
// Any provider that may be used for StatsComponent can be added here.
@DefaultVisibilityForTesting
static StatsComponent loadStatsComponent(@Nullable ClassLoader classLoader) {
try {
// Call Class.forName with literal string name of the class to help shading tools.
return Provider.createInstance(
Class.forName(
"io.opencensus.impl.stats.StatsComponentImpl", /*initialize=*/ true, classLoader),
StatsComponent.class);
} catch (ClassNotFoundException e) {
logger.log(
Level.FINE,
"Couldn't load full implementation for StatsComponent, now trying to load lite "
+ "implementation.",
e);
}
try {
// Call Class.forName with literal string name of the class to help shading tools.
return Provider.createInstance(
Class.forName(
"io.opencensus.impllite.stats.StatsComponentImplLite",
/*initialize=*/ true,
classLoader),
StatsComponent.class);
} catch (ClassNotFoundException e) {
logger.log(
Level.FINE,
"Couldn't load lite implementation for StatsComponent, now using "
+ "default implementation for StatsComponent.",
e);
}
return NoopStats.newNoopStatsComponent();
}
private Stats() {}
}
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