org.apache.hadoop.fs.statistics.IOStatisticsContext Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* 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
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*/
package org.apache.hadoop.fs.statistics;
import org.apache.hadoop.fs.statistics.impl.IOStatisticsContextIntegration;
import static java.util.Objects.requireNonNull;
/**
* An interface defined to capture thread-level IOStatistics by using per
* thread context.
*
* The aggregator should be collected in their constructor by statistics-generating
* classes to obtain the aggregator to update across all threads.
*
* The {@link #snapshot()} call creates a snapshot of the statistics;
*
* The {@link #reset()} call resets the statistics in the context so
* that later snapshots will get the incremental data.
*/
public interface IOStatisticsContext extends IOStatisticsSource {
/**
* Get the IOStatisticsAggregator for the context.
*
* @return return the aggregator for the context.
*/
IOStatisticsAggregator getAggregator();
/**
* Capture the snapshot of the context's IOStatistics.
*
* @return IOStatisticsSnapshot for the context.
*/
IOStatisticsSnapshot snapshot();
/**
* Get a unique ID for this context, for logging
* purposes.
*
* @return an ID unique for all contexts in this process.
*/
long getID();
/**
* Reset the context's IOStatistics.
*/
void reset();
/**
* Get the context's IOStatisticsContext.
*
* @return instance of IOStatisticsContext for the context.
*/
static IOStatisticsContext getCurrentIOStatisticsContext() {
// the null check is just a safety check to highlight exactly where a null value would
// be returned if HADOOP-18456 has resurfaced.
return requireNonNull(
IOStatisticsContextIntegration.getCurrentIOStatisticsContext(),
"Null IOStatisticsContext");
}
/**
* Set the IOStatisticsContext for the current thread.
* @param statisticsContext IOStatistics context instance for the
* current thread. If null, the context is reset.
*/
static void setThreadIOStatisticsContext(
IOStatisticsContext statisticsContext) {
IOStatisticsContextIntegration.setThreadIOStatisticsContext(
statisticsContext);
}
/**
* Static probe to check if the thread-level IO statistics enabled.
*
* @return if the thread-level IO statistics enabled.
*/
static boolean enabled() {
return IOStatisticsContextIntegration.isIOStatisticsThreadLevelEnabled();
}
}