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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.statistics;
import java.util.ArrayList;
import java.util.List;
import com.yahoo.statistics.SampleSet.Sampling;
/**
* Book-keeping class to know which SampleSet instances have unlogged data.
*
* @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
*/
final class SampleDirectory {
private final Object directoryLock = new Object();
private List<SampleSet> directory = new ArrayList<>(200);
void put(SampleSet s) {
synchronized (directoryLock) {
directory.add(s);
s.setRegisteredForLogging(true);
}
}
/**
* Get a view of the current generation of data and instantiate a new
* generation. This does the memory barrier two-step for the
* client.
*/
Sampling[] fetchValues() {
Sampling[] copyToReturn;
synchronized (directoryLock) {
List<SampleSet> tmpDir = directory;
copyToReturn = new Sampling[tmpDir.size()];
List<SampleSet> newDir = new ArrayList<>(200);
for (int i = 0; i < copyToReturn.length; ++i) {
copyToReturn[i] = tmpDir.get(i).getAndReset();
}
directory = newDir;
}
return copyToReturn;
}
/**
* Return a view of the current generation of data. This does the memory
* barrier two-step for the client.
*/
Sampling[] viewValues() {
Sampling[] copy;
synchronized (directoryLock) {
copy = new Sampling[directory.size()];
for (int i = 0; i < copy.length; ++i) {
copy[i] = directory.get(i).values;
}
}
return copy;
}
}
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