/**
* Uses random numbers to sample the entire map.
*
* @return an array of sampled elements
*/
private LfuPolicy.Metadata[] sampleElements(Map map) {
int[] offsets = LfuPolicy.generateRandomSample(map.size());
DiskElement[] elements = new DiskElement[offsets.length];
Iterator iterator = map.values().iterator();
for (int i = 0; i < offsets.length; i++) {
for (int j = 0; j < offsets[i]; j++) {
iterator.next();
}
elements[i] = (DiskElement) iterator.next();
}
return elements;
}
/**
* Uses random numbers to sample the entire map.
*
* <p>This implemenation uses the {@link ConcurrentHashMap} iterator.
*
* @return a random sample of elements
*/
protected Element[] sampleElements(int size) {
int[] offsets = LfuPolicy.generateRandomSample(size);
Element[] elements = new Element[offsets.length];
Iterator iterator = map.values().iterator();
for (int i = 0; i < offsets.length; i++) {
for (int j = 0; j < offsets[i]; j++) {
// fast forward
try {
iterator.next();
} catch (NoSuchElementException e) {
// e.printStackTrace();
}
}
try {
elements[i] = ((Element) iterator.next());
} catch (NoSuchElementException e) {
// e.printStackTrace();
}
}
return elements;
}
