if (cache == null) {
cache = new WeakHashMap();
}
synchronized (cache) { // check cache
BitSet cached = (BitSet) cache.get(reader);
if (shouldHaveCache) {
TestCase.assertNotNull("Cache should have data ", cached);
} else {
TestCase.assertNull("Cache should be null " + cached , cached);
}
if (cached != null) {
return cached;
}
}
final BitSet bits = filter.bits(reader);
synchronized (cache) { // update cache
cache.put(reader, bits);
}
return bits;
