public CachingWrapperFilter(Filter filter) 
{
	                  	 
		this(filter, DEFAULT_SIZE);
}

Parameters:

filter - Filter to cache results of

 public CachingWrapperFilter(Filter filter,
    int size) 
{
		this.filter = filter;
		this.size = size;
}

Parameters:

filter - Filter to cache results of

 public BitSet bits(IndexReader reader) throws IOException 
{
		if (cache == null) {
			log.debug("Initialising SoftLimitMRUCache with hard ref size of {}", size);
			cache = new SoftLimitMRUCache(size);
		}
		//memory barrier ensure cache == null will not always stay true on concurrent threads
		synchronized (cache) { // check cache
			BitSet cached = (BitSet) cache.get(reader);
			if (cached != null) {
				return cached;
			}
		}
		final BitSet bits = filter.bits(reader);
		synchronized (cache) { // update cache
			cache.put(reader, bits);
		}
		return bits;
}

 public boolean equals(Object o) 
{
		if (!(o instanceof CachingWrapperFilter))
			return false;
		return this.filter.equals(((CachingWrapperFilter) o).filter);
}

 public int hashCode() 
{
		return filter.hashCode() ^ 0x1117BF25;
}

 public String toString() 
{
		return this.getClass().getName() + "(" + filter + ")";
}