/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreemnets. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance 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
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package opennlp.tools.util.featuregen;
import java.util.ArrayList;
import java.util.List;
import opennlp.tools.util.Cache;
/**
* Caches features of the aggregated {@link AdaptiveFeatureGenerator}s.
*/
public class CachedFeatureGenerator implements AdaptiveFeatureGenerator {
private final AdaptiveFeatureGenerator generator;
private String[] prevTokens;
private Cache contextsCache;
private long numberOfCacheHits;
private long numberOfCacheMisses;
public CachedFeatureGenerator(AdaptiveFeatureGenerator... generators) {
this.generator = new AggregatedFeatureGenerator(generators);
contextsCache = new Cache(100);
}
@SuppressWarnings("unchecked")
public void createFeatures(List<String> features, String[] tokens, int index,
String[] previousOutcomes) {
List<String> cacheFeatures;
if (tokens == prevTokens) {
cacheFeatures = (List<String>) contextsCache.get(index);
if (cacheFeatures != null) {
numberOfCacheHits++;
features.addAll(cacheFeatures);
return;
}
} else {
contextsCache.clear();
prevTokens = tokens;
}
cacheFeatures = new ArrayList<String>();
numberOfCacheMisses++;
generator.createFeatures(cacheFeatures, tokens, index, previousOutcomes);
contextsCache.put(index, cacheFeatures);
features.addAll(cacheFeatures);
}
public void updateAdaptiveData(String[] tokens, String[] outcomes) {
generator.updateAdaptiveData(tokens, outcomes);
}
public void clearAdaptiveData() {
generator.clearAdaptiveData();
}
/**
* Retrieves the number of times a cache hit occurred.
*
* @return number of cache hits
*/
public long getNumberOfCacheHits() {
return numberOfCacheHits;
}
/**
* Retrieves the number of times a cache miss occurred.
*
* @return number of cache misses
*/
public long getNumberOfCacheMisses() {
return numberOfCacheMisses;
}
@Override
public String toString() {
return super.toString()+": hits=" + numberOfCacheHits+" misses="+ numberOfCacheMisses+" hit%"+ (numberOfCacheHits > 0 ?
(double) numberOfCacheHits/(numberOfCacheMisses+numberOfCacheHits) : 0);
}
}