+++ /dev/null
-package org.apache.lucene.facet.taxonomy.writercache;
-
-import org.apache.lucene.facet.taxonomy.CategoryPath;
-import org.apache.lucene.facet.taxonomy.lucene.LuceneTaxonomyWriter;
-
-/**
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. 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.
- */
-
-/**
- * TaxonomyWriterCache is a relatively simple interface for a cache of
- * category->ordinal mappings, used in TaxonomyWriter implementations
- * (such as {@link LuceneTaxonomyWriter}).
- * <P>
- * It basically has put() methods for adding a mapping, and get() for looking
- * a mapping up the cache. The cache does <B>not</B> guarantee to hold
- * everything that has been put into it, and might in fact selectively
- * delete some of the mappings (e.g., the ones least recently used).
- * This means that if get() returns a negative response, it does not
- * necessarily mean that the category doesn't exist - just that it is not
- * in the cache. The caller can only infer that the category doesn't exist
- * if it knows the cache to be complete (because all the categories were
- * loaded into the cache, and since then no put() returned true).
- * <P> However,
- * if it does so, it should clear out large parts of the cache at once, because
- * the user will typically need to work hard to recover from every cache
- * cleanup (see {@link #put(CategoryPath, int)}'s return value).
- *
- * @lucene.experimental
- */
-public interface TaxonomyWriterCache {
-
- /**
- * Let go of whatever resources the cache is holding. After a close(),
- * this object can no longer be used.
- */
- public void close();
-
- /**
- * Lookup a category in the cache, returning its ordinal, or a negative
- * number if the category is not in the cache.
- * <P>
- * It is up to the caller to remember what a negative response means:
- * If the caller knows the cache is <I>complete</I> (it was initially
- * fed with all the categories, and since then put() never returned true)
- * it means the category does not exist. Otherwise, the category might
- * still exist, but just be missing from the cache.
- */
- public int get(CategoryPath categoryPath);
-
- /**
- * Like {@link #get(CategoryPath)}, but for a given prefix of the
- * category path.
- * <P>
- * If the given length is negative or bigger than the path's actual
- * length, the full path is taken.
- */
- public int get(CategoryPath categoryPath, int length);
-
- /**
- * Add a category to the cache, with the given ordinal as the value.
- * <P>
- * If the implementation keeps only a partial cache (e.g., an LRU cache)
- * and finds that its cache is full, it should clear up part of the cache
- * and return <code>true</code>. Otherwise, it should return
- * <code>false</code>.
- * <P>
- * The reason why the caller needs to know if part of the cache was
- * cleared is that in that case it will have to commit its on-disk index
- * (so that all the latest category additions can be searched on disk, if
- * we can't rely on the cache to contain them).
- * <P>
- * Ordinals should be non-negative. Currently there is no defined way to
- * specify that a cache should remember a category does NOT exist.
- * It doesn't really matter, because normally the next thing we do after
- * finding that a category does not exist is to add it.
- */
- public boolean put(CategoryPath categoryPath, int ordinal);
-
- /**
- * Like {@link #put(CategoryPath, int)}, but for a given prefix of the
- * category path.
- * <P>
- * If the given length is negative or bigger than the path's actual
- * length, the full path is taken.
- */
- public boolean put(CategoryPath categoryPath, int prefixLen, int ordinal);
-
- /**
- * Sometimes the cache is either unlimited in size, or limited by a very
- * big size, and in that case when we add a lot of categories it might
- * make sense to pre-load the cache with all the existing categories.
- * However, this pre-load does not make sense when the allowed cache
- * size is small. The hasRoom() method allows to differentiate between
- * these cases.
- * <P>
- * After hasRoom(n) returned <code>true</code>, the following n put()
- * should return false (meaning that the cache was not cleared).
- */
- public boolean hasRoom(int numberOfEntries);
-
-}
fnp / pylucene.git / blobdiff