pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / facet / src / java / org / apache / lucene / facet / taxonomy / writercache / lru / LruTaxonomyWriterCache.java

diff --git a/lucene-java-3.5.0/lucene/contrib/facet/src/java/org/apache/lucene/facet/taxonomy/writercache/lru/LruTaxonomyWriterCache.java b/lucene-java-3.5.0/lucene/contrib/facet/src/java/org/apache/lucene/facet/taxonomy/writercache/lru/LruTaxonomyWriterCache.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/contrib/facet/src/java/org/apache/lucene/facet/taxonomy/writercache/lru/LruTaxonomyWriterCache.java
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+package org.apache.lucene.facet.taxonomy.writercache.lru;
+
+import org.apache.lucene.facet.taxonomy.CategoryPath;
+import org.apache.lucene.facet.taxonomy.writercache.TaxonomyWriterCache;
+
+/**
+ * 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.
+ */
+
+/**
+ * LRU {@link TaxonomyWriterCache} - good choice for huge taxonomies.
+ * 
+ * @lucene.experimental
+ */
+public class LruTaxonomyWriterCache implements TaxonomyWriterCache {
+
+  public enum LRUType { LRU_HASHED, LRU_STRING }
+
+  private NameIntCacheLRU cache;
+
+  public LruTaxonomyWriterCache(int cacheSize) {
+    // TODO (Facet): choose between NameHashIntCacheLRU and NameIntCacheLRU.
+    // For guaranteed correctness - not relying on no-collisions in the hash
+    // function, NameIntCacheLRU should be used:
+    // On the other hand, NameHashIntCacheLRU takes less RAM but if there
+    // are collisions (which we never found) two different paths would be
+    // mapped to the same ordinal...
+    this(cacheSize, LRUType.LRU_HASHED);
+  }
+
+  public LruTaxonomyWriterCache(int cacheSize, LRUType lruType) {
+    // TODO (Facet): choose between NameHashIntCacheLRU and NameIntCacheLRU.
+    // For guaranteed correctness - not relying on no-collisions in the hash
+    // function, NameIntCacheLRU should be used:
+    // On the other hand, NameHashIntCacheLRU takes less RAM but if there
+    // are collisions (which we never found) two different paths would be
+    // mapped to the same ordinal...
+    if (lruType == LRUType.LRU_HASHED) {
+      this.cache = new NameHashIntCacheLRU(cacheSize);
+    } else {
+      this.cache = new NameIntCacheLRU(cacheSize);
+    }
+  }
+
+  public boolean hasRoom(int n) {
+    return n<=(cache.getMaxSize()-cache.getSize());
+  }
+
+  public void close() {
+    cache.clear();
+    cache=null;
+  }
+
+  public int get(CategoryPath categoryPath) {
+    Integer res = cache.get(categoryPath);
+    if (res == null) {
+      return -1;
+    }
+
+    return res.intValue();
+  }
+
+  public int get(CategoryPath categoryPath, int length) {
+    if (length<0 || length>categoryPath.length()) {
+      length = categoryPath.length();
+    }
+    // TODO (Facet): unfortunately, we make a copy here! we can avoid part of
+    // the copy by creating a wrapper object (but this still creates a new
+    // object). A better implementation of the cache would not use Java's
+    // hash table, but rather some other hash table we can control, and
+    // pass the length parameter into it...
+    Integer res = cache.get(new CategoryPath(categoryPath, length));
+    if (res==null) {
+      return -1;
+    }
+    return res.intValue();
+  }
+
+  public boolean put(CategoryPath categoryPath, int ordinal) {
+    boolean ret = cache.put(categoryPath, new Integer(ordinal));
+    // If the cache is full, we need to clear one or more old entries
+    // from the cache. However, if we delete from the cache a recent
+    // addition that isn't yet in our reader, for this entry to be
+    // visible to us we need to make sure that the changes have been
+    // committed and we reopen the reader. Because this is a slow
+    // operation, we don't delete entries one-by-one but rather in bulk
+    // (put() removes the 2/3rd oldest entries).
+    if (ret) {
+      cache.makeRoomLRU();
+    }
+    return ret;
+  }
+
+  public boolean put(CategoryPath categoryPath, int prefixLen, int ordinal) {
+    boolean ret = cache.put(categoryPath, prefixLen, new Integer(ordinal));
+    // If the cache is full, we need to clear one or more old entries
+    // from the cache. However, if we delete from the cache a recent
+    // addition that isn't yet in our reader, for this entry to be
+    // visible to us we need to make sure that the changes have been
+    // committed and we reopen the reader. Because this is a slow
+    // operation, we don't delete entries one-by-one but rather in bulk
+    // (put() removes the 2/3rd oldest entries).
+    if (ret) { 
+      cache.makeRoomLRU(); 
+    }
+    return ret;
+  }
+
+}
+