pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / index / IndexCommit.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/IndexCommit.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/index/IndexCommit.java
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+package org.apache.lucene.index;
+
+/**
+ * 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.
+*/
+
+import java.util.Collection;
+import java.util.Map;
+import java.io.IOException;
+
+import org.apache.lucene.store.Directory;
+
+/**
+ * <p>Expert: represents a single commit into an index as seen by the
+ * {@link IndexDeletionPolicy} or {@link IndexReader}.</p>
+ *
+ * <p> Changes to the content of an index are made visible
+ * only after the writer who made that change commits by
+ * writing a new segments file
+ * (<code>segments_N</code>). This point in time, when the
+ * action of writing of a new segments file to the directory
+ * is completed, is an index commit.</p>
+ *
+ * <p>Each index commit point has a unique segments file
+ * associated with it. The segments file associated with a
+ * later index commit point would have a larger N.</p>
+ *
+ * @lucene.experimental
+*/
+
+public abstract class IndexCommit implements Comparable<IndexCommit> {
+
+  /**
+   * Get the segments file (<code>segments_N</code>) associated 
+   * with this commit point.
+   */
+  public abstract String getSegmentsFileName();
+
+  /**
+   * Returns all index files referenced by this commit point.
+   */
+  public abstract Collection<String> getFileNames() throws IOException;
+
+  /**
+   * Returns the {@link Directory} for the index.
+   */
+  public abstract Directory getDirectory();
+  
+  /**
+   * Delete this commit point.  This only applies when using
+   * the commit point in the context of IndexWriter's
+   * IndexDeletionPolicy.
+   * <p>
+   * Upon calling this, the writer is notified that this commit 
+   * point should be deleted. 
+   * <p>
+   * Decision that a commit-point should be deleted is taken by the {@link IndexDeletionPolicy} in effect
+   * and therefore this should only be called by its {@link IndexDeletionPolicy#onInit onInit()} or 
+   * {@link IndexDeletionPolicy#onCommit onCommit()} methods.
+  */
+  public abstract void delete();
+
+  public abstract boolean isDeleted();
+
+  /** Returns number of segments referenced by this commit. */
+  public abstract int getSegmentCount();
+
+  /** Two IndexCommits are equal if both their Directory and versions are equal. */
+  @Override
+  public boolean equals(Object other) {
+    if (other instanceof IndexCommit) {
+      IndexCommit otherCommit = (IndexCommit) other;
+      return otherCommit.getDirectory().equals(getDirectory()) && otherCommit.getVersion() == getVersion();
+    } else
+      return false;
+  }
+
+  @Override
+  public int hashCode() {
+    return (int) (getDirectory().hashCode() + getVersion());
+  }
+
+  /** Returns the version for this IndexCommit.  This is the
+   *  same value that {@link IndexReader#getVersion} would
+   *  return if it were opened on this commit. */
+  public abstract long getVersion();
+
+  /** Returns the generation (the _N in segments_N) for this
+   *  IndexCommit */
+  public abstract long getGeneration();
+
+  /** Convenience method that returns the last modified time
+   *  of the segments_N file corresponding to this index
+   *  commit, equivalent to
+   *  getDirectory().fileModified(getSegmentsFileName()). */
+  public long getTimestamp() throws IOException {
+    return getDirectory().fileModified(getSegmentsFileName());
+  }
+
+  /** Returns userData, previously passed to {@link
+   *  IndexWriter#commit(Map)} for this commit.  Map is
+   *  String -> String. */
+  public abstract Map<String,String> getUserData() throws IOException;
+  
+  public int compareTo(IndexCommit commit) {
+    long gen = getGeneration();
+    long comgen = commit.getGeneration();
+    if (gen < comgen) {
+      return -1;
+    } else if (gen > comgen) {
+      return 1;
+    } else {
+      return 0;
+    }
+  }
+
+}