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>
*
* <p><b>WARNING</b>: This API is a new and experimental and
* may suddenly change. </p>
*/
public abstract class 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 true if this commit is an optimized index. */
public abstract boolean isOptimized();
/** 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;
}