+++ /dev/null
-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.io.IOException;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-
-import org.apache.lucene.document.Document;
-import org.apache.lucene.document.Field;
-import org.apache.lucene.document.Fieldable;
-import org.apache.lucene.document.Field.Index;
-import org.apache.lucene.document.Field.Store;
-import org.apache.lucene.index.IndexWriterConfig.OpenMode;
-import org.apache.lucene.store.Directory;
-import org.apache.lucene.store.LockObtainFailedException;
-import org.apache.lucene.util.Version;
-
-/**
- * A {@link SnapshotDeletionPolicy} which adds a persistence layer so that
- * snapshots can be maintained across the life of an application. The snapshots
- * are persisted in a {@link Directory} and are committed as soon as
- * {@link #snapshot(String)} or {@link #release(String)} is called.
- * <p>
- * <b>NOTE:</b> this class receives a {@link Directory} to persist the data into
- * a Lucene index. It is highly recommended to use a dedicated directory (and on
- * stable storage as well) for persisting the snapshots' information, and not
- * reuse the content index directory, or otherwise conflicts and index
- * corruptions will occur.
- * <p>
- * <b>NOTE:</b> you should call {@link #close()} when you're done using this
- * class for safetyness (it will close the {@link IndexWriter} instance used).
- */
-public class PersistentSnapshotDeletionPolicy extends SnapshotDeletionPolicy {
-
- // Used to validate that the given directory includes just one document w/ the
- // given ID field. Otherwise, it's not a valid Directory for snapshotting.
- private static final String SNAPSHOTS_ID = "$SNAPSHOTS_DOC$";
-
- // The index writer which maintains the snapshots metadata
- private final IndexWriter writer;
-
- /**
- * Reads the snapshots information from the given {@link Directory}. This
- * method can be used if the snapshots information is needed, however you
- * cannot instantiate the deletion policy (because e.g., some other process
- * keeps a lock on the snapshots directory).
- */
- public static Map<String, String> readSnapshotsInfo(Directory dir) throws IOException {
- IndexReader r = IndexReader.open(dir, true);
- Map<String, String> snapshots = new HashMap<String, String>();
- try {
- int numDocs = r.numDocs();
- // index is allowed to have exactly one document or 0.
- if (numDocs == 1) {
- Document doc = r.document(r.maxDoc() - 1);
- Field sid = doc.getField(SNAPSHOTS_ID);
- if (sid == null) {
- throw new IllegalStateException("directory is not a valid snapshots store!");
- }
- doc.removeField(SNAPSHOTS_ID);
- for (Fieldable f : doc.getFields()) {
- snapshots.put(f.name(), f.stringValue());
- }
- } else if (numDocs != 0) {
- throw new IllegalStateException(
- "should be at most 1 document in the snapshots directory: " + numDocs);
- }
- } finally {
- r.close();
- }
- return snapshots;
- }
-
- /**
- * {@link PersistentSnapshotDeletionPolicy} wraps another
- * {@link IndexDeletionPolicy} to enable flexible snapshotting.
- *
- * @param primary
- * the {@link IndexDeletionPolicy} that is used on non-snapshotted
- * commits. Snapshotted commits, by definition, are not deleted until
- * explicitly released via {@link #release(String)}.
- * @param dir
- * the {@link Directory} which will be used to persist the snapshots
- * information.
- * @param mode
- * specifies whether a new index should be created, deleting all
- * existing snapshots information (immediately), or open an existing
- * index, initializing the class with the snapshots information.
- * @param matchVersion
- * specifies the {@link Version} that should be used when opening the
- * IndexWriter.
- */
- public PersistentSnapshotDeletionPolicy(IndexDeletionPolicy primary,
- Directory dir, OpenMode mode, Version matchVersion)
- throws CorruptIndexException, LockObtainFailedException, IOException {
- super(primary, null);
-
- // Initialize the index writer over the snapshot directory.
- writer = new IndexWriter(dir, new IndexWriterConfig(matchVersion, null).setOpenMode(mode));
- if (mode != OpenMode.APPEND) {
- // IndexWriter no longer creates a first commit on an empty Directory. So
- // if we were asked to CREATE*, call commit() just to be sure. If the
- // index contains information and mode is CREATE_OR_APPEND, it's a no-op.
- writer.commit();
- }
-
- try {
- // Initializes the snapshots information. This code should basically run
- // only if mode != CREATE, but if it is, it's no harm as we only open the
- // reader once and immediately close it.
- for (Entry<String, String> e : readSnapshotsInfo(dir).entrySet()) {
- registerSnapshotInfo(e.getKey(), e.getValue(), null);
- }
- } catch (RuntimeException e) {
- writer.close(); // don't leave any open file handles
- throw e;
- } catch (IOException e) {
- writer.close(); // don't leave any open file handles
- throw e;
- }
- }
-
- @Override
- public synchronized void onInit(List<? extends IndexCommit> commits)
- throws IOException {
- // super.onInit() needs to be called first to ensure that initialization
- // behaves as expected. The superclass, SnapshotDeletionPolicy, ensures
- // that any snapshot IDs with empty IndexCommits are released. Since this
- // happens, this class needs to persist these changes.
- super.onInit(commits);
- persistSnapshotInfos(null, null);
- }
-
- /**
- * Snapshots the last commit using the given ID. Once this method returns, the
- * snapshot information is persisted in the directory.
- *
- * @see SnapshotDeletionPolicy#snapshot(String)
- */
- @Override
- public synchronized IndexCommit snapshot(String id) throws IOException {
- checkSnapshotted(id);
- if (SNAPSHOTS_ID.equals(id)) {
- throw new IllegalArgumentException(id + " is reserved and cannot be used as a snapshot id");
- }
- persistSnapshotInfos(id, lastCommit.getSegmentsFileName());
- return super.snapshot(id);
- }
-
- /**
- * Deletes a snapshotted commit by ID. Once this method returns, the snapshot
- * information is committed to the directory.
- *
- * @see SnapshotDeletionPolicy#release(String)
- */
- @Override
- public synchronized void release(String id) throws IOException {
- super.release(id);
- persistSnapshotInfos(null, null);
- }
-
- /** Closes the index which writes the snapshots to the directory. */
- public void close() throws CorruptIndexException, IOException {
- writer.close();
- }
-
- /**
- * Persists all snapshots information. If the given id and segment are not
- * null, it persists their information as well.
- */
- private void persistSnapshotInfos(String id, String segment) throws IOException {
- writer.deleteAll();
- Document d = new Document();
- d.add(new Field(SNAPSHOTS_ID, "", Store.YES, Index.NO));
- for (Entry<String, String> e : super.getSnapshots().entrySet()) {
- d.add(new Field(e.getKey(), e.getValue(), Store.YES, Index.NO));
- }
- if (id != null) {
- d.add(new Field(id, segment, Store.YES, Index.NO));
- }
- writer.addDocument(d);
- writer.commit();
- }
-
-}
fnp / pylucene.git / blobdiff