/*
* 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.
*/
package org.apache.solr.core;
import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.lucene.index.IndexCommit;
import org.apache.lucene.index.IndexDeletionPolicy;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.store.Directory;
import org.apache.solr.core.snapshots.SolrSnapshotMetaDataManager;
import org.apache.solr.update.SolrIndexWriter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A wrapper for an IndexDeletionPolicy instance.
* <p>
* Provides features for looking up IndexCommit given a version. Allows reserving index
* commit points for certain amounts of time to support features such as index replication
* or snapshooting directly out of a live index directory.
* <p>
* <b>NOTE</b>: The {@link #clone()} method returns <tt>this</tt> in order to make
* this {@link IndexDeletionPolicy} instance trackable across {@link IndexWriter}
* instantiations. This is correct because each core has its own
* {@link IndexDeletionPolicy} and never has more than one open {@link IndexWriter}.
*
* @see org.apache.lucene.index.IndexDeletionPolicy
*/
public final class IndexDeletionPolicyWrapper extends IndexDeletionPolicy {
private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
private final IndexDeletionPolicy deletionPolicy;
private volatile Map<Long, IndexCommit> solrVersionVsCommits = new ConcurrentHashMap<>();
private final Map<Long, Long> reserves = new ConcurrentHashMap<>();
private volatile IndexCommit latestCommit;
private final ConcurrentHashMap<Long, AtomicInteger> savedCommits = new ConcurrentHashMap<>();
private final SolrSnapshotMetaDataManager snapshotMgr;
public IndexDeletionPolicyWrapper(IndexDeletionPolicy deletionPolicy, SolrSnapshotMetaDataManager snapshotMgr) {
this.deletionPolicy = deletionPolicy;
this.snapshotMgr = snapshotMgr;
}
/**
* Gets the most recent commit point
* <p>
* It is recommended to reserve a commit point for the duration of usage so that
* it is not deleted by the underlying deletion policy
*
* @return the most recent commit point
*/
public IndexCommit getLatestCommit() {
return latestCommit;
}
public IndexDeletionPolicy getWrappedDeletionPolicy() {
return deletionPolicy;
}
/**
* Set the duration for which commit point is to be reserved by the deletion policy.
*
* @param indexGen gen of the commit point to be reserved
* @param reserveTime time in milliseconds for which the commit point is to be reserved
*/
public void setReserveDuration(Long indexGen, long reserveTime) {
long timeToSet = System.nanoTime() + TimeUnit.NANOSECONDS.convert(reserveTime, TimeUnit.MILLISECONDS);
for(;;) {
Long previousTime = reserves.put(indexGen, timeToSet);
// this is the common success case: the older time didn't exist, or
// came before the new time.
if (previousTime == null || previousTime <= timeToSet) {
LOG.debug("Commit point reservation for generation {} set to {} (requested reserve time of {})",
indexGen, timeToSet, reserveTime);
break;
}
// At this point, we overwrote a longer reservation, so we want to restore the older one.
// the problem is that an even longer reservation may come in concurrently
// and we don't want to overwrite that one too. We simply keep retrying in a loop
// with the maximum time value we have seen.
timeToSet = previousTime;
}
}
private void cleanReserves() {
long currentTime = System.nanoTime();
for (Map.Entry<Long, Long> entry : reserves.entrySet()) {
if (entry.getValue() < currentTime) {
reserves.remove(entry.getKey());
}
}
}
private List<IndexCommitWrapper> wrap(List<? extends IndexCommit> list) {
List<IndexCommitWrapper> result = new ArrayList<>();
for (IndexCommit indexCommit : list) result.add(new IndexCommitWrapper(indexCommit));
return result;
}
/** Permanently prevent this commit point from being deleted.
* A counter is used to allow a commit point to be correctly saved and released
* multiple times. */
public synchronized void saveCommitPoint(Long indexCommitGen) {
AtomicInteger reserveCount = savedCommits.get(indexCommitGen);
if (reserveCount == null) reserveCount = new AtomicInteger();
reserveCount.incrementAndGet();
savedCommits.put(indexCommitGen, reserveCount);
}
/** Release a previously saved commit point */
public synchronized void releaseCommitPoint(Long indexCommitGen) {
AtomicInteger reserveCount = savedCommits.get(indexCommitGen);
if (reserveCount == null) return;// this should not happen
if (reserveCount.decrementAndGet() <= 0) {
savedCommits.remove(indexCommitGen);
}
}
/**
* Internal use for Lucene... do not explicitly call.
*/
@Override
public void onInit(List<? extends IndexCommit> list) throws IOException {
List<IndexCommitWrapper> wrapperList = wrap(list);
deletionPolicy.onInit(wrapperList);
updateCommitPoints(wrapperList);
cleanReserves();
}
/**
* Internal use for Lucene... do not explicitly call.
*/
@Override
public void onCommit(List<? extends IndexCommit> list) throws IOException {
List<IndexCommitWrapper> wrapperList = wrap(list);
deletionPolicy.onCommit(wrapperList);
updateCommitPoints(wrapperList);
cleanReserves();
}
private class IndexCommitWrapper extends IndexCommit {
IndexCommit delegate;
IndexCommitWrapper(IndexCommit delegate) {
this.delegate = delegate;
}
@Override
public String getSegmentsFileName() {
return delegate.getSegmentsFileName();
}
@Override
public Collection getFileNames() throws IOException {
return delegate.getFileNames();
}
@Override
public Directory getDirectory() {
return delegate.getDirectory();
}
@Override
public void delete() {
Long gen = delegate.getGeneration();
Long reserve = reserves.get(gen);
if (reserve != null && System.nanoTime() < reserve) return;
if (savedCommits.containsKey(gen)) return;
if (snapshotMgr.isSnapshotted(gen)) return;
delegate.delete();
}
@Override
public int getSegmentCount() {
return delegate.getSegmentCount();
}
@Override
public boolean equals(Object o) {
return delegate.equals(o);
}
@Override
public int hashCode() {
return delegate.hashCode();
}
@Override
public long getGeneration() {
return delegate.getGeneration();
}
@Override
public boolean isDeleted() {
return delegate.isDeleted();
}
@Override
public Map getUserData() throws IOException {
return delegate.getUserData();
}
}
/**
* @param gen the gen of the commit point
* @return a commit point corresponding to the given version
*/
public IndexCommit getCommitPoint(Long gen) {
return solrVersionVsCommits.get(gen);
}
/**
* Gets the commit points for the index.
* This map instance may change between commits and commit points may be deleted.
* It is recommended to reserve a commit point for the duration of usage
*
* @return a Map of version to commit points
*/
public Map<Long, IndexCommit> getCommits() {
return solrVersionVsCommits;
}
private void updateCommitPoints(List<IndexCommitWrapper> list) {
Map<Long, IndexCommit> map = new ConcurrentHashMap<>();
for (IndexCommitWrapper wrapper : list) {
if (!wrapper.isDeleted())
map.put(wrapper.delegate.getGeneration(), wrapper.delegate);
}
solrVersionVsCommits = map;
if (!list.isEmpty()) {
latestCommit = ((list.get(list.size() - 1)).delegate);
}
}
public static long getCommitTimestamp(IndexCommit commit) throws IOException {
final Map<String,String> commitData = commit.getUserData();
String commitTime = commitData.get(SolrIndexWriter.COMMIT_TIME_MSEC_KEY);
if (commitTime != null) {
return Long.parseLong(commitTime);
} else {
return 0;
}
}
@Override
public IndexDeletionPolicy clone() {
// see class-level javadocs
return this;
}
}