/**
* Copyright 2008 The Apache Software Foundation
*
* 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.hadoop.hbase.master;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.apache.hadoop.hbase.Chore;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.Server;
import org.apache.hadoop.hbase.TableExistsException;
import org.apache.hadoop.hbase.catalog.MetaEditor;
import org.apache.hadoop.hbase.catalog.MetaReader;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.Store;
import org.apache.hadoop.hbase.regionserver.StoreFile;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.hadoop.hbase.util.Writables;
/**
* A janitor for the catalog tables. Scans the <code>.META.</code> catalog
* table on a period looking for unused regions to garbage collect.
*/
class CatalogJanitor extends Chore {
private static final Log LOG = LogFactory.getLog(CatalogJanitor.class.getName());
private final Server server;
private final MasterServices services;
private boolean enabled = true;
CatalogJanitor(final Server server, final MasterServices services) {
super(server.getServerName() + "-CatalogJanitor",
server.getConfiguration().getInt("hbase.catalogjanitor.interval", 300000),
server);
this.server = server;
this.services = services;
}
@Override
protected boolean initialChore() {
try {
if (this.enabled) scan();
} catch (IOException e) {
LOG.warn("Failed initial scan of catalog table", e);
return false;
}
return true;
}
/**
* @param enabled
*/
public void setEnabled(final boolean enabled) {
this.enabled = enabled;
}
@Override
protected void chore() {
try {
scan();
} catch (IOException e) {
LOG.warn("Failed scan of catalog table", e);
}
}
/**
* Scans META and returns a number of scanned rows, and
* an ordered map of split parents.
*/
Pair<Integer, Map<HRegionInfo, Result>> getSplitParents() throws IOException {
// TODO: Only works with single .META. region currently. Fix.
final AtomicInteger count = new AtomicInteger(0);
// Keep Map of found split parents. There are candidates for cleanup.
// Use a comparator that has split parents come before its daughters.
final Map<HRegionInfo, Result> splitParents =
new TreeMap<HRegionInfo, Result>(new SplitParentFirstComparator());
// This visitor collects split parents and counts rows in the .META. table
MetaReader.Visitor visitor = new MetaReader.Visitor() {
@Override
public boolean visit(Result r) throws IOException {
if (r == null || r.isEmpty()) return true;
count.incrementAndGet();
HRegionInfo info = getHRegionInfo(r);
if (info == null) return true; // Keep scanning
if (info.isSplitParent()) splitParents.put(info, r);
// Returning true means "keep scanning"
return true;
}
};
// Run full scan of .META. catalog table passing in our custom visitor
MetaReader.fullScan(this.server.getCatalogTracker(), visitor);
return new Pair<Integer, Map<HRegionInfo, Result>>(count.get(), splitParents);
}
/**
* Run janitorial scan of catalog <code>.META.</code> table looking for
* garbage to collect.
* @throws IOException
*/
int scan() throws IOException {
Pair<Integer, Map<HRegionInfo, Result>> pair = getSplitParents();
int count = pair.getFirst();
Map<HRegionInfo, Result> splitParents = pair.getSecond();
// Now work on our list of found parents. See if any we can clean up.
int cleaned = 0;
HashSet<HRegionInfo> parentNotCleaned = new HashSet<HRegionInfo>(); //regions whose parents are still around
for (Map.Entry<HRegionInfo, Result> e : splitParents.entrySet()) {
if (!parentNotCleaned.contains(e.getKey()) && cleanParent(e.getKey(), e.getValue())) {
cleaned++;
} else {
// We could not clean the parent, so it's daughters should not be cleaned either (HBASE-6160)
parentNotCleaned.add(getDaughterRegionInfo(e.getValue(), HConstants.SPLITA_QUALIFIER));
parentNotCleaned.add(getDaughterRegionInfo(e.getValue(), HConstants.SPLITB_QUALIFIER));
}
}
if (cleaned != 0) {
LOG.info("Scanned " + count + " catalog row(s) and gc'd " + cleaned +
" unreferenced parent region(s)");
} else if (LOG.isDebugEnabled()) {
LOG.debug("Scanned " + count + " catalog row(s) and gc'd " + cleaned +
" unreferenced parent region(s)");
}
return cleaned;
}
/**
* Compare HRegionInfos in a way that has split parents sort BEFORE their
* daughters.
*/
static class SplitParentFirstComparator implements Comparator<HRegionInfo> {
@Override
public int compare(HRegionInfo left, HRegionInfo right) {
// This comparator differs from the one HRegionInfo in that it sorts
// parent before daughters.
if (left == null) return -1;
if (right == null) return 1;
// Same table name.
int result = Bytes.compareTo(left.getTableName(),
right.getTableName());
if (result != 0) return result;
// Compare start keys.
result = Bytes.compareTo(left.getStartKey(), right.getStartKey());
if (result != 0) return result;
// Compare end keys.
result = Bytes.compareTo(left.getEndKey(), right.getEndKey());
if (result != 0) {
if (left.getStartKey().length != 0
&& left.getEndKey().length == 0) {
return -1; // left is last region
}
if (right.getStartKey().length != 0
&& right.getEndKey().length == 0) {
return 1; // right is the last region
}
return -result; // Flip the result so parent comes first.
}
return result;
}
}
/**
* Get HRegionInfo from passed Map of row values.
* @param result Map to do lookup in.
* @return Null if not found (and logs fact that expected COL_REGIONINFO
* was missing) else deserialized {@link HRegionInfo}
* @throws IOException
*/
static HRegionInfo getHRegionInfo(final Result result)
throws IOException {
byte [] bytes =
result.getValue(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
if (bytes == null) {
LOG.warn("REGIONINFO_QUALIFIER is empty in " + result);
return null;
}
return Writables.getHRegionInfo(bytes);
}
/**
* If daughters no longer hold reference to the parents, delete the parent.
* @param server HRegionInterface of meta server to talk to
* @param parent HRegionInfo of split offlined parent
* @param rowContent Content of <code>parent</code> row in
* <code>metaRegionName</code>
* @return True if we removed <code>parent</code> from meta table and from
* the filesystem.
* @throws IOException
*/
boolean cleanParent(final HRegionInfo parent, Result rowContent)
throws IOException {
boolean result = false;
// Run checks on each daughter split.
HRegionInfo a_region = getDaughterRegionInfo(rowContent, HConstants.SPLITA_QUALIFIER);
HRegionInfo b_region = getDaughterRegionInfo(rowContent, HConstants.SPLITB_QUALIFIER);
Pair<Boolean, Boolean> a =
checkDaughterInFs(parent, a_region, HConstants.SPLITA_QUALIFIER);
Pair<Boolean, Boolean> b =
checkDaughterInFs(parent, b_region, HConstants.SPLITB_QUALIFIER);
if (hasNoReferences(a) && hasNoReferences(b)) {
LOG.debug("Deleting region " + parent.getRegionNameAsString() +
" because daughter splits no longer hold references");
// wipe out daughter references from parent region
removeDaughtersFromParent(parent);
// This latter regionOffline should not be necessary but is done for now
// until we let go of regionserver to master heartbeats. See HBASE-3368.
if (this.services.getAssignmentManager() != null) {
// The mock used in testing catalogjanitor returns null for getAssignmnetManager.
// Allow for null result out of getAssignmentManager.
this.services.getAssignmentManager().regionOffline(parent);
}
FileSystem fs = this.services.getMasterFileSystem().getFileSystem();
Path rootdir = this.services.getMasterFileSystem().getRootDir();
HRegion.deleteRegion(fs, rootdir, parent);
MetaEditor.deleteRegion(this.server.getCatalogTracker(), parent);
result = true;
}
return result;
}
/**
* @param p A pair where the first boolean says whether or not the daughter
* region directory exists in the filesystem and then the second boolean says
* whether the daughter has references to the parent.
* @return True the passed <code>p</code> signifies no references.
*/
private boolean hasNoReferences(final Pair<Boolean, Boolean> p) {
return !p.getFirst() || !p.getSecond();
}
/**
* Get daughter HRegionInfo out of parent info:splitA/info:splitB columns.
* @param result
* @param which Whether "info:splitA" or "info:splitB" column
* @return Deserialized content of the info:splitA or info:splitB as a
* HRegionInfo
* @throws IOException
*/
private HRegionInfo getDaughterRegionInfo(final Result result,
final byte [] which)
throws IOException {
byte [] bytes = result.getValue(HConstants.CATALOG_FAMILY, which);
return Writables.getHRegionInfoOrNull(bytes);
}
/**
* Remove mention of daughters from parent row.
* @param parent
* @throws IOException
*/
private void removeDaughtersFromParent(final HRegionInfo parent)
throws IOException {
MetaEditor.deleteDaughtersReferencesInParent(this.server.getCatalogTracker(), parent);
}
/**
* Checks if a daughter region -- either splitA or splitB -- still holds
* references to parent.
* @param parent Parent region name.
* @param split Which column family.
* @param qualifier Which of the daughters to look at, splitA or splitB.
* @return A pair where the first boolean says whether or not the daughter
* region directory exists in the filesystem and then the second boolean says
* whether the daughter has references to the parent.
* @throws IOException
*/
Pair<Boolean, Boolean> checkDaughterInFs(final HRegionInfo parent,
final HRegionInfo split,
final byte [] qualifier)
throws IOException {
boolean references = false;
boolean exists = false;
if (split == null) {
return new Pair<Boolean, Boolean>(Boolean.FALSE, Boolean.FALSE);
}
FileSystem fs = this.services.getMasterFileSystem().getFileSystem();
Path rootdir = this.services.getMasterFileSystem().getRootDir();
Path tabledir = new Path(rootdir, split.getTableNameAsString());
Path regiondir = new Path(tabledir, split.getEncodedName());
exists = fs.exists(regiondir);
if (!exists) {
LOG.warn("Daughter regiondir does not exist: " + regiondir.toString());
return new Pair<Boolean, Boolean>(exists, Boolean.FALSE);
}
HTableDescriptor parentDescriptor = getTableDescriptor(parent.getTableName());
for (HColumnDescriptor family: parentDescriptor.getFamilies()) {
Path p = Store.getStoreHomedir(tabledir, split.getEncodedName(),
family.getName());
if (!fs.exists(p)) continue;
// Look for reference files. Call listStatus with anonymous instance of PathFilter.
FileStatus [] ps = FSUtils.listStatus(fs, p,
new PathFilter () {
public boolean accept(Path path) {
return StoreFile.isReference(path);
}
}
);
if (ps != null && ps.length > 0) {
references = true;
break;
}
}
return new Pair<Boolean, Boolean>(Boolean.valueOf(exists),
Boolean.valueOf(references));
}
private HTableDescriptor getTableDescriptor(byte[] tableName)
throws FileNotFoundException, IOException {
return this.services.getTableDescriptors().get(Bytes.toString(tableName));
}
}