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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.db.compaction;
import java.util.*;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Joiner;
import com.google.common.collect.*;
import com.google.common.primitives.Doubles;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.db.rows.UnfilteredRowIterator;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.io.sstable.ISSTableScanner;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.apache.cassandra.utils.FBUtilities;
public class LeveledCompactionStrategy extends AbstractCompactionStrategy
{
private static final Logger logger = LoggerFactory.getLogger(LeveledCompactionStrategy.class);
private static final String SSTABLE_SIZE_OPTION = "sstable_size_in_mb";
@VisibleForTesting
final LeveledManifest manifest;
private final int maxSSTableSizeInMB;
public LeveledCompactionStrategy(ColumnFamilyStore cfs, Map options)
{
super(cfs, options);
int configuredMaxSSTableSize = 160;
SizeTieredCompactionStrategyOptions localOptions = new SizeTieredCompactionStrategyOptions(options);
if (options != null)
{
if (options.containsKey(SSTABLE_SIZE_OPTION))
{
configuredMaxSSTableSize = Integer.parseInt(options.get(SSTABLE_SIZE_OPTION));
if (!Boolean.getBoolean("cassandra.tolerate_sstable_size"))
{
if (configuredMaxSSTableSize >= 1000)
logger.warn("Max sstable size of {}MB is configured for {}.{}; having a unit of compaction this large is probably a bad idea",
configuredMaxSSTableSize, cfs.name, cfs.getColumnFamilyName());
if (configuredMaxSSTableSize < 50)
logger.warn("Max sstable size of {}MB is configured for {}.{}. Testing done for CASSANDRA-5727 indicates that performance improves up to 160MB",
configuredMaxSSTableSize, cfs.name, cfs.getColumnFamilyName());
}
}
}
maxSSTableSizeInMB = configuredMaxSSTableSize;
manifest = new LeveledManifest(cfs, this.maxSSTableSizeInMB, localOptions);
logger.trace("Created {}", manifest);
}
public int getLevelSize(int i)
{
return manifest.getLevelSize(i);
}
public int[] getAllLevelSize()
{
return manifest.getAllLevelSize();
}
@Override
public void startup()
{
manifest.calculateLastCompactedKeys();
super.startup();
}
/**
* the only difference between background and maximal in LCS is that maximal is still allowed
* (by explicit user request) even when compaction is disabled.
*/
@SuppressWarnings("resource")
public synchronized AbstractCompactionTask getNextBackgroundTask(int gcBefore)
{
while (true)
{
OperationType op;
LeveledManifest.CompactionCandidate candidate = manifest.getCompactionCandidates();
if (candidate == null)
{
// if there is no sstable to compact in standard way, try compacting based on droppable tombstone ratio
SSTableReader sstable = findDroppableSSTable(gcBefore);
if (sstable == null)
{
logger.trace("No compaction necessary for {}", this);
return null;
}
candidate = new LeveledManifest.CompactionCandidate(Collections.singleton(sstable),
sstable.getSSTableLevel(),
getMaxSSTableBytes());
op = OperationType.TOMBSTONE_COMPACTION;
}
else
{
op = OperationType.COMPACTION;
}
LifecycleTransaction txn = cfs.getTracker().tryModify(candidate.sstables, OperationType.COMPACTION);
if (txn != null)
{
LeveledCompactionTask newTask = new LeveledCompactionTask(cfs, txn, candidate.level, gcBefore, candidate.maxSSTableBytes, false);
newTask.setCompactionType(op);
return newTask;
}
}
}
@SuppressWarnings("resource")
public synchronized Collection getMaximalTask(int gcBefore, boolean splitOutput)
{
Iterable sstables = manifest.getAllSSTables();
Iterable filteredSSTables = filterSuspectSSTables(sstables);
if (Iterables.isEmpty(sstables))
return null;
LifecycleTransaction txn = cfs.getTracker().tryModify(filteredSSTables, OperationType.COMPACTION);
if (txn == null)
return null;
return Arrays.asList(new LeveledCompactionTask(cfs, txn, 0, gcBefore, getMaxSSTableBytes(), true));
}
@Override
public AbstractCompactionTask getUserDefinedTask(Collection sstables, int gcBefore)
{
throw new UnsupportedOperationException("LevelDB compaction strategy does not allow user-specified compactions");
}
@Override
public AbstractCompactionTask getCompactionTask(LifecycleTransaction txn, int gcBefore, long maxSSTableBytes)
{
assert txn.originals().size() > 0;
int level = -1;
// if all sstables are in the same level, we can set that level:
for (SSTableReader sstable : txn.originals())
{
if (level == -1)
level = sstable.getSSTableLevel();
if (level != sstable.getSSTableLevel())
level = 0;
}
return new LeveledCompactionTask(cfs, txn, level, gcBefore, maxSSTableBytes, false);
}
/**
* Leveled compaction strategy has guarantees on the data contained within each level so we
* have to make sure we only create groups of SSTables with members from the same level.
* This way we won't end up creating invalid sstables during anti-compaction.
* @param ssTablesToGroup
* @return Groups of sstables from the same level
*/
@Override
public Collection> groupSSTablesForAntiCompaction(Collection ssTablesToGroup)
{
int groupSize = 2;
Map> sstablesByLevel = new HashMap<>();
for (SSTableReader sstable : ssTablesToGroup)
{
Integer level = sstable.getSSTableLevel();
if (!sstablesByLevel.containsKey(level))
{
sstablesByLevel.put(level, new ArrayList());
}
sstablesByLevel.get(level).add(sstable);
}
Collection> groupedSSTables = new ArrayList<>();
for (Collection levelOfSSTables : sstablesByLevel.values())
{
Collection currGroup = new ArrayList<>();
for (SSTableReader sstable : levelOfSSTables)
{
currGroup.add(sstable);
if (currGroup.size() == groupSize)
{
groupedSSTables.add(currGroup);
currGroup = new ArrayList<>();
}
}
if (currGroup.size() != 0)
groupedSSTables.add(currGroup);
}
return groupedSSTables;
}
public int getEstimatedRemainingTasks()
{
return manifest.getEstimatedTasks();
}
public long getMaxSSTableBytes()
{
return maxSSTableSizeInMB * 1024L * 1024L;
}
public ScannerList getScanners(Collection sstables, Collection> ranges)
{
Set[] sstablesPerLevel = manifest.getSStablesPerLevelSnapshot();
Multimap byLevel = ArrayListMultimap.create();
for (SSTableReader sstable : sstables)
{
int level = sstable.getSSTableLevel();
// if an sstable is not on the manifest, it was recently added or removed
// so we add it to level -1 and create exclusive scanners for it - see below (#9935)
if (level >= sstablesPerLevel.length || !sstablesPerLevel[level].contains(sstable))
{
logger.warn("Live sstable {} from level {} is not on corresponding level in the leveled manifest." +
" This is not a problem per se, but may indicate an orphaned sstable due to a failed" +
" compaction not cleaned up properly.",
sstable.getFilename(), level);
level = -1;
}
byLevel.get(level).add(sstable);
}
List scanners = new ArrayList(sstables.size());
try
{
for (Integer level : byLevel.keySet())
{
// level can be -1 when sstables are added to Tracker but not to LeveledManifest
// since we don't know which level those sstable belong yet, we simply do the same as L0 sstables.
if (level <= 0)
{
// L0 makes no guarantees about overlapping-ness. Just create a direct scanner for each
for (SSTableReader sstable : byLevel.get(level))
scanners.add(sstable.getScanner(ranges, CompactionManager.instance.getRateLimiter()));
}
else
{
// Create a LeveledScanner that only opens one sstable at a time, in sorted order
Collection intersecting = LeveledScanner.intersecting(byLevel.get(level), ranges);
if (!intersecting.isEmpty())
{
@SuppressWarnings("resource") // The ScannerList will be in charge of closing (and we close properly on errors)
ISSTableScanner scanner = new LeveledScanner(intersecting, ranges);
scanners.add(scanner);
}
}
}
}
catch (Throwable t)
{
try
{
new ScannerList(scanners).close();
}
catch (Throwable t2)
{
t.addSuppressed(t2);
}
throw t;
}
return new ScannerList(scanners);
}
@Override
public void replaceSSTables(Collection removed, Collection added)
{
manifest.replace(removed, added);
}
@Override
public void addSSTable(SSTableReader added)
{
manifest.add(added);
}
@Override
public void removeSSTable(SSTableReader sstable)
{
manifest.remove(sstable);
}
// Lazily creates SSTableBoundedScanner for sstable that are assumed to be from the
// same level (e.g. non overlapping) - see #4142
private static class LeveledScanner extends AbstractIterator implements ISSTableScanner
{
private final Collection> ranges;
private final List sstables;
private final Iterator sstableIterator;
private final long totalLength;
private ISSTableScanner currentScanner;
private long positionOffset;
public LeveledScanner(Collection sstables, Collection> ranges)
{
this.ranges = ranges;
// add only sstables that intersect our range, and estimate how much data that involves
this.sstables = new ArrayList<>(sstables.size());
long length = 0;
for (SSTableReader sstable : sstables)
{
this.sstables.add(sstable);
long estimatedKeys = sstable.estimatedKeys();
double estKeysInRangeRatio = 1.0;
if (estimatedKeys > 0 && ranges != null)
estKeysInRangeRatio = ((double) sstable.estimatedKeysForRanges(ranges)) / estimatedKeys;
length += sstable.uncompressedLength() * estKeysInRangeRatio;
}
totalLength = length;
Collections.sort(this.sstables, SSTableReader.sstableComparator);
sstableIterator = this.sstables.iterator();
assert sstableIterator.hasNext(); // caller should check intersecting first
currentScanner = sstableIterator.next().getScanner(ranges, CompactionManager.instance.getRateLimiter());
}
public static Collection intersecting(Collection sstables, Collection> ranges)
{
if (ranges == null)
return Lists.newArrayList(sstables);
Set filtered = new HashSet<>();
for (Range range : ranges)
{
for (SSTableReader sstable : sstables)
{
Range sstableRange = new Range<>(sstable.first.getToken(), sstable.last.getToken());
if (range == null || sstableRange.intersects(range))
filtered.add(sstable);
}
}
return filtered;
}
public boolean isForThrift()
{
return false;
}
public CFMetaData metadata()
{
return sstables.get(0).metadata; // The ctor checks we have at least one sstable
}
protected UnfilteredRowIterator computeNext()
{
if (currentScanner == null)
return endOfData();
while (true)
{
if (currentScanner.hasNext())
return currentScanner.next();
positionOffset += currentScanner.getLengthInBytes();
currentScanner.close();
if (!sstableIterator.hasNext())
{
// reset to null so getCurrentPosition does not return wrong value
currentScanner = null;
return endOfData();
}
currentScanner = sstableIterator.next().getScanner(ranges, CompactionManager.instance.getRateLimiter());
}
}
public void close()
{
if (currentScanner != null)
currentScanner.close();
}
public long getLengthInBytes()
{
return totalLength;
}
public long getCurrentPosition()
{
return positionOffset + (currentScanner == null ? 0L : currentScanner.getCurrentPosition());
}
public String getBackingFiles()
{
return Joiner.on(", ").join(sstables);
}
}
@Override
public String toString()
{
return String.format("LCS@%d(%s)", hashCode(), cfs.name);
}
private SSTableReader findDroppableSSTable(final int gcBefore)
{
level:
for (int i = manifest.getLevelCount(); i >= 0; i--)
{
// sort sstables by droppable ratio in descending order
SortedSet sstables = manifest.getLevelSorted(i, new Comparator()
{
public int compare(SSTableReader o1, SSTableReader o2)
{
double r1 = o1.getEstimatedDroppableTombstoneRatio(gcBefore);
double r2 = o2.getEstimatedDroppableTombstoneRatio(gcBefore);
return -1 * Doubles.compare(r1, r2);
}
});
if (sstables.isEmpty())
continue;
Set compacting = cfs.getTracker().getCompacting();
for (SSTableReader sstable : sstables)
{
if (sstable.getEstimatedDroppableTombstoneRatio(gcBefore) <= tombstoneThreshold)
continue level;
else if (!compacting.contains(sstable) && !sstable.isMarkedSuspect() && worthDroppingTombstones(sstable, gcBefore))
return sstable;
}
}
return null;
}
public static Map validateOptions(Map options) throws ConfigurationException
{
Map uncheckedOptions = AbstractCompactionStrategy.validateOptions(options);
String size = options.containsKey(SSTABLE_SIZE_OPTION) ? options.get(SSTABLE_SIZE_OPTION) : "1";
try
{
int ssSize = Integer.parseInt(size);
if (ssSize < 1)
{
throw new ConfigurationException(String.format("%s must be larger than 0, but was %s", SSTABLE_SIZE_OPTION, ssSize));
}
}
catch (NumberFormatException ex)
{
throw new ConfigurationException(String.format("%s is not a parsable int (base10) for %s", size, SSTABLE_SIZE_OPTION), ex);
}
uncheckedOptions.remove(SSTABLE_SIZE_OPTION);
uncheckedOptions = SizeTieredCompactionStrategyOptions.validateOptions(options, uncheckedOptions);
return uncheckedOptions;
}
}
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