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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.util.concurrent.RateLimiter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Memtable;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.io.sstable.Component;
import org.apache.cassandra.io.sstable.SSTableReader;
/**
* Pluggable compaction strategy determines how SSTables get merged.
*
* There are two main goals:
* - perform background compaction constantly as needed; this typically makes a tradeoff between
* i/o done by compaction, and merging done at read time.
* - perform a full (maximum possible) compaction if requested by the user
*/
public abstract class AbstractCompactionStrategy
{
private static final Logger logger = LoggerFactory.getLogger(AbstractCompactionStrategy.class);
protected static final float DEFAULT_TOMBSTONE_THRESHOLD = 0.2f;
// minimum interval needed to perform tombstone removal compaction in seconds, default 86400 or 1 day.
protected static final long DEFAULT_TOMBSTONE_COMPACTION_INTERVAL = 86400;
protected static final String TOMBSTONE_THRESHOLD_OPTION = "tombstone_threshold";
protected static final String TOMBSTONE_COMPACTION_INTERVAL_OPTION = "tombstone_compaction_interval";
protected static final String COMPACTION_ENABLED = "enabled";
public final Map<String, String> options;
protected final ColumnFamilyStore cfs;
protected float tombstoneThreshold;
protected long tombstoneCompactionInterval;
/**
* pause/resume/getNextBackgroundTask must synchronize. This guarantees that after pause completes,
* no new tasks will be generated; or put another way, pause can't run until in-progress tasks are
* done being created.
*
* This allows runWithCompactionsDisabled to be confident that after pausing, once in-progress
* tasks abort, it's safe to proceed with truncate/cleanup/etc.
*
* See CASSANDRA-3430
*/
protected boolean isActive = true;
protected volatile boolean enabled = true;
protected AbstractCompactionStrategy(ColumnFamilyStore cfs, Map<String, String> options)
{
assert cfs != null;
this.cfs = cfs;
this.options = options;
/* checks must be repeated here, as user supplied strategies might not call validateOptions directly */
try
{
validateOptions(options);
String optionValue = options.get(TOMBSTONE_THRESHOLD_OPTION);
tombstoneThreshold = optionValue == null ? DEFAULT_TOMBSTONE_THRESHOLD : Float.parseFloat(optionValue);
optionValue = options.get(TOMBSTONE_COMPACTION_INTERVAL_OPTION);
tombstoneCompactionInterval = optionValue == null ? DEFAULT_TOMBSTONE_COMPACTION_INTERVAL : Long.parseLong(optionValue);
optionValue = options.get(COMPACTION_ENABLED);
if (optionValue != null)
{
if (optionValue.equalsIgnoreCase("false"))
this.enabled = false;
}
}
catch (ConfigurationException e)
{
logger.warn("Error setting compaction strategy options ({}), defaults will be used", e.getMessage());
tombstoneThreshold = DEFAULT_TOMBSTONE_THRESHOLD;
tombstoneCompactionInterval = DEFAULT_TOMBSTONE_COMPACTION_INTERVAL;
}
}
/**
* For internal, temporary suspension of background compactions so that we can do exceptional
* things like truncate or major compaction
*/
public synchronized void pause()
{
isActive = false;
}
/**
* For internal, temporary suspension of background compactions so that we can do exceptional
* things like truncate or major compaction
*/
public synchronized void resume()
{
isActive = true;
}
/**
* Releases any resources if this strategy is shutdown (when the CFS is reloaded after a schema change).
*/
public void shutdown()
{
isActive = false;
}
/**
* @param gcBefore throw away tombstones older than this
*
* @return the next background/minor compaction task to run; null if nothing to do.
*
* Is responsible for marking its sstables as compaction-pending.
*/
public abstract AbstractCompactionTask getNextBackgroundTask(final int gcBefore);
/**
* @param gcBefore throw away tombstones older than this
*
* @return a compaction task that should be run to compact this columnfamilystore
* as much as possible. Null if nothing to do.
*
* Is responsible for marking its sstables as compaction-pending.
*/
public abstract AbstractCompactionTask getMaximalTask(final int gcBefore);
/**
* @param sstables SSTables to compact. Must be marked as compacting.
* @param gcBefore throw away tombstones older than this
*
* @return a compaction task corresponding to the requested sstables.
* Will not be null. (Will throw if user requests an invalid compaction.)
*
* Is responsible for marking its sstables as compaction-pending.
*/
public abstract AbstractCompactionTask getUserDefinedTask(Collection<SSTableReader> sstables, final int gcBefore);
/**
* @return the number of background tasks estimated to still be needed for this columnfamilystore
*/
public abstract int getEstimatedRemainingTasks();
/**
* @return size in bytes of the largest sstables for this strategy
*/
public abstract long getMaxSSTableBytes();
public boolean isEnabled()
{
return this.enabled && this.isActive;
}
public void enable()
{
this.enabled = true;
}
public void disable()
{
this.enabled = false;
}
/**
* @return whether or not MeteredFlusher should be able to trigger memtable flushes for this CF.
*/
public boolean isAffectedByMeteredFlusher()
{
return true;
}
/**
* Handle a flushed memtable.
*
* @param memtable the flushed memtable
* @param sstable the written sstable. can be null if the memtable was clean.
*/
public void replaceFlushed(Memtable memtable, SSTableReader sstable)
{
cfs.getDataTracker().replaceFlushed(memtable, sstable);
if (sstable != null)
CompactionManager.instance.submitBackground(cfs);
}
/**
* @return a subset of the suggested sstables that are relevant for read requests.
*/
public List<SSTableReader> filterSSTablesForReads(List<SSTableReader> sstables)
{
return sstables;
}
/**
* Filters SSTables that are to be blacklisted from the given collection
*
* @param originalCandidates The collection to check for blacklisted SSTables
* @return list of the SSTables with blacklisted ones filtered out
*/
public static Iterable<SSTableReader> filterSuspectSSTables(Iterable<SSTableReader> originalCandidates)
{
return Iterables.filter(originalCandidates, new Predicate<SSTableReader>()
{
public boolean apply(SSTableReader sstable)
{
return !sstable.isMarkedSuspect();
}
});
}
/**
* Returns a list of KeyScanners given sstables and a range on which to scan.
* The default implementation simply grab one SSTableScanner per-sstable, but overriding this method
* allow for a more memory efficient solution if we know the sstable don't overlap (see
* LeveledCompactionStrategy for instance).
*/
public List<ICompactionScanner> getScanners(Collection<SSTableReader> sstables, Range<Token> range)
{
RateLimiter limiter = CompactionManager.instance.getRateLimiter();
ArrayList<ICompactionScanner> scanners = new ArrayList<ICompactionScanner>();
for (SSTableReader sstable : sstables)
scanners.add(sstable.getScanner(range, limiter));
return scanners;
}
public List<ICompactionScanner> getScanners(Collection<SSTableReader> toCompact)
{
return getScanners(toCompact, null);
}
/**
* Check if given sstable is worth dropping tombstones at gcBefore.
* Check is skipped if tombstone_compaction_interval time does not elapse since sstable creation and returns false.
*
* @param sstable SSTable to check
* @param gcBefore time to drop tombstones
* @return true if given sstable's tombstones are expected to be removed
*/
protected boolean worthDroppingTombstones(SSTableReader sstable, int gcBefore)
{
// since we use estimations to calculate, there is a chance that compaction will not drop tombstones actually.
// if that happens we will end up in infinite compaction loop, so first we check enough if enough time has
// elapsed since SSTable created.
if (System.currentTimeMillis() < sstable.getCreationTimeFor(Component.DATA) + tombstoneCompactionInterval * 1000)
return false;
double droppableRatio = sstable.getEstimatedDroppableTombstoneRatio(gcBefore);
if (droppableRatio <= tombstoneThreshold)
return false;
Set<SSTableReader> overlaps = cfs.getOverlappingSSTables(Collections.singleton(sstable));
if (overlaps.isEmpty())
{
// there is no overlap, tombstones are safely droppable
return true;
}
else if (CompactionController.getFullyExpiredSSTables(cfs, Collections.singleton(sstable), overlaps, gcBefore).size() > 0)
{
return true;
}
else
{
// what percentage of columns do we expect to compact outside of overlap?
if (sstable.getIndexSummarySize() < 2)
{
// we have too few samples to estimate correct percentage
return false;
}
// first, calculate estimated keys that do not overlap
long keys = sstable.estimatedKeys();
Set<Range<Token>> ranges = new HashSet<Range<Token>>(overlaps.size());
for (SSTableReader overlap : overlaps)
ranges.add(new Range<Token>(overlap.first.token, overlap.last.token, overlap.partitioner));
long remainingKeys = keys - sstable.estimatedKeysForRanges(ranges);
// next, calculate what percentage of columns we have within those keys
long columns = sstable.getEstimatedColumnCount().mean() * remainingKeys;
double remainingColumnsRatio = ((double) columns) / (sstable.getEstimatedColumnCount().count() * sstable.getEstimatedColumnCount().mean());
// return if we still expect to have droppable tombstones in rest of columns
return remainingColumnsRatio * droppableRatio > tombstoneThreshold;
}
}
public static Map<String, String> validateOptions(Map<String, String> options) throws ConfigurationException
{
String threshold = options.get(TOMBSTONE_THRESHOLD_OPTION);
if (threshold != null)
{
try
{
float thresholdValue = Float.parseFloat(threshold);
if (thresholdValue < 0)
{
throw new ConfigurationException(String.format("%s must be greater than 0, but was %f", TOMBSTONE_THRESHOLD_OPTION, thresholdValue));
}
}
catch (NumberFormatException e)
{
throw new ConfigurationException(String.format("%s is not a parsable int (base10) for %s", threshold, TOMBSTONE_THRESHOLD_OPTION), e);
}
}
String interval = options.get(TOMBSTONE_COMPACTION_INTERVAL_OPTION);
if (interval != null)
{
try
{
long tombstoneCompactionInterval = Long.parseLong(interval);
if (tombstoneCompactionInterval < 0)
{
throw new ConfigurationException(String.format("%s must be greater than 0, but was %d", TOMBSTONE_COMPACTION_INTERVAL_OPTION, tombstoneCompactionInterval));
}
}
catch (NumberFormatException e)
{
throw new ConfigurationException(String.format("%s is not a parsable int (base10) for %s", interval, TOMBSTONE_COMPACTION_INTERVAL_OPTION), e);
}
}
String compactionEnabled = options.get(COMPACTION_ENABLED);
if (compactionEnabled != null)
{
if (!compactionEnabled.equalsIgnoreCase("true") && !compactionEnabled.equalsIgnoreCase("false"))
{
throw new ConfigurationException(String.format("enabled should either be 'true' or 'false', not %s", compactionEnabled));
}
}
Map<String, String> uncheckedOptions = new HashMap<String, String>(options);
uncheckedOptions.remove(TOMBSTONE_THRESHOLD_OPTION);
uncheckedOptions.remove(TOMBSTONE_COMPACTION_INTERVAL_OPTION);
uncheckedOptions.remove(COMPACTION_ENABLED);
return uncheckedOptions;
}
}