org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy Maven / Gradle / Ivy
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cassandra.db.compaction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.TreeSet;
import java.util.concurrent.TimeUnit;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.cql3.statements.CFPropDefs;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.apache.cassandra.utils.Pair;
public class TimeWindowCompactionStrategy extends AbstractCompactionStrategy
{
private static final Logger logger = LoggerFactory.getLogger(TimeWindowCompactionStrategy.class);
private final TimeWindowCompactionStrategyOptions options;
protected volatile int estimatedRemainingTasks;
private final Set sstables = new HashSet<>();
private long lastExpiredCheck;
public TimeWindowCompactionStrategy(ColumnFamilyStore cfs, Map options)
{
super(cfs, options);
this.estimatedRemainingTasks = 0;
this.options = new TimeWindowCompactionStrategyOptions(options);
if (!options.containsKey(AbstractCompactionStrategy.TOMBSTONE_COMPACTION_INTERVAL_OPTION) && !options.containsKey(AbstractCompactionStrategy.TOMBSTONE_THRESHOLD_OPTION))
{
disableTombstoneCompactions = true;
logger.debug("Disabling tombstone compactions for TWCS");
}
else
logger.debug("Enabling tombstone compactions for TWCS");
}
@Override
@SuppressWarnings("resource")
public synchronized AbstractCompactionTask getNextBackgroundTask(int gcBefore)
{
if (!isEnabled())
return null;
while (true)
{
List latestBucket = getNextBackgroundSSTables(gcBefore);
if (latestBucket.isEmpty())
return null;
LifecycleTransaction modifier = cfs.getTracker().tryModify(latestBucket, OperationType.COMPACTION);
if (modifier != null)
return new CompactionTask(cfs, modifier, gcBefore, false);
}
}
/**
*
* @param gcBefore
* @return
*/
private List getNextBackgroundSSTables(final int gcBefore)
{
if (!isEnabled() || cfs.getSSTables().isEmpty())
return Collections.emptyList();
Set uncompacting = Sets.intersection(sstables, cfs.getUncompactingSSTables());
Set expired = Collections.emptySet();
if (System.currentTimeMillis() - lastExpiredCheck > options.expiredSSTableCheckFrequency)
{
logger.debug("TWCS expired check sufficiently far in the past, checking for fully expired SSTables");
expired = CompactionController.getFullyExpiredSSTables(cfs, uncompacting, cfs.getOverlappingSSTables(uncompacting), gcBefore);
lastExpiredCheck = System.currentTimeMillis();
}
else
{
logger.debug("TWCS skipping check for fully expired SSTables");
}
Set candidates = Sets.newHashSet(filterSuspectSSTables(uncompacting));
List compactionCandidates = new ArrayList<>(getNextNonExpiredSSTables(Sets.difference(candidates, expired), gcBefore));
if (!expired.isEmpty())
{
logger.debug("Including expired sstables: {}", expired);
compactionCandidates.addAll(expired);
}
return compactionCandidates;
}
private List getNextNonExpiredSSTables(Iterable nonExpiringSSTables, final int gcBefore)
{
List mostInteresting = getCompactionCandidates(nonExpiringSSTables);
if (mostInteresting != null)
{
return mostInteresting;
}
// if there is no sstable to compact in standard way, try compacting single sstable whose droppable tombstone
// ratio is greater than threshold.
List sstablesWithTombstones = new ArrayList<>();
for (SSTableReader sstable : nonExpiringSSTables)
{
if (worthDroppingTombstones(sstable, gcBefore))
sstablesWithTombstones.add(sstable);
}
if (sstablesWithTombstones.isEmpty())
return Collections.emptyList();
return Collections.singletonList(Collections.min(sstablesWithTombstones, new SSTableReader.SizeComparator()));
}
private List getCompactionCandidates(Iterable candidateSSTables)
{
HashMultimap buckets = getBuckets(candidateSSTables, options.sstableWindowUnit, options.sstableWindowSize, options.timestampResolution);
updateEstimatedCompactionsByTasks(buckets);
List mostInteresting = newestBucket(buckets,
cfs.getMinimumCompactionThreshold(),
cfs.getMaximumCompactionThreshold(),
options.sstableWindowUnit,
options.sstableWindowSize,
options.stcsOptions);
if (!mostInteresting.isEmpty())
return mostInteresting;
return null;
}
@Override
public synchronized void addSSTable(SSTableReader sstable)
{
sstables.add(sstable);
}
@Override
public synchronized void removeSSTable(SSTableReader sstable)
{
sstables.remove(sstable);
}
/**
* Find the lowest and highest timestamps in a given timestamp/unit pair
* Returns milliseconds, caller should adjust accordingly
*/
public static Pair getWindowBoundsInMillis(TimeUnit windowTimeUnit, int windowTimeSize, long timestampInMillis)
{
long lowerTimestamp;
long upperTimestamp;
long timestampInSeconds = timestampInMillis / 1000L;
switch(windowTimeUnit)
{
case MINUTES:
lowerTimestamp = timestampInSeconds - ((timestampInSeconds) % (60 * windowTimeSize));
upperTimestamp = (lowerTimestamp + (60L * (windowTimeSize - 1L))) + 59L;
break;
case HOURS:
lowerTimestamp = timestampInSeconds - ((timestampInSeconds) % (3600 * windowTimeSize));
upperTimestamp = (lowerTimestamp + (3600L * (windowTimeSize - 1L))) + 3599L;
break;
case DAYS:
default:
lowerTimestamp = timestampInSeconds - ((timestampInSeconds) % (86400 * windowTimeSize));
upperTimestamp = (lowerTimestamp + (86400L * (windowTimeSize - 1L))) + 86399L;
break;
}
return Pair.create(lowerTimestamp * 1000L, upperTimestamp * 1000L);
}
/**
* Group files with similar max timestamp into buckets.
*
* @param files pairs consisting of a file and its min timestamp
* @param sstableWindowUnit
* @param sstableWindowSize
* @param timestampResolution
* @return a list of buckets of files. The list is ordered such that the files with newest timestamps come first.
* Each bucket is also a list of files ordered from newest to oldest.
*/
@VisibleForTesting
static HashMultimap getBuckets(Iterable files, TimeUnit sstableWindowUnit, int sstableWindowSize, TimeUnit timestampResolution)
{
HashMultimap buckets = HashMultimap.create();
// Create hash map to represent buckets
// For each sstable, add sstable to the time bucket
// Where the bucket is the file's max timestamp rounded to the nearest window bucket
for (SSTableReader f : files)
{
long tStamp = f.getMaxTimestamp();
if (timestampResolution.equals(TimeUnit.MICROSECONDS))
tStamp = tStamp / 1000L;
else if (timestampResolution.equals(TimeUnit.NANOSECONDS))
tStamp = tStamp / 1000000L;
else if (timestampResolution.equals(TimeUnit.SECONDS))
tStamp = tStamp * 1000L;
else
assert TimeWindowCompactionStrategyOptions.validTimestampTimeUnits.contains(timestampResolution);
Pair bounds = getWindowBoundsInMillis(sstableWindowUnit, sstableWindowSize, tStamp);
buckets.put(bounds.left, f );
}
logger.debug("buckets {}", buckets);
return buckets;
}
private void updateEstimatedCompactionsByTasks(HashMultimap tasks)
{
int n = 0;
long now = System.currentTimeMillis();
Pair nowBounds = getWindowBoundsInMillis(options.sstableWindowUnit, options.sstableWindowSize, now);
now = nowBounds.left;
for(Long key : tasks.keySet())
{
// For current window, make sure it's compactable
if (key.compareTo(now) >= 0 && tasks.get(key).size() >= cfs.getMinimumCompactionThreshold())
n++;
else if (key.compareTo(now) < 0 && tasks.get(key).size() >= 2)
n++;
}
this.estimatedRemainingTasks = n;
}
/**
* @param buckets list of buckets, sorted from newest to oldest, from which to return the newest bucket within thresholds.
* @param minThreshold minimum number of sstables in a bucket to qualify.
* @param maxThreshold maximum number of sstables to compact at once (the returned bucket will be trimmed down to this).
* @return a bucket (list) of sstables to compact.
*/
@VisibleForTesting
static List newestBucket(HashMultimap buckets, int minThreshold, int maxThreshold, TimeUnit sstableWindowUnit, int sstableWindowSize, SizeTieredCompactionStrategyOptions stcsOptions)
{
// If the current bucket has at least minThreshold SSTables, choose that one.
// For any other bucket, at least 2 SSTables is enough.
// In any case, limit to maxThreshold SSTables.
long now = System.currentTimeMillis();
Pair nowBounds = getWindowBoundsInMillis(sstableWindowUnit, sstableWindowSize, now);
now = nowBounds.left;
TreeSet allKeys = new TreeSet<>(buckets.keySet());
Iterator it = allKeys.descendingIterator();
while(it.hasNext())
{
Long key = it.next();
Set bucket = buckets.get(key);
if (bucket.size() >= minThreshold && key >= now)
{
// If we're in the newest bucket, we'll use STCS to prioritize sstables
List> pairs = SizeTieredCompactionStrategy.createSSTableAndLengthPairs(bucket);
List> stcsBuckets = SizeTieredCompactionStrategy.getBuckets(pairs, stcsOptions.bucketHigh, stcsOptions.bucketLow, stcsOptions.minSSTableSize);
logger.debug("Using STCS compaction for first window of bucket: data files {} , options {}", pairs, stcsOptions);
List stcsInterestingBucket = SizeTieredCompactionStrategy.mostInterestingBucket(stcsBuckets, minThreshold, maxThreshold);
if (!stcsInterestingBucket.isEmpty())
return stcsInterestingBucket;
}
else if (bucket.size() >= 2 && key < now)
{
logger.debug("bucket size {} >= 2 and not in current bucket, compacting what's here: {}", bucket.size(), bucket);
return trimToThreshold(bucket, maxThreshold);
}
else
{
logger.debug("No compaction necessary for bucket size {} , key {}, now {}", bucket.size(), key, now);
}
}
return Collections.emptyList();
}
/**
* @param bucket set of sstables
* @param maxThreshold maximum number of sstables in a single compaction task.
* @return A bucket trimmed to the maxThreshold newest sstables.
*/
@VisibleForTesting
static List trimToThreshold(Set bucket, int maxThreshold)
{
List ssTableReaders = new ArrayList<>(bucket);
// Trim the largest sstables off the end to meet the maxThreshold
Collections.sort(ssTableReaders, new SSTableReader.SizeComparator());
return ImmutableList.copyOf(Iterables.limit(ssTableReaders, maxThreshold));
}
@Override
@SuppressWarnings("resource")
public synchronized Collection getMaximalTask(int gcBefore, boolean splitOutput)
{
Iterable filteredSSTables = filterSuspectSSTables(sstables);
if (Iterables.isEmpty(filteredSSTables))
return null;
LifecycleTransaction txn = cfs.getTracker().tryModify(filteredSSTables, OperationType.COMPACTION);
if (txn == null)
return null;
return Collections.singleton(new CompactionTask(cfs, txn, gcBefore, false));
}
@Override
@SuppressWarnings("resource")
public synchronized AbstractCompactionTask getUserDefinedTask(Collection sstables, int gcBefore)
{
assert !sstables.isEmpty(); // checked for by CM.submitUserDefined
LifecycleTransaction modifier = cfs.getTracker().tryModify(sstables, OperationType.COMPACTION);
if (modifier == null)
{
logger.debug("Unable to mark {} for compaction; probably a background compaction got to it first. You can disable background compactions temporarily if this is a problem", sstables);
return null;
}
return new CompactionTask(cfs, modifier, gcBefore, false).setUserDefined(true);
}
public int getEstimatedRemainingTasks()
{
return this.estimatedRemainingTasks;
}
public long getMaxSSTableBytes()
{
return Long.MAX_VALUE;
}
public static Map validateOptions(Map options) throws ConfigurationException
{
Map uncheckedOptions = AbstractCompactionStrategy.validateOptions(options);
uncheckedOptions = TimeWindowCompactionStrategyOptions.validateOptions(options, uncheckedOptions);
uncheckedOptions.remove(CFPropDefs.KW_MINCOMPACTIONTHRESHOLD);
uncheckedOptions.remove(CFPropDefs.KW_MAXCOMPACTIONTHRESHOLD);
return uncheckedOptions;
}
public String toString()
{
return String.format("TimeWindowCompactionStrategy[%s/%s]",
cfs.getMinimumCompactionThreshold(),
cfs.getMaximumCompactionThreshold());
}
}
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