Java SSTableReader.getEstimatedDroppableTombstoneRatio方法代码示例

import org.apache.cassandra.io.sstable.SSTableReader; //导入方法依赖的package包/类
private SSTableReader findDroppableSSTable(final int gcBefore)
{
    level:
    for (int i = manifest.getLevelCount(); i >= 0; i--)
    {
        // sort sstables by droppable ratio in descending order
        SortedSet<SSTableReader> sstables = manifest.getLevelSorted(i, new Comparator<SSTableReader>()
        {
            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<SSTableReader> compacting = cfs.getDataTracker().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;
}
 

import org.apache.cassandra.io.sstable.SSTableReader; //导入方法依赖的package包/类
/**
 * 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;

    //sstable range overlap check is disabled. See CASSANDRA-6563.
    if (uncheckedTombstoneCompaction)
        return true;

    Collection<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.getToken(), overlap.last.getToken(), 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;
    }
}
 

import org.apache.cassandra.io.sstable.SSTableReader; //导入方法依赖的package包/类
/**
 * 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.getKeySampleSize() < 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;
    }
}