import org.apache.cassandra.utils.AlwaysPresentFilter; //导入依赖的package包/类
/**
 * @return the largest timestamp before which it's okay to drop tombstones for the given partition;
 * i.e., after the maxPurgeableTimestamp there may exist newer data that still needs to be suppressed
 * in other sstables.  This returns the minimum timestamp for any SSTable that contains this partition and is not
 * participating in this compaction, or LONG.MAX_VALUE if no such SSTable exists.
 */
public long maxPurgeableTimestamp(DecoratedKey key)
{
    List<SSTableReader> filteredSSTables = overlappingTree.search(key);
    long min = Long.MAX_VALUE;
    for (SSTableReader sstable : filteredSSTables)
    {
        // if we don't have bloom filter(bf_fp_chance=1.0 or filter file is missing),
        // we check index file instead.
        if (sstable.getBloomFilter() instanceof AlwaysPresentFilter && sstable.getPosition(key, SSTableReader.Operator.EQ, false) != null)
            min = Math.min(min, sstable.getMinTimestamp());
        else if (sstable.getBloomFilter().isPresent(key.getKey()))
            min = Math.min(min, sstable.getMinTimestamp());
    }
    return min;
}
 

import org.apache.cassandra.utils.AlwaysPresentFilter; //导入依赖的package包/类
/**
 * @return true if it's okay to drop tombstones for the given row, i.e., if we know all the verisons of the row
 * are included in the compaction set
 */
public boolean shouldPurge(DecoratedKey key, long maxDeletionTimestamp)
{
    List<SSTableReader> filteredSSTables = overlappingTree.search(key);
    for (SSTableReader sstable : filteredSSTables)
    {
        if (sstable.getMinTimestamp() <= maxDeletionTimestamp)
        {
            // if we don't have bloom filter(bf_fp_chance=1.0 or filter file is missing),
            // we check index file instead.
            if (sstable.getBloomFilter() instanceof AlwaysPresentFilter && sstable.getPosition(key, SSTableReader.Operator.EQ, false) != null)
                return false;
            else if (sstable.getBloomFilter().isPresent(key.key))
                return false;
        }
    }
    return true;
}
 

import org.apache.cassandra.utils.AlwaysPresentFilter; //导入依赖的package包/类
/**
 * @return the largest timestamp before which it's okay to drop tombstones for the given partition;
 * i.e., after the maxPurgeableTimestamp there may exist newer data that still needs to be suppressed
 * in other sstables.  This returns the minimum timestamp for any SSTable that contains this partition and is not
 * participating in this compaction, or memtable that contains this partition,
 * or LONG.MAX_VALUE if no SSTable or memtable exist.
 */
public long maxPurgeableTimestamp(DecoratedKey key)
{
    if (!compactingRepaired() || NEVER_PURGE_TOMBSTONES)
        return Long.MIN_VALUE;

    long min = Long.MAX_VALUE;
    overlapIterator.update(key);
    for (SSTableReader sstable : overlapIterator.overlaps())
    {
        // if we don't have bloom filter(bf_fp_chance=1.0 or filter file is missing),
        // we check index file instead.
        if (sstable.getBloomFilter() instanceof AlwaysPresentFilter && sstable.getPosition(key, SSTableReader.Operator.EQ, false) != null)
            min = Math.min(min, sstable.getMinTimestamp());
        else if (sstable.getBloomFilter().isPresent(key))
            min = Math.min(min, sstable.getMinTimestamp());
    }

    for (Memtable memtable : cfs.getTracker().getView().getAllMemtables())
    {
        Partition partition = memtable.getPartition(key);
        if (partition != null)
            min = Math.min(min, partition.stats().minTimestamp);
    }
    return min;
}
 

import org.apache.cassandra.utils.AlwaysPresentFilter; //导入依赖的package包/类
/**
 * @return the largest timestamp before which it's okay to drop tombstones for the given partition;
 * i.e., after the maxPurgeableTimestamp there may exist newer data that still needs to be suppressed
 * in other sstables.  This returns the minimum timestamp for any SSTable that contains this partition and is not
 * participating in this compaction, or LONG.MAX_VALUE if no such SSTable exists.
 */
public long maxPurgeableTimestamp(DecoratedKey key)
{
    List<SSTableReader> filteredSSTables = overlappingTree.search(key);
    long min = Long.MAX_VALUE;
    for (SSTableReader sstable : filteredSSTables)
    {
        // if we don't have bloom filter(bf_fp_chance=1.0 or filter file is missing),
        // we check index file instead.
        if (sstable.getBloomFilter() instanceof AlwaysPresentFilter && sstable.getPosition(key, SSTableReader.Operator.EQ, false) != null)
            min = Math.min(min, sstable.getMinTimestamp());
        else if (sstable.getBloomFilter().isPresent(key.key))
            min = Math.min(min, sstable.getMinTimestamp());
    }
    return min;
}