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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;
import java.io.IOException;
import java.nio.ByteBuffer;
import com.google.common.base.Objects;
import org.apache.cassandra.cache.IMeasurableMemory;
import org.apache.cassandra.db.rows.Cell;
import org.apache.cassandra.io.ISerializer;
import org.apache.cassandra.io.sstable.format.Version;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.CassandraUInt;
import org.apache.cassandra.utils.ObjectSizes;
import static java.lang.Math.min;
/**
* Information on deletion of a storage engine object.
*/
public class DeletionTime implements Comparable, IMeasurableMemory
{
public static final long EMPTY_SIZE = ObjectSizes.measure(new DeletionTime(0, 0));
/**
* A special DeletionTime that signifies that there is no top-level (row) tombstone.
*/
public static final DeletionTime LIVE = new DeletionTime(Long.MIN_VALUE, Long.MAX_VALUE);
private static final Serializer serializer = new Serializer();
private static final Serializer legacySerializer = new LegacySerializer();
private final long markedForDeleteAt;
final int localDeletionTimeUnsignedInteger;
public static DeletionTime build(long markedForDeleteAt, long localDeletionTime)
{
// Negative ldts can only be a result of a corruption or when scrubbing legacy sstables with overflown int ldts
return localDeletionTime < 0 || localDeletionTime > Cell.MAX_DELETION_TIME
? new InvalidDeletionTime(markedForDeleteAt)
: new DeletionTime(markedForDeleteAt, localDeletionTime);
}
// Do not use. This is a perf optimization where some data structures known to hold valid uints are allowed to use it.
// You should use 'build' instead to not workaround validations, corruption detections, etc
static DeletionTime buildUnsafeWithUnsignedInteger(long markedForDeleteAt, int localDeletionTimeUnsignedInteger)
{
return CassandraUInt.compare(Cell.MAX_DELETION_TIME_UNSIGNED_INTEGER, localDeletionTimeUnsignedInteger) < 0
? new InvalidDeletionTime(markedForDeleteAt)
: new DeletionTime(markedForDeleteAt, localDeletionTimeUnsignedInteger);
}
private DeletionTime(long markedForDeleteAt, long localDeletionTime)
{
this(markedForDeleteAt, Cell.deletionTimeLongToUnsignedInteger(localDeletionTime));
}
private DeletionTime(long markedForDeleteAt, int localDeletionTimeUnsignedInteger)
{
this.markedForDeleteAt = markedForDeleteAt;
this.localDeletionTimeUnsignedInteger = localDeletionTimeUnsignedInteger;
}
/**
* A timestamp (typically in microseconds since the unix epoch, although this is not enforced) after which
* data should be considered deleted. If set to Long.MIN_VALUE, this implies that the data has not been marked
* for deletion at all.
*/
public long markedForDeleteAt()
{
return markedForDeleteAt;
}
/**
* The local server timestamp, in seconds since the unix epoch, at which this tombstone was created. This is
* only used for purposes of purging the tombstone after gc_grace_seconds have elapsed.
*/
public long localDeletionTime()
{
return Cell.deletionTimeUnsignedIntegerToLong(localDeletionTimeUnsignedInteger);
}
/**
* Returns whether this DeletionTime is live, that is deletes no columns.
*/
public boolean isLive()
{
return markedForDeleteAt() == Long.MIN_VALUE && localDeletionTime() == Long.MAX_VALUE;
}
public void digest(Digest digest)
{
// localDeletionTime is basically a metadata of the deletion time that tells us when it's ok to purge it.
// It's thus intrinsically a local information and shouldn't be part of the digest (which exists for
// cross-nodes comparisons).
digest.updateWithLong(markedForDeleteAt());
}
/**
* Check if this deletion time is valid. This is always true, because
* - as we permit negative timestamps, markedForDeleteAt can be negative.
* - localDeletionTime is stored as an unsigned int and cannot be negative.
* @return true if it is valid
*/
public boolean validate()
{
return true;
}
@Override
public boolean equals(Object o)
{
if(!(o instanceof DeletionTime))
return false;
DeletionTime that = (DeletionTime)o;
return markedForDeleteAt() == that.markedForDeleteAt() && localDeletionTime() == that.localDeletionTime();
}
@Override
public final int hashCode()
{
return Objects.hashCode(markedForDeleteAt(), localDeletionTime());
}
@Override
public String toString()
{
return String.format("deletedAt=%d, localDeletion=%d", markedForDeleteAt(), localDeletionTime());
}
public int compareTo(DeletionTime dt)
{
if (markedForDeleteAt() < dt.markedForDeleteAt())
return -1;
else if (markedForDeleteAt() > dt.markedForDeleteAt())
return 1;
else return CassandraUInt.compare(localDeletionTimeUnsignedInteger, dt.localDeletionTimeUnsignedInteger);
}
public boolean supersedes(DeletionTime dt)
{
return markedForDeleteAt() > dt.markedForDeleteAt() || (markedForDeleteAt() == dt.markedForDeleteAt() && localDeletionTime() > dt.localDeletionTime());
}
public boolean deletes(LivenessInfo info)
{
return deletes(info.timestamp());
}
public boolean deletes(Cell cell)
{
return deletes(cell.timestamp());
}
public boolean deletes(long timestamp)
{
return timestamp <= markedForDeleteAt();
}
public int dataSize()
{
return 12;
}
public long unsharedHeapSize()
{
if (this == LIVE)
return 0;
return EMPTY_SIZE;
}
public static Serializer getSerializer(Version version)
{
if (version.hasUIntDeletionTime())
return serializer;
else
return legacySerializer;
}
/* Serializer for Usigned Integer ldt
*
* ldt is encoded as a uint in seconds since unix epoch, it can go up o 2106-02-07T06:28:13+00:00 only.
* mfda is a positive timestamp. We use the sign bit to encode LIVE DeletionTimes
* Throw IOException to mark sstable as corrupt.
*/
public static class Serializer implements ISerializer
{
// We use the sign bit to signal LIVE DeletionTimes
private final static int IS_LIVE_DELETION = 0b1000_0000;
public void serialize(DeletionTime delTime, DataOutputPlus out) throws IOException
{
if (delTime == LIVE)
out.writeByte(IS_LIVE_DELETION);
else
{
// The sign bit is zero here, so we can write a long directly
out.writeLong(delTime.markedForDeleteAt());
out.writeInt(delTime.localDeletionTimeUnsignedInteger);
}
}
public DeletionTime deserialize(DataInputPlus in) throws IOException
{
int flags = in.readByte();
if ((flags & IS_LIVE_DELETION) != 0)
{
if ((flags & 0xFF) != IS_LIVE_DELETION)
throw new IOException("Corrupted sstable. Invalid flags found deserializing DeletionTime: " + Integer.toBinaryString(flags & 0xFF));
return LIVE;
}
else
{
// Read the remaining 7 bytes
int bytes1 = in.readByte();
int bytes2 = in.readShort();
int bytes4 = in.readInt();
long mfda = readBytesToMFDA(flags, bytes1, bytes2, bytes4);
int localDeletionTimeUnsignedInteger = in.readInt();
return new DeletionTime(mfda, localDeletionTimeUnsignedInteger);
}
}
public DeletionTime deserialize(ByteBuffer buf, int offset) throws IOException
{
int flags = buf.get(offset);
if ((flags & IS_LIVE_DELETION) != 0)
{
if ((flags & 0xFF) != IS_LIVE_DELETION)
throw new IOException("Corrupted sstable. Invalid flags found deserializing DeletionTime: " + Integer.toBinaryString(flags & 0xFF));
return LIVE;
}
else
{
long mfda = buf.getLong(offset);
int localDeletionTimeUnsignedInteger = buf.getInt(offset + TypeSizes.LONG_SIZE);
return new DeletionTime(mfda, localDeletionTimeUnsignedInteger);
}
}
public void skip(DataInputPlus in) throws IOException
{
int flags = in.readByte();
if ((flags & IS_LIVE_DELETION) != 0)
{
if ((flags & 0xFF) != IS_LIVE_DELETION)
throw new IOException("Corrupted sstable. Invalid flags found deserializing DeletionTime: " + Integer.toBinaryString(flags & 0xFF));
// We read the flags already and there's nothing left to skip over
return;
}
else
// We read the flags already but there is mfda and ldt to skip over still
in.skipBytesFully(TypeSizes.LONG_SIZE - 1 + TypeSizes.INT_SIZE);
}
public long serializedSize(DeletionTime delTime)
{
if (delTime == LIVE)
// Just the flags
return 1;
else
// 1 for the flags, 7 for mfda and 4 for ldt
return TypeSizes.LONG_SIZE
+ TypeSizes.INT_SIZE;
}
private long readBytesToMFDA(int flagsByte, int bytes1, int bytes2, int bytes4)
{
long mfda = flagsByte & 0xFFL;
mfda = (mfda << 8) + (bytes1 & 0xFFL);
mfda = (mfda << 16) + (bytes2 & 0xFFFFL);
mfda = (mfda << 32) + (bytes4 & 0xFFFFFFFFL);
return mfda;
}
}
// Serializer for Int TTL/localDeletionTime for legacy versions
public static class LegacySerializer extends Serializer
{
public void serialize(DeletionTime delTime, DataOutputPlus out) throws IOException
{
int ldt = delTime.localDeletionTime() == Cell.NO_DELETION_TIME ? Integer.MAX_VALUE : (int) min(delTime.localDeletionTime(), (long)Integer.MAX_VALUE - 1);
out.writeInt(ldt);
out.writeLong(delTime.markedForDeleteAt);
}
public DeletionTime deserialize(DataInputPlus in) throws IOException
{
int ldt = in.readInt();
long mfda = in.readLong();
return mfda == Long.MIN_VALUE && ldt == Integer.MAX_VALUE
? LIVE
: DeletionTime.build(mfda, ldt);
}
public DeletionTime deserialize(ByteBuffer buf, int offset)
{
int ldt = buf.getInt(offset);
long mfda = buf.getLong(offset + 4);
return mfda == Long.MIN_VALUE && ldt == Integer.MAX_VALUE
? LIVE
: new DeletionTime(mfda, ldt);
}
public void skip(DataInputPlus in) throws IOException
{
in.skipBytesFully(4 + 8);
}
public long serializedSize(DeletionTime delTime)
{
return TypeSizes.sizeof(Integer.MAX_VALUE)
+ TypeSizes.sizeof(delTime.markedForDeleteAt());
}
}
// When scrubbing legacy sstables (overflown) or upon sstable corruption we could have negative ldts
public static class InvalidDeletionTime extends DeletionTime
{
private InvalidDeletionTime(long markedForDeleteAt)
{
// We're calling the super constructor with int ldt to force invalid values through
// and workaround any validation
super(markedForDeleteAt, Cell.INVALID_DELETION_TIME);
}
@Override
public long localDeletionTime()
{
return Cell.INVALID_DELETION_TIME;
}
@Override
public boolean validate()
{
return false;
}
}
}
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