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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.rows;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.apache.cassandra.config.*;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.context.CounterContext;
import org.apache.cassandra.db.marshal.ByteType;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.ObjectSizes;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.memory.AbstractAllocator;
public class BufferCell extends AbstractCell
{
private static final long EMPTY_SIZE = ObjectSizes.measure(new BufferCell(ColumnDefinition.regularDef("", "", "", ByteType.instance), 0L, 0, 0, ByteBufferUtil.EMPTY_BYTE_BUFFER, null));
private final long timestamp;
private final int ttl;
private final int localDeletionTime;
private final ByteBuffer value;
private final CellPath path;
public BufferCell(ColumnDefinition column, long timestamp, int ttl, int localDeletionTime, ByteBuffer value, CellPath path)
{
super(column);
assert column.isComplex() == (path != null);
this.timestamp = timestamp;
this.ttl = ttl;
this.localDeletionTime = localDeletionTime;
this.value = value;
this.path = path;
}
public static BufferCell live(CFMetaData metadata, ColumnDefinition column, long timestamp, ByteBuffer value)
{
return live(metadata, column, timestamp, value, null);
}
public static BufferCell live(CFMetaData metadata, ColumnDefinition column, long timestamp, ByteBuffer value, CellPath path)
{
if (metadata.params.defaultTimeToLive != NO_TTL)
return expiring(column, timestamp, metadata.params.defaultTimeToLive, FBUtilities.nowInSeconds(), value, path);
return new BufferCell(column, timestamp, NO_TTL, NO_DELETION_TIME, value, path);
}
public static BufferCell expiring(ColumnDefinition column, long timestamp, int ttl, int nowInSec, ByteBuffer value)
{
return expiring(column, timestamp, ttl, nowInSec, value, null);
}
public static BufferCell expiring(ColumnDefinition column, long timestamp, int ttl, int nowInSec, ByteBuffer value, CellPath path)
{
assert ttl != NO_TTL;
return new BufferCell(column, timestamp, ttl, ExpirationDateOverflowHandling.computeLocalExpirationTime(nowInSec, ttl), value, path);
}
public static BufferCell tombstone(ColumnDefinition column, long timestamp, int nowInSec)
{
return tombstone(column, timestamp, nowInSec, null);
}
public static BufferCell tombstone(ColumnDefinition column, long timestamp, int nowInSec, CellPath path)
{
return new BufferCell(column, timestamp, NO_TTL, nowInSec, ByteBufferUtil.EMPTY_BYTE_BUFFER, path);
}
public boolean isCounterCell()
{
return !isTombstone() && column.isCounterColumn();
}
public boolean isLive(int nowInSec)
{
return localDeletionTime == NO_DELETION_TIME || (ttl != NO_TTL && nowInSec < localDeletionTime);
}
public boolean isTombstone()
{
return localDeletionTime != NO_DELETION_TIME && ttl == NO_TTL;
}
public boolean isExpiring()
{
return ttl != NO_TTL;
}
public long timestamp()
{
return timestamp;
}
public int ttl()
{
return ttl;
}
public int localDeletionTime()
{
return localDeletionTime;
}
public ByteBuffer value()
{
return value;
}
public CellPath path()
{
return path;
}
public Cell withUpdatedColumn(ColumnDefinition newColumn)
{
return new BufferCell(newColumn, timestamp, ttl, localDeletionTime, value, path);
}
public Cell withUpdatedValue(ByteBuffer newValue)
{
return new BufferCell(column, timestamp, ttl, localDeletionTime, newValue, path);
}
public Cell withUpdatedTimestampAndLocalDeletionTime(long newTimestamp, int newLocalDeletionTime)
{
return new BufferCell(column, newTimestamp, ttl, newLocalDeletionTime, value, path);
}
public Cell copy(AbstractAllocator allocator)
{
if (!value.hasRemaining())
return this;
return new BufferCell(column, timestamp, ttl, localDeletionTime, allocator.clone(value), path == null ? null : path.copy(allocator));
}
public Cell markCounterLocalToBeCleared()
{
if (!isCounterCell())
return this;
ByteBuffer marked = CounterContext.instance().markLocalToBeCleared(value());
return marked == value() ? this : new BufferCell(column, timestamp, ttl, localDeletionTime, marked, path);
}
public Cell purge(DeletionPurger purger, int nowInSec)
{
if (!isLive(nowInSec))
{
if (purger.shouldPurge(timestamp, localDeletionTime))
return null;
// We slightly hijack purging to convert expired but not purgeable columns to tombstones. The reason we do that is
// that once a column has expired it is equivalent to a tombstone but actually using a tombstone is more compact since
// we don't keep the column value. The reason we do it here is that 1) it's somewhat related to dealing with tombstones
// so hopefully not too surprising and 2) we want to this and purging at the same places, so it's simpler/more efficient
// to do both here.
if (isExpiring())
{
// Note that as long as the expiring column and the tombstone put together live longer than GC grace seconds,
// we'll fulfil our responsibility to repair. See discussion at
// http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/repair-compaction-and-tombstone-rows-td7583481.html
return BufferCell.tombstone(column, timestamp, localDeletionTime - ttl, path).purge(purger, nowInSec);
}
}
return this;
}
public Cell updateAllTimestamp(long newTimestamp)
{
return new BufferCell(column, isTombstone() ? newTimestamp - 1 : newTimestamp, ttl, localDeletionTime, value, path);
}
public int dataSize()
{
return TypeSizes.sizeof(timestamp)
+ TypeSizes.sizeof(ttl)
+ TypeSizes.sizeof(localDeletionTime)
+ value.remaining()
+ (path == null ? 0 : path.dataSize());
}
public long unsharedHeapSizeExcludingData()
{
return EMPTY_SIZE + ObjectSizes.sizeOnHeapExcludingData(value) + (path == null ? 0 : path.unsharedHeapSizeExcludingData());
}
/**
* The serialization format for cell is:
* [ flags ][ timestamp ][ deletion time ][ ttl ][ path size ][ path ][ value size ][ value ]
* [ 1b ][ 8b (vint) ][ 4b (vint) ][ 4b (vint) ][ 4b (vint) ][ arb ][ 4b (vint) ][ arb ]
*
* where not all field are always present (in fact, only the [ flags ] are guaranteed to be present). The fields have the following
* meaning:
* - [ flags ] is the cell flags. It is a byte for which each bit represents a flag whose meaning is explained below (*_MASK constants)
* - [ timestamp ] is the cell timestamp. Present unless the cell has the USE_TIMESTAMP_MASK.
* - [ deletion time]: the local deletion time for the cell. Present if either the cell is deleted (IS_DELETED_MASK)
* or it is expiring (IS_EXPIRING_MASK) but doesn't have the USE_ROW_TTL_MASK.
* - [ ttl ]: the ttl for the cell. Present if the row is expiring (IS_EXPIRING_MASK) but doesn't have the
* USE_ROW_TTL_MASK.
* - [ value size ] is the size of the [ value ] field. It's present unless either the cell has the HAS_EMPTY_VALUE_MASK, or the value
* for columns of this type have a fixed length.
* - [ path size ] is the size of the [ path ] field. Present iff this is the cell of a complex column.
* - [ value ]: the cell value, unless it has the HAS_EMPTY_VALUE_MASK.
* - [ path ]: the cell path if the column this is a cell of is complex.
*/
static class Serializer implements Cell.Serializer
{
private final static int IS_DELETED_MASK = 0x01; // Whether the cell is a tombstone or not.
private final static int IS_EXPIRING_MASK = 0x02; // Whether the cell is expiring.
private final static int HAS_EMPTY_VALUE_MASK = 0x04; // Wether the cell has an empty value. This will be the case for tombstone in particular.
private final static int USE_ROW_TIMESTAMP_MASK = 0x08; // Wether the cell has the same timestamp than the row this is a cell of.
private final static int USE_ROW_TTL_MASK = 0x10; // Wether the cell has the same ttl than the row this is a cell of.
public void serialize(Cell cell, ColumnDefinition column, DataOutputPlus out, LivenessInfo rowLiveness, SerializationHeader header) throws IOException
{
assert cell != null;
boolean hasValue = cell.value().hasRemaining();
boolean isDeleted = cell.isTombstone();
boolean isExpiring = cell.isExpiring();
boolean useRowTimestamp = !rowLiveness.isEmpty() && cell.timestamp() == rowLiveness.timestamp();
boolean useRowTTL = isExpiring && rowLiveness.isExpiring() && cell.ttl() == rowLiveness.ttl() && cell.localDeletionTime() == rowLiveness.localExpirationTime();
int flags = 0;
if (!hasValue)
flags |= HAS_EMPTY_VALUE_MASK;
if (isDeleted)
flags |= IS_DELETED_MASK;
else if (isExpiring)
flags |= IS_EXPIRING_MASK;
if (useRowTimestamp)
flags |= USE_ROW_TIMESTAMP_MASK;
if (useRowTTL)
flags |= USE_ROW_TTL_MASK;
out.writeByte((byte)flags);
if (!useRowTimestamp)
header.writeTimestamp(cell.timestamp(), out);
if ((isDeleted || isExpiring) && !useRowTTL)
header.writeLocalDeletionTime(cell.localDeletionTime(), out);
if (isExpiring && !useRowTTL)
header.writeTTL(cell.ttl(), out);
if (column.isComplex())
column.cellPathSerializer().serialize(cell.path(), out);
if (hasValue)
header.getType(column).writeValue(cell.value(), out);
}
public Cell deserialize(DataInputPlus in, LivenessInfo rowLiveness, ColumnDefinition column, SerializationHeader header, SerializationHelper helper) throws IOException
{
int flags = in.readUnsignedByte();
boolean hasValue = (flags & HAS_EMPTY_VALUE_MASK) == 0;
boolean isDeleted = (flags & IS_DELETED_MASK) != 0;
boolean isExpiring = (flags & IS_EXPIRING_MASK) != 0;
boolean useRowTimestamp = (flags & USE_ROW_TIMESTAMP_MASK) != 0;
boolean useRowTTL = (flags & USE_ROW_TTL_MASK) != 0;
long timestamp = useRowTimestamp ? rowLiveness.timestamp() : header.readTimestamp(in);
int localDeletionTime = useRowTTL
? rowLiveness.localExpirationTime()
: (isDeleted || isExpiring ? header.readLocalDeletionTime(in) : NO_DELETION_TIME);
int ttl = useRowTTL ? rowLiveness.ttl() : (isExpiring ? header.readTTL(in) : NO_TTL);
CellPath path = column.isComplex()
? column.cellPathSerializer().deserialize(in)
: null;
boolean isCounter = localDeletionTime == NO_DELETION_TIME && column.type.isCounter();
ByteBuffer value = ByteBufferUtil.EMPTY_BYTE_BUFFER;
if (hasValue)
{
if (helper.canSkipValue(column) || (path != null && helper.canSkipValue(path)))
{
header.getType(column).skipValue(in);
}
else
{
value = header.getType(column).readValue(in, DatabaseDescriptor.getMaxValueSize());
if (isCounter)
value = helper.maybeClearCounterValue(value);
}
}
return new BufferCell(column, timestamp, ttl, localDeletionTime, value, path);
}
public long serializedSize(Cell cell, ColumnDefinition column, LivenessInfo rowLiveness, SerializationHeader header)
{
long size = 1; // flags
boolean hasValue = cell.value().hasRemaining();
boolean isDeleted = cell.isTombstone();
boolean isExpiring = cell.isExpiring();
boolean useRowTimestamp = !rowLiveness.isEmpty() && cell.timestamp() == rowLiveness.timestamp();
boolean useRowTTL = isExpiring && rowLiveness.isExpiring() && cell.ttl() == rowLiveness.ttl() && cell.localDeletionTime() == rowLiveness.localExpirationTime();
if (!useRowTimestamp)
size += header.timestampSerializedSize(cell.timestamp());
if ((isDeleted || isExpiring) && !useRowTTL)
size += header.localDeletionTimeSerializedSize(cell.localDeletionTime());
if (isExpiring && !useRowTTL)
size += header.ttlSerializedSize(cell.ttl());
if (column.isComplex())
size += column.cellPathSerializer().serializedSize(cell.path());
if (hasValue)
size += header.getType(column).writtenLength(cell.value());
return size;
}
// Returns if the skipped cell was an actual cell (i.e. it had its presence flag).
public boolean skip(DataInputPlus in, ColumnDefinition column, SerializationHeader header) throws IOException
{
int flags = in.readUnsignedByte();
boolean hasValue = (flags & HAS_EMPTY_VALUE_MASK) == 0;
boolean isDeleted = (flags & IS_DELETED_MASK) != 0;
boolean isExpiring = (flags & IS_EXPIRING_MASK) != 0;
boolean useRowTimestamp = (flags & USE_ROW_TIMESTAMP_MASK) != 0;
boolean useRowTTL = (flags & USE_ROW_TTL_MASK) != 0;
if (!useRowTimestamp)
header.skipTimestamp(in);
if (!useRowTTL && (isDeleted || isExpiring))
header.skipLocalDeletionTime(in);
if (!useRowTTL && isExpiring)
header.skipTTL(in);
if (column.isComplex())
column.cellPathSerializer().skip(in);
if (hasValue)
header.getType(column).skipValue(in);
return true;
}
}
}
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