/*
* 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 java.util.Comparator;
import org.apache.cassandra.config.*;
import org.apache.cassandra.db.*;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.memory.AbstractAllocator;
/**
* A cell is our atomic unit for a single value of a single column.
* <p>
* A cell always holds at least a timestamp that gives us how the cell reconcile. We then
* have 3 main types of cells:
* 1) live regular cells: those will also have a value and, if for a complex column, a path.
* 2) expiring cells: on top of regular cells, those have a ttl and a local deletion time (when they are expired).
* 3) tombstone cells: those won't have value, but they have a local deletion time (when the tombstone was created).
*/
public abstract class Cell extends ColumnData
{
public static final int NO_TTL = 0;
public static final int NO_DELETION_TIME = Integer.MAX_VALUE;
public final static Comparator<Cell> comparator = (c1, c2) ->
{
int cmp = c1.column().compareTo(c2.column());
if (cmp != 0)
return cmp;
Comparator<CellPath> pathComparator = c1.column().cellPathComparator();
return pathComparator == null ? 0 : pathComparator.compare(c1.path(), c2.path());
};
public static final Serializer serializer = new BufferCell.Serializer();
protected Cell(ColumnMetadata column)
{
super(column);
}
/**
* Whether the cell is a counter cell or not.
*
* @return whether the cell is a counter cell or not.
*/
public abstract boolean isCounterCell();
/**
* The cell value.
*
* @return the cell value.
*/
public abstract ByteBuffer value();
/**
* The cell timestamp.
* <p>
* @return the cell timestamp.
*/
public abstract long timestamp();
/**
* The cell ttl.
*
* @return the cell ttl, or {@code NO_TTL} if the cell isn't an expiring one.
*/
public abstract int ttl();
/**
* The cell local deletion time.
*
* @return the cell local deletion time, or {@code NO_DELETION_TIME} if the cell is neither
* a tombstone nor an expiring one.
*/
public abstract int localDeletionTime();
/**
* Whether the cell is a tombstone or not.
*
* @return whether the cell is a tombstone or not.
*/
public abstract boolean isTombstone();
/**
* Whether the cell is an expiring one or not.
* <p>
* Note that this only correspond to whether the cell liveness info
* have a TTL or not, but doesn't tells whether the cell is already expired
* or not. You should use {@link #isLive} for that latter information.
*
* @return whether the cell is an expiring one or not.
*/
public abstract boolean isExpiring();
/**
* Whether the cell is live or not given the current time.
*
* @param nowInSec the current time in seconds. This is used to
* decide if an expiring cell is expired or live.
* @return whether the cell is live or not at {@code nowInSec}.
*/
public abstract boolean isLive(int nowInSec);
/**
* For cells belonging to complex types (non-frozen collection and UDT), the
* path to the cell.
*
* @return the cell path for cells of complex column, and {@code null} for other cells.
*/
public abstract CellPath path();
public abstract Cell withUpdatedColumn(ColumnMetadata newColumn);
public abstract Cell withUpdatedValue(ByteBuffer newValue);
public abstract Cell copy(AbstractAllocator allocator);
@Override
// Overrides super type to provide a more precise return type.
public abstract Cell markCounterLocalToBeCleared();
@Override
// Overrides super type to provide a more precise return type.
public abstract Cell purge(DeletionPurger purger, int nowInSec);
/**
* 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
{
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, ColumnMetadata 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, ColumnMetadata 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;
ByteBuffer value = ByteBufferUtil.EMPTY_BYTE_BUFFER;
if (hasValue)
{
if (helper.canSkipValue(column) || (path != null && helper.canSkipValue(path)))
{
header.getType(column).skipValue(in);
}
else
{
boolean isCounter = localDeletionTime == NO_DELETION_TIME && column.type.isCounter();
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, ColumnMetadata 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, ColumnMetadata 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;
}
}
}