/**
* 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 java.security.MessageDigest;
import java.util.Collection;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.MarshalException;
import org.apache.cassandra.io.util.DataOutputBuffer;
import org.apache.cassandra.utils.ByteBufferUtil;
/**
* Column is immutable, which prevents all kinds of confusion in a multithreaded environment.
* (TODO: look at making SuperColumn immutable too. This is trickier but is probably doable
* with something like PCollections -- http://code.google.com
*/
public class Column implements IColumn
{
private static Logger logger = LoggerFactory.getLogger(Column.class);
public static ColumnSerializer serializer()
{
return new ColumnSerializer();
}
protected final ByteBuffer name;
protected final ByteBuffer value;
protected final long timestamp;
Column(ByteBuffer name)
{
this(name, ByteBufferUtil.EMPTY_BYTE_BUFFER);
}
public Column(ByteBuffer name, ByteBuffer value)
{
this(name, value, 0);
}
public Column(ByteBuffer name, ByteBuffer value, long timestamp)
{
assert name != null;
assert value != null;
assert name.remaining() <= IColumn.MAX_NAME_LENGTH;
this.name = name;
this.value = value;
this.timestamp = timestamp;
}
public ByteBuffer name()
{
return name;
}
public Column getSubColumn(ByteBuffer columnName)
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public ByteBuffer value()
{
return value;
}
public Collection<IColumn> getSubColumns()
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public long timestamp()
{
return timestamp;
}
public boolean isMarkedForDelete()
{
return false;
}
public long getMarkedForDeleteAt()
{
throw new IllegalStateException("column is not marked for delete");
}
public long mostRecentLiveChangeAt()
{
return timestamp;
}
public int size()
{
/*
* Size of a column is =
* size of a name (short + length of the string)
* + 1 byte to indicate if the column has been deleted
* + 8 bytes for timestamp
* + 4 bytes which basically indicates the size of the byte array
* + entire byte array.
*/
return DBConstants.shortSize_ + name.remaining() + DBConstants.boolSize_ + DBConstants.tsSize_ + DBConstants.intSize_ + value.remaining();
}
/*
* This returns the size of the column when serialized.
* @see com.facebook.infrastructure.db.IColumn#serializedSize()
*/
public int serializedSize()
{
return size();
}
public void addColumn(IColumn column)
{
throw new UnsupportedOperationException("This operation is not supported for simple columns.");
}
public IColumn diff(IColumn column)
{
if (timestamp() < column.timestamp())
{
return column;
}
return null;
}
public void updateDigest(MessageDigest digest)
{
digest.update(name.duplicate());
digest.update(value.duplicate());
DataOutputBuffer buffer = new DataOutputBuffer();
try
{
buffer.writeLong(timestamp);
buffer.writeByte((isMarkedForDelete()) ? ColumnSerializer.DELETION_MASK : 0);
}
catch (IOException e)
{
throw new RuntimeException(e);
}
digest.update(buffer.getData(), 0, buffer.getLength());
}
public int getLocalDeletionTime()
{
throw new IllegalStateException("column is not marked for delete");
}
public IColumn reconcile(IColumn column)
{
// tombstones take precedence. (if both are tombstones, then it doesn't matter which one we use.)
if (isMarkedForDelete())
return timestamp() < column.timestamp() ? column : this;
if (column.isMarkedForDelete())
return timestamp() > column.timestamp() ? this : column;
// break ties by comparing values.
if (timestamp() == column.timestamp())
return value().compareTo(column.value()) < 0 ? column : this;
// neither is tombstoned and timestamps are different
return timestamp() < column.timestamp() ? column : this;
}
@Override
public boolean equals(Object o)
{
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
Column column = (Column)o;
if (timestamp != column.timestamp)
return false;
if (!name.equals(column.name))
return false;
return value.equals(column.value);
}
@Override
public int hashCode()
{
int result = name != null ? name.hashCode() : 0;
result = 31 * result + (value != null ? value.hashCode() : 0);
result = 31 * result + (int)(timestamp ^ (timestamp >>> 32));
return result;
}
public IColumn deepCopy()
{
return new Column(ByteBufferUtil.clone(name), ByteBufferUtil.clone(value), timestamp);
}
public String getString(AbstractType comparator)
{
StringBuilder sb = new StringBuilder();
sb.append(comparator.getString(name));
sb.append(":");
sb.append(isMarkedForDelete());
sb.append(":");
sb.append(value.remaining());
sb.append("@");
sb.append(timestamp());
return sb.toString();
}
public boolean isLive()
{
return !isMarkedForDelete();
}
protected void validateName(CFMetaData metadata) throws MarshalException
{
AbstractType nameValidator = metadata.cfType == ColumnFamilyType.Super ? metadata.subcolumnComparator : metadata.comparator;
nameValidator.validate(name());
}
public void validateFields(CFMetaData metadata) throws MarshalException
{
validateName(metadata);
AbstractType valueValidator = metadata.getValueValidator(name());
if (valueValidator != null)
valueValidator.validate(value());
}
}