/**
* 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.util.Collection;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.io.IOException;
import org.apache.commons.lang.ArrayUtils;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.io.DataOutputBuffer;
/**
* 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 final class Column implements IColumn
{
private static ColumnSerializer serializer_ = new ColumnSerializer();
static ColumnSerializer serializer()
{
return serializer_;
}
private final byte[] name;
private final byte[] value;
private final long timestamp;
private final boolean isMarkedForDelete;
Column(byte[] name)
{
this(name, ArrayUtils.EMPTY_BYTE_ARRAY);
}
Column(byte[] name, byte[] value)
{
this(name, value, 0);
}
public Column(byte[] name, byte[] value, long timestamp)
{
this(name, value, timestamp, false);
}
public Column(byte[] name, byte[] value, long timestamp, boolean isDeleted)
{
assert name != null;
assert value != null;
assert name.length <= IColumn.MAX_NAME_LENGTH;
this.name = name;
this.value = value;
this.timestamp = timestamp;
isMarkedForDelete = isDeleted;
}
public byte[] name()
{
return name;
}
public Column getSubColumn(byte[] columnName)
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public byte[] value()
{
return value;
}
public byte[] value(byte[] key)
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public Collection<IColumn> getSubColumns()
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public int getObjectCount()
{
return 1;
}
public long timestamp()
{
return timestamp;
}
public long timestamp(byte[] key)
{
throw new UnsupportedOperationException("This operation is unsupported on simple columns.");
}
public boolean isMarkedForDelete()
{
return isMarkedForDelete;
}
public long getMarkedForDeleteAt()
{
if (!isMarkedForDelete())
{
throw new IllegalStateException("column is not marked for delete");
}
return timestamp;
}
public long mostRecentChangeAt()
{
return timestamp;
}
public int size()
{
/*
* Size of a column is =
* size of a name (UtfPrefix + 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.
*/
/*
* We store the string as UTF-8 encoded, so when we calculate the length, it
* should be converted to UTF-8.
*/
return IColumn.UtfPrefix_ + name.length + DBConstants.boolSize_ + DBConstants.tsSize_ + DBConstants.intSize_ + value.length;
}
/*
* 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);
digest.update(value);
DataOutputBuffer buffer = new DataOutputBuffer();
try
{
buffer.writeLong(timestamp);
buffer.writeBoolean(isMarkedForDelete);
}
catch (IOException e)
{
throw new RuntimeException(e);
}
digest.update(buffer.getData(), 0, buffer.getLength());
}
public int getLocalDeletionTime()
{
assert isMarkedForDelete;
return ByteBuffer.wrap(value).getInt();
}
// note that we do not call this simply compareTo since it also makes sense to compare Columns by name
public long comparePriority(Column o)
{
if (isMarkedForDelete)
{
// tombstone always wins ties.
return timestamp < o.timestamp ? -1 : 1;
}
return timestamp - o.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.length);
sb.append("@");
sb.append(timestamp());
return sb.toString();
}
}