/*
* 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.DataInput;
import java.io.IOException;
import org.apache.cassandra.db.composites.CellName;
import org.apache.cassandra.db.composites.CellNameType;
import org.apache.cassandra.db.composites.Composite;
import org.apache.cassandra.io.sstable.Descriptor;
/**
* Helper class to deserialize OnDiskAtom efficiently.
*
* More precisely, this class is used by the low-level readers
* (IndexedSliceReader and SSTableNamesIterator) to ensure we don't
* do more work than necessary (i.e. we don't allocate/deserialize
* objects for things we don't care about).
*/
public class AtomDeserializer
{
private final CellNameType type;
private final CellNameType.Deserializer nameDeserializer;
private final DataInput in;
private final ColumnSerializer.Flag flag;
private final int expireBefore;
private final Descriptor.Version version;
public AtomDeserializer(CellNameType type, DataInput in, ColumnSerializer.Flag flag, int expireBefore, Descriptor.Version version)
{
this.type = type;
this.nameDeserializer = type.newDeserializer(in);
this.in = in;
this.flag = flag;
this.expireBefore = expireBefore;
this.version = version;
}
/**
* Whether or not there is more atom to read.
*/
public boolean hasNext() throws IOException
{
return nameDeserializer.hasNext();
}
/**
* Whether or not some atom has been read but not processed (neither readNext() nor
* skipNext() has been called for that atom) yet.
*/
public boolean hasUnprocessed() throws IOException
{
return nameDeserializer.hasUnprocessed();
}
/**
* Compare the provided composite to the next atom to read on disk.
*
* This will not read/deserialize the whole atom but only what is necessary for the
* comparison. Whenever we know what to do with this atom (read it or skip it),
* readNext or skipNext should be called.
*/
public int compareNextTo(Composite composite) throws IOException
{
return nameDeserializer.compareNextTo(composite);
}
/**
* Returns the next atom.
*/
public OnDiskAtom readNext() throws IOException
{
Composite name = nameDeserializer.readNext();
assert !name.isEmpty(); // This would imply hasNext() hasn't been called
int b = in.readUnsignedByte();
if ((b & ColumnSerializer.RANGE_TOMBSTONE_MASK) != 0)
return type.rangeTombstoneSerializer().deserializeBody(in, name, version);
else
return type.columnSerializer().deserializeColumnBody(in, (CellName)name, b, flag, expireBefore);
}
/**
* Skips the next atom.
*/
public void skipNext() throws IOException
{
nameDeserializer.skipNext();
int b = in.readUnsignedByte();
if ((b & ColumnSerializer.RANGE_TOMBSTONE_MASK) != 0)
type.rangeTombstoneSerializer().skipBody(in, version);
else
type.columnSerializer().skipColumnBody(in, b);
}
}