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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.io.sstable;
import java.util.EnumSet;
import java.util.regex.Pattern;
import com.google.common.base.Objects;
/**
* SSTables are made up of multiple components in separate files. Components are
* identified by a type and an id, but required unique components (such as the Data
* and Index files) may have implicit ids assigned to them.
*/
public class Component
{
public static final char separator = '-';
final static EnumSet TYPES = EnumSet.allOf(Type.class);
/**
* WARNING: Be careful while changing the names or string representation of the enum
* members. Streaming code depends on the names during streaming (Ref: CASSANDRA-14556).
*/
public enum Type
{
// the base data for an sstable: the remaining components can be regenerated
// based on the data component
DATA("Data.db"),
// index of the row keys with pointers to their positions in the data file
PRIMARY_INDEX("Index.db"),
// serialized bloom filter for the row keys in the sstable
FILTER("Filter.db"),
// file to hold information about uncompressed data length, chunk offsets etc.
COMPRESSION_INFO("CompressionInfo.db"),
// statistical metadata about the content of the sstable
STATS("Statistics.db"),
// holds CRC32 checksum of the data file
DIGEST("Digest.crc32"),
// holds the CRC32 for chunks in an a uncompressed file.
CRC("CRC.db"),
// holds SSTable Index Summary (sampling of Index component)
SUMMARY("Summary.db"),
// table of contents, stores the list of all components for the sstable
TOC("TOC.txt"),
// built-in secondary index (may be multiple per sstable)
SECONDARY_INDEX("SI_.*.db"),
// custom component, used by e.g. custom compaction strategy
CUSTOM(null);
final String repr;
Type(String repr)
{
this.repr = repr;
}
static Type fromRepresentation(String repr)
{
for (Type type : TYPES)
{
if (type.repr != null && Pattern.matches(type.repr, repr))
return type;
}
return CUSTOM;
}
}
// singleton components for types that don't need ids
public final static Component DATA = new Component(Type.DATA);
public final static Component PRIMARY_INDEX = new Component(Type.PRIMARY_INDEX);
public final static Component FILTER = new Component(Type.FILTER);
public final static Component COMPRESSION_INFO = new Component(Type.COMPRESSION_INFO);
public final static Component STATS = new Component(Type.STATS);
public final static Component DIGEST = new Component(Type.DIGEST);
public final static Component CRC = new Component(Type.CRC);
public final static Component SUMMARY = new Component(Type.SUMMARY);
public final static Component TOC = new Component(Type.TOC);
public final Type type;
public final String name;
public final int hashCode;
public Component(Type type)
{
this(type, type.repr);
assert type != Type.CUSTOM;
}
public Component(Type type, String name)
{
assert name != null : "Component name cannot be null";
this.type = type;
this.name = name;
this.hashCode = Objects.hashCode(type, name);
}
/**
* @return The unique (within an sstable) name for this component.
*/
public String name()
{
return name;
}
/**
* Parse the component part of a sstable filename into a {@code Component} object.
*
* @param name a string representing a sstable component.
* @return the component corresponding to {@code name}. Note that this always return a component as an unrecognized
* name is parsed into a CUSTOM component.
*/
public static Component parse(String name)
{
Type type = Type.fromRepresentation(name);
// Build (or retrieve singleton for) the component object
switch (type)
{
case DATA: return Component.DATA;
case PRIMARY_INDEX: return Component.PRIMARY_INDEX;
case FILTER: return Component.FILTER;
case COMPRESSION_INFO: return Component.COMPRESSION_INFO;
case STATS: return Component.STATS;
case DIGEST: return Component.DIGEST;
case CRC: return Component.CRC;
case SUMMARY: return Component.SUMMARY;
case TOC: return Component.TOC;
case SECONDARY_INDEX: return new Component(Type.SECONDARY_INDEX, name);
case CUSTOM: return new Component(Type.CUSTOM, name);
default: throw new AssertionError();
}
}
@Override
public String toString()
{
return this.name();
}
@Override
public boolean equals(Object o)
{
if (o == this)
return true;
if (!(o instanceof Component))
return false;
Component that = (Component)o;
return this.type == that.type && this.name.equals(that.name);
}
@Override
public int hashCode()
{
return hashCode;
}
}