Package aQute.libg.cafs

Class CAFS

java.lang.Object

aQute.libg.cafs.CAFS

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.lang.Iterable<SHA1>

public class CAFS
extends java.lang.Object
implements java.io.Closeable, java.lang.Iterable<SHA1>

CAFS implements a SHA-1 based file store. The basic idea is that every file in the universe has a unique SHA-1. Hard to believe but people smarter than me have come to that conclusion. This class maintains a compressed store of SHA-1 identified files. So if you have the SHA-1, you can get the contents. This makes it easy to store a SHA-1 instead of the whole file or maintain a naming scheme. An added advantage is that it is always easy to verify you get the right stuff. The SHA-1 Content Addressable File Store is the core underlying idea in Git.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static java.lang.String	ALGORITHM
(package private) static byte[]	CAFE
(package private) static byte[]	CAFS
(package private) java.nio.channels.FileChannel	channel
(package private) static int	HEADERLENGTH
(package private) java.io.File	home
(package private) Index	index
(package private) static java.lang.String	INDEXFILE
(package private) static int	KEYLENGTH
(package private) java.io.RandomAccessFile	store
(package private) static java.lang.String	STOREFILE

Constructor Summary

Constructors

Constructor	Description
CAFS(java.io.File home, boolean create)	Constructor for a Content Addressable File Store

Method Summary

Modifier and Type	Method	Description
(package private) short	checksum(int flags, int compressedLength, int totalLength, byte[] sha1)
void	close()
boolean	exists(byte[] sha1)
private java.io.InputStream	getSha1Stream(SHA1 sha1, byte[] buffer, int total)
boolean	isEmpty()
java.util.Iterator<SHA1>	iterator()
java.io.InputStream	read(SHA1 sha1)	Read the contents of a sha 1 key.
void	reindex()
private void	update(byte[] sha1, byte[] compressed, int totalLength)	Update a record in the store, assuming the store is at the right position.
private SHA1	verifyEntry(java.io.RandomAccessFile in)
private boolean	verifySignature(java.io.DataInput din, byte[] org)
SHA1	write(java.io.InputStream in)	Store an input stream in the CAFS while calculating and returning the SHA-1 code.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

CAFS

static final byte[] CAFS

CAFE

static final byte[] CAFE

INDEXFILE

static final java.lang.String INDEXFILE

See Also:

Constant Field Values

STOREFILE

static final java.lang.String STOREFILE

See Also:

Constant Field Values

ALGORITHM

static final java.lang.String ALGORITHM

See Also:

Constant Field Values

KEYLENGTH

static final int KEYLENGTH

See Also:

Constant Field Values

HEADERLENGTH

static final int HEADERLENGTH

See Also:

Constant Field Values

home

final java.io.File home

index

Index index

store

java.io.RandomAccessFile store

channel

java.nio.channels.FileChannel channel

Constructor Detail

CAFS

public CAFS(java.io.File home,
            boolean create)
     throws java.lang.Exception

Constructor for a Content Addressable File Store

Parameters:

home -

create -

Throws:

java.lang.Exception

Method Detail

write

public SHA1 write(java.io.InputStream in)
           throws java.lang.Exception

Store an input stream in the CAFS while calculating and returning the SHA-1 code.

Parameters:

in - The input stream to store.

Returns:

The SHA-1 code.

Throws:

java.lang.Exception - if anything goes wrong

read

public java.io.InputStream read(SHA1 sha1)
                         throws java.lang.Exception

Read the contents of a sha 1 key.

Parameters:

sha1 - The key

Returns:

An Input Stream on the content or null of key not found

Throws:

java.lang.Exception

exists

public boolean exists(byte[] sha1)
               throws java.lang.Exception

Throws:

java.lang.Exception

reindex

public void reindex()
             throws java.lang.Exception

Throws:

java.lang.Exception

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException

verifyEntry

private SHA1 verifyEntry(java.io.RandomAccessFile in)
                  throws java.io.IOException,
                         java.security.NoSuchAlgorithmException

Throws:

java.io.IOException

java.security.NoSuchAlgorithmException

verifySignature

private boolean verifySignature(java.io.DataInput din,
                                byte[] org)
                         throws java.io.IOException

Throws:

java.io.IOException

getSha1Stream

private java.io.InputStream getSha1Stream(SHA1 sha1,
                                          byte[] buffer,
                                          int total)
                                   throws java.security.NoSuchAlgorithmException

Throws:

java.security.NoSuchAlgorithmException

update

private void update(byte[] sha1,
                    byte[] compressed,
                    int totalLength)
             throws java.io.IOException

Update a record in the store, assuming the store is at the right position.

Parameters:

sha1 - The checksum

compressed - The compressed length

totalLength - The uncompressed length

Throws:

java.io.IOException - The exception

checksum

short checksum(int flags,
               int compressedLength,
               int totalLength,
               byte[] sha1)

iterator

public java.util.Iterator<SHA1> iterator()

Specified by:

iterator in interface java.lang.Iterable<SHA1>

isEmpty

public boolean isEmpty()
                throws java.io.IOException

Throws:

java.io.IOException