org.eclipse.jgit.lib
Class ObjectDatabase

java.lang.Object
  org.eclipse.jgit.lib.ObjectDatabase

Direct Known Subclasses:

DfsObjDatabase, ObjectDirectory

public abstract class ObjectDatabase
extends Object

Abstraction of arbitrary object storage.

An object database stores one or more Git objects, indexed by their unique ObjectId.

Constructor Summary

protected

ObjectDatabase() Initialize a new database instance for access.

Method Summary

abstract void	close() Close any resources held by this database.
void	create() Initialize a new object database at this location.
boolean	exists() Does this database exist yet?
boolean	has(AnyObjectId objectId) Does the requested object exist in this database?
ObjectDatabase	newCachedDatabase() Create a new cached database instance over this database.
abstract ObjectInserter	newInserter() Create a new ObjectInserter to insert new objects.
abstract ObjectReader	newReader() Create a new ObjectReader to read existing objects.
ObjectLoader	open(AnyObjectId objectId) Open an object from this database.
ObjectLoader	open(AnyObjectId objectId, int typeHint) Open an object from this database.

Methods inherited from class java.lang.Object

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

Constructor Detail

ObjectDatabase

protected ObjectDatabase()

Initialize a new database instance for access.

Method Detail

exists

public boolean exists()

Does this database exist yet?

Returns:

true if this database is already created; false if the caller should invoke create() to create this database location.

create

public void create()
            throws IOException

Initialize a new object database at this location.

Throws:

IOException - the database could not be created.

newInserter

public abstract ObjectInserter newInserter()

Create a new ObjectInserter to insert new objects.

The returned inserter is not itself thread-safe, but multiple concurrent inserter instances created from the same ObjectDatabase must be thread-safe.

Returns:

writer the caller can use to create objects in this database.

newReader

public abstract ObjectReader newReader()

Create a new ObjectReader to read existing objects.

The returned reader is not itself thread-safe, but multiple concurrent reader instances created from the same ObjectDatabase must be thread-safe.

Returns:

reader the caller can use to load objects from this database.

close

public abstract void close()

Close any resources held by this database.

has

public boolean has(AnyObjectId objectId)
            throws IOException

Does the requested object exist in this database?

This is a one-shot call interface which may be faster than allocating a newReader() to perform the lookup.

Parameters:

objectId - identity of the object to test for existence of.

Returns:

true if the specified object is stored in this database.

Throws:

IOException - the object store cannot be accessed.

open

public ObjectLoader open(AnyObjectId objectId)
                  throws IOException

Open an object from this database.

This is a one-shot call interface which may be faster than allocating a newReader() to perform the lookup.

Parameters:

objectId - identity of the object to open.

Returns:

a ObjectLoader for accessing the object.

Throws:

MissingObjectException - the object does not exist.

IOException - the object store cannot be accessed.

open

public ObjectLoader open(AnyObjectId objectId,
                         int typeHint)
                  throws MissingObjectException,
                         IncorrectObjectTypeException,
                         IOException

Open an object from this database.

This is a one-shot call interface which may be faster than allocating a newReader() to perform the lookup.

Parameters:

objectId - identity of the object to open.

typeHint - hint about the type of object being requested; ObjectReader.OBJ_ANY if the object type is not known, or does not matter to the caller.

Returns:

a ObjectLoader for accessing the object.

Throws:

MissingObjectException - the object does not exist.

IncorrectObjectTypeException - typeHint was not OBJ_ANY, and the object's actual type does not match typeHint.

IOException - the object store cannot be accessed.

newCachedDatabase

public ObjectDatabase newCachedDatabase()

Create a new cached database instance over this database. This instance might optimize queries by caching some information about database. So some modifications done after instance creation might fail to be noticed.

Returns:

new cached database instance