Class ObjectDatabase

java.lang.Object
org.eclipse.jgit.lib.ObjectDatabase
Direct Known Subclasses:
DfsObjDatabase, FileObjectDatabase

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 Details

    • ObjectDatabase

      protected ObjectDatabase()
      Initialize a new database instance for access.
  • Method Details

    • 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

      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, e.g. Constants.OBJ_BLOB; 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