gitty_driver_bdb.pl -- Gitty BDB driver

This version of the driver uses library(bdb), the BerkeyDB database. This driver is particularly suited for large numbers of files. The store uses less disk space and starts much faster on large numbers of files.

The BDB database file contains two databases:

• heads maps a file name to the hash of the last object
• objects contains the object blobs.

 gitty_close(+Store) is det

Close the BDB environment associated with a gitty store

 gitty_file(+Store, ?File, ?Head) is nondet

True when File entry in the gitty store and Head is the HEAD revision.

 gitty_update_head(+Store, +Name, +OldCommit, +NewCommit) is det

Update the head of a gitty store for Name. OldCommit is the current head and NewCommit is the new head. If Name is created, and thus there is no head, OldCommit must be -.

This operation can fail because another writer has updated the head. This can both be in-process or another process.

Errors

- gitty(file_exists(Name) if the file already exists

- gitty(not_at_head(Name, OldCommit) if the head was moved by someone else.

 delete_head(+Store, +Name) is det

Delete the named head.

 set_head(+Store, +File, +Hash) is det

Set the head of the given File to Hash

 load_plain_commit(+Store, +Hash, -Meta:dict) is semidet

Load the commit data as a dict. Fails if Hash does not exist or is not a commit.

 store_object(+Store, +Hash, +Header:string, +Data:string) is det

Store the actual object. The store must associate Hash with the concatenation of Hdr and Data.

 load_object(+Store, +Hash, -Data, -Type, -Size) is det

Load an object given its Hash. Data holds the content as a string, Type is the object type (an atom) and Size is the size of the object in bytes.

 gitty_hash(+Store, ?Hash) is nondet

True when Hash is an object in the store.

 delete_object(+Store, +Hash)

Delete an existing object