gitty_driver_files.pl -- Gitty plain files driver
This version of the driver uses plain files to store the gitty data. It
consists of a nested directory structure with files named after the
hash. Objects and hash computation is the same as for git. The heads
(files) are computed on startup by scanning all objects. There is a file
ref/head that is updated if a head is updated. Other clients can watch
this file and update their notion of the head. This implies that the
store can handle multiple clients that can access a shared file system,
optionally shared using NFS from different machines.
The store is simple and robust. The main disadvantages are long startup times as the store holds more objects and relatively high disk usage due to rounding the small objects to disk allocation units.
- gitty_close(+Store) is det
- Close resources associated with a store.
- gitty_file(+Store, ?File, ?Ext, ?Head) is nondet
- True when File entry in the gitty store and Head is the HEAD revision.
- load_plain_commit(+Store, +Hash, -Meta:dict) is semidet
- Load the commit data as a dict. Loaded commits are cached in commit/3. Note that only adding a fact to the cache is synchronized. This means that during a race situation we may load the same object multiple times from disk, but this is harmless while a lock around the whole predicate serializes loading different objects, which is not needed.
- 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 the given object.
- load_object_header(+Store, +Hash, -Type, -Size) is det[private]
- Load the header of an object
- gitty_rescan(?Store) is det
- Update our view of the shared storage for all stores matching Store.
- gitty_scan(+Store) is det[private]
- Scan gitty store for files (entries), filling head/3. This is
performed lazily at first access to the store.
@tdb Possibly we need to maintain a cached version of this index to avoid having to open all objects of the gitty store.
- read_heads_from_objects(+Store) is det[private]
- Establish the
head(Store,File,Ext,Hash)relation by reading all objects and adding a fact for the most recent commit. - gitty_scan_latest(+Store)[private]
- Scans the gitty store, extracting the latest version of each named entry.
- gitty_hash(+Store, ?Hash) is nondet
- True when Hash is an object in the store.
- delete_object(+Store, +Hash)
- Delete an existing object
- gitty_object_file(+Store, +Hash, -Path) is det
- True when Path is the file at which the object with Hash is stored.
- 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.
- remote_updates(+Store)[private]
- Watch for remote updates to the store. We only do this if we did not do so the last second.
- remote_updates(+Store, -List) is det[private]
- Find updates from other gitties on the same filesystem. Note that we have to push/pop the input context to avoid creating a notion of an input context which possibly relate messages incorrectly to the sync file.
- restore_heads_from_remote(Store)[private]
- Restore the known heads by reading the remote sync file.
- delete_head(+Store, +Head) is det
- Delete Head from Store. Used by gitty_fsck/1 to remove heads that have no commits. Should we forward this to remotes, or should they do their own thing?
- set_head(+Store, +File, +Hash) is det
- Set the head of the given File to Hash
- repack_objects(+Store, +Options) is det[multifile]
- Repack objects of Store for reduced disk usage and enhanced
performance. By default this picks up all file objects of the store
and all existing small pack files. Options:
- small_pack(+Bytes)
- Consider all packs with less than Bytes as small and repack them. Default 10Mb
- min_files(+Count)
- Do not repack if there are less than Count new files. Default 1,000.
- pack_objects(+Store, +Objects, +Packs, +PackDir, -PackFile, +Options) is det
- Pack the given objects and pack files into a new pack.
- add_file(+Out, +Store, +Object) is det[private]
- Add Object from Store to the pack stream Out.
- gitty_fsck(+Store) is det
- Validate all packs associated with Store
- fsck_pack(+File) is det
- Validate the integrity of the pack file File.
- gitty_attach_packs(+Store) is det[private]
- Attach all packs for Store
- attach_pack(+Store, +PackFile)
- Load the index of Pack into memory.
- detach_pack(+Store, +Pack) is det[private]
- Remove a pack file from the memory index.
- load_object_from_pack(+Hash, -Data, -Type, -Size) is semidet
- True when Hash is in a pack and can be loaded.
- unpack_packs(+Store) is det[multifile]
- Unpack all packs.
- unpack_pack(+Store, +Pack) is det
- Turn a pack back into a plain object files
- remove_objects_after_pack(+Store, +Objects, +Options) is det[private]
- Remove the indicated (file) objects from Store.
- remove_repacked_packs(+Store, +Packs, +Options)[private]
- Remove packs that have been repacked.
- prune_empty_directories(+Dir) is det[private]
- Prune directories that are empty below Dir. Dir itself is not removed, even if it is empty.