66 lines
2.2 KiB
Markdown
66 lines
2.2 KiB
Markdown
# Git-kv, a simple Key-Value store synchronized with a Git repository
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This library is a simple implementation of a Git repository that can be read
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and/or modified. It offers two ways to create such a local repository:
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1) The local repository can be created in a serialized state
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2) The local repository can be created from a remote repository
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The first method has the advantage of not requiring an internet connection. The
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serialized state can be created with the `mgit` tool:
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```sh
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$ mgit https://github.com/mirage/mirage <<EOF
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> save db.pack
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> quit
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$ ls db.pack
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db.pack
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```
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The disadvantage is that the serialized state may be out of sync with the state
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of the remote repository. In this case, the user has access to the `pull`
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function, which allows the internet state of the local repository to be
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re-synchronised with the remote repository.
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```ocaml
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let contents_of_file filename =
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let ic = open_in filename in
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let ln = in_channel_length ic in
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let rs = Bytes.create ln in
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really_input ic rs 0 ln ;
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Bytes.unsafe_to_string rs
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let _ =
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Git_kv.of_octets ctx
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~remote:"git@github.com:mirage/mirage.git"
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(contents_of_file "db.pack") >>= fun t ->
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Git_kv.pull t >>= fun diff ->
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...
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```
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The second method initiates a connection to the remote repository in order to
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download its state and reproduce a synchronised internal state. The type of
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connections supported are described in the given `ctx`. We recommend the
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tutorial about [Mimic][mimic] to understand its use.
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```sh
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let _ =
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Git_kv.connect ctx "git@github.com:mirage/mirage.git" >>= fun t ->
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...
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```
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The user can manipulate the repository as an [RW][mirage-kv-rw] repository. Any
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change to the repository requires a new commit. These changes can be sent to
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the remote repository by deriving manipulation functions with the `and_push`
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suffix:
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```ocaml
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module Store = Git_kv.Make (Pclock)
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let new_file_locally t =
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Store.set t Mirage_kv.Key.(empty / "foo") "foo" >>= fun () ->
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...
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let new_file_locally_and_remotely t =
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Git_kv.pull t >>= fun _diff ->
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Store.set_and_push t Mirage_kv.Key.(empty / "foo") "foo" >>= fun () ->
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...
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```
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[mimic]: https://dinosaure.github.io/mimic/mimic/index.html
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[mirage-kv-rw]: https://github.com/mirage/mirage-kv
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