-
irmin-mirage-git
-
Library
Module
Module type
Parameter
Class
Class type
Functor to create a MirageOS' KV_RW store from a Git repository.
Parameters
module G : Irmin_git.G
module C : Mirage_clock.PCLOCK
Signature
include Mirage_kv.RW
Read-write Stores
There is a trade-off between durability and performance. If you want performance, use the batch
operation with a chain of sets and removes. They will be applied on the underlying storage layer all at once. Otherwise set
and remove
will cause a flush in the underlying storage layer every time, which could degrade performance.
include Mirage_kv.RO
Read-only key-value stores
The type for errors.
Disconnect from the key-value store. While this might take some time to complete, it can never result in an error.
type key = Mirage_kv.Key.t
The type for keys.
exists t k
is Some `Value
if k
is bound to a value in t
, Some `Dictionary
if k
is a prefix of a valid key in t
and None
if no key with that prefix exists in t
.
exists
answers two questions: does the key exist and is it referring to a value or a dictionary.
An error occurs when the underlying storage layer fails.
get t k
is the value bound to k
in t
.
The result is Error (`Value_expected k)
if k
refers to a dictionary in t
.
list t k
is the list of entries and their types in the dictionary referenced by k
in t
.
The result is Error (`Dictionary_expected k)
if k
refers to a value in t
.
last_modified t k
is the last time the value bound to k
in t
has been modified.
The modification time (d, ps)
is a span for the signed POSIX picosecond span d
* 86_400e12 + ps
. d
is a signed number of POSIX days and ps
a number of picoseconds in the range [0
;86_399_999_999_999_999L
].
When the value bound to k
is a dictionary, the modification time is the latest modification of all entries in that dictionary. This behaviour is only one level deep and not recursive.
The type for write errors.
val pp_write_error : write_error Fmt.t
The pretty-printer for pp_write_error
.
val set : t -> key -> string -> (unit, write_error) result Lwt.t
set t k v
replaces the binding k -> v
in t
.
Durability is guaranteed unless set
is run inside an enclosing batch
operation, where durability will be guaranteed at the end of the batch.
val remove : t -> key -> (unit, write_error) result Lwt.t
remove t k
removes any binding of k
in t
. If k
was bound to a dictionary, the full dictionary will be removed.
Durability is guaranteed unless remove
is run inside an enclosing batch
operation, where durability will be guaranteed at the end of the batch.
batch t f
run f
in batch. Ensure the durability of operations.
Since a batch is applied at once, the readings inside a batch will return the state before the entire batch. Concurrent operations will not affect other ones executed during the batch.
Batch applications can fail to apply if other operations are happening concurrently. In case of failure, f
will run again with the most recent version of t
. The result is Error `Too_many_retries
if f
is run for more then retries
attemps (default is 13
).
val connect :
?depth:int ->
?branch:string ->
?root:key ->
?ctx:Mimic.ctx ->
?headers:Cohttp.Header.t ->
?author:(unit -> string) ->
?msg:([ `Set of key | `Remove of key | `Batch ] -> string) ->
G.t ->
string ->
t Lwt.t
connect ?depth ?branch ?path ?author ?msg g c uri
clones the given uri
into g
repository, using the given branch
, depth
and '/'
-separated sub-path
. By default, branch
is master, depth
is 1
and path
is empty, ie. reads will be relative to the root of the repository. author
, msg
and c
are used to create new commit info values on every update. By defaut author
is fun () -> "irmin" <irmin@mirage.io>
and msg
returns basic information about the kind of operations performed.