package irmin
Contents
is the underlying contents store.
include Indexable.S with type key = Val.contents_key
Read-only stores
Read-only stores are store where it is only possible to read existing values.
type key = Val.contents_key
The type for keys.
val mem : [> Perms.read ] t -> key -> bool Lwt.t
mem t k
is true iff k
is present in t
.
val find : [> Perms.read ] t -> key -> value option Lwt.t
find t k
is Some v
if k
is associated to v
in t
and None
is k
is not present in t
.
close t
frees up all the resources associated with t
. Any operations run on a closed handle will raise Closed
.
val add : [> Perms.write ] t -> value -> key Lwt.t
Write the contents of a value to the store, and obtain its key.
Same as add
but allows specifying the value's hash directly. The backend might choose to discard that hash and/or can be corrupt if the hash is not consistent.
val index : [> Perms.read ] t -> hash -> key option Lwt.t
Indexing maps the hash of a value to a corresponding key of that value in the store. For stores that are addressed by hashes directly, this is typically fun _t h -> Lwt.return (Key.of_hash h)
; for stores with more complex addressing schemes, index
may attempt a lookup operation in the store.
In general, indexing is best-effort and reveals no information about the membership of the value in the store. In particular:
index t hash = Some key
doesn't guaranteemem t key
: the value with hashhash
may still be absent from the store;
index t hash = None
doesn't guarantee that there is nokey
such thatmem t key
andKey.to_hash key = hash
: the value may still be present in the store under a key that is not indexed.
val batch :
Perms.read t ->
([ Perms.read | Perms.write ] t -> 'a Lwt.t) ->
'a Lwt.t
batch t f
applies the writes in f
in a separate batch. The exact guarantees depend on the implementation.
val merge : [> Perms.read_write ] t -> key option Merge.t
merge t
lifts the merge functions defined on contents values to contents key. The merge function will: (i) read the values associated with the given keys, (ii) use the merge function defined on values and (iii) write the resulting values into the store to get the resulting key. See val-S.merge
.
If any of these operations fail, return `Conflict
.
module Val : sig ... end