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|
module Error = struct
open Concepts.Condition
let invalid_root head =
condition "invalid-root" "The root hash for the database state is missing from the backend. Either your storage is corrupted, or this is a bug in RNT!"
("hash" |=| (Concepts.Value.String (Concepts.Hash.to_hum_string head)))
end
module Make (S : Abstract.Storage.STORAGE) = struct
module M = Merkle.Make (S) (Merkle.StringKey)
module SI = Storage.Make (S)
module B = Branch.Make (S)
let root_for tx label =
let open Utilities.Result in
let* label = S.get tx (S.Label label) in
let label = Option.map Concepts.Hash.hash_of_blob label in
Ok label
let persist_root tx label addr =
let data = Concepts.Hash.blob_of_hash addr in
S.put tx (S.Label label) data
class manager storage label head = object (self)
inherit Lifecycle.null
inherit Identity.of_id
val storage : S.connection = storage
val label : string = label
val head : M.node Atomic.t = Atomic.make head
method fetch branch_name =
SI.with_transaction storage (fun tx ->
let head = Atomic.get head in
M.lookup tx branch_name head)
method protocols = Protocols.[Directory.make self; Registry.make self]
method list = SI.with_transaction storage (fun tx -> Atomic.get head |> M.keys tx)
method find key =
let open Utilities.Result in
SI.with_transaction storage (fun tx ->
let* head = Atomic.get head |> M.lookup tx key in
match head with
| None -> Ok None
| Some head -> B.load tx storage head |> Result.map Option.some)
method update key reference value =
let open Utilities.Result in
SI.with_transaction storage (fun tx ->
match
Utilities.Atomic.mswap head (fun head ->
let* branch = M.lookup tx key head |> Result.map_error (fun e -> Some e) in
(* FIXME: we should have an addressable protocol rather than assuming the hash is the content store address *)
let reference = Option.map Protocols.Handle.hash reference in
let value = Option.map Protocols.Handle.hash value in
if branch = reference then
begin
let* new_head = match value with
| Some value -> M.insert tx key value head
| None -> M.remove tx key head
in
let* _ = persist_root tx label (M.hash_of new_head) in
Ok new_head
end
|> Result.map_error (fun e -> Some e)
else
Error None)
with
| Ok _ -> Ok true
| Error None -> Ok false
| Error (Some e) -> Error e)
end
let make storage label =
let open Utilities.Result in
SI.with_transaction storage (fun tx ->
let* addr = root_for tx label in
match addr with
| None ->
Ok (new manager storage label M.empty |> Protocols.Handle.make)
| Some addr ->
let* head = M.find tx addr in
let* head = Option.to_result ~none:(Error.invalid_root addr) head in
Ok (new manager storage label head |> Protocols.Handle.make))
end
|
