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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 data =
Option.map
(fun blob ->
Concepts.Blob.bytes_of_blob blob |> Bytes.to_string |> Concepts.Hash.of_raw_string )
label
in
Ok data
let persist_root tx label addr =
let data = Concepts.Hash.blob_of_hash addr in
S.put tx (S.Label label) data
class manager ?root storage label head =
object (self)
inherit Lifecycle.null
inherit Identity.of_id
method to_string = "branch-manager"
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 ?root tx storage head |> Result.map Option.some )
(* a head moves only to a valid state, judged before the head is
taken, since judging may run stored programs that read storage *)
method update key reference value =
let open Utilities.Result in
let open Protocols in
let* () = Option.fold ~none:(Ok ()) ~some:Denial.check value in
SI.with_transaction storage (fun tx ->
match
Utilities.Atomic.mswap head (fun head ->
let address_of h =
let* i = Handle.require Addressable.from h in
Ok (Addressable.address i)
in
let* branch = M.lookup tx key head |> Result.map_error (fun e -> Some e) in
let* reference =
Option.map address_of reference
|> Utilities.Option.sequence
|> Result.map_error (fun e -> Some e)
in
let* value =
Option.map address_of value
|> Utilities.Option.sequence
|> Result.map_error (fun e -> Some e)
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 ?root 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 ?root 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 ?root storage label head |> Protocols.Handle.make) )
end
|
