diff options
Diffstat (limited to 'lib/disk.ml')
| -rw-r--r-- | lib/disk.ml | 202 |
1 files changed, 0 insertions, 202 deletions
diff --git a/lib/disk.ml b/lib/disk.ml deleted file mode 100644 index aa971dd..0000000 --- a/lib/disk.ml +++ /dev/null @@ -1,202 +0,0 @@ -module type Configuration = sig - val base_dir: string - val storage: string - val transactions: string - val assure: unit -> unit -end - -module DevelopmentConfiguration: Configuration = struct - let base_dir = "/tmp/relational-engine/" - let storage = base_dir ^ "storage/" - let transactions = base_dir ^ "transactions/" - let assure () = - if Sys.file_exists base_dir - then Sys.remove base_dir; - Sys.mkdir base_dir 0o700; - Sys.mkdir storage 0o700; - Sys.mkdir transactions 0o700; -end - -module type FileSystem = sig - type target = - | Storage - | Transaction - val append: target -> bytes -> (int*int64, string) result -end - -module FileSystem (C: Configuration): FileSystem = struct - type target = - | Storage - | Transaction - let target_to_string = function - | Storage -> "storage" - | Transaction -> "transaction" - - (** [append target content] writes content to file in append only format, returning [content_length * offset_written] *) - let append target content = - let register channel = - let offset_written = Out_channel.length channel in - Out_channel.seek channel offset_written; - Out_channel.output_bytes channel content; - Out_channel.flush channel; - Out_channel.close channel; - Ok (Bytes.length content, offset_written) - in - try Out_channel.with_open_bin (target_to_string target) register - with _ -> Error (Printf.sprintf "Error on appending to target '%s'" (target_to_string target)) -end - -module Executor = struct - module StringMap = Map.Make(String) - module FS = FileSystem(DevelopmentConfiguration) - module Location = struct - type t = - { offset: int64; - size: int; - hash: string } - end - module Hashes = struct - type t = { values: string list; - hash: string } - type history = t list - end - type commit = { state: string; files: Hashes.history StringMap.t } - type history = commit list - type locations = Location.t StringMap.t - let _EMPTY_SHA_HASH_ = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" - - (** Initializes the virtual file or opens it. *) - let init_file (files: Hashes.history StringMap.t) filename: Hashes.history StringMap.t = - match StringMap.find_opt filename files with - | None -> - let default: Hashes.t = { values = []; hash = _EMPTY_SHA_HASH_} in - let new_files = StringMap.add filename [default] files - in new_files - | Some _ -> - files - - let compose_new_state files = - let history = StringMap.to_list files in - let all_hashes = List.concat - @@ List.map (fun (_, (history:Hashes.history)) -> - List.map (fun ({hash; _}: Hashes.t) -> hash) history) history - in Interop.Merkle.merkle_generate_root all_hashes - - let write ({files;_} as commit: commit) (locations: locations) ~filename ?hash_to_replace (content: Bytes.t) = - let files = init_file files filename in - let computed_hash: string = Interop.Sha256.compute_hash content in - match StringMap.find_opt computed_hash locations with - | None -> - begin match hash_to_replace with - | None -> - begin - (* This instead should store a list of list to keep the history *) - let files = - StringMap.update - filename - (function - | Some (file_hashes: Hashes.history) -> - let {values; _}: Hashes.t = List.hd file_hashes in - let new_state = Interop.Merkle.merkle_generate_root (computed_hash::values) in - Some ({values = computed_hash::values; hash = new_state}::file_hashes) - | None -> Some [{values = [computed_hash]; hash = computed_hash}]) - files - in - let open Extensions.Result in - let+ (size, offset) = FS.append Storage content in - let locations = StringMap.add computed_hash ({size; offset; hash = computed_hash}: Location.t) locations in - let commit = {state = compose_new_state files; files} - in Ok (commit, locations) - end - | Some hash_to_replace -> - let update_fun = function - | Some (file_hashes: Hashes.history) -> - let {values; _}: Hashes.t = List.hd file_hashes in - let updated_entry = List.map (fun hash -> if hash = hash_to_replace then computed_hash else hash) values in - let new_entry: Hashes.t = {values = updated_entry; hash = Interop.Merkle.merkle_generate_root updated_entry} in - Some (new_entry::file_hashes) - | None -> Some [{values = [computed_hash]; hash = computed_hash}] - in - let files = StringMap.update filename update_fun files in - let open Extensions.Result in - let+ (size, offset) = FS.append Storage content in - let locations = StringMap.add computed_hash ({size; offset; hash = computed_hash}: Location.t) locations in - let commit = {state = compose_new_state files; files} - in Ok (commit, locations) - end - | Some _ -> - begin match hash_to_replace with - | Some hash_to_replace -> - let update_fun = function - | Some (file_hashes: Hashes.history) -> - let {values; _}: Hashes.t = List.hd file_hashes in - let updated_entry = List.map (fun hash -> if hash = hash_to_replace then computed_hash else hash) values in - let new_entry: Hashes.t = {values = updated_entry; hash = Interop.Merkle.merkle_generate_root updated_entry} in - Some (new_entry::file_hashes) - | None -> Some [{values = [computed_hash]; hash = computed_hash}] - in - let files = StringMap.update filename update_fun files in - let commit = {state = compose_new_state files; files} - in Ok (commit, locations) - | None -> - Ok (commit, locations) - end -end - -module Startup = struct - (* TODO: Weird behavior with a system error on the dir /tmp/relational-engine opening. Disabling for now *) - (* let () = DevelopmentConfiguration.assure() *) -end - -module Command = struct - module FS = FileSystem(DevelopmentConfiguration) - open Data_encoding - type command_kind = - | OPEN - | WRITE - | READ - let command_kind_encoding = - union [ - case ~title:"open" (Tag 0) - Data_encoding.empty - (function OPEN -> Some () | _ -> None) - (function () -> OPEN); - case ~title:"write" (Tag 1) - Data_encoding.empty - (function WRITE -> Some () | _ -> None) - (function () -> WRITE); - case ~title:"read" (Tag 2) - Data_encoding.empty - (function READ -> Some () | _ -> None) - (function () -> READ); - ] - type t = - { kind: command_kind; - timestamp: float; - hash: string; - filename: string; - (* branch must be added here later *) - content: string } - let command_encoding = - conv - (fun {kind; timestamp; hash; filename; content} -> (kind, timestamp, hash, filename, content)) - (fun (kind, timestamp, hash, filename, content) -> {kind; timestamp; hash; filename; content}) - Data_encoding.(tup5 command_kind_encoding float string string string) - - let parse_command ~data = - let contract_encoding = Data_encoding.(tup4 command_kind_encoding string string string) in - match Binary.of_bytes_opt contract_encoding data with - | Some (kind, hash, filename, content) -> Ok {kind; timestamp = Unix.time(); hash; filename; content} - | None -> Error "Failed to parse command" - - (** TODO: This does not write atomically. If the system crashes while it attempts to write, it will corrupt. - Solve this with a temporary file and move later. *) - let commit - (* (_files: Filesystem.files) (_locations: Filesystem.locations) *) - command = - let open Extensions.Result in - let+ serialized_command = - Result.map_error (fun _ -> "Failed to serialize command to binary format.") - @@ Binary.to_bytes command_encoding command in - FS.append FS.Transaction serialized_command -end |