wip: update config schema/examples for file_stores

Specifically, Config.Rdb_dest.file_stores. This code is untested but
compiles up to the point that something outside the config tries to
access the old files_path field.

issue #4

_env/config.example.json

@@ -32,9 +32,22 @@
   , "log_namespace" : "Source" }
 
 , "rdb_dest" : 
-  { // Absolute path to where the video and thumbnail files should be
-    // downloaded to within the Docker container. 
-    "files_path" : "/data/files"
+  { // Where to store files. Multiple locations can be specified to accomodate 
+    // spanning multiple volumes. The system distributes files based on order
+    // of location definition (first to last), available space, and max allowed
+    // usage. 
+    //
+    // Each location is defined by a "path" and "max_usage". Path should be
+    // absolute. Max usage follows the PHP-style suffixes of K, M, G, and T 
+    // (kilo-, mega-, giga-, and terabytes respectively). Case-insensitive. If
+    // no suffix is given, then the number will be taken as bytes. Setting 
+    // "max_usage" to `null` means use as much storage as is available.
+    // 
+    // See https://www.php.net/manual/en/faq.using.php#faq.using.shorthandbytes
+    "file_stores" : 
+    [ {"path": "/data/files/volume_a", "max_usage": "3G"}
+    , {"path": "/data/files/volume_b", "max_usage": "4G"}
+    , {"path": "/data/files/volume_c", "max_usage": null} ]
   , "log_level" : "info"
   , "log_namespace" : "Dest" }
 

app/bin/config/dune

@@ -1,3 +1,3 @@
 (library
  (name config)
- (libraries atdgen batteries))
+ (libraries atdgen batteries re re.perl))

app/bin/config/file_store.atd

@@ -0,0 +1,9 @@
+
+
+type max_usage = string option wrap 
+  <ocaml module="Rdb_dest.File_store.Max_usage">
+
+type t =
+  { path : string
+  ; max_usage : max_usage
+    <ocaml valid="Rdb_dest.File_store.Max_usage.validate"> }

app/bin/config/rdb_dest.atd

@@ -1,7 +1,8 @@
 
 type log_level <ocaml from="Log_level" t="t"> = abstract
+type file_store <ocaml from="File_store" t="t"> = abstract
 
 type t =
-  { files_path : string
+  { file_stores : file_store list
   ; log_level : log_level
   ; log_namespace : string }

app/bin/config/rdb_dest.ml

@@ -0,0 +1,60 @@
+
+
+module File_store = struct
+  module Max_usage = struct
+    type t = int option
+
+    let valid_pattern = "^([1-9]\\d*)([kmgt])?$" |> Re.Perl.compile_pat
+
+    let clean s = 
+      let separators = "[_, ]+" |> Re.Perl.compile_pat in
+      s 
+      |> Re.replace_string separators ~by:""
+      |> String.lowercase_ascii
+
+    let validate s =
+      match s with
+      | None -> true
+      | Some s -> 
+        s |> clean |> Re.execp valid_pattern
+
+    let wrap s = 
+      if not (validate s) then failwith "Invalid byte string."
+      else
+
+      match s with
+      | None -> 
+          None
+
+      | Some s -> begin
+        let matches = s |> clean |> Re.exec valid_pattern in
+        match matches |> Re.Group.all with 
+        | [| _; amount; "" |] -> 
+            Some (amount |> int_of_string)
+
+        | [| _; amount; suffix |] -> begin
+          let amount = amount |> int_of_string in
+          match suffix with 
+          | "k" -> Some (amount * 1024)
+          | "m" -> Some (amount * 1024 * 1024)
+          | "g" -> Some (amount * 1024 * 1024 * 1024)
+          | "t" -> Some (amount * 1024 * 1024 * 1024 * 1024)
+          | suffix -> 
+              Printf.sprintf "Unknown suffix '%s'" suffix 
+              |> failwith
+        end
+
+        | _ -> 
+          failwith "Unexpected array structure returned from Re.Group.all"
+      end
+
+    let unwrap t = 
+      match t with
+      | None ->
+        None
+
+      | Some b ->
+        Some (b |> string_of_int)
+
+  end
+end

docker-compose.dev.yml

@@ -11,8 +11,10 @@ services:
       # Required for building.
       - ./app:${APP_PREFIX_DIR}/app
 
-      # Required for running app
-      # - ./_env/config.json:${APP_PREFIX_DIR}/_env/config.json:ro
+      # File stores
+      - ./_data/app/store_a:${APP_PREFIX_DIR}/_data/store_a
+      - ./_data/app/store_b:${APP_PREFIX_DIR}/_data/store_b
+      - /Volumes/WILLY/OVPSync:${APP_PREFIX_DIR}/_data/store_c
 
   db: 
     ports: [ "3306:3306" ]

docker-compose.yml

@@ -16,7 +16,11 @@ services:
     volumes:
       - ./app/entrypoint.sh:${APP_PREFIX_DIR}/entrypoint.sh
       - ./_env/config.json:${APP_PREFIX_DIR}/_env/config.json:ro
-      - ./_data/app:${APP_PREFIX_DIR}/_data
+      # File store volumes should be defined in docker-compose.override.yml.
+      # They need to match up with the [rdb_dest.file_store] parameter in
+      # _env/config.json. Below values are just examples.
+      # - ./_data/app:${APP_PREFIX_DIR}/_data/volume_a
+      # - /Volumes/OVPSync_extra:${APP_PREFIX_DIR}/_data/volume_b
     depends_on:
       - db