Increase performance of nested queries

With nested queries the code was switching on the option so that it could display a custom message. This was causing a massive increase in compilation time as the queries got deeper and wider. In my project we were seeing build times of about 6 minutes, after this change the build went down to about 10-11 seconds. Instead of displaying a custom message, the PPX will now just call out to `Js.Option.getExn`.
teamwalnut · Oct 16, 2019 · 2e17ed6 · 2e17ed6
1 parent c7fab6c
commit 2e17ed6
Showing 1 changed file with 79 additions and 93 deletions.
diff --git a/src/bucklescript/output_bucklescript_decoder.re b/src/bucklescript/output_bucklescript_decoder.re
@@ -202,22 +202,14 @@ and generate_nullable_decoder = (config, loc, inner) =>
 and generate_array_decoder = (config, loc, inner) =>
   [@metaloc loc]
   {
-    switch%expr (Js.Json.decodeArray(value)) {
-    | None =>
-      %e
-      make_error_raiser(
-        [%expr "Expected array, got " ++ Js.Json.stringify(value)],
-      )
-    | Some(value) =>
-      Js.Array.map(
-        value => {
-          let _ = ();
-          %e
-          generate_decoder(config, inner);
-        },
-        value,
-      )
-    };
+    %expr
+    value
+    |> Js.Json.decodeArray
+    |> Js.Option.getExn
+    |> Js.Array.map(value => {
+         %e
+         generate_decoder(config, inner)
+       });
   }
 and generate_custom_decoder = (config, loc, ident, inner) => {
   let fn_expr =
@@ -374,89 +366,83 @@ and generate_object_decoder = (config, loc, name, fields) => {
         make_obj_constructor_fn(i + 1, next),
       );
   [@metaloc loc]
-  (
-    switch%expr (Js.Json.decodeObject(value)) {
-    | None =>
-      %e
-      make_error_raiser([%expr "Object is not a value"])
-    | Some(value) =>
-      %e
-      Ast_helper.Exp.letmodule(
-        {txt: "GQL", loc: Location.none},
-        Ast_helper.Mod.structure([
-          Ast_helper.Str.primitive({
-            pval_name: {
-              txt: "make_obj",
-              loc: Location.none,
-            },
-            pval_type: make_obj_constructor_fn(0, fields),
-            pval_prim: [""],
-            pval_attributes: [
-              ({txt: "bs.obj", loc: Location.none}, PStr([])),
-            ],
-            pval_loc: Location.none,
-          }),
-        ]),
-        Ast_helper.Exp.apply(
-          Ast_helper.Exp.ident({
-            txt: Longident.parse("GQL.make_obj"),
+  {
+    let%expr value = value |> Js.Json.decodeObject |> Js.Option.getExn;
+
+    %e
+    Ast_helper.Exp.letmodule(
+      {txt: "GQL", loc: Location.none},
+      Ast_helper.Mod.structure([
+        Ast_helper.Str.primitive({
+          pval_name: {
+            txt: "make_obj",
             loc: Location.none,
-          }),
-          List.append(
-            fields
-            |> List.map(
-                 fun
-                 | Fr_named_field(key, _, inner) => (
+          },
+          pval_type: make_obj_constructor_fn(0, fields),
+          pval_prim: [""],
+          pval_attributes: [
+            ({txt: "bs.obj", loc: Location.none}, PStr([])),
+          ],
+          pval_loc: Location.none,
+        }),
+      ]),
+      Ast_helper.Exp.apply(
+        Ast_helper.Exp.ident({
+          txt: Longident.parse("GQL.make_obj"),
+          loc: Location.none,
+        }),
+        List.append(
+          fields
+          |> List.map(
+               fun
+               | Fr_named_field(key, _, inner) => (
+                   Labelled(key),
+                   switch%expr (Js.Dict.get(value, [%e const_str_expr(key)])) {
+                   | Some(value) =>
+                     %e
+                     generate_decoder(config, inner)
+                   | None =>
+                     if%e (can_be_absent_as_field(inner)) {
+                       %expr
+                       None;
+                     } else {
+                       make_error_raiser(
+                         [%expr
+                           "Field "
+                           ++ [%e const_str_expr(key)]
+                           ++ " on type "
+                           ++ [%e const_str_expr(name)]
+                           ++ " is missing"
+                         ],
+                       );
+                     }
+                   },
+                 )
+               | Fr_fragment_spread(key, loc, name) => {
+                   let loc = conv_loc(loc);
+                   (
                      Labelled(key),
-                     switch%expr (
-                       Js.Dict.get(value, [%e const_str_expr(key)])
-                     ) {
-                     | Some(value) =>
+                     {
+                       let%expr value = Js.Json.object_(value);
                        %e
-                       generate_decoder(config, inner)
-                     | None =>
-                       if%e (can_be_absent_as_field(inner)) {
-                         %expr
-                         None;
-                       } else {
-                         make_error_raiser(
-                           [%expr
-                             "Field "
-                             ++ [%e const_str_expr(key)]
-                             ++ " on type "
-                             ++ [%e const_str_expr(name)]
-                             ++ " is missing"
-                           ],
-                         );
-                       }
+                       generate_solo_fragment_spread(loc, name);
                      },
-                   )
-                 | Fr_fragment_spread(key, loc, name) => {
-                     let loc = conv_loc(loc);
-                     (
-                       Labelled(key),
-                       {
-                         let%expr value = Js.Json.object_(value);
-                         %e
-                         generate_solo_fragment_spread(loc, name);
-                       },
-                     );
-                   },
-               ),
-            [
-              (
-                Nolabel,
-                Ast_helper.Exp.construct(
-                  {txt: Longident.Lident("()"), loc: Location.none},
-                  None,
-                ),
+                   );
+                 },
+             ),
+          [
+            (
+              Nolabel,
+              Ast_helper.Exp.construct(
+                {txt: Longident.Lident("()"), loc: Location.none},
+                None,
               ),
-            ],
-          ),
+            ),
+          ],
         ),
-      )
-    }
-  );
+      ),
+    );
+  };
 }
 and generate_poly_variant_selection_set = (config, loc, name, fields) => {
   let rec generator_loop =