perf: more fast paths in webidl dict converter

denoland · Apr 19, 2021 · 1209b5e · aapoalas · Apr 20, 2021 · 1209b5e
1 parent 4cb808c
commit 1209b5e
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Showing 2 changed files with 60 additions and 11 deletions.
diff --git a/op_crates/webgpu/02_idl_types.js b/op_crates/webgpu/02_idl_types.js
@@ -135,15 +135,19 @@
       converter: webidl.createSequenceConverter(
         webidl.converters["GPUFeatureName"],
       ),
-      defaultValue: [],
+      get defaultValue() {
+        return [];
+      },
     },
     {
       key: "nonGuaranteedLimits",
       converter: webidl.createRecordConverter(
         webidl.converters["DOMString"],
         webidl.converters["GPUSize32"],
       ),
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
   ];
   webidl.converters["GPUDeviceDescriptor"] = webidl.createDictionaryConverter(
@@ -1046,7 +1050,9 @@
           webidl.converters["GPUVertexBufferLayout"],
         ),
       ),
-      defaultValue: [],
+      get defaultValue() {
+        return [];
+      },
     },
   ];
   webidl.converters["GPUVertexState"] = webidl.createDictionaryConverter(
@@ -1187,12 +1193,16 @@
     {
       key: "stencilFront",
       converter: webidl.converters["GPUStencilFaceState"],
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
     {
       key: "stencilBack",
       converter: webidl.converters["GPUStencilFaceState"],
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
     {
       key: "stencilReadMask",
@@ -1379,7 +1389,9 @@
     {
       key: "primitive",
       converter: webidl.converters["GPUPrimitiveState"],
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
     {
       key: "depthStencil",
@@ -1388,7 +1400,9 @@
     {
       key: "multisample",
       converter: webidl.converters["GPUMultisampleState"],
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
     { key: "fragment", converter: webidl.converters["GPUFragmentState"] },
   ];
@@ -1530,7 +1544,9 @@
     {
       key: "origin",
       converter: webidl.converters["GPUOrigin3D"],
-      defaultValue: {},
+      get defaultValue() {
+        return {};
+      },
     },
     {
       key: "aspect",
@@ -1793,7 +1809,9 @@
       converter: webidl.createSequenceConverter(
         webidl.converters["GPUPipelineStatisticName"],
       ),
-      defaultValue: [],
+      get defaultValue() {
+        return [];
+      },
     },
   ];
   webidl.converters["GPUQuerySetDescriptor"] = webidl.createDictionaryConverter(

diff --git a/op_crates/webidl/00_webidl.js b/op_crates/webidl/00_webidl.js
@@ -580,10 +580,19 @@
     }
   }
 
+  function isEmptyObject(V) {
+    for (const _ in V) return false;
+    return true;
+  }
+
   function createDictionaryConverter(name, ...dictionaries) {
+    let hasRequiredKey = false;
     const allMembers = [];
     for (const members of dictionaries) {
       for (const member of members) {
+        if (member.required) {
+          hasRequiredKey = true;
+        }
         allMembers.push(member);
       }
     }
@@ -597,8 +606,23 @@
     const defaultValues = {};
     for (const member of allMembers) {
       if ("defaultValue" in member) {
-        const idlMemberValue = member.defaultValue;
-        defaultValues[member.key] = idlMemberValue;
+        let idlMemberValue = member.defaultValue;
+        let imvType = typeof idlMemberValue;
+        // Copy by value types can be directly assigned, copy by reference types
+        // need to be re-created for each allocation.
+        if (
+          imvType === "number" || imvType === "boolean" ||
+          imvType === "string" || imvType === "bigint" ||
+          imvType === "undefined"
+        ) {
+          defaultValues[member.key] = idlMemberValue;
+        } else {
+          Object.defineProperty(defaultValues, member.key, {
+            get() {
+              return member.defaultValue;
+            },
+          });
+        }
       }
     }
 
@@ -620,6 +644,13 @@
 
       const idlDict = Object.assign({}, defaultValues);
 
+      // NOTE: fast path Null and Undefined and empty objects.
+      if (
+        (V === undefined || V === null || isEmptyObject(V)) && !hasRequiredKey
+      ) {
+        return idlDict;
+      }
+
       for (const member of allMembers) {
         const key = member.key;