node-api: optimize napi_set_property for perf

PR-URL: #50282 Reviewed-By: Vladimir Morozov <vmorozov@microsoft.com> Reviewed-By: Michael Dawson <midawson@redhat.com> Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
nodejs · Feb 15, 2024 · 66c11f3 · 66c11f3
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diff --git a/doc/api/n-api.md b/doc/api/n-api.md
@@ -3085,6 +3085,50 @@ The native string is copied.
 The JavaScript `string` type is described in
 [Section 6.1.4][] of the ECMAScript Language Specification.
 
+#### `node_api_create_property_key_utf16`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+```c
+napi_status NAPI_CDECL node_api_create_property_key_utf16(napi_env env,
+                                                          const char16_t* str,
+                                                          size_t length,
+                                                          napi_value* result);
+```
+
+* `[in] env`: The environment that the API is invoked under.
+* `[in] str`: Character buffer representing a UTF16-LE-encoded string.
+* `[in] length`: The length of the string in two-byte code units, or
+  `NAPI_AUTO_LENGTH` if it is null-terminated.
+* `[out] result`: A `napi_value` representing an optimized JavaScript `string`
+  to be used as a property key for objects.
+
+Returns `napi_ok` if the API succeeded.
+
+This API creates an optimized JavaScript `string` value from
+a UTF16-LE-encoded C string to be used as a property key for objects.
+The native string is copied.
+
+Many JavaScript engines including V8 use internalized strings as keys
+to set and get property values. They typically use a hash table to create
+and lookup such strings. While it adds some cost per key creation, it improves
+the performance after that by enabling comparison of string pointers instead
+of the whole strings.
+
+If a new JavaScript string is intended to be used as a property key, then for
+some JavaScript engines it will be more efficient to use
+the `node_api_create_property_key_utf16` function.
+Otherwise, use the `napi_create_string_utf16` or
+`node_api_create_external_string_utf16` functions as there may be additional
+overhead in creating/storing strings with this method.
+
+The JavaScript `string` type is described in
+[Section 6.1.4][] of the ECMAScript Language Specification.
+
 ### Functions to convert from Node-API to C types
 
 #### `napi_get_array_length`

diff --git a/src/js_native_api.h b/src/js_native_api.h
@@ -111,6 +111,13 @@ node_api_create_external_string_utf16(napi_env env,
                                       napi_value* result,
                                       bool* copied);
 #endif  // NAPI_EXPERIMENTAL
+
+#ifdef NAPI_EXPERIMENTAL
+#define NODE_API_EXPERIMENTAL_HAS_PROPERTY_KEYS
+NAPI_EXTERN napi_status NAPI_CDECL node_api_create_property_key_utf16(
+    napi_env env, const char16_t* str, size_t length, napi_value* result);
+#endif  // NAPI_EXPERIMENTAL
+
 NAPI_EXTERN napi_status NAPI_CDECL napi_create_symbol(napi_env env,
                                                       napi_value description,
                                                       napi_value* result);

diff --git a/src/js_native_api_v8.cc b/src/js_native_api_v8.cc
@@ -1705,6 +1705,18 @@ napi_status NAPI_CDECL node_api_create_external_string_utf16(
       });
 }
 
+napi_status NAPI_CDECL node_api_create_property_key_utf16(napi_env env,
+                                                          const char16_t* str,
+                                                          size_t length,
+                                                          napi_value* result) {
+  return v8impl::NewString(env, str, length, result, [&](v8::Isolate* isolate) {
+    return v8::String::NewFromTwoByte(isolate,
+                                      reinterpret_cast<const uint16_t*>(str),
+                                      v8::NewStringType::kInternalized,
+                                      static_cast<int>(length));
+  });
+}
+
 napi_status NAPI_CDECL napi_create_double(napi_env env,
                                           double value,
                                           napi_value* result) {

diff --git a/test/js-native-api/test_string/test.js b/test/js-native-api/test_string/test.js
@@ -16,6 +16,8 @@ assert.strictEqual(test_string.TestLatin1External(empty), empty);
 assert.strictEqual(test_string.TestUtf16External(empty), empty);
 assert.strictEqual(test_string.TestLatin1ExternalAutoLength(empty), empty);
 assert.strictEqual(test_string.TestUtf16ExternalAutoLength(empty), empty);
+assert.strictEqual(test_string.TestPropertyKeyUtf16(empty), empty);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(empty), empty);
 assert.strictEqual(test_string.Utf16Length(empty), 0);
 assert.strictEqual(test_string.Utf8Length(empty), 0);
 
@@ -33,6 +35,8 @@ assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str1), str1);
 assert.strictEqual(test_string.TestLatin1Insufficient(str1), str1.slice(0, 3));
 assert.strictEqual(test_string.TestUtf8Insufficient(str1), str1.slice(0, 3));
 assert.strictEqual(test_string.TestUtf16Insufficient(str1), str1.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str1), str1);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str1), str1);
 assert.strictEqual(test_string.Utf16Length(str1), 11);
 assert.strictEqual(test_string.Utf8Length(str1), 11);
 
@@ -50,6 +54,8 @@ assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str2), str2);
 assert.strictEqual(test_string.TestLatin1Insufficient(str2), str2.slice(0, 3));
 assert.strictEqual(test_string.TestUtf8Insufficient(str2), str2.slice(0, 3));
 assert.strictEqual(test_string.TestUtf16Insufficient(str2), str2.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str2), str2);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str2), str2);
 assert.strictEqual(test_string.Utf16Length(str2), 62);
 assert.strictEqual(test_string.Utf8Length(str2), 62);
 
@@ -67,6 +73,8 @@ assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str3), str3);
 assert.strictEqual(test_string.TestLatin1Insufficient(str3), str3.slice(0, 3));
 assert.strictEqual(test_string.TestUtf8Insufficient(str3), str3.slice(0, 3));
 assert.strictEqual(test_string.TestUtf16Insufficient(str3), str3.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str3), str3);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str3), str3);
 assert.strictEqual(test_string.Utf16Length(str3), 27);
 assert.strictEqual(test_string.Utf8Length(str3), 27);
 
@@ -84,6 +92,8 @@ assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str4), str4);
 assert.strictEqual(test_string.TestLatin1Insufficient(str4), str4.slice(0, 3));
 assert.strictEqual(test_string.TestUtf8Insufficient(str4), str4.slice(0, 1));
 assert.strictEqual(test_string.TestUtf16Insufficient(str4), str4.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str4), str4);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str4), str4);
 assert.strictEqual(test_string.Utf16Length(str4), 31);
 assert.strictEqual(test_string.Utf8Length(str4), 62);
 
@@ -101,6 +111,8 @@ assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str5), str5);
 assert.strictEqual(test_string.TestLatin1Insufficient(str5), str5.slice(0, 3));
 assert.strictEqual(test_string.TestUtf8Insufficient(str5), str5.slice(0, 1));
 assert.strictEqual(test_string.TestUtf16Insufficient(str5), str5.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str5), str5);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str5), str5);
 assert.strictEqual(test_string.Utf16Length(str5), 63);
 assert.strictEqual(test_string.Utf8Length(str5), 126);
 
@@ -113,6 +125,8 @@ assert.strictEqual(test_string.TestUtf16External(str6), str6);
 assert.strictEqual(test_string.TestUtf16ExternalAutoLength(str6), str6);
 assert.strictEqual(test_string.TestUtf8Insufficient(str6), str6.slice(0, 1));
 assert.strictEqual(test_string.TestUtf16Insufficient(str6), str6.slice(0, 3));
+assert.strictEqual(test_string.TestPropertyKeyUtf16(str6), str6);
+assert.strictEqual(test_string.TestPropertyKeyUtf16AutoLength(str6), str6);
 assert.strictEqual(test_string.Utf16Length(str6), 5);
 assert.strictEqual(test_string.Utf8Length(str6), 14);
 

diff --git a/test/js-native-api/test_string/test_string.c b/test/js-native-api/test_string/test_string.c
@@ -294,6 +294,23 @@ static napi_value TestUtf16Insufficient(napi_env env, napi_callback_info info) {
   return output;
 }
 
+static napi_value TestPropertyKeyUtf16(napi_env env, napi_callback_info info) {
+  return TestTwoByteImpl(env,
+                         info,
+                         napi_get_value_string_utf16,
+                         node_api_create_property_key_utf16,
+                         actual_length);
+}
+
+static napi_value TestPropertyKeyUtf16AutoLength(napi_env env,
+                                                 napi_callback_info info) {
+  return TestTwoByteImpl(env,
+                         info,
+                         napi_get_value_string_utf16,
+                         node_api_create_property_key_utf16,
+                         auto_length);
+}
+
 static napi_value Utf16Length(napi_env env, napi_callback_info info) {
   napi_value args[1];
   NODE_API_CALL(env, validate_and_retrieve_single_string_arg(env, info, args));
@@ -410,6 +427,9 @@ napi_value Init(napi_env env, napi_value exports) {
       DECLARE_NODE_API_PROPERTY("TestLargeLatin1", TestLargeLatin1),
       DECLARE_NODE_API_PROPERTY("TestLargeUtf16", TestLargeUtf16),
       DECLARE_NODE_API_PROPERTY("TestMemoryCorruption", TestMemoryCorruption),
+      DECLARE_NODE_API_PROPERTY("TestPropertyKeyUtf16", TestPropertyKeyUtf16),
+      DECLARE_NODE_API_PROPERTY("TestPropertyKeyUtf16AutoLength",
+                                TestPropertyKeyUtf16AutoLength),
   };
 
   init_test_null(env, exports);