buffer: optimize writing short strings

PR-URL: nodejs#54310

Author: ronag

benchmark/buffers/buffer-write-string-short.js

@@ -0,0 +1,20 @@
+'use strict';
+
+const common = require('../common.js');
+const bench = common.createBenchmark(main, {
+  encoding: [
+    '', 'utf8', 'ascii', 'latin1',
+  ],
+  len: [0, 1, 8, 16, 32],
+  n: [1e6],
+});
+
+function main({ len, n, encoding }) {
+  const buf = Buffer.allocUnsafe(len);
+  const string = Buffer.from('a'.repeat(len)).toString()
+  bench.start();
+  for (let i = 0; i < n; ++i) {
+    buf.write(string, 0, encoding);
+  }
+  bench.end(n);
+}

lib/buffer.js

@@ -74,6 +74,8 @@ const {
   atob: _atob,
   btoa: _btoa,
 } = internalBinding('buffer');
+const bufferBinding = internalBinding('buffer');
+
 const {
   constants: {
     ALL_PROPERTIES,
@@ -620,7 +622,7 @@ const encodingOps = {
     encoding: 'utf8',
     encodingVal: encodingsMap.utf8,
     byteLength: byteLengthUtf8,
-    write: (buf, string, offset, len) => buf.utf8Write(string, offset, len),
+    write: (buf, string, offset, len) => bufferBinding.utf8WriteStatic(buf, string, offset, len),
     slice: (buf, start, end) => buf.utf8Slice(start, end),
     indexOf: (buf, val, byteOffset, dir) =>
       indexOfString(buf, val, byteOffset, encodingsMap.utf8, dir),
@@ -647,7 +649,7 @@ const encodingOps = {
     encoding: 'latin1',
     encodingVal: encodingsMap.latin1,
     byteLength: (string) => string.length,
-    write: (buf, string, offset, len) => buf.latin1Write(string, offset, len),
+    write: (buf, string, offset, len) => bufferBinding.latin1WriteStatic(buf, string, offset, len),
     slice: (buf, start, end) => buf.latin1Slice(start, end),
     indexOf: (buf, val, byteOffset, dir) =>
       indexOfString(buf, val, byteOffset, encodingsMap.latin1, dir),
@@ -656,7 +658,7 @@ const encodingOps = {
     encoding: 'ascii',
     encodingVal: encodingsMap.ascii,
     byteLength: (string) => string.length,
-    write: (buf, string, offset, len) => buf.asciiWrite(string, offset, len),
+    write: (buf, string, offset, len) => bufferBinding.asciiWriteStatic(buf, string, offset, len),
     slice: (buf, start, end) => buf.asciiSlice(start, end),
     indexOf: (buf, val, byteOffset, dir) =>
       indexOfBuffer(buf,

src/node_buffer.cc

@@ -1425,6 +1425,59 @@ void CopyArrayBuffer(const FunctionCallbackInfo<Value>& args) {
   memcpy(dest, src, bytes_to_copy);
 }
 
+template <encoding encoding>
+void SlowWriteString(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+
+  THROW_AND_RETURN_UNLESS_BUFFER(env, args[0]);
+  SPREAD_BUFFER_ARG(args[0], ts_obj);
+
+  THROW_AND_RETURN_IF_NOT_STRING(env, args[1], "argument");
+
+  Local<String> str = args[1]->ToString(env->context()).ToLocalChecked();
+
+  size_t offset = 0;
+  size_t max_length = 0;
+
+  THROW_AND_RETURN_IF_OOB(ParseArrayIndex(env, args[2], 0, &offset));
+  if (offset > ts_obj_length) {
+    return node::THROW_ERR_BUFFER_OUT_OF_BOUNDS(
+        env, "\"offset\" is outside of buffer bounds");
+  }
+
+  THROW_AND_RETURN_IF_OOB(ParseArrayIndex(env, args[3], ts_obj_length - offset,
+                                          &max_length));
+
+  max_length = std::min(ts_obj_length - offset, max_length);
+
+  if (max_length == 0)
+    return args.GetReturnValue().Set(0);
+
+  uint32_t written = StringBytes::Write(
+      env->isolate(), ts_obj_data + offset, max_length, str, encoding);
+  args.GetReturnValue().Set(written);
+}
+
+uint32_t FastWriteString(Local<Value> receiver,
+                       const v8::FastApiTypedArray<uint8_t>& dst,
+                       const v8::FastOneByteString& src,
+                       uint32_t offset,
+                       uint32_t max_length) {
+  uint8_t* dst_data;
+  CHECK(dst.getStorageIfAligned(&dst_data));
+
+  if (offset > dst.length()) {
+    // TODO: Throw "\"offset\" is outside of buffer bound
+  }
+
+  memcpy(dst_data, src.data, max_length);
+
+  return max_length;
+}
+
+static v8::CFunction fast_write_string(
+    v8::CFunction::Make(FastWriteString));
+
 void Initialize(Local<Object> target,
                 Local<Value> unused,
                 Local<Context> context,
@@ -1494,6 +1547,22 @@ void Initialize(Local<Object> target,
   SetMethod(context, target, "ucs2Write", StringWrite<UCS2>);
   SetMethod(context, target, "utf8Write", StringWrite<UTF8>);
 
+  SetFastMethod(context,
+                target,
+                "asciiWriteStatic",
+                SlowWriteString<ASCII>,
+                &fast_write_string);
+  SetFastMethod(context,
+                target,
+                "latin1WriteStatic",
+                SlowWriteString<LATIN1>,
+                &fast_write_string);
+  SetFastMethod(context,
+                target,
+                "utf8WriteStatic",
+                SlowWriteString<UTF8>,
+                &fast_write_string);
+
   SetMethod(context, target, "getZeroFillToggle", GetZeroFillToggle);
 }
 
@@ -1535,6 +1604,9 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(StringSlice<UCS2>);
   registry->Register(StringSlice<UTF8>);
 
+  registry->Register(SlowWriteString<ASCII>);
+  registry->Register(fast_write_string.GetTypeInfo());
+  registry->Register(FastWriteString);
   registry->Register(StringWrite<ASCII>);
   registry->Register(StringWrite<BASE64>);
   registry->Register(StringWrite<BASE64URL>);

src/node_external_reference.h

@@ -56,6 +56,13 @@ using CFunctionWithInt64Fallback = void (*)(v8::Local<v8::Value>,
                                             v8::FastApiCallbackOptions&);
 using CFunctionWithBool = void (*)(v8::Local<v8::Value>, bool);
 
+using CFunctionWriteString =
+    uint32_t (*)(v8::Local<v8::Value> receiver,
+                 const v8::FastApiTypedArray<uint8_t>& dst,
+                 const v8::FastOneByteString& src,
+                 uint32_t offset,
+                 uint32_t max_length);
+
 using CFunctionBufferCopy =
     uint32_t (*)(v8::Local<v8::Value> receiver,
                  const v8::FastApiTypedArray<uint8_t>& source,
@@ -88,6 +95,7 @@ class ExternalReferenceRegistry {
   V(CFunctionWithInt64Fallback)                                                \
   V(CFunctionWithBool)                                                         \
   V(CFunctionBufferCopy)                                                       \
+  V(CFunctionWriteString)                                                      \
   V(const v8::CFunctionInfo*)                                                  \
   V(v8::FunctionCallback)                                                      \
   V(v8::AccessorNameGetterCallback)                                            \