buffer: use fast API for writing one-byte strings

[ronag]

                                                                        confidence improvement accuracy (*)    (**)   (***)
buffers/buffer-write-string-short.js n=1000000 len=0 encoding='ascii'          ***     65.81 %       ±5.23%  ±7.49% ±10.96%
buffers/buffer-write-string-short.js n=1000000 len=0 encoding='latin1'         ***     58.19 %      ±20.88% ±29.89% ±43.73%
buffers/buffer-write-string-short.js n=1000000 len=0 encoding='utf8'           ***     61.74 %      ±13.09% ±18.14% ±25.14%
buffers/buffer-write-string-short.js n=1000000 len=1 encoding='ascii'          ***    136.24 %      ±11.25% ±15.57% ±21.57%
buffers/buffer-write-string-short.js n=1000000 len=1 encoding='latin1'         ***    135.68 %      ±34.53% ±49.25% ±71.59%
buffers/buffer-write-string-short.js n=1000000 len=1 encoding='utf8'           ***    131.19 %      ±13.69% ±19.05% ±26.59%
buffers/buffer-write-string-short.js n=1000000 len=16 encoding='ascii'         ***    105.31 %      ±22.74% ±32.63% ±47.91%
buffers/buffer-write-string-short.js n=1000000 len=16 encoding='latin1'        ***    146.98 %      ±15.12% ±20.88% ±28.83%
buffers/buffer-write-string-short.js n=1000000 len=16 encoding='utf8'          ***    231.98 %      ±39.44% ±56.50% ±82.72%
buffers/buffer-write-string-short.js n=1000000 len=32 encoding='ascii'         ***    119.88 %      ±17.20% ±23.74% ±32.73%
buffers/buffer-write-string-short.js n=1000000 len=32 encoding='latin1'        ***    127.78 %      ±14.96% ±21.09% ±30.09%
buffers/buffer-write-string-short.js n=1000000 len=32 encoding='utf8'          ***    286.10 %      ±36.29% ±51.94% ±75.93%
buffers/buffer-write-string-short.js n=1000000 len=8 encoding='ascii'          ***    126.35 %      ±20.58% ±28.48% ±39.41%
buffers/buffer-write-string-short.js n=1000000 len=8 encoding='latin1'         ***    155.13 %       ±8.24% ±11.43% ±15.90%
buffers/buffer-write-string-short.js n=1000000 len=8 encoding='utf8'           ***    200.61 %      ±33.84% ±48.37% ±70.55%

[anonrig]

Probably because the benchmark has a flaw, and the input is not a one byte string. I recommend reading this amazing blog post: https://iliazeus.github.io/articles/js-string-optimizations-en/

[ronag]

@anonrig still only minimal difference:

buffers/buffer-write-string.js n=1000000 len=1                  9.21 %      ±12.42% ±17.25% ±24.00%
buffers/buffer-write-string.js n=1000000 len=16          *      5.12 %       ±4.58%  ±6.53%  ±9.52%
buffers/buffer-write-string.js n=1000000 len=32                 2.87 %       ±8.49% ±12.18% ±17.88%
buffers/buffer-write-string.js n=1000000 len=8          **      8.27 %       ±5.40%  ±7.68% ±11.10%

[anonrig]

Can you add a printf to fast api function and make sure that it runs? I've had several occasions that I couldn't trigger fast path for super simple calls.

[ronag]

@anonrig You are right. It's never called and I have no idea why. Do you know anyone that might know more?

[ronag]

Ah, it's because buffer is this and not the first arg. Do you know if fast API works with this args?

[targos]

The first arg (receiver) is the this arg.

[ronag]

Tried with no this and still no success... seems like a dead end for me

[santigimeno]

This works for me and the fast api path is hit starting around 1e4 iterations in the benchmark:

diff --git a/lib/buffer.js b/lib/buffer.js
index 37051c94073..cd4f8f296a1 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -54,8 +54,9 @@ const {
   Uint8ArrayPrototype,
 } = primordials;
 
+const bufferBinding = internalBinding('buffer');
+
 const {
-  stringWrite,
   byteLengthUtf8,
   compare: _compare,
   compareOffset,
@@ -658,7 +659,7 @@ const encodingOps = {
     encoding: 'ascii',
     encodingVal: encodingsMap.ascii,
     byteLength: (string) => string.length,
-    write: (buf, string, offset, len) => stringWrite(buf, string, offset, len),
+    write: (buf, string, offset, len) => bufferBinding.stringWrite(buf, string, offset, len),
     slice: (buf, start, end) => buf.asciiSlice(start, end),
     indexOf: (buf, val, byteOffset, dir) =>
       indexOfBuffer(buf,
diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 3247797dec4..acf2677d65a 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -1422,6 +1422,7 @@ 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>);

[ronag]

Got it to work!

buffers/buffer-write-string.js n=1000000 str='a'           ***    306.67 %       ±7.42% ±10.17% ±13.87%
buffers/buffer-write-string.js n=1000000 str='aa'          ***    289.45 %       ±3.26%  ±4.59%  ±6.55%
buffers/buffer-write-string.js n=1000000 str='aaaa'        ***    271.79 %      ±12.09% ±16.96% ±24.00%

looks promising

[nodejs-github-bot]

Landed in ccf05ef

[ShenHongFei]

Access violation occurred in FastWriteString function, causing the process to crash and exit. @ronag

[ronag]

@ShenHongFei Thanks for reporting! Fix is ready.

[ShenHongFei]

I tried applying the patch https://github.com/nodejs/node/pull/54391/files and the problem was solved. Thank you.