buffer: use FastBuffer when fill is set to 0

A large number of libraries seem to use Buffer.alloc(size, 0) instead of just Buffer.alloc(size). We don't need to follow the "create unsafe buffer and fill it" path (i.e. actually allocate and perform fill) in that situation, that is better handled by Uint8Array constructor. Buffer.alloc(size) and Buffer.alloc(size, 0) are equivalent, so use the same code path. Not performing the zero-fill manually and having the underlying memory allocator do it for us can improve speed and reduce the memory usage for situations where Buffer.alloc(size, 0) is used. PR-URL: #21989 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: Minwoo Jung <minwoo@nodesource.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com> Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de>

Author: ChALkeR

lib/buffer.js

@@ -276,7 +276,7 @@ function assertSize(size) {
  */
 Buffer.alloc = function alloc(size, fill, encoding) {
  assertSize(size);
- if (fill !== undefined && size > 0) {
+ if (fill !== undefined && fill !== 0 && size > 0) {
  return _fill(createUnsafeBuffer(size), fill, encoding);
  }
  return new FastBuffer(size);