buffer: improve creation performance
Checklist
-
tests and code linting passes -
the commit message follows commit guidelines
Affected core subsystem(s)
buffer
Description of change
Improves performance of allocating unsafe buffers, creating buffers from an existing ArrayBuffer and creating .slice(...) from existing Buffer by avoiding deoptimizing change of prototype after Uint8Array allocation in favor of ES6 native subclassing.
This is done through an internal ES6 class that extends Uint8Array and
is used for allocations, but the regular Buffer function is exposed, so
calling Buffer(...) with or without new
continues to work as usual
and prototype chains are also preserved.
Performance wins for .slice are +120% (2.2x), and, consequently, for unsafe allocations up to +95% (1.9x) for small buffers, and for safe allocations (zero-filled) up to +30% (1.3x).