Skip to content

stream: code cleanup and micro-optimization #2479

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
bnoordhuis merged 3 commits into from
Aug 24, 2015
Merged

stream: code cleanup and micro-optimization #2479

Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
1a3f4a8
stream: fix off-by-factor-16 error in comment
bnoordhuis Aug 20, 2015
3af8e45
stream: micro-optimize high water mark calculation
bnoordhuis Aug 20, 2015
caa0d0c
stream: rename poorly named function
bnoordhuis Aug 20, 2015
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
stream: micro-optimize high water mark calculation 
Don't iterate over all 32 bits, use some hacker's delight bit twiddling
to compute the next power of two.

The logic can be reduced to `n = 1 << 32 - Math.clz32(n)` but then it
can't easily be backported to v2.x; Math.clz32() was added in V8 4.3.

PR-URL: #2479
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
  • Loading branch information
@bnoordhuis
bnoordhuis committed Aug 24, 2015
commit 3af8e451f272f1398acf7336f9eff0c64340ffe3
6 changes: 5 additions & 1 deletion lib/_stream_readable.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -198,7 +198,11 @@ function roundUpToNextPowerOf2(n) {
} else {
// Get the next highest power of 2
n--;
for (var p = 1; p < 32; p <<= 1) n |= n >> p;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
n++;
}
return n;
Expand Down