path: refactor for performance and consistency #9289

nwoltman · 2015-02-26T07:55:01Z

Improve performance by:

Not leaking the arguments object! (in win32.join)
Getting the last character of a string by index, instead of with .substr() (here) or .slice() (here)

Improve code consistency by:

Using [] instead of .charAt() where possible (such as here)
Using a function declaration instead of a var declaration (here)
Using .slice() with clearer arguments (such as here)

Improve both by:

Making the reusable trimArray() function
Standardizing getting certain path statistics with the new win32StatPath() function

Benchmarks: (higher is better)

function (path.)	current (ops/sec)	this PR (ops/sec)
win32.resolve	315,019	399,543
win32.normalize	873,559	1,051,170
win32.isAbsolute	1,915,332	1,939,849
win32.join	452,879	815,033
win32.relative	153,821	219,928
win32.format	13,118,588	16,364,384
posix.relative	244,638	304,456

Benchmark code (gist)

jasnell · 2015-03-04T03:25:05Z

@woollybogger ... do you have benchmark numbers showing that this provides a net performance improvement? The nature of the changes would indicate an improvement but numbers always help :-).

nwoltman · 2015-03-04T09:05:51Z

@jasnell I updated the PR description with benchmark data. I only included the functions that had a >1% change in performance.

nwoltman · 2015-03-12T07:32:06Z

It's been over a week so...bump?

jasnell · 2015-03-12T17:38:07Z

@woollybogger ... sorry, was catching up on a few other items. Thanks for the profiling numbers. I'll queue this up to review on Monday.

// cc @joyent/node-coreteam ... can one of you take a look as well?

trevnorris · 2015-03-13T18:05:50Z

Generally LGTM. But let's run this on the servers and make sure all tests pass on all platforms.

cjihrig · 2015-03-13T19:12:29Z

lib/path.js

+  var lastIndex = arr.length - 1;
+  var start = 0;
+  for (; start <= lastIndex; start++) {
+    if (arr[start]) break;


Please move break to the next line.

Good catch! I forgot that's the coding style.

misterdjules · 2015-03-16T19:53:26Z

lib/path.js

-        isUnc = device && device.charAt(1) !== ':',
-        isAbsolute = win32.isAbsolute(path),
+        isUnc = device && device[1] !== ':',
+        isAbsolute = isUnc || result[2],


I'm not a big fan on inlining the call to win32.isAbsolute here and in win32.normalize. I'm concerned that we could get to a point where win32.isAbsolute and these inline versions diverge.

We could have another function similar to win32SplitPath that returns the following properties:

device

isUnc

isAbsolute

tail

Also, is there any reason why win32SplitPath returns an array? I feel like the code would be more readable if it returned an object instead.

Ah, I'm guessing the answer to my question ^ is so that win32SplitPath returns the same data structure as posixSplitPath.

@misterdjules Are things good enough inline or should there be a helper function such as the one I outlined above? I tested Node with the changes in the PR against a version with the helper function and it does slow things down a little (about 2% to 5% slower for the functions the helper touches).

Unless win32.isAbsolute is on the critical path of a very common use case in terms of performance, I have a preference for using a helper function such as the one you described in your comment above.

I want to avoid subtle regressions due to potential divergence between several versions of inlined win32.isAbsolute.

misterdjules · 2015-03-16T19:54:13Z

@woollybogger @trevnorris @jasnell Added a comment inline. Thoughts?

piscisaureus · 2015-03-16T20:07:06Z

I know the damage has already been done, but one of the objections I have against exposing the unix code on windows and vice versa is that path.resolve() and maybe other functions produce garbage when relative paths are used.

Does anyone have an idea for fixing this. Maybe throw if the path is relative?

misterdjules · 2015-03-17T21:18:49Z

@piscisaureus I'm not sure I understand what you're saying, could you please give us an example of what you're describing?

piscisaureus · 2015-03-17T21:28:14Z

@misterdjules

> path.posix.resolve('foo/bar')
'C:\\Users\\Bert Belder/foo/bar'

I don't know what would happen if you did the opposite on unix, e.g.

> path.win32.resolve('\\\\myserver\\myshare\\foo.txt');
???
> path.win32.resolve('c:appdata\\node.js');
???

But I am sure the results would not make sense.

misterdjules · 2015-03-17T21:52:03Z

@piscisaureus OK thank you for the clarification!

> path.win32.resolve('\\\\myserver\\myshare\\foo.txt');
???
> path.win32.resolve('c:appdata\\node.js');
???

work as expected because they are absolute paths, but like you said path.win32.resolve with relative paths would fail on any UNIX system.

It seems that only path.resolve would be affected by this, as it seems to be the only one calling a platform-specific function (process.cwd). path.relative uses path.resolve, but it doesn't seem to be affected by it since it seems to deal only with relative paths. We would need to investigate more though.

Anyway, I think this should be handled outside of this PR and in my opinion it's worth creating a new issue. Do you want to do that @piscisaureus or should I do it?

Thank you again!

piscisaureus · 2015-03-17T22:14:08Z

@misterdjules

Ah, oops, you're right.
(The second path c:appdata\\node.js isn't absolute btw). It does a drive-specific cwd lookup here.

Agreed btw that I should be handled in a separate issue.

misterdjules · 2015-03-17T22:42:59Z

@piscisaureus created new issue here: #9430.

nwoltman · 2015-03-19T09:08:22Z

@misterdjules @jasnell Updated with the helper function as discussed here and updated the benchmark data.

misterdjules · 2015-03-19T19:18:01Z

lib/path.js

  if (dir) {
+    if (dir[dir.length - 1] === win32.sep) {


Does this change (moving the check inside if (dir)) fixes a bug where sometime dir would be undefined and thus the code would throw? If so, then it would be great to add at least a test for that.

Yes, I can think of at least two test cases that this fixes. I'll add some tests tonight.

misterdjules · 2015-03-19T19:23:13Z

Could you please take a look at my comment? Otherwise, LGTM. Thanks @woollybogger! 👍

Adding to the 0.12.2 milestone as node v0.12.1 will be a security release following the recent OpenSSL releases.

nwoltman · 2015-03-20T05:24:02Z

@roryrjb You wrote the path.format and path.parse functions so I have a question for you. In path.format, root isn't used anywhere except to throw an error. Is there a good reason for this or can that check just be removed?

roryrjb · 2015-03-20T06:53:51Z

@woollybogger no, there's no reason I can think of, it can be removed.

nwoltman · 2015-03-20T06:59:44Z

@roryrjb Cool, thanks! 👍

nwoltman · 2015-03-21T00:08:30Z

@misterdjules Ran into a little snag when writing tests:

path.posix.format({root:'', dir: 'dir/other dir/', base: 'index.html'});
// -> 'dir/other dir//index.html'
path.win32.format({root:'', dir: 'dir\\other dir\\', base: 'index.html'});
// -> 'dir\\other dir\\index.html'

The posix version doubles the directory separator while the win32 version does not.
I know 0.12 is a stable branch, so even though I'd like to fix the posix version to work the same as it's win32 counterpart, I'm guessing that won't be accepted in this brach? Or is it small enough that this would be okay?
Update: Or maybe the win32 version should also duplicate the directory separator since the input dir property shouldn't end with a directory separator? Plus that way:

path.format(path.parse(input)) === input; // true

for all win32 input (because that is already true for posix).

misterdjules · 2015-03-23T17:34:57Z

@woollybogger If we want to make changes to path.format, let's do that on master and in another issue/PR. The documentation in v0.12 doesn't mention a specific behavior for any platform, and it's not clear how many users currently rely on that behavior.

Thank you very much again!

nwoltman · 2015-03-24T08:09:21Z

@misterdjules Added a new commit with the tests and a couple other changes related to path.parse and path.format. If it's good I'll squash the commits.

misterdjules · 2015-03-24T23:24:10Z

Thank you again @woollybogger. Added some comments, please let me know what you think.

For some of the more controversial changes, we can always tackle them later in separate PRs. That way we can land the improvements you already made to the path's module performance and take more time to discuss the rest.

Improve performance by: + Not leaking the `arguments` object! + Getting the last character of a string by index, instead of with `.substr()` or `.slice()` Improve code consistency by: + Using `[]` instead of `.charAt()` where possible + Using a function declaration instead of a var declaration + Using `.slice()` with clearer arguments + Checking if `dir` is truthy in `win32.format` (added tests for this) Improve both by: + Making the reusable `trimArray()` function + Standardizing getting certain path statistics with the new `win32StatPath()` function

nwoltman · 2015-03-25T05:36:44Z

@misterdjules I removed the controversial code and squashed into one commit.

misterdjules · 2015-03-25T17:35:12Z

@woollybogger LGTM, thank you very much! 👍

Improve performance by: + Not leaking the `arguments` object! + Getting the last character of a string by index, instead of with `.substr()` or `.slice()` Improve code consistency by: + Using `[]` instead of `.charAt()` where possible + Using a function declaration instead of a var declaration + Using `.slice()` with clearer arguments + Checking if `dir` is truthy in `win32.format` (added tests for this) Improve both by: + Making the reusable `trimArray()` function + Standardizing getting certain path statistics with the new `win32StatPath()` function Reviewed-By: Julien Gilli <[email protected]> PR-URL: #9289

misterdjules · 2015-03-25T20:41:26Z

Landed in c66f8c2.

Nodejs-Jenkins added pr v0.12 labels Feb 26, 2015

tjfontaine removed pr v0.12 labels Feb 26, 2015

Nodejs-Jenkins added pr v0.12 labels Feb 26, 2015

nwoltman force-pushed the refactor-path branch 2 times, most recently from bbe4a0c to 1b25d91 Compare March 4, 2015 08:09

jasnell self-assigned this Mar 12, 2015

cjihrig reviewed Mar 13, 2015
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nwoltman force-pushed the refactor-path branch from 1b25d91 to 6f28815 Compare March 14, 2015 03:43

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nwoltman force-pushed the refactor-path branch from 6f28815 to e4a5c63 Compare March 17, 2015 05:41

misterdjules mentioned this pull request Mar 17, 2015

platform specific path.resolve on a different platform fails for relative paths #9430

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nwoltman force-pushed the refactor-path branch 2 times, most recently from 7abada1 to b770526 Compare March 19, 2015 08:26

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misterdjules added this to the 0.12.2 milestone Mar 19, 2015

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nwoltman force-pushed the refactor-path branch from b770526 to 6048b25 Compare March 24, 2015 07:48

nwoltman force-pushed the refactor-path branch from 6048b25 to 61b53a5 Compare March 25, 2015 05:05

nwoltman force-pushed the refactor-path branch from 61b53a5 to 6eed25b Compare March 25, 2015 05:31

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nwoltman mentioned this pull request May 23, 2015

path: refactor for performance and consistency nodejs/node#1778

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path: refactor for performance and consistency #9289

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nwoltman commented Feb 26, 2015

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path: refactor for performance and consistency #9289

path: refactor for performance and consistency #9289

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nwoltman commented Feb 26, 2015

Benchmarks: (higher is better)

jasnell commented Mar 4, 2015

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