537290 - Reduce uses of aNode.localName, namespaceURI in XPath generation

Status: VERIFIED FIXED

(Firefox :: Session Restore, defect)

Description

[Paul O'Shannessy [:zpao] (not reading much bugmail, email directly)]

These hit "various XPConnect slow paths due to the cross-origin access" - bz in bug 536910 comment #29

We access these each iteration in a loop (counting sibling nodes) and once before even getting in the loop. We can take bring that down to 1 total per node (I don't think we can get rid accessing these in the sibling nodes).

Comment 1

[Paul O'Shannessy [:zpao] (not reading much bugmail, email directly)]

Attachment: Patch v0.1

I didn't move the assignment of nName up because we don't need to access it if the node has an ID, so it wasn't worth moving it up for slightly better looking code.

Comment 2

[Paul O'Shannessy [:zpao] (not reading much bugmail, email directly)]

FWIW, Boris profiled with the test case in bug 536910 after this patch. We dropped from 24000 samples to 17500 samples (which is ~27% (or .11 seconds) savings).

Comment 3

[Paul O'Shannessy [:zpao] (not reading much bugmail, email directly)]

Pushed http://hg.mozilla.org/mozilla-central/rev/ae840f673072

Comment 4

[u279076]

What can QA do to verify this bug?

Comment 5

[Paul O'Shannessy [:zpao] (not reading much bugmail, email directly)]

If things didn't break, we're good.

Comment 6

[u279076]

(In reply to comment #5)
> If things didn't break, we're good.

Good enough!  Marking verified.