Bug 74641 – [MutationObservers] Add a document-level flag that can trivially be checked to avoid doing unnessary work if mutation observers absent

• Component: DOM
• Status: RESOLVED FIXED

[Rafael Weinstein]

Right now, discovering there is no work to do still costs a number of function calls and checks. We should get this down to one function call and one check at most.

[Rafael Weinstein]

Created attachment 119486 [details]
Patch

[WebKit Review Bot]

Attachment 119486 [details] did not pass style-queue:

Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/WebCore/CMakeLists.txt', u'Source/W..." exit_code: 1

Source/WebCore/WebCore.vcproj/WebCore.vcproj:43816:  mismatched tag  [xml/syntax] [5]
Total errors found: 1 in 17 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Ojan Vafai]

Comment on attachment 119486 [details]
Patch

Patch looks fine. EWS seems unhappy with your build file changes though.

[Ryosuke Niwa]

Comment on attachment 119486 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=119486&action=review

> Source/WebCore/ChangeLog:8
> +        This patch adds a byte of flags to Document, of which three bits are used to signal if any

Enum usually takes 4 bytes in 32-bit architecture and 8 bytes in 64-bit architecture due to alignments. Because the previous member variable (m_listenerTypes) is unsigned short, gcc/clang may pack it into the same 4 byte but cl.exe will almost certainly allocate 4 bytes for each. It's not big of a deal anyway though.

[Adam Klein]

Comment on attachment 119486 [details]
Patch

Clearing flags on attachment: 119486

Committed r103001: <http://trac.webkit.org/changeset/103001>

[Adam Klein]

All reviewed patches have been landed.  Closing bug.