Bug 200925 – WebSQLiteDatabaseTracker does not ensure it is still alive after dispatching to the main thread

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit2

[Chris Dumez]

WebSQLiteDatabaseTracker does not ensure it is still alive after dispatching to the main thread, which is not safe.

[Chris Dumez]

Created attachment 376781 [details]
Patch

[Geoffrey Garen]

Comment on attachment 376781 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=376781&action=review

r=me

> Source/WebKit/Shared/WebSQLiteDatabaseTracker.cpp:39
> +    : m_weakThis(makeWeakPtr(*this))

This data member is just a copy of the pointer held by CanMakeWeakPtr<WebSQLiteDatabaseTracker>. It would be slightly more efficient to remove this data member, and instead do [weakThis = makeWeakPtr(*this)] in our lambda capture expressions.

If there's an issue where it's not safe to call makeWeakPtr(*this) in our lambda capture expressions because they execute on another thread, then I'd recommend just calling makeWeakPtr(*this) here but not storing the result, with a comment explaining that we want to avoid initializing our weak pointer on a secondary thread.

[Chris Dumez]

Created attachment 376791 [details]
Patch

[Chris Dumez]

(In reply to Chris Dumez from comment #3)
> Created attachment 376791 [details]
> Patch

Ok, what do you think of this approach?

[EWS Watchlist]

Attachment 376791 [details] did not pass style-queue:


ERROR: Source/WTF/wtf/WeakPtr.h:159:  Multi line control clauses should use braces.  [whitespace/braces] [4]
Total errors found: 1 in 4 files


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

[Geoffrey Garen]

Comment on attachment 376791 [details]
Patch

cq+

[Geoffrey Garen]

Comment on attachment 376791 [details]
Patch

cq- because we came up with an even better idea in person

[Chris Dumez]

Created attachment 376797 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 376797 [details]
Patch

Clearing flags on attachment: 376797

Committed r248918: <https://trac.webkit.org/changeset/248918>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/54530876>