Bug 209254

Summary: Delay calling 'notifyThisWebProcessPoolWasCreated' until constructor finishes
Product: WebKit Reporter: Brent Fulgham <bfulgham>
Component: WebKit2Assignee: Brent Fulgham <bfulgham>
Status: RESOLVED FIXED    
Severity: Normal CC: achristensen, beidson, bfulgham, cdumez, ggaren, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch
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Patch for landing
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Patch for landing none

Description Brent Fulgham 2020-03-18 16:11:23 PDT 
The constructor for WebProcessPool calls a method 'notifyThisWebProcessPoolWasCreated', which calls a set of functions registered by observers interested in knowing that the pool was constructed.

However, since this call is made during the construction of the object, code that attempts to do things like Ref<> the WebProcessPool do so with a partially-constructed object.

Instead, we should enqueue the notification call so that it fires on the next spin of the runloop, after the current object is finished being constructed.
Comment 1 Brent Fulgham 2020-03-18 16:15:46 PDT 
<rdar://problem/60564526>
Comment 2 Brent Fulgham 2020-03-18 16:31:12 PDT 
Created attachment 393914 [details]
Patch
Comment 3 Chris Dumez 2020-03-18 16:43:00 PDT 
Comment on attachment 393914 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=393914&action=review

I think this is likely fine. I have added Brady in cc though because I think he added this code.

> Source/WebKit/UIProcess/WebProcessPool.cpp:309
> +    ASSERT(isMainThread());

We should not be using isMainThread() in the UIProcess because an app on iOS may be using for WK1 and WK2. You want RunLoop::isMain() instead.

> Source/WebKit/UIProcess/WebProcessPool.cpp:310
> +    callOnMainThread([weakPtr = makeWeakPtr(this)] {

makeWeakPtr(*this) will save a branch.

Also this needs to be RunLoop::main() dispatch() for same reasons as above.
Comment 4 Brent Fulgham 2020-03-18 16:58:27 PDT 
Created attachment 393918 [details]
Patch for landing
Comment 5 Brent Fulgham 2020-03-18 17:04:16 PDT 
Created attachment 393920 [details]
Patch for landing
Comment 6 EWS 2020-03-18 17:41:41 PDT 
Committed r258671: <https://trac.webkit.org/changeset/258671>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 393920 [details].