344789 - "WARNING: Asked to remove non-existent observer" in <nsImageLoadingContent.cpp> |RemoveObserver()|

Status: VERIFIED FIXED

(Core :: Layout: Images, Video, and HTML Frames, defect)

Description

[Mats Palmgren (inactive)]

(followup from bug 342710 comment 4)

STEPS TO REPRODUCE
1. load an image URL in a debug build
2. quit

ACTUAL RESULTS
WARNING: Asked to remove non-existent observer: file nsImageLoadingContent.cpp, line 370

(I don't see the other warning mentioned in 342710 comment 4 anymore)

http://bonsai.mozilla.org/cvsblame.cgi?file=/mozilla/content/base/src/nsImageLoadingContent.cpp&rev=1.74&root=/cvsroot&mark=370#342

BUILDS AND PLATFORMS TESTED
Bug occurs in SeaMonkey trunk debug build on Linux.

Comment 1

[Mats Palmgren (inactive)]

Attachment: stack

We have two calls to nsImageLoadingContent::RemoveObserver() for
aObserver=0x881cf6c - the first from ImageListener::OnStopRequest()
during load, and the second from nsImageDocument::Destroy() when
shutting down.

Comment 2

[Boris Zbarsky [:bzbarsky]]

If we actually care, we should probably either remove the warning or store a boolean on nsImageDocument indicating whether it's observing the node.

Comment 3

[Robert Sayre]

(In reply to comment #2)
> If we actually care, we should probably either remove the warning or store a
> boolean on nsImageDocument indicating whether it's observing the node.
> 

This seems to be causing png images on http://www.tbray.org/ongoing/ to fail loading.

Comment 4

[Boris Zbarsky [:bzbarsky]]

> This seems to be causing png images on http://www.tbray.org/ongoing/ to fail
> loading.

_very_ unlikely.

If there is a problem on that site, please file a separate bug on it with steps to reproduce -- site loads ok here as far as I can tell.

Comment 5

[Robert Sayre]

(In reply to comment #4)
> 
> _very_ unlikely.

Fair enough, probably just a symptom or coincidence.

Comment 6

[Serge Gautherie (:sgautherie)]

(In reply to comment #1)
> We have two calls to nsImageLoadingContent::RemoveObserver() for
> aObserver=0x881cf6c - the first from ImageListener::OnStopRequest()
> during load, and the second from nsImageDocument::Destroy() when
> shutting down.

Exactly:
<http://bonsai.mozilla.org/cvsblame.cgi?file=mozilla/content/html/document/src/nsImageDocument.cpp&rev=1.175&mark=221,230,329,339#219>

Comment 7

[Serge Gautherie (:sgautherie)]

Attachment: (Av1) Add boolean

(In reply to comment #2)
> store a boolean on nsImageDocument indicating whether it's observing the node.

Comment 8

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 331271 [details] [diff] [review]
(Av1) Add boolean

Call it mObservingImageLoader, and r+sr=bzbarsky

Comment 9

[Serge Gautherie (:sgautherie)]

Attachment: (Av1a) Add boolean

Av1, with comment 8 suggestion(s).

Comment 10

[Serge Gautherie (:sgautherie)]

Attachment: (Av1b) Add boolean (Checkin: Comment 11)

Av1a, with a missed replace.

Comment 11

[Ian Neal]

Comment on attachment 331342 [details] [diff] [review]
(Av1b) Add boolean (Checkin: Comment 11)

http://hg.mozilla.org/mozilla-central/index.cgi/rev/ab8b0ec8dbcb

Comment 12

[Serge Gautherie (:sgautherie)]

(In reply to comment #0)
> 2. quit

To close the Browser window is enough (having the Error Console open, for example).

***

[Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9.1a2pre) Gecko/2008080208 SeaMonkey/2.0a1pre] (home, debug) (W2Ksp4)

V.Fixed