Bug 34177 - atomic refcounting required
Summary: atomic refcounting required
Alias: None
Product: cairo
Classification: Unclassified
Component: image backend (show other bugs)
Version: 1.10.3
Hardware: Other All
: medium enhancement
Assignee: Carl Worth
QA Contact: cairo-bugs mailing list
Depends on:
Reported: 2011-02-11 05:50 UTC by Jasper St. Pierre
Modified: 2011-02-19 08:06 UTC (History)
0 users

See Also:
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i915 features:


Description Jasper St. Pierre 2011-02-11 05:50:39 UTC
talking in #cairo on IRC, sanooj came up with this patch:


which fixed the problem
Comment 1 Søren Sandmann Pedersen 2011-02-11 08:44:57 UTC
This is a patch against cairo, although atomic ref counting would be useful in pixman too.
Comment 2 Chris Wilson 2011-02-11 08:55:54 UTC
Søren, the patch is irrelevant. It just highlights how Cairo needs atomic refcounting on pixman_image_t, without which the alternative is such a monstrosity.

The solution lies within pixman.
Comment 3 Søren Sandmann Pedersen 2011-02-11 09:11:27 UTC
Comment 4 M Joonas Pihlaja 2011-02-11 09:57:26 UTC
Here's a patch that removes the need for atomic pixman_image_ref()/unref() in cairo, mostly by dropping the global solid colour cache:

Comment 5 Alessandro 2011-02-11 10:12:36 UTC
I really think the bug should be flagged as still open. 

Adding atomic refcounting would be fairly easy using GCC builtins. See http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Atomic-Builtins.html
Comment 6 M Joonas Pihlaja 2011-02-19 08:06:04 UTC
Fixed in cairo master.

commit 71e8a4c23019b01aa43b334fcb2784c70daae9b5
Author: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
Date:   Sat Feb 19 17:46:45 2011 +0200

    image: Avoid reusing pixman images for threadsafety.

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