[Webkit-unassigned] [Bug 136478] Initialize m_usesNetworkProcess earlier in WebProcess::initializeWebProcess()

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed Sep 3 23:02:21 PDT 2014


--- Comment #7 from Carlos Garcia Campos <cgarcia at igalia.com>  2014-09-03 23:02:23 PST ---
(In reply to comment #6)
> (From update of attachment 237552 [details])
> I needed to check Mac code, and now that I've done that, it looks like this patch breaks Mac.


> What happens is that in platformInitializeWebProcess(), we make WebProcess use the same on-disk cache that UI process and NetworkProcess use. There is some sad history of mistakes there - we had code that seemed like it made us use a different code path, but it didn't because m_usesNetworkProcess was not initialized yet. The code was mistakenly changed to actually respect the network process setting in <http://trac.webkit.org/changeset/170155>,

That was also my first approach until I realized I also had the check in platformSetCacheModel().

> and then we started to hit sandbox violations accessing the wrong cache. Then in <http://trac.webkit.org/r171156> I reverted the behavior, removing the broken usesNetworkProcess() check. I forgot to remove a comment saying that we wanted a standalone cache.
> After platformInitializeWebProcess(), initializeWebProcess() calls setCacheModel(), which calls platformSetCacheModel(), which once again checks usesNetworkProcess() and disables the cache. This is also currently dead code, because m_usesNetworkProcess is still not initialized. But after this proposed patch, m_usesNetworkProcess will be true, so we will disable the shared disk cache in all processes!

I see.

> Here is what I think needs to be done to fix the patch:
> 1. Remove this dead code from WebProcessCocoa.mm:
>     // FIXME: Once there is no loading being done in the WebProcess, we should remove this,
>     // as calling [NSURLCache sharedURLCache] initializes the cache, which we would rather not do.
>     if (usesNetworkProcess()) {
>         [nsurlCache setMemoryCapacity:0];
>         [nsurlCache setDiskCapacity:0];
>         return;
>     }
> 2. Remove this comment from the same file:
>     // When the network process is enabled, each web process wants a stand-alone
>     // NSURLCache, which it can disable to save memory.
> 3. Notify Apple folks working on WebKit performance that the optimization to disable caching in WebProcess has been broken for a long time, and that we are removing what remains of that code (I will do it).


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