Don't use magic statics in SincResampler for thread safe init.

Don't use magic statics in SincResampler for thread safe init.

SincResampler uses magic statics for thread safe initialization
of runtime detected SIMD support functions.  Sadly, this is not
supported on MSVC++ until VS2012.

Crash reports seem to indicate that every once in a while this
fails on Windows and kConvolveProc ends up initialized to NULL.

This patch moves initializtion from once per renderer to once
per SincResampler construction.  Not ideal, but there should
never be very many instantiations of this class.  Long term
we'll be moving to an SSE baseline which obviates the runtime
selection process.

BUG=179986
TEST=media_unittests


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=187732

[DaleCurtis, 2013-03-08 02:10:14]

If this fixes the crash I'll make a fix for VectorMath as well -- which will
sadly be a bit more complicated (LazyInstance) since it's not contained in a
class.

[scherkus (not reviewing), 2013-03-08 02:33:07]

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.cc
File media/base/sinc_resampler.cc (right):

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.cc#...
media/base/sinc_resampler.cc:143: #if defined(ARCH_CPU_X86_FAMILY)
how about moving all of this inside of a static helper like:

ConvolveProc GetConvolveProc() { ... }

... and then always using convolve_proc_? it'll isolate all the #ifdef crud to a
single location instead of both the .h and .cc.

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.h
File media/base/sinc_resampler.h (right):

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.h#n...
media/base/sinc_resampler.h:111: typedef float (*ConvolveProc)(const float* src,
const float* k1,
nit: you don't need arg names here

[DaleCurtis, 2013-03-12 00:28:28]

The original race occurs because the code boils down to:

static = NULL;
bool have_set_static = false;
if (have_set_static) {
  have_set_static = true;
  < do stuff >
  static = < C || SSE >
}

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.cc
File media/base/sinc_resampler.cc (right):

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.cc#...
media/base/sinc_resampler.cc:143: #if defined(ARCH_CPU_X86_FAMILY)
On 2013/03/08 02:33:08, scherkus wrote:
> how about moving all of this inside of a static helper like:
> 
> ConvolveProc GetConvolveProc() { ... }
> 
> ... and then always using convolve_proc_? it'll isolate all the #ifdef crud to
a
> single location instead of both the .h and .cc.

I prefer this because it's closer to what the final solution w/o SSE detection
will look like.  At that time (hopefully next milestone or so) the non __SSE__
path with convolve_proc_ will simply be deleted.

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.h
File media/base/sinc_resampler.h (right):

https://codereview.chromium.org/12530005/diff/1/media/base/sinc_resampler.h#n...
media/base/sinc_resampler.h:111: typedef float (*ConvolveProc)(const float* src,
const float* k1,
On 2013/03/08 02:33:08, scherkus wrote:
> nit: you don't need arg names here

Done.

[DaleCurtis, 2013-03-12 00:29:20]

I forgot: Another solution would be to just do what we do in YUVConvert:

static = NULL;
if (!static)
  static = < C || SSE >

[scherkus (not reviewing), 2013-03-12 18:55:58]

lgtm

[commit-bot: I haz the power, 2013-03-12 20:13:03]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/12530005/7001

[commit-bot: I haz the power, 2013-03-13 01:17:28]

Change committed as 187732