better exclusion for stack traces

better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

Plus...
   refactor slightly so that crash_handler() shows up at the top of the stack
   trace rather than some odd name for a lambda inside setup_crash_handler().

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002

Committed: https://skia.googlesource.com/skia/+/5b64dab5bcb1823d465be1833db1f716f9b903e5

[mtklein_C, 2016-06-09 14:53:48]

Description was changed from

==========
better exclusion for stack traces

BUG=skia:
==========

to

==========
better exclusion for stack traces

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

[mtklein_C, 2016-06-09 15:15:48]

Description was changed from

==========
better exclusion for stack traces

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

to

==========
better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack
trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

[mtklein_C, 2016-06-09 15:19:55]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-06-09 15:20:06]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2051863002/20001

[mtklein_C, 2016-06-09 15:26:07]

Description was changed from

==========
better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack
trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

to

==========
better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack
trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

Plus...
   refactor slightly so that crash_handler() shows up at the top of the stack
   trace rather than some odd name for a lambda inside setup_crash_handler().

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

[mtklein_C, 2016-06-09 15:27:02]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-06-09 15:27:06]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2051863002/40001

[commit-bot: I haz the power, 2016-06-09 15:40:53]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-06-09 15:40:54]

Dry run: This issue passed the CQ dry run.

[mtklein_C, 2016-06-09 15:46:39]

mtklein@chromium.org changed reviewers:
+ herb@google.com

[mtklein_C, 2016-06-09 15:46:39]

The CQ bit was checked by mtklein@chromium.org

[commit-bot: I haz the power, 2016-06-09 15:46:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2051863002/40001

[commit-bot: I haz the power, 2016-06-09 15:46:44]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2016-06-09 21:46 UTC

[herb_g, 2016-06-09 15:57:58]

lgtm

[commit-bot: I haz the power, 2016-06-09 15:59:51]

Description was changed from

==========
better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack
trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

Plus...
   refactor slightly so that crash_handler() shows up at the top of the stack
   trace rather than some odd name for a lambda inside setup_crash_handler().

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002
==========

to

==========
better exclusion for stack traces

Instead of two synchronization systems (in_signal_handler, gMutex), 
we can just use one.  This simplifies the signal handler logic to:
   - first thread through grabs the lock, prints what's running and a stack
trace,
     then exits
   - all other threads just sit waiting on that lock until exit kills them

Previously I think all threads were racing to exit, which can kill the process
before the printing thread is done.  That truncated the output, which is dumb.

Plus...
   refactor slightly so that crash_handler() shows up at the top of the stack
   trace rather than some odd name for a lambda inside setup_crash_handler().

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2051863002

Committed:
https://skia.googlesource.com/skia/+/5b64dab5bcb1823d465be1833db1f716f9b903e5
==========

[commit-bot: I haz the power, 2016-06-09 15:59:51]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/5b64dab5bcb1823d465be1833db1f716f9b903e5