[WIP] A sampler thread in d8 for consuming the new API.

[WIP] A sampler thread in d8 for consuming the new API.

[gholap, 2014-08-21 22:41:17]

Initial version, please take a look...

[Benedikt Meurer, 2014-08-26 04:56:26]

bmeurer@chromium.org changed reviewers:
+ bmeurer@chromium.org, jarin@chromium.org, svenpanne@chromium.org

[Benedikt Meurer, 2014-08-26 04:59:09]

Jaroslav did the perf integration for d8, so he can probably comment on whether
this will be sufficient for perf based tracing.

[Benedikt Meurer, 2014-08-26 05:03:57]

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h
File include/v8-sampler.h (right):

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h#newcode87
include/v8-sampler.h:87: virtual void SharedLibrary(const std::string&
library_path,
As discussed earlier, this should really not be handled by V8. V8 is a
JavaScript engine and the only thing we care about is the Code objects we
create/delete/move.

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h#newcode100
include/v8-sampler.h:100: static void Install(Isolate* isolate,
Jochen suggested that all functions that operate on the Isolate should be member
methods of Isolate. So please move this to Isolate, and rename it to i.e.
InstallCodeEventHandler().

[Jarin, 2014-08-26 08:23:57]

I think this is unrelated to perf. For perf, we produce a file with code events
(similar to what this CL produces) + file with the actual code so that perf can
show disassembly.

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h
File include/v8-sampler.h (right):

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h#newcode72
include/v8-sampler.h:72: virtual void Delete(const void* from) = 0;
FYI: V8 does not send notifications about deleted code.

https://codereview.chromium.org/499483002/diff/1/src/log.cc
File src/log.cc (right):

https://codereview.chromium.org/499483002/diff/1/src/log.cc#newcode1366
src/log.cc:1366: codeEventHandler()->Create((const void*)code->address(),
If you are interested in the address of actual code (without header), you might
want to call code->instruction_start().

https://codereview.chromium.org/499483002/diff/1/src/log.cc#newcode1571
src/log.cc:1571: codeEventHandler()->Delete((const void*)from);
I think this is never called.

[Sven Panne, 2014-08-28 07:14:40]

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h
File include/v8-sampler.h (right):

https://codereview.chromium.org/499483002/diff/1/include/v8-sampler.h#newcode54
include/v8-sampler.h:54: class V8_EXPORT CodeEventHandler {
Hmmm, this seems to duplicate functionality from JitCodeEventHandler (under a
more or less equivalent interface). We should really, really try to merge the
functionalities as far as possible unless there is a very compelling reason not
to do it.