Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class.

Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class.

These classes are meant to replace OS::Ticks() and OS::TimeCurrentMillis(),
which are broken in several ways. The ElapsedTimer class implements a
stopwatch using TimeTicks::HighResNow() for high resolution, monotonic
timing.

Also fix the CpuProfile::GetStartTime() and CpuProfile::GetEndTime()
methods to actually return the time relative to the unix epoch as stated
in the documentation (previously that was relative to some arbitrary
point in time, i.e. boot time).

BUG=v8:2853
R=machenbach@chromium.org, yurys@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=16388

Committed: https://code.google.com/p/v8/source/detail?r=16390

[Benedikt Meurer, 2013-08-26 12:07:23]

The initial part of the time related cleanup I mentioned. All required bits for
the CPU profiling are included. Additional cleanup delayed for followup CLs.

PTAL

[yurys, 2013-08-27 08:06:14]

Patch set #2 doesn't compile on Windows:

2>..\..\src\platform-win32.cc(249): error C2011: 'v8::internal::Time' : 'class'
type redefinition
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(328): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(329): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(330): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(330): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(331): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(331): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(335): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(335): error C2059: syntax error : ')'
2>..\..\src\platform-win32.cc(335): error C2143: syntax error : missing ';'
before '{'
2>..\..\src\platform-win32.cc(335): error C2447: '{' : missing function header
(old-style formal list?)
2>..\..\src\platform-win32.cc(341): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(341): error C2062: type 'double' unexpected
2>..\..\src\platform-win32.cc(341): error C2143: syntax error : missing ';'
before '{'
2>..\..\src\platform-win32.cc(341): error C2447: '{' : missing function header
(old-style formal list?)
2>..\..\src\platform-win32.cc(347): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(347): error C2062: type 'int' unexpected
2>..\..\src\platform-win32.cc(347): error C2143: syntax error : missing ';'
before '{'
2>..\..\src\platform-win32.cc(347): error C2447: '{' : missing function header
(old-style formal list?)
2>..\..\src\platform-win32.cc(361): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(362): error C2065: 'kTimeEpoc' : undeclared
identifier
2>..\..\src\platform-win32.cc(362): error C2065: 'kTimeScaler' : undeclared
identifier
2>..\..\src\platform-win32.cc(362): error C3861: 't': identifier not found
2>..\..\src\platform-win32.cc(368): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(393): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(416): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(417): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(419): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(420): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(427): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(432): error C2065: 'kTzNameSize' : undeclared
identifier
2>..\..\src\platform-win32.cc(443): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(444): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(444): error C2227: left of '->t' must point to
class/struct/union/generic type
2>..\..\src\platform-win32.cc(444): error C2065: 'kTimeScaler' : undeclared
identifier
2>..\..\src\platform-win32.cc(444): error C3861: 't': identifier not found
2>..\..\src\platform-win32.cc(449): error C2027: use of undefined type
'v8::internal::Time'
2>          c:\src\yurys\v8\src\time/time.h(174) : see declaration of
'v8::internal::Time'
2>..\..\src\platform-win32.cc(468): error C2146: syntax error : missing ';'
before identifier 'init_time'
2>..\..\src\platform-win32.cc(468): error C4430: missing type specifier - int
assumed. Note: C++ does not support default-int
2>..\..\src\platform-win32.cc(468): error C2065: 'init_time' : undeclared
identifier
2>..\..\src\platform-win32.cc(478): error C2146: syntax error : missing ';'
before identifier 'time_now'
2>..\..\src\platform-win32.cc(478): error C2065: 'time_now' : undeclared
identifier
2>..\..\src\platform-win32.cc(479): error C2065: 'time_now' : undeclared
identifier
2>..\..\src\platform-win32.cc(479): error C2228: left of '.ft_' must have
class/struct/union
2>          type is ''unknown-type''

[Benedikt Meurer, 2013-08-27 08:26:00]

Ups, I'll fix that.

[Benedikt Meurer, 2013-08-27 11:08:02]

On 2013/08/27 08:26:00, Benedikt Meurer wrote:
> Ups, I'll fix that.

Done.

[Benedikt Meurer, 2013-08-27 11:08:55]

On 2013/08/27 11:08:02, Benedikt Meurer wrote:
> On 2013/08/27 08:26:00, Benedikt Meurer wrote:
> > Ups, I'll fix that.
> 
> Done.

The fix depends on https://codereview.chromium.org/23557002

[yurys, 2013-08-28 07:04:21]

lgtm

https://codereview.chromium.org/23295034/diff/21001/test/cctest/test-cpu-prof...
File test/cctest/test-cpu-profiler.cc (left):

https://codereview.chromium.org/23295034/diff/21001/test/cctest/test-cpu-prof...
test/cctest/test-cpu-profiler.cc:422: int64_t time_before_profiling =
i::OS::Ticks();
You can take Time::NowFromSystemTime() here and leave the checks below.

[Benedikt Meurer, 2013-08-28 07:06:31]

https://codereview.chromium.org/23295034/diff/21001/test/cctest/test-cpu-prof...
File test/cctest/test-cpu-profiler.cc (left):

https://codereview.chromium.org/23295034/diff/21001/test/cctest/test-cpu-prof...
test/cctest/test-cpu-profiler.cc:422: int64_t time_before_profiling =
i::OS::Ticks();
On 2013/08/28 07:04:21, Yury Semikhatsky wrote:
> You can take Time::NowFromSystemTime() here and leave the checks below.

That's a bad idea, because NowFromSystemTime() is using the wallclock, which is
not monotonic and subject to adjustment by ntpd.

[Michael Achenbach, 2013-08-28 10:47:17]

lgtm with nit

https://codereview.chromium.org/23295034/diff/15001/src/time/elapsed-timer.h
File src/time/elapsed-timer.h (right):

https://codereview.chromium.org/23295034/diff/15001/src/time/elapsed-timer.h#...
src/time/elapsed-timer.h:69: ASSERT(start_ticks_.IsNull() || started_);
Is the second assert adding any value?

https://codereview.chromium.org/23295034/diff/21001/src/time/time.cc
File src/time/time.cc (right):

https://codereview.chromium.org/23295034/diff/21001/src/time/time.cc#newcode274
src/time/time.cc:274: #endif  // V8_OS_WIN
Is this comment not confusing, since it is the V8_OS_POSIX block that just
ended?

https://codereview.chromium.org/23295034/diff/21001/src/time/time.h
File src/time/time.h (right):

https://codereview.chromium.org/23295034/diff/21001/src/time/time.h#newcode52
src/time/time.h:52: // microseonds.
microseconds

https://codereview.chromium.org/23295034/diff/21001/tools/gyp/v8.gyp
File tools/gyp/v8.gyp (right):

https://codereview.chromium.org/23295034/diff/21001/tools/gyp/v8.gyp#newcode709
tools/gyp/v8.gyp:709: '../../src/platform-posix.cc'
We normally leave trailing commas in python lists for per-line-elements. But I
can see that this file is already inconsistent in that regard.

[Benedikt Meurer, 2013-08-28 10:58:36]

Nits addressed.

https://codereview.chromium.org/23295034/diff/15001/src/time/elapsed-timer.h
File src/time/elapsed-timer.h (right):

https://codereview.chromium.org/23295034/diff/15001/src/time/elapsed-timer.h#...
src/time/elapsed-timer.h:69: ASSERT(start_ticks_.IsNull() || started_);
On 2013/08/28 10:47:17, machenbach wrote:
> Is the second assert adding any value?

Nope, it's missing negations, will fix that.

https://codereview.chromium.org/23295034/diff/21001/src/time/time.cc
File src/time/time.cc (right):

https://codereview.chromium.org/23295034/diff/21001/src/time/time.cc#newcode274
src/time/time.cc:274: #endif  // V8_OS_WIN
On 2013/08/28 10:47:17, machenbach wrote:
> Is this comment not confusing, since it is the V8_OS_POSIX block that just
> ended?

That's how we do it all over the place, unfortunately.

[Benedikt Meurer, 2013-08-28 10:59:37]

Committed patchset #6 manually as r16388.

[Benedikt Meurer, 2013-08-28 11:06:40]

Committed patchset #7 manually as r16390.

[tfarina, 2013-09-07 04:15:40]

https://codereview.chromium.org/23295034/diff/35001/src/time/elapsed-timer.h
File src/time/elapsed-timer.h (right):

https://codereview.chromium.org/23295034/diff/35001/src/time/elapsed-timer.h#...
src/time/elapsed-timer.h:79: ASSERT(IsStarted());
why all the implementations are in the header file? does that brings any
advantage over declaring in the header and implementing in the source file? if
yes, how did you measure it?

[Benedikt Meurer, 2013-09-09 05:55:17]

https://codereview.chromium.org/23295034/diff/35001/src/time/elapsed-timer.h
File src/time/elapsed-timer.h (right):

https://codereview.chromium.org/23295034/diff/35001/src/time/elapsed-timer.h#...
src/time/elapsed-timer.h:79: ASSERT(IsStarted());
On 2013/09/07 04:15:40, tfarina wrote:
> why all the implementations are in the header file? does that brings any
> advantage over declaring in the header and implementing in the source file? if
> yes, how did you measure it?

The implementation is trivial, one method invocation and one subtraction
(inlined from TimeTicks - operator). We usually just inline stuff like this in
the header.