Condition variables are synchronization primitives that can be used
to block one or more threads while waiting for condition to become
true.

Right now we have only semaphores, mutexes and atomic operations for
synchronization, which results in quite complex solutions where an
implementation using condition variables and mutexes would be straight
forward.

There's also a performance benefit to condition variables and mutexes
vs semaphores, especially on Windows, where semaphores are kernel
objects, while mutexes are implemented as fast critical sections,
it CAN be beneficial performance-wise to use condition variables
instead of semaphores.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/23548007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Drop the previous Semaphore class from platform files.

Add new Semaphore class using the new TimeDelta class for
the WaitFor() operation. Consistently assert correct behaviour
for the different implementations.

Improve test coverage of the Semaphore class.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/23748003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16473 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/23819005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16456 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Drop the previous Mutex and ScopedLock classes from platform files.

Add new Mutex, RecursiveMutex and LockGuard classes, which are
designed after their C++11 counterparts, so that at some point
we can simply drop our custom code and switch to the C++11
classes. We distinguish regular and recursive mutexes, as the
latter don't work well with condition variables, which will be
introduced by a followup CL.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/23625003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16416 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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).

The previous Windows issues have been resolved, and we now use GetTickCount64()
on Windows Vista and later, falling back to timeGetTime() with rollover
protection for earlier Windows versions.

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

Review URL: https://codereview.chromium.org/23490015

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16413 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Revert "Cross-compiling from Linux to Android requires -lrt for the host toolset.", "Fix Visual Studio debug build after r16398." and "Reland "Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class.""

This reverts commit r16398, r16399 and r16402 for breaking the Windows
WebKit tests. Will reland fix which doesn't use High Resolution Timer
for ElapsedTimer (we suspect QueryPerformanceCounter overhead is
responsible for test breakage).

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/23710002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16405 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/23624006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16399 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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

Review URL: https://codereview.chromium.org/23469013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16398 ce2b1a6d-e550-0410-aec6-3dcde31c8c00