PR uses TBB internal atomic's for atomic CAS on non-atomic data
Corresponding PR https://github.com/Project-OSRM/osrm-backend/pull/4199
Other options:
* use sequential update
* use an internal packed vector lock -> makes packed vector non-movable
* use boost.interprocess atomics implementation -> outdated and only 32 bit version
* use glib atomic's -> requires new dependency
* wait for https://isocpp.org/blog/2014/05/n4013 as_atomic
* use c11 _Atomic and atomic_compare_exchange_weak -> not possible to mix c++11 and c11
* use builtin functions gcc __sync_bool_compare_and_swap and msvc _InterlockedCompareExchange64 -> possible, but requires proper testing
boolean CompareAndSwapPointer(volatile * void * ptr,
void * new_value,
void * old_value) {
if defined(_MSC_VER)
if (InterlockedCompareExchange(ptr, new_value, old_value) == old_value) return false;
else return true;
elif (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) > 40100
return __sync_bool_compare_and_swap(ptr, old_value, new_value);
else
error No implementation
endif
}
* use Boost.Atomic -> requires new dependency
WordT local_lower_word = lower_word, new_lower_word;
do
{
new_lower_word = set_lower_value<WordT, T>(local_lower_word,
lower_mask[internal_index.element],
lower_offset[internal_index.element],
value);
} while (!boost::atomics::detail::operations<sizeof(WordT), false>::compare_exchange_weak(
lower_word,
local_lower_word,
new_lower_word,
boost::memory_order_release,
boost::memory_order_relaxed));
- template function for tile functionality with edge finder operator
- refactors unit tests into single function (reduce code duplication)
- adds unit tests for core-ch
The alpha constant is for the local optimality T-Test threshold.
Before we used epsilon for the T-Test threshold, but the epsilon
constant is meant to be used for the stretch test(s) only.
This changeset fixes the local optimality T-Test and uses the
epsilon constant for the two stretch tests:
- We test the stretch for the total route against epsilon and
- We test the detour against the epsilon now, too
We can discuss if the second stretch test should actually use
epsilon, too, or a adapted value of it - but definitly not alpha.
