explicit flex_barrier( std::ptrdiff_t num_threads );
(1) (concurrency TS)
template < class F >
flex_barrier( std::ptrdiff_t num_threads, F completion );
(2) (concurrency TS)
flex_barrier( const flex_barrier & ) = delete;
(3) (concurrency TS)
1) Has the same effect as flex_barrier(num_threads, c), where c is a Callable object whose invocation returns -1 and has no side effects.
2) Constructs a flex_barrier for num_threads participating threads, using completion for the completion phase. The set of participating threads is the first num_threads threads to arrive at the synchronization point.
3) Copy constructor is deleted; flex_barrier is not copyable.

[edit] Parameters

num_threads - the number of participating threads for the flex_barrier; must be non-negative
completion - A function object controlling the completion phase; must be Callable with no arguments and return type std::ptrdiff_t, and when invoked, must return a value no less than -1 and must not throw an exception.
Type requirements
F must meet the requirements of CopyConstructible.

[edit] Notes

If num_threads is zero, the set of participating threads is empty, and flex_barrier can only be destroyed.