1. Fix places where data race warnings were relevant.
tls_worker_data::m_state should be modified under mutex protection,
since both maintainence timer and current worker set this flag.
2. Suppress warnings that are legitimate, yet harmless.
Apparently, the dirty reads in waitable_task::get_ref_count() or
write_slots->pending_io_count()
Avoiding race entirely without side-effects here is tricky,
and the effects of race is harmless.
The worst thing that can happen due to race is an extra wait notification,
under rare circumstances.
- wait notification, tpool_wait_begin/tpool_wait_end - to notify the
threadpool that current thread is going to wait
Use it to wait for IOs to complete and also when purge waits for workers.
The library is capable of
- asynchronous execution of tasks (and optionally waiting for them)
- asynchronous file IO
This is implemented using libaio on Linux and completion ports on
Windows. Elsewhere, async io is "simulated", which means worker threads
are performing synchronous IO.
- timers, scheduling work asynchronously in some point of the future.
Also periodic timers are implemented.
