This is Step-2 : change the API towards application
Notably all invocation variants to support member functions
or a reference to bool flags are retracted, since today a
λ-binding directly at usage site tends to be more readable.
The function names are harmonised with the C++ standard and
emergency shutdown in the Subsystem-Runner is rationalised.
The old thread-wrapper test is repurposed to demonstrate
the effectiveness of monitor based locking.
FamilyMember::allocateNextMember() was actually a post-increment,
so (different than with TypedCounter) here no correction is necessary
As an asside, WorkForce_test is sometimes unstable immediately after a build.
Seemingly a headstart of 50µs is not enough to compensate for scheduler leeway
- the deadlock was caused by leaking error state through the C-style lumiera_error
- but the reason for the deadlock lies in the »convenience shortcut«
in the Object-Monitor scope guard for entering a wait state immediately.
This function undermines the unlocking-guarantee, when an exception
emanates from within the wait() function itself.
While it would be straight forward from an implementation POV
to just expose both variants on the API (as the C++ standard does),
it seems prudent to enforce the distinction, and to highlight the
auto-detaching behaviour as the preferred standard case.
Creating worker threads just for one computation and joining the results
seemed like a good idea 30 years ago; today we prefer Futures or asynchronous
messaging to achieve similar results in a robust and performant way.
ThreadJoinable can come in handy however for writing unit tests, were
the controlling master thread has to wait prior to perform verification.
So the old design seems well advised in this respect and will be retained
This was prompted by a test failing under Boost-1.65 (--> see #294)
When reviewed now, the whole idea of testing Steam-Layer Commands for
equivalence feels a bit sketchy.
Just the comparison for the command ''identity'' alone seems sufficient,
i.e. the test if a command-ID is associated with the same backend-handle
and thus the same functor binding.
- we got occasional hangups when waiting for disabled state
- the builder was not triggered properly, sometimes redundant, sometimes without timeout
As it turned out, the loop control logic is more like a state machine,
and the state variables need to be separated from the external influenced variables.
As a consequence, the inChange_ variable was not calculated properly when disabled in a race,
and then the loop went into infinite wait state, without propagating this to
the externally waiting client, which caused the deadlock
