The current SEGV handling on posix is not useful: as soon as our handler
is left, it's triggered again, infinitely.
This patch changes to restore the original handler, so the OS can create
a core dump, etc.
This makes sure we add the lockstep_scheduler_test even if the
ENABLE_LOCKSTEP_SCHEDULER is not set to yes. This means the
lockstep_scheduler is not used for SITL but the CMakeLists.txt file
still used and the test added.
It turns out that we can fix the unit tests of the lockstep_scheduler
just by checking if `passed_lock` is not `nullptr`.
Without this check, the unit tests segfaulted.
This solves a potential dead-lock when trying to shutdown: a call to exit()
stops all threads and calls all destructors for static objects.
The destructor of LockstepScheduler takes a lock. However this is not
safe, as the lock could already be taken (by any thread).
Some threads do not exit and are still running when
trying to exit SITL running under Windows in Cygwin.
This problem was introduced with:
- posix shell #10173 because of strating a child process
for the startup script and mixing up the signal handling
(only Ctrl+C broken)
- lockstep #10648 because of simulator threads not
stopping gracefully anymore with timing race conditions
(no graceful exit possible anymore)
I leave the SIGINT handler on its default implementation for
Cygwin which kills the process and all its threads when pressing
Ctrl+C.
This hotfix at least allows the usage of Ctrl+C again instead
of forcing the user to use the task manager to shut down
px4.exe going crazy on CPU load instead of exiting
everytime.
- use a linked-list instead of std::vector. Insertion and removal are now
O(1)
- avoid malloc and use a thread_local instance of TimedWait.
It gets destroyed when the thread exits, so we have to add protection
in case a thread exits too quickly. This in turn requires a fix to the
unit-tests.
The API of cond_timedwait was wrong. It used return -1 and set errno
instead of returning the error as specified for pthread_cond_timedwait
which it tries to mock.
@bkueng found that the old implementation was likely to wrap-around
given seconds is only a uint32_t. We now cast it directly to uint64_t
and therefore should fix this problem.
This uses the "fake" px4_sem based on mutex and condition_variable on
all POSIX system, not just macOS and Cygwin. This means that we can
change px4_sem_timedwait under the hood and inject the simulated time.
This integrates the lockstep_scheduler, so that the system time is set
by the mavlink HIL_SENSOR message.
This means that the speed factor is removed and the speed is entirely
given by the simulator.
Julian Oes