For the previous couple of months, the PID tests have been hanging.
The reason that the tests have been hanging lies with the Notifier,
not the PID controller. Basically, a deadlock was occuring during
Notifier destruction when the notifier destructor was called while
the notifier interrupt handler was being called. Because the low-level
interrupt manager waits for the interrupt handler to finish executing before
disabling itself, the notifier destructor would not exit until the
ProcessQueue function finished. However, at the same time, the handler
was attempting to lock the queueMutex before continuing; the Notifier
destructor had locked the queueMutex while wrapping things up, meaning
that the last run of the handler would not complete until the destructor
did, resulting in a deadlock.
In order to repair this, I reduced the scope of the lock on the queueMutex
in the destructor so that it only locks when absolutely necessary. This
should work now.
This bug was likely introduced over the summer when we updated to stl
mutexes and locks, which may have messed up the original lock structure.
This likely did not affect any teams, as it can only occur if you are actively
destroying every* Notifier object present and if the destructor happens to be
called while the handler is being run.
*Note: the component of the destructor causing issues only ran if the last
Notifier object is being destroyed.
Change-Id: I38ba4e60816a2a8d523e927c25378390a0755444
This is a major restructuring of the WPILib repository to simply build
procedures and remove the remnants of Maven from everything except the
eclipse plugins. Gradle files have been largely simplified or rewritten,
taking advantage of splitting up parts of the build into separate build
files for ease of reading.
The eclipse plugins are now in a separate project, as is ntcore. All
dependencies are resolved via Maven dependencies, with the
Jenkins-maintained WPILib repo. Project structures have also been
simplified: we no longer have separate subprojects inside wpilibc and
wpilibj. Where possible, these changes hav been done with git renames,
to make sure we still have full history for all repositories. Other
unrelated subprojects have also been broken out: OutlineViewer is now a
separate project.
Change-Id: Ib4e2a6e1a2f66427a14f16612b0e0d69ed661878
