This refactors Alert in both c++ and java to fix the issues with the current c++ implementation and improve performance.
Currently, constructing an Alert adds it to a list of Alerts with the same group and type. Activating an alert sets a flag on the alert. When the SendableAlerts is polled (GetStrings), the entire list is iterated over, filtered, and the filtered list is sorted by timestamp. This leads to a worst case O(m + nlog(n)) time complexity for GetStrings, where m and n are the count of total constructed alerts active alerts respectively. It also allocates intermediate data structures to hold the active alert strings for sorting.
This changes the implementation to improve the performance of GetStrings, by shifting the sorting overhead to Alert.Set
Constructing the Alert only initializes the alert's initial state, and initializes the SendableAlerts for the group if it is not already initialized.
Activating or deactivating an alert sets an internal flag for state tracking, and inserts or removes a structure containing the timestamp and text into a self-sorting data structure (std::set, TreeSet) containing other active alerts with the same group and type. (worst case O(log(n))
Now, SendableAlerts.GetStrings only has to iterate over the structure and copy the strings to the returned array. (amortized O(n))
This also fixes the c++ implementation by removing the need for SendableAlerts to directly access the Alert.
This also adds a helper method to SendableRegistry to force initialization of the instance to prevent static initialization ordering issues.
Java generics are too limited to do what we need. This refactors generic code previously in Unit and Measure into unit-specific classes that can have unit-safe math operations (notably, times and divide) that can return values in known units instead of a wildcarded Measure<?>.
Unit-specific measure implementations are automatically generated by ./wpiunits/generate_units.py, which generates generic interfaces and mutable and immutable implementations of those interfaces. These make up the bulk of the diff of this PR (approximately 9300 LOC).
This also adds units for angular and linear velocities, accelerations, and momenta; moment of inertia; and torque.
Fixes error when >3 are constructed- in java, m_filterAllocated[index] would be evaluated before the bounds check and throw IndexOutOfBounds, in c++ a vague assertion error would be thrown.
Makes DoAdd static in c++
Makes the error message when HAL_SetFilterSelect fails consistent with java
If the interrupt edge tests are running while under heavy CPU load (like building wpilib) they are prone to failure since the interrupt thread doesn't have enough time to set up callbacks. The interrupt edge tests now copy the original AsynchronousInterrupt test, which has a 0.5s delay after the interrupt is enabled. Running the new interrupt tests while building allwpilib causes far less failures than the old tests.
That behavior has not been present since PR #4158 was merged more than 2 years ago and imo should not be added back because it was surprising and not consistent with the most common use case of registering a callback permanently.
If one of the *Init() functions takes several multiples of the nominal
loop time, the callbacks after that will run, then increment their
expiration time by the nominal loop time. Since the new expiration time
is still in the past, this will cause the callback to get repeatedly run
in quick succession until its expiration time catches up with the
current time.
This change keeps incrementing the expiration time until it's in the
future, which will avoid repeated runs. This doesn't delay other
callbacks, so they'll get a chance to run once before their expiration
times are corrected.
The other option is correcting all the expiration times at once, which
would starve the other callbacks even longer so that the callback
scheduling returns to a regular cadence sooner. The problem with this
approach is if a previous callback overruns the start of the next
callback, the next callback could potentially never get a chance to run.
