1. Make the OpMode interface itself periodic; this means the only
differences between `OpMode` and `PeriodicOpMode` are the latter's
methods to add sideloaded periodic callbacks
2. Make OpModeRobot process callbacks in a similar fashion to TimedRobot
and
3. Add some lifecycle functions (discussed below)
4. Pull the callback priority queue from TimedRobot to a new class
called `PeriodicPriorityQueue` so that `TimedRobot` and `OpModeRobot`
have less duplication
5. Fix a typo in the DriverStationJNI class that causes a memory leak
when certain driver station sim calls
6. Port the C++ OpModeRobot tests to Java
`OpModeRobot` now possesses some `IterativeRobotBase`-stye lifecycle
functions; these functions
1. `robotPeriodic`
2. `simulationInit` and `simulationPeriodic`
3. `disabledInit`, `disabledPeriodic`, and `disabledExit`
(note that `simulationInit` and `disabledInit` may be renamed to match
wpilibsuite#8719)
`OpModeRobot` also now processes `OpMode` changes (by the Driver
Station) in its `loopFunc` method, similar to
`IterativeRobotBase.loopFunc` processing game mode changes; `loopFunc`
is, similarly to `TimedRobot`, provided as a default `Callback`
---------
Signed-off-by: Zach Harel <zach@zharel.me>
Co-authored-by: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>
Commands are no longer able to outlive their schedule-site's scope,
regardless of how they were scheduled (set as a default command, bound
to a trigger, or manually scheduled)
As a consequence, default commands need better tracking so the default
command setting can be released when their scope exits and the next-most
appropriate default command can be rescheduled (eg, an opmode sets a
default command, then the globally-scoped default is restored when the
opmode exits). Some complexity is required here to make it work well for
edge cases.
Like `schedule()`, `setDefaultCommand()` will immediately start the new
default command if called inside of another command to avoid 1-loop
delays. However, this does not apply when called by the _current_
default command, as it would result in attempting to cancel the default
command while it's mounted (which is impossible and would throw an
exception)
```java
class Robot extends OpModeRobot {
final Drive drive = new Drive();
final CommandXboxController controller = new CommandXboxController(1);
public Robot() {
// global default command, active unless overridden in an opmode or command
drive.setDefaultCommand(drive.stop());
// global trigger binding, always active
controller.rightBumper().onTrue(drive.setX());
}
}
@Teleop
class ExampleOpMode extends PeriodicOpMode {
public ExampleOpMode(Robot robot) {
// opmode-specific default command
robot.drive.setDefaultCommand(robot.drive.operatorControl(robot.controller));
// opmode-specific binding
robot.controller.leftBumper().whileTrue(robot.drive.stop());
// opmode-specific binding that takes precedence over the global binding
// because it happens last; it "wins out" over the `setX()` binding
robot.controller.rightBumper().onTrue(robot.drive.selfTest());
}
@Override
public void periodic() {
Scheduler.getDefault().run();
}
}
```
Since sched_setscheduler() requires non-RT priorities to be 0, we can
use that as a sentinel value for disabling RT and condense the Java API
to just two functions with fewer parameters. The thread priority setter
is deprecated since only experts should use it.
The HAL Notifier thread priority setter was replaced with setting the
priority in the thread itself.
The C++ Notifier non-RT and RT constructors were deduplicated.
The real-time scheduler was changed from SCHED_FIFO to SCHED_RR, which
is SCHED_FIFO with threads allowed to run for a maximum time quantum
before yielding (100 ms by default).
User code:
- OpModeRobot used as the robot base class
- LinearOpMode and PeriodicOpMode are provided opmode base classes
- In Java, annotations can be used to automatically register opmode classes
Additional user code functionality:
- OpMode (string) is available in addition to the overall
auto/teleop/test robot mode
- OpMode does not indicate enable (enable/disable is still separate)
- The HAL API uses integer UIDs; these are exposed at the user API level
as well for faster checks
- User code creates opmodes on startup (these have name, category,
description, etc).
DS:
- DS will present opmode selection lists for auto and teleop for
match/practice. During a match, the DS will automatically activate the
selected opmode in the corresponding match period.
- For testing, an overall mode is selected (e.g. teleop/auto/test) and a
single opmode is selected
Future work:
- Command framework support/integration
- Python annotation support
- Unit tests (needs race-free DS sim updates)
- Porting of examples
Co-authored-by: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>
The framework fundamentally relies on the continuation API added in Java 21 (which is currently internal to the JDK). Continuations allow for call stacks to be saved to the heap and resumed later.
The async framework allows command bodies to be written in an imperative style. However, an async command will need to be actively cooperative and periodically call coroutine.yield() in loops to yield control back to the command scheduler to let it process other commands.
There are also some other additions like priority levels (as opposed to a blanket yes/no for ignoring incoming commands), factories requiring names be provided for commands, and the scheduler tracking all running commands and not just the highest-level groups. However, those changes aren't unique to an async framework, and could just as easily be used in a traditional command framework.
