CoroutineYieldInLoopDetector
This checks for while loops where coroutines are in scope but without calling a blocking method on at least one of those coroutines:
```
drivetrain.run(theCoroutine -> {
while (drivetrain.getDistance() < 10) { // ERROR: "Missing call to `theCoroutine.yield()` inside loop"
drivetrain.setSpeed(1);
}
});
```
Note that, because we assume most looping constructs in commands will use while loops, we don't check for-loops, for-each loops, or do-while loops.
This check can be disabled with `@SuppressWarnings("CoroutineYieldInLoop")`
CodeAfterCoroutineParkDetector
Essentially acts like the Java compiler's check for code after a while (true) loop, but for coroutine.park():
```
drivetrain.run(theCoroutine -> {
drivetrain.setSpeed(1.0);
theCoroutine.park();
drivetrain.setSpeed(0.0); // ERROR: "Unreachable statement: `theCoroutine.park()` will never exit"
});
```
This check can be disabled with `@SuppressWarnings("CodeAfterCoroutinePark")`
IncorrectCoroutineUseDetector
Checks for usage of captured (outer) coroutine parameters and assignments to fields.
```
drivetrain.run(outer -> {
outer.await(arm.run(inner -> {
outer.yield(); // ERROR: "Coroutine `outer` may not be in scope. Consider using `inner`"
}))
});
```
This check can be disabled with `@SuppressWarnings("CoroutineMayNotBeInScope")`
```
private Coroutine coroutineField;
drivetrain.run(co -> coroutineField = co); // ERROR: "Captured coroutines may not be stored in fields"
```
This check can be disabled with `@SuppressWarnings("CoroutineCapture")`
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.
