Skip to content

simclock.md

Latest commit

 

History

History
78 lines (56 loc) · 3.83 KB

simclock.md

File metadata and controls

78 lines (56 loc) · 3.83 KB
Raw

simclock

org.horizon36596.simloop.simclock

Puts your own timer code on the sim clock without changing a line of it. You rarely touch this package directly: OpModeRunner.forTeamClass(...) in opmode uses it for you.

Why it exists

A default tick advances 20 ms of simulated time, regardless of how long it takes on the laptop. Code that reads the laptop's clock (new ElapsedTime(), System.nanoTime()) or waits with Thread.sleep can therefore behave differently between runs. This package loads your team's classes with supported clock reads and sleeps rewritten to use sim time.

How you use it

Name the OpMode's class instead of building it:

OpModeRunResult result = OpModeRunner.forTeamClass("org.firstinspires.ftc.teamcode.MyAuto", hardwareMap)
        .activeTicks(1500)                         // a 30 s auto at 50 Hz
        .run();

That is the whole change. The full guide, with the build settings it needs and every warning and error message, is Running your timer code unchanged.

What you might see

Type What it is
SimClockLoader The class loader. Loads your team's classes a second time, with their clock calls rewritten. OpModeRunner.forTeamClass makes one per run.
SimClockElapsedTime What your unchanged new ElapsedTime() becomes. It is the SDK's ElapsedTime, reading the run's sim clock. You never build one.
SimClockHooks The static methods the rewritten calls go to (nanoTime(), threadSleep(...), opModeSleep(...), ...). You never call them.
SimClockScheduler, JvmInstructions Plumbing between the loader and the runner, and the bytecode reader. Public only so the runner can reach them.

For a timer your test builds and hands to your code, use org.horizon36596.simloop.sim.SimElapsedTime instead. It takes the FakeTimer it reads. See Making your timers sim-safe.

What it rewrites

Only classes in your team packages. By default those are org.firstinspires.ftc.teamcode. and com.seattlesolvers.solverslib.; .teamPackages(...) on the runner replaces the list. The JDK, the FTC SDK, SimLoop, PsiKit and JUnit are never rewritten, whatever the list says.

Inside those packages it moves:

  • ElapsedTime: all three constructors, and your own subclasses of it;
  • System.nanoTime() and System.currentTimeMillis();
  • Thread.sleep, TimeUnit.sleep, Android's SystemClock reads and SystemClock.sleep;
  • LinearOpMode.sleep(ms) with any duration, computed or not, and idle().

Units

  • Sim time: seconds on the FakeTimer, read back as nanoseconds or milliseconds wherever the call it replaces returned those units.
  • A sleep of ms milliseconds holds the OpMode for ceil(ms / tick) ticks of sim time.

The price

Your classes are loaded a second time for each run. So:

  • the OpMode cannot be cast to its own class in the test (read its fields by reflection, or through the SDK's types, telemetry, the blackboard or the fake hardware);
  • a team object built by the test, or left by an earlier run, cannot cross into the run;
  • your statics start fresh every run.

What this package will not do

  • It will not move clock reads outside your team packages. The SDK's Deadline timer, the real date and time (java.time, Date, Calendar) and libraries that read the clock are left alone. The ones it can see are listed in result.warnings().
  • It will not move Object.wait, Thread.join, latches, futures or executors.
  • It refuses some things outright, and fails the run even if your code catches the refusal: a Thread.sleep on any thread but a LinearOpMode's own, and a method reference this::sleep (write ms -> sleep(ms) instead).
  • It will not rewrite an OpMode instance you built yourself. Only forTeamClass loads classes through it.