Real-ish time Go simulation loop with support for simultaneous fixed step (simulation) and elastic step (rendering) functions. Includes a heartbeat channel to monitor loop health and performance metrics.

Example

A full example using Vulkan and metrics publishing is availabe in _examples/gloopex folder.

render := func(step time.Duration) error {
    // Do elastic-step work here.
    // The step param will be larger than RenderLatency
    // if we start to fall behind. 
    return nil
}
simulate := func(step time.Duration) error {
    // Do fixed-step work here.
    // The step param will always be SimulationLatency,
    // and we'll invoke the function more often if
    // we start to fall behind.
    return nil
}
// Set up the loop here.
loop, err := gloop.NewLoop(render, simulate, gloop.Hz60Delay, gloop.Hz60Delay)
// Start up the loop. This is not blocking.
loop.Start()
// Wait some period of time...
<-time.NewTimer(time.Minute).C
// At some point, call Stop.
// It's safe to do this from inside render() or simulate().
// The loop will also stop if render() or simulate() return an error.
loop.Stop(nil)
// Wait for the loop to finish.
// Once this chan is closed, it is guaranteed that
// neither render() nor simulate() will be called again.
<-loop.Done()

Quick Tutorial

loop.Start(...) starts the loop in a different goroutine.

loop.Stop(...) will halt the loop. This is thread safe, and can be called from within loop.Render(...) or loop.Simulate(...).

If loop.Render(...) or loop.Simulate(...) return an error, the loop will halt and the loop's loop.Err() will be set to non-nil.

Pull performance metrics out of the loop with sample <- loop.Heartbeat().

Wait for the loop to finish with <- loop.Done(). Once this closes, loop.Render(...) and loop.Simulate(...) will not be called again. The chan will also not close until any currently-executing calls to either of those functions finish.

There is no need to use synchronization objects; only one call to loop.Render(...) or loop.Simulate(...) will run at a time.

Install

go get -u github.com/erinpentecost/gloop

Testing

# You can use normal go tooling...
go test ./...
# Or the makefile...
make test