Cancelling a workflow instance

[cschleiden]

When a workflow with a finished timer is canceled, we run into an invalid state transition for the timer command.

Should probably remove the callback once the command is done, or check if the state of the command is cancelable before attempting to do so.

[daadajuan]

This is a similar problem. I have a MainWorkflow with 2 SubWorkflow like this:

If I cancel the MainWorkflow by CancelWorkflowInstance before SubWorkflow2 has finished(in this time SubWorkflow1 has finished), there will be a panic raised.

"invalid state transition for command ScheduleSubWorkflow: Done -> Canceled"

package main

import (
    "context"
    "github.com/cschleiden/go-workflows/workflow"
    "github.com/google/uuid"
    "sync"
    "time"
)

func MainWorkflow(ctx workflow.Context, input string) (string, error) {
    println("MainWorkflow start")

    fs := make([]workflow.Future[string], 0, 2)
    fs = append(fs, workflow.CreateSubWorkflowInstance[string](ctx, workflow.SubWorkflowOptions{InstanceID: uuid.NewString()}, SubWorkflow1, "SubWorkflow1"))
    fs = append(fs, workflow.CreateSubWorkflowInstance[string](ctx, workflow.SubWorkflowOptions{InstanceID: uuid.NewString()}, SubWorkflow2, "SubWorkflow2"))

    var wg sync.WaitGroup

    for i := range fs {
        wg.Add(1)
        go func(i int) {
            defer wg.Done()
            f := fs[i]
            workflow.Select(ctx, workflow.Await(f, func(c workflow.Context, f workflow.Future[string]) {
                res, err := f.Get(ctx)
                println(res)
                println(err)
            }))
        }(i)
    }

    wg.Wait()

    return "succeed MainWorkflow", nil
}

func SubWorkflow1(ctx workflow.Context, input string) (string, error) {
    return workflow.ExecuteActivity[string](ctx, workflow.DefaultActivityOptions, Activity1).Get(ctx)
}

func SubWorkflow2(ctx workflow.Context, input string) (string, error) {
    return workflow.ExecuteActivity[string](ctx, workflow.DefaultActivityOptions, Activity2).Get(ctx)
}

func Activity1(ctx context.Context) (string, error) {
    return "Activity1 ok", nil
}

func Activity2(ctx context.Context) (string, error) {
    time.Sleep(30 * time.Second)
    return "Activity2 ok", nil
}