Go Transactions

This is an experimental project implementing something like a super simple version of temporal.io workers.

A unit of work is called a Transaction. Transactions have Stages and a State. Stages are executed in order. Stages can return three different States: Success, Failure and Yield. Success moves the Transaction to the next Stage. Failure stops the Transaction and Yield pauses the Transaction and puts it back into the queue after a specified delay.

Example Stage:

type PrintStage struct {
}

func (s *PrintStage) Name() string {
	return "PrintStage"
}

func (s *PrintStage) Concurrency() int {
	return 1
}

func (s *PrintStage) Execute(t *gotransactions.Transaction) gotransactions.StageResult {
	message := t.GetState("", "message")
	if message == nil {
		message = "Hello, World!"
	}
	Print(message)
	return gotransactions.StageResult{
		Status: gotransactions.StageStatusSuccess,
	}
}

func (s *PrintStage) Rollback(t *gotransactions.Transaction) error {
	return nil
}

var _ gotransactions.Stager = (*PrintStage)(nil)

Transactions wrap multiple Stages and specify a state saver. A FileStateSaver is provided.

Example Transaction:

	stages := []gotransactions.Stager{
		&PrintStage{},
		&SleepStage{},
		&DiceStage{},
		&PrintStage{},
	}
	saver := &gotransactions.FileStateSaver{}
	t := gotransactions.NewTransaction("HelloWorld", stages, saver)
	t.SetState("", "message", "My roll is gonna be great!")

This transaction can be run as-is with t.RunAll(). But a "kanban" style runner is also provided. The runner looks at the Concurrency() of each Stage and runs that many workers to service that type of Stage across Transaction types.

Example runner:

    r := gotransactions.NewRunner()
	ctx := context.Background()
	r.Start(ctx)
	r.ExecuteAll([]*gotransactions.Transaction{t, t2, t3})

The runner is cancellable via the context. Start() starts the goroutines necessary to run Transactions in the background. ExecuteAll() is a non-blocking call that queues up Transactions to be run, according to their Concurrency().