mostafa-asg/dag

Simple DSL for executing functions in Go

dag has two main concept:

1. Pipeline executes the functions sequentially and in order.
2. Spawns executes the functions concurrently, so there is no ordering guarantee.

Example 1

d := dag.New()
d.Pipeline(f1, f2, f3)
d.Run()

In the above example, f1 starts first, and after completion, f2 starts then f3.
Full example : examples/ex1/ex1.go

Example 2

d := dag.New()
d.Spawns(f1, f2, f3)
d.Run()

The order of execution of f1, f2 and f3 is nondeterministic
Full example : examples/ex2/ex2.go

Example 3

In this example f4 must be executed after complition of f1, f2 and f3. You can use Join method:

d := dag.New()
d.Spawns(f1, f2, f3).Join().Pipeline(f4)
d.Run()

Full example : examples/ex3/ex3.go

Example 4

After pipeline we can use Then method:

d := dag.New()
d.Pipeline(f1, f2, f3).Then().Spawns(f4, f5, f6)
d.Run()

Full example : examples/ex4/ex4.go

Example 5

d := dag.New()
d.Spawns(f1, f2, f3).
	Join().
	Pipeline(f4, f5).
	Then().
	Spawns(f6, f7, f8)
d.Run()

Full example : examples/ex5/ex5.go

Example 6

We want to execute two pipeline concrrently, we can use pipeline.Of inside the Spawns method:

d := dag.New()
d.Spawns(pipeline.Of(f1, f3), pipeline.Of(f2, f4)).
	Join().
	Pipeline(f5)
d.Run()

Full example : examples/ex6/ex6.go

Example 7

We can use OnComplete method after Pipeline or Spawns to notify when functions has completed.

d := dag.New()
d.Pipeline(f1, f2).OnComplete(f3).
	  Then().
  Spawns(f1, f2).OnComplete(f4)
d.Run()

Full example : examples/ex7/ex7.go

Example 8

Basically, Run() will block until all functions are done. If you don't want to be blocked, you can use RunAsync() method. It accepts a callback function, that will be called when all functions are done.

d := dag.New()
d.Pipeline(f1, f2).Then().Spawns(f3, f4)
d.RunAsync(onComplete)

Full example : examples/ex8/ex8.go