flow cleanup: separate TaskFunc from RunnerFunc

Extracted from #140

This will help be more flexible in what gets executed and how (e.g. for
running tests for instance)

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

dagger/env.go

@@ -146,7 +146,7 @@ func (env *Env) LocalDirs() map[string]string {
 	// 1. Scan the environment state
 	// FIXME: use a common `flow` instance to avoid rescanning the tree.
 	inst := env.state.CueInst()
-	flow := cueflow.New(&cueflow.Config{}, inst, newDummyTaskFunc(inst))
+	flow := cueflow.New(&cueflow.Config{}, inst, newTaskFunc(inst, noOpRunner))
 	for _, t := range flow.Tasks() {
 		v := compiler.Wrap(t.Value(), inst)
 		localdirs(v.Get("#compute"))
@@ -225,7 +225,7 @@ func (env *Env) Compute(ctx context.Context, s Solver) error {
 	lg := log.Ctx(ctx)
 
 	// Cueflow cue instance
-	flowInst := env.state.CueInst()
+	inst := env.state.CueInst()
 
 	// Reset the output
 	env.output = compiler.EmptyStruct()
@@ -260,7 +260,7 @@ func (env *Env) Compute(ctx context.Context, s Solver) error {
 		},
 	}
 	// Orchestrate execution with cueflow
-	flow := cueflow.New(flowCfg, flowInst, newPipelineTaskFunc(flowInst, s))
+	flow := cueflow.New(flowCfg, inst, newTaskFunc(inst, newPipelineRunner(inst, s)))
 	if err := flow.Run(ctx); err != nil {
 		return err
 	}
@@ -273,77 +273,71 @@ func (env *Env) Compute(ctx context.Context, s Solver) error {
 	}
 }
 
-func newDummyTaskFunc(inst *cue.Instance) cueflow.TaskFunc {
+func newTaskFunc(inst *cue.Instance, runner cueflow.RunnerFunc) cueflow.TaskFunc {
 	return func(flowVal cue.Value) (cueflow.Runner, error) {
 		v := compiler.Wrap(flowVal, inst)
 		if !isComponent(v) {
 			// No compute script
 			return nil, nil
 		}
-		return cueflow.RunnerFunc(func(t *cueflow.Task) error {
+		return runner, nil
-			return nil
-		}), nil
 	}
 }
 
-func newPipelineTaskFunc(inst *cue.Instance, s Solver) cueflow.TaskFunc {
+func noOpRunner(t *cueflow.Task) error {
-	return func(flowVal cue.Value) (cueflow.Runner, error) {
+	return nil
-		v := compiler.Wrap(flowVal, inst)
+}
-		if !isComponent(v) {
-			// No compute script
-			return nil, nil
-		}
-		// Cueflow run func:
-		return cueflow.RunnerFunc(func(t *cueflow.Task) error {
-			ctx := t.Context()
-			lg := log.
-				Ctx(ctx).
-				With().
-				Str("component", t.Path().String()).
-				Logger()
-			ctx = lg.WithContext(ctx)
-			span, ctx := opentracing.StartSpanFromContext(ctx,
-				fmt.Sprintf("compute: %s", t.Path().String()),
-			)
-			defer span.Finish()
 
-			start := time.Now()
+func newPipelineRunner(inst *cue.Instance, s Solver) cueflow.RunnerFunc {
+	return cueflow.RunnerFunc(func(t *cueflow.Task) error {
+		ctx := t.Context()
+		lg := log.
+			Ctx(ctx).
+			With().
+			Str("component", t.Path().String()).
+			Logger()
+		ctx = lg.WithContext(ctx)
+		span, ctx := opentracing.StartSpanFromContext(ctx,
+			fmt.Sprintf("compute: %s", t.Path().String()),
+		)
+		defer span.Finish()
+
+		start := time.Now()
+		lg.
+			Info().
+			Msg("computing")
+		for _, dep := range t.Dependencies() {
 			lg.
-				Info().
+				Debug().
-				Msg("computing")
+				Str("dependency", dep.Path().String()).
-			for _, dep := range t.Dependencies() {
+				Msg("dependency detected")
-				lg.
+		}
-					Debug().
+		v := compiler.Wrap(t.Value(), inst)
-					Str("dependency", dep.Path().String()).
+		p := NewPipeline(t.Path().String(), s, NewFillable(t))
-					Msg("dependency detected")
+		err := p.Do(ctx, v)
-			}
+		if err != nil {
-			v := compiler.Wrap(t.Value(), inst)
+			span.LogFields(otlog.String("error", err.Error()))
-			p := NewPipeline(t.Path().String(), s, NewFillable(t))
+			ext.Error.Set(span, true)
-			err := p.Do(ctx, v)
-			if err != nil {
-				span.LogFields(otlog.String("error", err.Error()))
-				ext.Error.Set(span, true)
 
-				// FIXME: this should use errdefs.IsCanceled(err)
+			// FIXME: this should use errdefs.IsCanceled(err)
-				if strings.Contains(err.Error(), "context canceled") {
+			if strings.Contains(err.Error(), "context canceled") {
-					lg.
-						Error().
-						Dur("duration", time.Since(start)).
-						Msg("canceled")
-					return err
-				}
 				lg.
 					Error().
 					Dur("duration", time.Since(start)).
-					Err(err).
+					Msg("canceled")
-					Msg("failed")
 				return err
 			}
 			lg.
-				Info().
+				Error().
 				Dur("duration", time.Since(start)).
-				Msg("completed")
+				Err(err).
-			return nil
+				Msg("failed")
-		}), nil
+			return err
-	}
+		}
+		lg.
+			Info().
+			Dur("duration", time.Since(start)).
+			Msg("completed")
+		return nil
+	})
 }