changed cyclic dep detection

since interpolation can be used, detection should be a execution time,
and not before

now, to prevent infinite execution, there's a miximum of 100 calls per
task

closes #37

Author: andreynering

cyclic.go

@@ -6,8 +6,6 @@ import (
 )
 
 var (
-	// ErrCyclicDepDetected is returned when a cyclic dependency was found in the Taskfile
-	ErrCyclicDepDetected = errors.New("task: cyclic dependency detected")
 	// ErrTaskfileAlreadyExists is returned on creating a Taskfile if one already exists
 	ErrTaskfileAlreadyExists = errors.New("task: A Taskfile already exists")
 )
@@ -61,3 +59,18 @@ type dynamicVarError struct {
 func (err *dynamicVarError) Error() string {
 	return fmt.Sprintf(`task: Command "%s" in taskvars file failed: %s`, err.cmd, err.cause)
 }
+
+// MaximumTaskCallExceededError is returned when a task is called too
+// many times. In this case you probably have a cyclic dependendy or
+// infinite loop
+type MaximumTaskCallExceededError struct {
+	task string
+}
+
+func (e *MaximumTaskCallExceededError) Error() string {
+	return fmt.Sprintf(
+		`task: maximum task call exceeded (%d) for task "%s": probably an cyclic dep or infinite loop`,
+		MaximumTaskCall,
+		e.task,
+	)
+}

cyclic_test.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"sync/atomic"
 
 	"github.com/go-task/task/execext"
 
@@ -18,6 +19,9 @@ import (
 const (
 	// TaskFilePath is the default Taskfile
 	TaskFilePath = "Taskfile"
+	// MaximumTaskCall is the max number of times a task can be called.
+	// This exists to prevent infinite loops on cyclic dependencies
+	MaximumTaskCall = 100
 )
 
 // Executor executes a Taskfile
@@ -57,14 +61,12 @@ type Task struct {
 	Vars      Vars
 	Set       string
 	Env       Vars
+
+	callCount int32
 }
 
 // Run runs Task
 func (e *Executor) Run(args ...string) error {
-	if err := e.CheckCyclicDep(); err != nil {
-		return err
-	}
-
 	if e.Stdin == nil {
 		e.Stdin = os.Stdin
 	}
@@ -110,6 +112,10 @@ func (e *Executor) RunTask(ctx context.Context, name string, vars Vars) error {
 		return &taskNotFoundError{name}
 	}
 
+	if atomic.AddInt32(&t.callCount, 1) >= MaximumTaskCall {
+		return &MaximumTaskCallExceededError{task: name}
+	}
+
 	if err := e.runDeps(ctx, name, vars); err != nil {
 		return err
 	}

errors.go

@@ -199,3 +199,15 @@ func TestParams(t *testing.T) {
 		assert.Equal(t, f.content, string(content))
 	}
 }
+
+func TestCyclicDep(t *testing.T) {
+	const dir = "testdata/cyclic"
+
+	e := task.Executor{
+		Dir:    dir,
+		Stdout: ioutil.Discard,
+		Stderr: ioutil.Discard,
+	}
+	assert.NoError(t, e.ReadTaskfile())
+	assert.IsType(t, &task.MaximumTaskCallExceededError{}, e.Run("task-1"))
+}

task.go

@@ -0,0 +1,7 @@
+task-1:
+  deps:
+    - task: task-2
+
+task-2:
+  deps:
+    - task: task-1