Add app source, add vendoring and module support

vendor/gopkg.in/tomb.v2/context.go

@@ -0,0 +1,74 @@
+// +build go1.7
+
+package tomb
+
+import (
+	"context"
+)
+
+// WithContext returns a new tomb that is killed when the provided parent
+// context is canceled, and a copy of parent with a replaced Done channel
+// that is closed when either the tomb is dying or the parent is canceled.
+// The returned context may also be obtained via the tomb's Context method.
+func WithContext(parent context.Context) (*Tomb, context.Context) {
+	var t Tomb
+	t.init()
+	if parent.Done() != nil {
+		go func() {
+			select {
+			case <-t.Dying():
+			case <-parent.Done():
+				t.Kill(parent.Err())
+			}
+		}()
+	}
+	t.parent = parent
+	child, cancel := context.WithCancel(parent)
+	t.addChild(parent, child, cancel)
+	return &t, child
+}
+
+// Context returns a context that is a copy of the provided parent context with
+// a replaced Done channel that is closed when either the tomb is dying or the
+// parent is cancelled.
+//
+// If parent is nil, it defaults to the parent provided via WithContext, or an
+// empty background parent if the tomb wasn't created via WithContext.
+func (t *Tomb) Context(parent context.Context) context.Context {
+	t.init()
+	t.m.Lock()
+	defer t.m.Unlock()
+
+	if parent == nil {
+		if t.parent == nil {
+			t.parent = context.Background()
+		}
+		parent = t.parent.(context.Context)
+	}
+
+	if child, ok := t.child[parent]; ok {
+		return child.context.(context.Context)
+	}
+
+	child, cancel := context.WithCancel(parent)
+	t.addChild(parent, child, cancel)
+	return child
+}
+
+func (t *Tomb) addChild(parent context.Context, child context.Context, cancel func()) {
+	if t.reason != ErrStillAlive {
+		cancel()
+		return
+	}
+	if t.child == nil {
+		t.child = make(map[interface{}]childContext)
+	}
+	t.child[parent] = childContext{child, cancel, child.Done()}
+	for parent, child := range t.child {
+		select {
+		case <-child.done:
+			delete(t.child, parent)
+		default:
+		}
+	}
+}