pkg/wait: move wait to pkg/wait

pkg/wait/wait.go

@@ -0,0 +1,57 @@
+/*
+   Copyright 2014 CoreOS, Inc.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package wait
+
+import (
+	"sync"
+)
+
+type Wait interface {
+	Register(id uint64) <-chan interface{}
+	Trigger(id uint64, x interface{})
+}
+
+type List struct {
+	l sync.Mutex
+	m map[uint64]chan interface{}
+}
+
+func New() *List {
+	return &List{m: make(map[uint64]chan interface{})}
+}
+
+func (w *List) Register(id uint64) <-chan interface{} {
+	w.l.Lock()
+	defer w.l.Unlock()
+	ch := w.m[id]
+	if ch == nil {
+		ch = make(chan interface{}, 1)
+		w.m[id] = ch
+	}
+	return ch
+}
+
+func (w *List) Trigger(id uint64, x interface{}) {
+	w.l.Lock()
+	ch := w.m[id]
+	delete(w.m, id)
+	w.l.Unlock()
+	if ch != nil {
+		ch <- x
+		close(ch)
+	}
+}

pkg/wait/wait_test.go

@@ -0,0 +1,67 @@
+/*
+   Copyright 2014 CoreOS, Inc.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package wait
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestWait(t *testing.T) {
+	const eid = 1
+	wt := New()
+	ch := wt.Register(eid)
+	wt.Trigger(eid, "foo")
+	v := <-ch
+	if g, w := fmt.Sprintf("%v (%T)", v, v), "foo (string)"; g != w {
+		t.Errorf("<-ch = %v, want %v", g, w)
+	}
+
+	if g := <-ch; g != nil {
+		t.Errorf("unexpected non-nil value: %v (%T)", g, g)
+	}
+}
+
+func TestRegisterDupSuppression(t *testing.T) {
+	const eid = 1
+	wt := New()
+	ch1 := wt.Register(eid)
+	ch2 := wt.Register(eid)
+	wt.Trigger(eid, "foo")
+	<-ch1
+	g := <-ch2
+	if g != nil {
+		t.Errorf("unexpected non-nil value: %v (%T)", g, g)
+	}
+}
+
+func TestTriggerDupSuppression(t *testing.T) {
+	const eid = 1
+	wt := New()
+	ch := wt.Register(eid)
+	wt.Trigger(eid, "foo")
+	wt.Trigger(eid, "bar")
+
+	v := <-ch
+	if g, w := fmt.Sprintf("%v (%T)", v, v), "foo (string)"; g != w {
+		t.Errorf("<-ch = %v, want %v", g, w)
+	}
+
+	if g := <-ch; g != nil {
+		t.Errorf("unexpected non-nil value: %v (%T)", g, g)
+	}
+}