Address comments; also, demonstrate one more property in test.

pkg/api/helper.go

@@ -37,6 +37,8 @@ func init() {
 		MinionList{},
 		Minion{},
 		Status{},
+		ServerOpList{},
+		ServerOp{},
 	)
 }
 

pkg/api/types.go

@@ -207,3 +207,14 @@ const (
 	StatusFailure = "failure"
 	StatusWorking = "working"
 )
+
+// Operation information, as delivered to API clients.
+type ServerOp struct {
+	JSONBase `yaml:",inline" json:",inline"`
+}
+
+// Operation list, as delivered to API clients.
+type ServerOpList struct {
+	JSONBase `yaml:",inline" json:",inline"`
+	Items    []ServerOp `yaml:"items,omitempty" json:"items,omitempty"`
+}

pkg/apiserver/apiserver.go

@@ -41,9 +41,14 @@ type RESTStorage interface {
 	Update(interface{}) (<-chan interface{}, error)
 }
 
+// WorkFunc is used to perform any time consuming work for an api call, after
+// the input has been validated. Pass one of these to MakeAsync to create an
+// appropriate return value for the Update, Delete, and Create methods.
+type WorkFunc func() (result interface{}, err error)
+
 // MakeAsync takes a function and executes it, delivering the result in the way required
 // by RESTStorage's Update, Delete, and Create methods.
-func MakeAsync(fn func() (interface{}, error)) <-chan interface{} {
+func MakeAsync(fn WorkFunc) <-chan interface{} {
 	channel := make(chan interface{})
 	go func() {
 		defer util.HandleCrash()
@@ -171,7 +176,7 @@ func (server *ApiServer) finishReq(out <-chan interface{}, sync bool, timeout ti
 	if sync {
 		op.WaitFor(timeout)
 	}
-	obj, complete := op.Describe()
+	obj, complete := op.StatusOrResult()
 	if complete {
 		server.write(http.StatusOK, obj, w)
 	} else {
@@ -308,7 +313,7 @@ func (server *ApiServer) handleOperationRequest(parts []string, w http.ResponseW
 		server.notFound(req, w)
 	}
 
-	obj, complete := op.Describe()
+	obj, complete := op.StatusOrResult()
 	if complete {
 		server.write(http.StatusOK, obj, w)
 	} else {

pkg/apiserver/apiserver_test.go

@@ -60,7 +60,8 @@ type SimpleRESTStorage struct {
 	updated Simple
 	created Simple
 
-	// called when answering update, delete, create
+	// If non-nil, called inside the WorkFunc when answering update, delete, create.
+	// obj recieves the original input to the update, delete, or create call.
 	injectedFunction func(obj interface{}) (returnObj interface{}, err error)
 }
 

pkg/apiserver/operation.go

@@ -17,30 +17,16 @@ limitations under the License.
 package apiserver
 
 import (
-	"fmt"
 	"sort"
+	"strconv"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 )
 
-func init() {
-	api.AddKnownTypes(ServerOp{}, ServerOpList{})
-}
-
-// Operation information, as delivered to API clients.
-type ServerOp struct {
-	api.JSONBase `yaml:",inline" json:",inline"`
-}
-
-// Operation list, as delivered to API clients.
-type ServerOpList struct {
-	api.JSONBase `yaml:",inline" json:",inline"`
-	Items        []ServerOp `yaml:"items,omitempty" json:"items,omitempty"`
-}
-
 // Operation represents an ongoing action which the server is performing.
 type Operation struct {
 	ID       string
@@ -53,9 +39,12 @@ type Operation struct {
 
 // Operations tracks all the ongoing operations.
 type Operations struct {
+	// Access only using functions from atomic.
+	lastID int64
+
+	// 'lock' guards the ops map.
 	lock sync.Mutex
 	ops  map[string]*Operation
-	nextID int
 }
 
 // Returns a new Operations repository.
@@ -67,25 +56,28 @@ func NewOperations() *Operations {
 	return ops
 }
 
-// Add a new operation.
+// Add a new operation. Lock-free.
 func (ops *Operations) NewOperation(from <-chan interface{}) *Operation {
-	ops.lock.Lock()
+	id := atomic.AddInt64(&ops.lastID, 1)
-	defer ops.lock.Unlock()
-	id := fmt.Sprintf("%v", ops.nextID)
-	ops.nextID++
-
 	op := &Operation{
-		ID:       id,
+		ID:       strconv.FormatInt(id, 10),
 		awaiting: from,
 		notify:   make(chan bool, 1),
 	}
 	go op.wait()
-	ops.ops[id] = op
+	go ops.insert(op)
 	return op
 }
 
+// Inserts op into the ops map.
+func (ops *Operations) insert(op *Operation) {
+	ops.lock.Lock()
+	defer ops.lock.Unlock()
+	ops.ops[op.ID] = op
+}
+
 // List operations for an API client.
-func (ops *Operations) List() ServerOpList {
+func (ops *Operations) List() api.ServerOpList {
 	ops.lock.Lock()
 	defer ops.lock.Unlock()
 
@@ -94,9 +86,9 @@ func (ops *Operations) List() ServerOpList {
 		ids = append(ids, id)
 	}
 	sort.StringSlice(ids).Sort()
-	ol := ServerOpList{}
+	ol := api.ServerOpList{}
 	for _, id := range ids {
-		ol.Items = append(ol.Items, ServerOp{JSONBase: api.JSONBase{ID: id}})
+		ol.Items = append(ol.Items, api.ServerOp{JSONBase: api.JSONBase{ID: id}})
 	}
 	return ol
 }
@@ -124,7 +116,9 @@ func (ops *Operations) expire(maxAge time.Duration) {
 
 // Waits forever for the operation to complete; call via go when
 // the operation is created. Sets op.finished when the operation
-// does complete. Does not keep op locked while waiting.
+// does complete, and sends on the notify channel, in case there
+// are any WaitFor() calls in progress.
+// Does not keep op locked while waiting.
 func (op *Operation) wait() {
 	defer util.HandleCrash()
 	result := <-op.awaiting
@@ -161,7 +155,7 @@ func (op *Operation) expired(limitTime time.Time) bool {
 
 // Return status information or the result of the operation if it is complete,
 // with a bool indicating true in the latter case.
-func (op *Operation) Describe() (description interface{}, finished bool) {
+func (op *Operation) StatusOrResult() (description interface{}, finished bool) {
 	op.lock.Lock()
 	defer op.lock.Unlock()
 

pkg/apiserver/operation_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package apiserver
 
 import (
+	"sync/atomic"
 	"testing"
 	"time"
 )
@@ -26,6 +27,10 @@ func TestOperation(t *testing.T) {
 
 	c := make(chan interface{})
 	op := ops.NewOperation(c)
+	// Allow context switch, so that op's ID can get added to the map and Get will work.
+	// This is just so we can test Get. Ordinary users have no need to call Get immediately
+	// after calling NewOperation, because it returns the operation directly.
+	time.Sleep(time.Millisecond)
 	go func() {
 		time.Sleep(500 * time.Millisecond)
 		c <- "All done"
@@ -40,16 +45,28 @@ func TestOperation(t *testing.T) {
 	}
 
 	op.WaitFor(10 * time.Millisecond)
-	if _, completed := op.Describe(); completed {
+	if _, completed := op.StatusOrResult(); completed {
 		t.Errorf("Unexpectedly fast completion")
 	}
 
-	op.WaitFor(time.Second)
+	const waiters = 10
-	if _, completed := op.Describe(); !completed {
+	var waited int32
+	for i := 0; i < waiters; i++ {
+		go func() {
+			op.WaitFor(time.Hour)
+			atomic.AddInt32(&waited, 1)
+		}()
+	}
+
+	op.WaitFor(time.Minute)
+	if _, completed := op.StatusOrResult(); !completed {
 		t.Errorf("Unexpectedly slow completion")
 	}
 
 	time.Sleep(100 * time.Millisecond)
+	if waited != waiters {
+		t.Errorf("Multiple waiters doesn't work, only %v finished", waited)
+	}
 
 	if op.expired(time.Now().Add(-time.Second)) {
 		t.Errorf("Should not be expired: %#v", op)