Test atomic PUTs, and make them work.

Improve apiserver/logger.go's interface (it's pretty cool now).

Improve apiserver's error reporting to clients.

Improve client's handling of errors from apiserver.

Make failed PUTs return 409 (conflict)-- http status codes are amazingly
well defined for what we're doing!

cmd/integration/integration.go

@@ -23,7 +23,9 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"reflect"
 	"runtime"
+	"sync"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
@@ -128,8 +130,73 @@ func runReplicationControllerTest(kubeClient *client.Client) {
 	glog.Infof("Replication controller produced:\n\n%#v\n\n", pods)
 }
 
+func runAtomicPutTest(c *client.Client) {
+	var svc api.Service
+	err := c.Post().Path("services").Body(
+		api.Service{
+			JSONBase: api.JSONBase{ID: "atomicService"},
+			Port:     12345,
+			Labels: map[string]string{
+				"name": "atomicService",
+			},
+		},
+	).Do().Into(&svc)
+	if err != nil {
+		glog.Fatalf("Failed creating atomicService: %v", err)
+	}
+
+	testLabels := labels.Set{}
+	for i := 0; i < 26; i++ {
+		// a: z, b: y, etc...
+		testLabels[string([]byte{byte('a' + i)})] = string([]byte{byte('z' - i)})
+	}
+	var wg sync.WaitGroup
+	wg.Add(len(testLabels))
+	for label, value := range testLabels {
+		go func(l, v string) {
+			for {
+				var tmpSvc api.Service
+				err := c.Get().Path("services").Path(svc.ID).Do().Into(&tmpSvc)
+				if err != nil {
+					glog.Errorf("Error getting atomicService: %v", err)
+					continue
+				}
+				if tmpSvc.Selector == nil {
+					tmpSvc.Selector = map[string]string{l: v}
+				} else {
+					tmpSvc.Selector[l] = v
+				}
+				err = c.Put().Path("services").Path(svc.ID).Body(&tmpSvc).Do().Error()
+				if err != nil {
+					if se, ok := err.(*client.StatusErr); ok {
+						if se.Status.Code == http.StatusConflict {
+							// This is what we expect.
+							continue
+						}
+					}
+					glog.Errorf("Unexpected error putting atomicService: %v", err)
+					continue
+				}
+				break
+			}
+			wg.Done()
+		}(label, value)
+	}
+	wg.Wait()
+	err = c.Get().Path("services").Path(svc.ID).Do().Into(&svc)
+	if err != nil {
+		glog.Fatalf("Failed getting atomicService after writers are complete: %v", err)
+	}
+	if !reflect.DeepEqual(testLabels, labels.Set(svc.Selector)) {
+		glog.Fatalf("Selector PUTs were not atomic: wanted %v, got %v", testLabels, svc.Selector)
+	}
+	glog.Info("Atomic PUTs work.")
+}
+
+type testFunc func(*client.Client)
+
 func main() {
-	runtime.GOMAXPROCS(4)
+	runtime.GOMAXPROCS(runtime.NumCPU())
 	util.ReallyCrash = true
 	util.InitLogs()
 	defer util.FlushLogs()
@@ -150,7 +217,22 @@ func main() {
 	time.Sleep(time.Second * 10)
 
 	kubeClient := client.New(apiServerURL, nil)
-	runReplicationControllerTest(kubeClient)
+
+	// Run tests in parallel
+	testFuncs := []testFunc{
+		runReplicationControllerTest,
+		runAtomicPutTest,
+	}
+	var wg sync.WaitGroup
+	wg.Add(len(testFuncs))
+	for i := range testFuncs {
+		f := testFuncs[i]
+		go func() {
+			f(kubeClient)
+			wg.Done()
+		}()
+	}
+	wg.Wait()
 
 	// Check that kubelet tried to make the pods.
 	// Using a set to list unique creation attempts. Our fake is

pkg/api/helper.go

@@ -56,6 +56,23 @@ func FindJSONBase(obj interface{}) (*JSONBase, error) {
 	return jsonBase, err
 }
 
+// Takes an arbitary api type, return a copy of its JSONBase field.
+// obj may be a pointer to an api type, or a non-pointer struct api type.
+func FindJSONBaseRO(obj interface{}) (JSONBase, error) {
+	v := reflect.ValueOf(obj)
+	if v.Kind() == reflect.Ptr {
+		v = v.Elem()
+	}
+	if v.Kind() != reflect.Struct {
+		return JSONBase{}, fmt.Errorf("expected struct, but got %v", v.Type().Name())
+	}
+	jsonBase := v.FieldByName("JSONBase")
+	if !jsonBase.IsValid() {
+		return JSONBase{}, fmt.Errorf("struct %v lacks embedded JSON type", v.Type().Name())
+	}
+	return jsonBase.Interface().(JSONBase), nil
+}
+
 // Encode turns the given api object into an appropriate JSON string.
 // Will return an error if the object doesn't have an embedded JSONBase.
 // Obj may be a pointer to a struct, or a struct. If a struct, a copy

pkg/api/types.go

@@ -267,8 +267,12 @@ type Status struct {
 	// One of: "success", "failure", "working" (for operations not yet completed)
 	// TODO: if "working", include an operation identifier so final status can be
 	// checked.
-	Status  string `json:"status,omitempty" yaml:"status,omitempty"`
+	Status string `json:"status,omitempty" yaml:"status,omitempty"`
+	// Details about the status. May be an error description or an
+	// operation number for later polling.
 	Details string `json:"details,omitempty" yaml:"details,omitempty"`
+	// Suggested HTTP return code for this status, 0 if not set.
+	Code int `json:"code,omitempty" yaml:"code,omitempty"`
 }
 
 // Values of Status.Status

pkg/apiserver/apiserver.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/tools"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 	"github.com/golang/glog"
 )
@@ -54,9 +55,15 @@ func MakeAsync(fn WorkFunc) <-chan interface{} {
 		defer util.HandleCrash()
 		obj, err := fn()
 		if err != nil {
+			status := http.StatusInternalServerError
+			switch {
+			case tools.IsEtcdConflict(err):
+				status = http.StatusConflict
+			}
 			channel <- &api.Status{
 				Status:  api.StatusFailure,
 				Details: err.Error(),
+				Code:    status,
 			}
 		} else {
 			channel <- obj
@@ -110,9 +117,13 @@ func (server *ApiServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 			glog.Infof("ApiServer panic'd on %v %v: %#v\n%s\n", req.Method, req.RequestURI, x, debug.Stack())
 		}
 	}()
-	logger := MakeLogged(req, w)
-	w = logger
-	defer logger.Log()
+	defer MakeLogged(req, &w).StacktraceWhen(
+		StatusIsNot(
+			http.StatusOK,
+			http.StatusAccepted,
+			http.StatusConflict,
+		),
+	).Log()
 	url, err := url.ParseRequestURI(req.RequestURI)
 	if err != nil {
 		server.error(err, w)
@@ -141,7 +152,7 @@ func (server *ApiServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 	storage := server.storage[requestParts[0]]
 	if storage == nil {
-		logger.Addf("'%v' has no storage object", requestParts[0])
+		LogOf(w).Addf("'%v' has no storage object", requestParts[0])
 		server.notFound(req, w)
 		return
 	} else {
@@ -171,8 +182,7 @@ func (server *ApiServer) error(err error, w http.ResponseWriter) {
 
 func (server *ApiServer) readBody(req *http.Request) ([]byte, error) {
 	defer req.Body.Close()
-	body, err := ioutil.ReadAll(req.Body)
-	return body, err
+	return ioutil.ReadAll(req.Body)
 }
 
 // finishReq finishes up a request, waiting until the operation finishes or, after a timeout, creating an
@@ -184,7 +194,19 @@ func (server *ApiServer) finishReq(out <-chan interface{}, sync bool, timeout ti
 	}
 	obj, complete := op.StatusOrResult()
 	if complete {
-		server.write(http.StatusOK, obj, w)
+		status := http.StatusOK
+		switch stat := obj.(type) {
+		case api.Status:
+			LogOf(w).Addf("programmer error: use *api.Status as a result, not api.Status.")
+			if stat.Code != 0 {
+				status = stat.Code
+			}
+		case *api.Status:
+			if stat.Code != 0 {
+				status = stat.Code
+			}
+		}
+		server.write(status, obj, w)
 	} else {
 		server.write(http.StatusAccepted, obj, w)
 	}

pkg/apiserver/logger.go

@@ -25,6 +25,9 @@ import (
 	"github.com/golang/glog"
 )
 
+// Return true if a stacktrace should be logged for this status
+type StacktracePred func(httpStatus int) (logStacktrace bool)
+
 // Add a layer on top of ResponseWriter, so we can track latency and error
 // message sources.
 type respLogger struct {
@@ -35,17 +38,64 @@ type respLogger struct {
 
 	req *http.Request
 	w   http.ResponseWriter
+
+	logStacktracePred StacktracePred
 }
 
+func DefaultStacktracePred(status int) bool {
+	return status != http.StatusOK && status != http.StatusAccepted
+}
+
+// MakeLogged turns a normal response writer into a logged response writer.
+//
 // Usage:
-// logger := MakeLogged(req, w)
-// w = logger // Route response writing actions through w
-// defer logger.Log()
-func MakeLogged(req *http.Request, w http.ResponseWriter) *respLogger {
-	return &respLogger{
-		startTime: time.Now(),
-		req:       req,
-		w:         w,
+//
+// defer MakeLogged(req, &w).StacktraceWhen(StatusIsNot(200, 202)).Log()
+//
+// (Only the call to Log() is defered, so you can set everything up in one line!)
+//
+// Note that this *changes* your writer, to route response writing actions
+// through the logger.
+//
+// Use LogOf(w).Addf(...) to log something along with the response result.
+func MakeLogged(req *http.Request, w *http.ResponseWriter) *respLogger {
+	rl := &respLogger{
+		startTime:         time.Now(),
+		req:               req,
+		w:                 *w,
+		logStacktracePred: DefaultStacktracePred,
+	}
+	*w = rl // hijack caller's writer!
+	return rl
+}
+
+// LogOf returns the logger hiding in w. Panics if there isn't such a logger,
+// because MakeLogged() must have been previously called for the log to work.
+func LogOf(w http.ResponseWriter) *respLogger {
+	if rl, ok := w.(*respLogger); ok {
+		return rl
+	}
+	panic("Logger not installed yet!")
+	return nil
+}
+
+// Sets the stacktrace logging predicate, which decides when to log a stacktrace.
+// There's a default, so you don't need to call this unless you don't like the default.
+func (rl *respLogger) StacktraceWhen(pred StacktracePred) *respLogger {
+	rl.logStacktracePred = pred
+	return rl
+}
+
+// StatusIsNot returns a StacktracePred which will cause stacktraces to be logged
+// for any status *not* in the given list.
+func StatusIsNot(statuses ...int) StacktracePred {
+	return func(status int) bool {
+		for _, s := range statuses {
+			if status == s {
+				return false
+			}
+		}
+		return true
 	}
 }
 
@@ -73,7 +123,7 @@ func (rl *respLogger) Write(b []byte) (int, error) {
 // Implement http.ResponseWriter
 func (rl *respLogger) WriteHeader(status int) {
 	rl.status = status
-	if status != http.StatusOK && status != http.StatusAccepted {
+	if rl.logStacktracePred(status) {
 		// Only log stacks for errors
 		stack := make([]byte, 2048)
 		stack = stack[:runtime.Stack(stack, false)]

pkg/client/client.go

@@ -100,16 +100,27 @@ func (c *Client) doRequest(request *http.Request) ([]byte, error) {
 	if err != nil {
 		return body, err
 	}
-	if response.StatusCode < http.StatusOK || response.StatusCode > http.StatusPartialContent {
+
+	// Did the server give us a status response?
+	isStatusResponse := false
+	var status api.Status
+	if err := api.DecodeInto(body, &status); err == nil && status.Status != "" {
+		isStatusResponse = true
+	}
+
+	switch {
+	case response.StatusCode == http.StatusConflict:
+		// Return error given by server, if there was one.
+		if isStatusResponse {
+			return nil, &StatusErr{status}
+		}
+		fallthrough
+	case response.StatusCode < http.StatusOK || response.StatusCode > http.StatusPartialContent:
 		return nil, fmt.Errorf("request [%#v] failed (%d) %s: %s", request, response.StatusCode, response.Status, string(body))
 	}
 
 	// If the server gave us a status back, look at what it was.
-	var status api.Status
-	if err := api.DecodeInto(body, &status); err == nil && status.Status != "" {
-		if status.Status == api.StatusSuccess {
-			return body, nil
-		}
+	if isStatusResponse && status.Status != api.StatusSuccess {
 		// "Working" requests need to be handled specially.
 		// "Failed" requests are clearly just an error and it makes sense to return them as such.
 		return nil, &StatusErr{status}

pkg/kubelet/kubelet_server.go

@@ -46,9 +46,7 @@ func (s *KubeletServer) error(w http.ResponseWriter, err error) {
 }
 
 func (s *KubeletServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	logger := apiserver.MakeLogged(req, w)
-	w = logger
-	defer logger.Log()
+	defer apiserver.MakeLogged(req, &w).Log()
 
 	u, err := url.ParseRequestURI(req.RequestURI)
 	if err != nil {

pkg/tools/etcd_tools.go

@@ -118,14 +118,8 @@ func (h *EtcdHelper) ExtractList(key string, slicePtr interface{}) error {
 // a zero object of the requested type, or an error, depending on ignoreNotFound. Treats
 // empty responses and nil response nodes exactly like a not found error.
 func (h *EtcdHelper) ExtractObj(key string, objPtr interface{}, ignoreNotFound bool) error {
-	_, index, err := h.bodyAndExtractObj(key, objPtr, ignoreNotFound)
-	if err != nil {
-		return err
-	}
-	if jsonBase, err := api.FindJSONBase(objPtr); err == nil {
-		jsonBase.ResourceVersion = index
-	}
-	return nil
+	_, _, err := h.bodyAndExtractObj(key, objPtr, ignoreNotFound)
+	return err
 }
 
 func (h *EtcdHelper) bodyAndExtractObj(key string, objPtr interface{}, ignoreNotFound bool) (body string, modifiedIndex uint64, err error) {
@@ -145,20 +139,30 @@ func (h *EtcdHelper) bodyAndExtractObj(key string, objPtr interface{}, ignoreNot
 		return "", 0, fmt.Errorf("key '%v' found no nodes field: %#v", key, response)
 	}
 	body = response.Node.Value
-	return body, response.Node.ModifiedIndex, json.Unmarshal([]byte(body), objPtr)
+	err = json.Unmarshal([]byte(body), objPtr)
+	if jsonBase, err := api.FindJSONBase(objPtr); err == nil {
+		jsonBase.ResourceVersion = response.Node.ModifiedIndex
+		// Note that err shadows the err returned below, so we won't
+		// return an error just because we failed to find a JSONBase.
+		// This is intentional.
+	}
+	return body, response.Node.ModifiedIndex, err
 }
 
-// SetObj marshals obj via json, and stores under key.
+// SetObj marshals obj via json, and stores under key. Will do an
+// atomic update if obj's ResourceVersion field is set.
 func (h *EtcdHelper) SetObj(key string, obj interface{}) error {
 	data, err := json.Marshal(obj)
 	if err != nil {
 		return err
 	}
-	if jsonBase, err := api.FindJSONBase(obj); err == nil && jsonBase.ResourceVersion != 0 {
+	if jsonBase, err := api.FindJSONBaseRO(obj); err == nil && jsonBase.ResourceVersion != 0 {
 		_, err = h.Client.CompareAndSwap(key, string(data), 0, "", jsonBase.ResourceVersion)
-	} else {
-		_, err = h.Client.Set(key, string(data), 0)
+		return err // err is shadowed!
 	}
+
+	// TODO: when client supports atomic creation, integrate this with the above.
+	_, err = h.Client.Set(key, string(data), 0)
 	return err
 }