X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/b2bcd45082d2df2b5a17645eb60473cc17c76e88..ae8aaa4c55762222c837fcce8e9ad6800ff8b128:/services/keepstore/azure_blob_volume_test.go

diff --git a/services/keepstore/azure_blob_volume_test.go b/services/keepstore/azure_blob_volume_test.go
index 619c013a31..4b015a9962 100644
--- a/services/keepstore/azure_blob_volume_test.go
+++ b/services/keepstore/azure_blob_volume_test.go
@@ -1,11 +1,16 @@
 package main
 
 import (
+	"bytes"
+	"context"
+	"crypto/md5"
 	"encoding/base64"
+	"encoding/json"
 	"encoding/xml"
 	"flag"
+	"fmt"
 	"io/ioutil"
-	"log"
+	"math/rand"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -17,13 +22,18 @@ import (
 	"testing"
 	"time"
 
-	"github.com/Azure/azure-sdk-for-go/storage"
+	log "github.com/Sirupsen/logrus"
+	"github.com/curoverse/azure-sdk-for-go/storage"
+	check "gopkg.in/check.v1"
 )
 
 const (
-	// The same fake credentials used by Microsoft's Azure emulator
-	emulatorAccountName = "devstoreaccount1"
-	emulatorAccountKey = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw=="
+	// This cannot be the fake account name "devstoreaccount1"
+	// used by Microsoft's Azure emulator: the Azure SDK
+	// recognizes that magic string and changes its behavior to
+	// cater to the Azure SDK's own test suite.
+	fakeAccountName = "fakeAccountName"
+	fakeAccountKey  = "Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw=="
 )
 
 var azureTestContainer string
@@ -36,15 +46,18 @@ func init() {
 		"Name of Azure container to use for testing. Do not use a container with real data! Use -azure-storage-account-name and -azure-storage-key-file arguments to supply credentials.")
 }
 
-type azBlob struct{
+type azBlob struct {
 	Data        []byte
+	Etag        string
+	Metadata    map[string]string
 	Mtime       time.Time
 	Uncommitted map[string][]byte
 }
 
 type azStubHandler struct {
 	sync.Mutex
-	blobs  map[string]*azBlob
+	blobs map[string]*azBlob
+	race  chan chan struct{}
 }
 
 func newAzStubHandler() *azStubHandler {
@@ -54,23 +67,41 @@ func newAzStubHandler() *azStubHandler {
 }
 
 func (h *azStubHandler) TouchWithDate(container, hash string, t time.Time) {
-	if blob, ok := h.blobs[container + "|" + hash]; !ok {
+	blob, ok := h.blobs[container+"|"+hash]
+	if !ok {
 		return
-	} else {
-		blob.Mtime = t
 	}
+	blob.Mtime = t
 }
 
 func (h *azStubHandler) PutRaw(container, hash string, data []byte) {
 	h.Lock()
 	defer h.Unlock()
-	h.blobs[container + "|" + hash] = &azBlob{
-		Data: data,
-		Mtime: time.Now(),
+	h.blobs[container+"|"+hash] = &azBlob{
+		Data:        data,
+		Mtime:       time.Now(),
+		Metadata:    make(map[string]string),
 		Uncommitted: make(map[string][]byte),
 	}
 }
 
+func (h *azStubHandler) unlockAndRace() {
+	if h.race == nil {
+		return
+	}
+	h.Unlock()
+	// Signal caller that race is starting by reading from
+	// h.race. If we get a channel, block until that channel is
+	// ready to receive. If we get nil (or h.race is closed) just
+	// proceed.
+	if c := <-h.race; c != nil {
+		c <- struct{}{}
+	}
+	h.Lock()
+}
+
+var rangeRegexp = regexp.MustCompile(`^bytes=(\d+)-(\d+)$`)
+
 func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 	h.Lock()
 	defer h.Unlock()
@@ -99,17 +130,41 @@ func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		Uncommitted []string
 	}
 
-	blob, blobExists := h.blobs[container + "|" + hash]
+	blob, blobExists := h.blobs[container+"|"+hash]
 
 	switch {
-	case r.Method == "PUT" && r.Form.Get("comp") == "" && r.Header.Get("Content-Length") == "0":
-		rw.WriteHeader(http.StatusCreated)
-		h.blobs[container + "|" + hash] = &azBlob{
-			Data:  body,
-			Mtime: time.Now(),
+	case r.Method == "PUT" && r.Form.Get("comp") == "":
+		// "Put Blob" API
+		if _, ok := h.blobs[container+"|"+hash]; !ok {
+			// Like the real Azure service, we offer a
+			// race window during which other clients can
+			// list/get the new blob before any data is
+			// committed.
+			h.blobs[container+"|"+hash] = &azBlob{
+				Mtime:       time.Now(),
+				Uncommitted: make(map[string][]byte),
+				Metadata:    make(map[string]string),
+				Etag:        makeEtag(),
+			}
+			h.unlockAndRace()
+		}
+		metadata := make(map[string]string)
+		for k, v := range r.Header {
+			if strings.HasPrefix(strings.ToLower(k), "x-ms-meta-") {
+				name := k[len("x-ms-meta-"):]
+				metadata[strings.ToLower(name)] = v[0]
+			}
+		}
+		h.blobs[container+"|"+hash] = &azBlob{
+			Data:        body,
+			Mtime:       time.Now(),
 			Uncommitted: make(map[string][]byte),
+			Metadata:    metadata,
+			Etag:        makeEtag(),
 		}
+		rw.WriteHeader(http.StatusCreated)
 	case r.Method == "PUT" && r.Form.Get("comp") == "block":
+		// "Put Block" API
 		if !blobExists {
 			log.Printf("Got block for nonexistent blob: %+v", r)
 			rw.WriteHeader(http.StatusBadRequest)
@@ -124,6 +179,7 @@ func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		blob.Uncommitted[string(blockID)] = body
 		rw.WriteHeader(http.StatusCreated)
 	case r.Method == "PUT" && r.Form.Get("comp") == "blocklist":
+		// "Put Block List" API
 		bl := &blockListRequestBody{}
 		if err := xml.Unmarshal(body, bl); err != nil {
 			log.Printf("xml Unmarshal: %s", err)
@@ -138,29 +194,77 @@ func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 				return
 			}
 			blob.Data = blob.Uncommitted[string(blockID)]
-			log.Printf("body %+q, bl %+v, blockID %+q, data %+q", body, bl, blockID, blob.Data)
+			blob.Etag = makeEtag()
+			blob.Mtime = time.Now()
+			delete(blob.Uncommitted, string(blockID))
 		}
 		rw.WriteHeader(http.StatusCreated)
+	case r.Method == "PUT" && r.Form.Get("comp") == "metadata":
+		// "Set Metadata Headers" API. We don't bother
+		// stubbing "Get Metadata Headers": AzureBlobVolume
+		// sets metadata headers only as a way to bump Etag
+		// and Last-Modified.
+		if !blobExists {
+			log.Printf("Got metadata for nonexistent blob: %+v", r)
+			rw.WriteHeader(http.StatusBadRequest)
+			return
+		}
+		blob.Metadata = make(map[string]string)
+		for k, v := range r.Header {
+			if strings.HasPrefix(strings.ToLower(k), "x-ms-meta-") {
+				name := k[len("x-ms-meta-"):]
+				blob.Metadata[strings.ToLower(name)] = v[0]
+			}
+		}
+		blob.Mtime = time.Now()
+		blob.Etag = makeEtag()
+	case (r.Method == "GET" || r.Method == "HEAD") && r.Form.Get("comp") == "metadata" && hash != "":
+		// "Get Blob Metadata" API
+		if !blobExists {
+			rw.WriteHeader(http.StatusNotFound)
+			return
+		}
+		for k, v := range blob.Metadata {
+			rw.Header().Set(fmt.Sprintf("x-ms-meta-%s", k), v)
+		}
+		return
 	case (r.Method == "GET" || r.Method == "HEAD") && hash != "":
+		// "Get Blob" API
 		if !blobExists {
 			rw.WriteHeader(http.StatusNotFound)
 			return
 		}
+		data := blob.Data
+		if rangeSpec := rangeRegexp.FindStringSubmatch(r.Header.Get("Range")); rangeSpec != nil {
+			b0, err0 := strconv.Atoi(rangeSpec[1])
+			b1, err1 := strconv.Atoi(rangeSpec[2])
+			if err0 != nil || err1 != nil || b0 >= len(data) || b1 >= len(data) || b0 > b1 {
+				rw.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", len(data)))
+				rw.WriteHeader(http.StatusRequestedRangeNotSatisfiable)
+				return
+			}
+			rw.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", b0, b1, len(data)))
+			rw.WriteHeader(http.StatusPartialContent)
+			data = data[b0 : b1+1]
+		}
 		rw.Header().Set("Last-Modified", blob.Mtime.Format(time.RFC1123))
-		rw.Header().Set("Content-Length", strconv.Itoa(len(blob.Data)))
+		rw.Header().Set("Content-Length", strconv.Itoa(len(data)))
 		if r.Method == "GET" {
-			if _, err := rw.Write(blob.Data); err != nil {
-				log.Printf("write %+q: %s", blob.Data, err)
+			if _, err := rw.Write(data); err != nil {
+				log.Printf("write %+q: %s", data, err)
 			}
 		}
+		h.unlockAndRace()
 	case r.Method == "DELETE" && hash != "":
+		// "Delete Blob" API
 		if !blobExists {
 			rw.WriteHeader(http.StatusNotFound)
 			return
 		}
-		delete(h.blobs, container + "|" + hash)
+		delete(h.blobs, container+"|"+hash)
 		rw.WriteHeader(http.StatusAccepted)
 	case r.Method == "GET" && r.Form.Get("comp") == "list" && r.Form.Get("restype") == "container":
+		// "List Blobs" API
 		prefix := container + "|" + r.Form.Get("prefix")
 		marker := r.Form.Get("marker")
 
@@ -170,7 +274,7 @@ func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		}
 
 		resp := storage.BlobListResponse{
-			Marker: marker,
+			Marker:     marker,
 			NextMarker: "",
 			MaxResults: int64(maxResults),
 		}
@@ -187,14 +291,21 @@ func (h *azStubHandler) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 				break
 			}
 			if len(resp.Blobs) > 0 || marker == "" || marker == hash {
-				blob := h.blobs[container + "|" + hash]
-				resp.Blobs = append(resp.Blobs, storage.Blob{
+				blob := h.blobs[container+"|"+hash]
+				bmeta := map[string]string(nil)
+				if r.Form.Get("include") == "metadata" {
+					bmeta = blob.Metadata
+				}
+				b := storage.Blob{
 					Name: hash,
 					Properties: storage.BlobProperties{
-						LastModified: blob.Mtime.Format(time.RFC1123),
+						LastModified:  blob.Mtime.Format(time.RFC1123),
 						ContentLength: int64(len(blob.Data)),
+						Etag:          blob.Etag,
 					},
-				})
+					Metadata: bmeta,
+				}
+				resp.Blobs = append(resp.Blobs, b)
 			}
 		}
 		buf, err := xml.Marshal(resp)
@@ -217,6 +328,7 @@ type azStubDialer struct {
 }
 
 var localHostPortRe = regexp.MustCompile(`(127\.0\.0\.1|localhost|\[::1\]):\d+`)
+
 func (d *azStubDialer) Dial(network, address string) (net.Conn, error) {
 	if hp := localHostPortRe.FindString(address); hp != "" {
 		log.Println("azStubDialer: dial", hp, "instead of", address)
@@ -229,10 +341,10 @@ type TestableAzureBlobVolume struct {
 	*AzureBlobVolume
 	azHandler *azStubHandler
 	azStub    *httptest.Server
-	t         *testing.T
+	t         TB
 }
 
-func NewTestableAzureBlobVolume(t *testing.T, readonly bool) TestableVolume {
+func NewTestableAzureBlobVolume(t TB, readonly bool, replication int) *TestableAzureBlobVolume {
 	azHandler := newAzStubHandler()
 	azStub := httptest.NewServer(azHandler)
 
@@ -243,7 +355,7 @@ func NewTestableAzureBlobVolume(t *testing.T, readonly bool) TestableVolume {
 		// Connect to stub instead of real Azure storage service
 		stubURLBase := strings.Split(azStub.URL, "://")[1]
 		var err error
-		if azClient, err = storage.NewClient(emulatorAccountName, emulatorAccountKey, stubURLBase, storage.DefaultAPIVersion, false); err != nil {
+		if azClient, err = storage.NewClient(fakeAccountName, fakeAccountKey, stubURLBase, storage.DefaultAPIVersion, false); err != nil {
 			t.Fatal(err)
 		}
 		container = "fakecontainername"
@@ -259,14 +371,44 @@ func NewTestableAzureBlobVolume(t *testing.T, readonly bool) TestableVolume {
 		}
 	}
 
-	v := NewAzureBlobVolume(azClient, container, readonly)
+	bs := azClient.GetBlobService()
+	v := &AzureBlobVolume{
+		ContainerName:    container,
+		ReadOnly:         readonly,
+		AzureReplication: replication,
+		azClient:         azClient,
+		bsClient:         &azureBlobClient{client: &bs},
+	}
 
 	return &TestableAzureBlobVolume{
 		AzureBlobVolume: v,
-		azHandler: azHandler,
-		azStub: azStub,
-		t: t,
+		azHandler:       azHandler,
+		azStub:          azStub,
+		t:               t,
+	}
+}
+
+var _ = check.Suite(&StubbedAzureBlobSuite{})
+
+type StubbedAzureBlobSuite struct {
+	volume            *TestableAzureBlobVolume
+	origHTTPTransport http.RoundTripper
+}
+
+func (s *StubbedAzureBlobSuite) SetUpTest(c *check.C) {
+	s.origHTTPTransport = http.DefaultTransport
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
 	}
+	azureWriteRaceInterval = time.Millisecond
+	azureWriteRacePollTime = time.Nanosecond
+
+	s.volume = NewTestableAzureBlobVolume(c, false, 3)
+}
+
+func (s *StubbedAzureBlobSuite) TearDownTest(c *check.C) {
+	s.volume.Teardown()
+	http.DefaultTransport = s.origHTTPTransport
 }
 
 func TestAzureBlobVolumeWithGeneric(t *testing.T) {
@@ -276,11 +418,34 @@ func TestAzureBlobVolumeWithGeneric(t *testing.T) {
 	http.DefaultTransport = &http.Transport{
 		Dial: (&azStubDialer{}).Dial,
 	}
-	DoGenericVolumeTests(t, func(t *testing.T) TestableVolume {
-		return NewTestableAzureBlobVolume(t, false)
+	azureWriteRaceInterval = time.Millisecond
+	azureWriteRacePollTime = time.Nanosecond
+	DoGenericVolumeTests(t, func(t TB) TestableVolume {
+		return NewTestableAzureBlobVolume(t, false, azureStorageReplication)
 	})
 }
 
+func TestAzureBlobVolumeConcurrentRanges(t *testing.T) {
+	defer func(b int) {
+		azureMaxGetBytes = b
+	}(azureMaxGetBytes)
+
+	defer func(t http.RoundTripper) {
+		http.DefaultTransport = t
+	}(http.DefaultTransport)
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
+	}
+	azureWriteRaceInterval = time.Millisecond
+	azureWriteRacePollTime = time.Nanosecond
+	// Test (BlockSize mod azureMaxGetBytes)==0 and !=0 cases
+	for _, azureMaxGetBytes = range []int{2 << 22, 2<<22 - 1} {
+		DoGenericVolumeTests(t, func(t TB) TestableVolume {
+			return NewTestableAzureBlobVolume(t, false, azureStorageReplication)
+		})
+	}
+}
+
 func TestReadonlyAzureBlobVolumeWithGeneric(t *testing.T) {
 	defer func(t http.RoundTripper) {
 		http.DefaultTransport = t
@@ -288,19 +453,264 @@ func TestReadonlyAzureBlobVolumeWithGeneric(t *testing.T) {
 	http.DefaultTransport = &http.Transport{
 		Dial: (&azStubDialer{}).Dial,
 	}
-	DoGenericVolumeTests(t, func(t *testing.T) TestableVolume {
-		return NewTestableAzureBlobVolume(t, true)
+	azureWriteRaceInterval = time.Millisecond
+	azureWriteRacePollTime = time.Nanosecond
+	DoGenericVolumeTests(t, func(t TB) TestableVolume {
+		return NewTestableAzureBlobVolume(t, true, azureStorageReplication)
+	})
+}
+
+func TestAzureBlobVolumeRangeFenceposts(t *testing.T) {
+	defer func(t http.RoundTripper) {
+		http.DefaultTransport = t
+	}(http.DefaultTransport)
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
+	}
+
+	v := NewTestableAzureBlobVolume(t, false, 3)
+	defer v.Teardown()
+
+	for _, size := range []int{
+		2<<22 - 1, // one <max read
+		2 << 22,   // one =max read
+		2<<22 + 1, // one =max read, one <max
+		2 << 23,   // two =max reads
+		BlockSize - 1,
+		BlockSize,
+	} {
+		data := make([]byte, size)
+		for i := range data {
+			data[i] = byte((i + 7) & 0xff)
+		}
+		hash := fmt.Sprintf("%x", md5.Sum(data))
+		err := v.Put(context.Background(), hash, data)
+		if err != nil {
+			t.Error(err)
+		}
+		gotData := make([]byte, len(data))
+		gotLen, err := v.Get(context.Background(), hash, gotData)
+		if err != nil {
+			t.Error(err)
+		}
+		gotHash := fmt.Sprintf("%x", md5.Sum(gotData))
+		if gotLen != size {
+			t.Errorf("length mismatch: got %d != %d", gotLen, size)
+		}
+		if gotHash != hash {
+			t.Errorf("hash mismatch: got %s != %s", gotHash, hash)
+		}
+	}
+}
+
+func TestAzureBlobVolumeReplication(t *testing.T) {
+	for r := 1; r <= 4; r++ {
+		v := NewTestableAzureBlobVolume(t, false, r)
+		defer v.Teardown()
+		if n := v.Replication(); n != r {
+			t.Errorf("Got replication %d, expected %d", n, r)
+		}
+	}
+}
+
+func TestAzureBlobVolumeCreateBlobRace(t *testing.T) {
+	defer func(t http.RoundTripper) {
+		http.DefaultTransport = t
+	}(http.DefaultTransport)
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
+	}
+
+	v := NewTestableAzureBlobVolume(t, false, 3)
+	defer v.Teardown()
+
+	azureWriteRaceInterval = time.Second
+	azureWriteRacePollTime = time.Millisecond
+
+	allDone := make(chan struct{})
+	v.azHandler.race = make(chan chan struct{})
+	go func() {
+		err := v.Put(context.Background(), TestHash, TestBlock)
+		if err != nil {
+			t.Error(err)
+		}
+	}()
+	continuePut := make(chan struct{})
+	// Wait for the stub's Put to create the empty blob
+	v.azHandler.race <- continuePut
+	go func() {
+		buf := make([]byte, len(TestBlock))
+		_, err := v.Get(context.Background(), TestHash, buf)
+		if err != nil {
+			t.Error(err)
+		}
+		close(allDone)
+	}()
+	// Wait for the stub's Get to get the empty blob
+	close(v.azHandler.race)
+	// Allow stub's Put to continue, so the real data is ready
+	// when the volume's Get retries
+	<-continuePut
+	// Wait for volume's Get to return the real data
+	<-allDone
+}
+
+func TestAzureBlobVolumeCreateBlobRaceDeadline(t *testing.T) {
+	defer func(t http.RoundTripper) {
+		http.DefaultTransport = t
+	}(http.DefaultTransport)
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
+	}
+
+	v := NewTestableAzureBlobVolume(t, false, 3)
+	defer v.Teardown()
+
+	azureWriteRaceInterval = 2 * time.Second
+	azureWriteRacePollTime = 5 * time.Millisecond
+
+	v.PutRaw(TestHash, nil)
+
+	buf := new(bytes.Buffer)
+	v.IndexTo("", buf)
+	if buf.Len() != 0 {
+		t.Errorf("Index %+q should be empty", buf.Bytes())
+	}
+
+	v.TouchWithDate(TestHash, time.Now().Add(-1982*time.Millisecond))
+
+	allDone := make(chan struct{})
+	go func() {
+		defer close(allDone)
+		buf := make([]byte, BlockSize)
+		n, err := v.Get(context.Background(), TestHash, buf)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if n != 0 {
+			t.Errorf("Got %+q, expected empty buf", buf[:n])
+		}
+	}()
+	select {
+	case <-allDone:
+	case <-time.After(time.Second):
+		t.Error("Get should have stopped waiting for race when block was 2s old")
+	}
+
+	buf.Reset()
+	v.IndexTo("", buf)
+	if !bytes.HasPrefix(buf.Bytes(), []byte(TestHash+"+0")) {
+		t.Errorf("Index %+q should have %+q", buf.Bytes(), TestHash+"+0")
+	}
+}
+
+func TestAzureBlobVolumeContextCancelGet(t *testing.T) {
+	testAzureBlobVolumeContextCancel(t, func(ctx context.Context, v *TestableAzureBlobVolume) error {
+		v.PutRaw(TestHash, TestBlock)
+		_, err := v.Get(ctx, TestHash, make([]byte, BlockSize))
+		return err
+	})
+}
+
+func TestAzureBlobVolumeContextCancelPut(t *testing.T) {
+	testAzureBlobVolumeContextCancel(t, func(ctx context.Context, v *TestableAzureBlobVolume) error {
+		return v.Put(ctx, TestHash, make([]byte, BlockSize))
+	})
+}
+
+func TestAzureBlobVolumeContextCancelCompare(t *testing.T) {
+	testAzureBlobVolumeContextCancel(t, func(ctx context.Context, v *TestableAzureBlobVolume) error {
+		v.PutRaw(TestHash, TestBlock)
+		return v.Compare(ctx, TestHash, TestBlock2)
 	})
 }
 
+func testAzureBlobVolumeContextCancel(t *testing.T, testFunc func(context.Context, *TestableAzureBlobVolume) error) {
+	defer func(t http.RoundTripper) {
+		http.DefaultTransport = t
+	}(http.DefaultTransport)
+	http.DefaultTransport = &http.Transport{
+		Dial: (&azStubDialer{}).Dial,
+	}
+
+	v := NewTestableAzureBlobVolume(t, false, 3)
+	defer v.Teardown()
+	v.azHandler.race = make(chan chan struct{})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	allDone := make(chan struct{})
+	go func() {
+		defer close(allDone)
+		err := testFunc(ctx, v)
+		if err != context.Canceled {
+			t.Errorf("got %T %q, expected %q", err, err, context.Canceled)
+		}
+	}()
+	releaseHandler := make(chan struct{})
+	select {
+	case <-allDone:
+		t.Error("testFunc finished without waiting for v.azHandler.race")
+	case <-time.After(10 * time.Second):
+		t.Error("timed out waiting to enter handler")
+	case v.azHandler.race <- releaseHandler:
+	}
+
+	cancel()
+
+	select {
+	case <-time.After(10 * time.Second):
+		t.Error("timed out waiting to cancel")
+	case <-allDone:
+	}
+
+	go func() {
+		<-releaseHandler
+	}()
+}
+
+func (s *StubbedAzureBlobSuite) TestStats(c *check.C) {
+	stats := func() string {
+		buf, err := json.Marshal(s.volume.InternalStats())
+		c.Check(err, check.IsNil)
+		return string(buf)
+	}
+
+	c.Check(stats(), check.Matches, `.*"Ops":0,.*`)
+	c.Check(stats(), check.Matches, `.*"Errors":0,.*`)
+
+	loc := "acbd18db4cc2f85cedef654fccc4a4d8"
+	_, err := s.volume.Get(context.Background(), loc, make([]byte, 3))
+	c.Check(err, check.NotNil)
+	c.Check(stats(), check.Matches, `.*"Ops":[^0],.*`)
+	c.Check(stats(), check.Matches, `.*"Errors":[^0],.*`)
+	c.Check(stats(), check.Matches, `.*"storage\.AzureStorageServiceError 404 \(404 Not Found\)":[^0].*`)
+	c.Check(stats(), check.Matches, `.*"InBytes":0,.*`)
+
+	err = s.volume.Put(context.Background(), loc, []byte("foo"))
+	c.Check(err, check.IsNil)
+	c.Check(stats(), check.Matches, `.*"OutBytes":3,.*`)
+	c.Check(stats(), check.Matches, `.*"CreateOps":1,.*`)
+
+	_, err = s.volume.Get(context.Background(), loc, make([]byte, 3))
+	c.Check(err, check.IsNil)
+	_, err = s.volume.Get(context.Background(), loc, make([]byte, 3))
+	c.Check(err, check.IsNil)
+	c.Check(stats(), check.Matches, `.*"InBytes":6,.*`)
+}
+
 func (v *TestableAzureBlobVolume) PutRaw(locator string, data []byte) {
-	v.azHandler.PutRaw(v.containerName, locator, data)
+	v.azHandler.PutRaw(v.ContainerName, locator, data)
 }
 
 func (v *TestableAzureBlobVolume) TouchWithDate(locator string, lastPut time.Time) {
-	v.azHandler.TouchWithDate(v.containerName, locator, lastPut)
+	v.azHandler.TouchWithDate(v.ContainerName, locator, lastPut)
 }
 
 func (v *TestableAzureBlobVolume) Teardown() {
 	v.azStub.Close()
 }
+
+func makeEtag() string {
+	return fmt.Sprintf("0x%x", rand.Int63())
+}