X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/2eaa77dc327c024f2faa3fbd322e7054454b6442..93cfe7c262708fb09eda5aad1839c832816d4591:/services/keepstore/azure_blob_volume.go

diff --git a/services/keepstore/azure_blob_volume.go b/services/keepstore/azure_blob_volume.go
index 43cf83a07e..3c17b3bd06 100644
--- a/services/keepstore/azure_blob_volume.go
+++ b/services/keepstore/azure_blob_volume.go
@@ -1,3 +1,7 @@
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: AGPL-3.0
+
 package main
 
 import (
@@ -14,14 +18,19 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"git.curoverse.com/arvados.git/sdk/go/arvados"
-	log "github.com/Sirupsen/logrus"
-	"github.com/curoverse/azure-sdk-for-go/storage"
+	"github.com/Azure/azure-sdk-for-go/storage"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
-const azureDefaultRequestTimeout = arvados.Duration(10 * time.Minute)
+const (
+	azureDefaultRequestTimeout       = arvados.Duration(10 * time.Minute)
+	azureDefaultListBlobsMaxAttempts = 12
+	azureDefaultListBlobsRetryDelay  = arvados.Duration(10 * time.Second)
+)
 
 var (
 	azureMaxGetBytes           int
@@ -97,13 +106,25 @@ func init() {
 type AzureBlobVolume struct {
 	StorageAccountName    string
 	StorageAccountKeyFile string
+	StorageBaseURL        string // "" means default, "core.windows.net"
 	ContainerName         string
 	AzureReplication      int
 	ReadOnly              bool
 	RequestTimeout        arvados.Duration
+	StorageClasses        []string
+	ListBlobsRetryDelay   arvados.Duration
+	ListBlobsMaxAttempts  int
 
-	azClient storage.Client
-	bsClient storage.BlobStorageClient
+	azClient  storage.Client
+	container *azureContainer
+}
+
+// singleSender is a single-attempt storage.Sender.
+type singleSender struct{}
+
+// Send performs req exactly once.
+func (*singleSender) Send(c *storage.Client, req *http.Request) (resp *http.Response, err error) {
+	return c.HTTPClient.Do(req)
 }
 
 // Examples implements VolumeWithExamples.
@@ -116,6 +137,14 @@ func (*AzureBlobVolume) Examples() []Volume {
 			AzureReplication:      3,
 			RequestTimeout:        azureDefaultRequestTimeout,
 		},
+		&AzureBlobVolume{
+			StorageAccountName:    "cn-account-name",
+			StorageAccountKeyFile: "/etc/azure_cn_storage_account_key.txt",
+			StorageBaseURL:        "core.chinacloudapi.cn",
+			ContainerName:         "cn-container-name",
+			AzureReplication:      3,
+			RequestTimeout:        azureDefaultRequestTimeout,
+		},
 	}
 }
 
@@ -125,7 +154,13 @@ func (v *AzureBlobVolume) Type() string {
 }
 
 // Start implements Volume.
-func (v *AzureBlobVolume) Start() error {
+func (v *AzureBlobVolume) Start(vm *volumeMetricsVecs) error {
+	if v.ListBlobsRetryDelay == 0 {
+		v.ListBlobsRetryDelay = azureDefaultListBlobsRetryDelay
+	}
+	if v.ListBlobsMaxAttempts == 0 {
+		v.ListBlobsMaxAttempts = azureDefaultListBlobsMaxAttempts
+	}
 	if v.ContainerName == "" {
 		return errors.New("no container name given")
 	}
@@ -136,10 +171,14 @@ func (v *AzureBlobVolume) Start() error {
 	if err != nil {
 		return err
 	}
-	v.azClient, err = storage.NewBasicClient(v.StorageAccountName, accountKey)
+	if v.StorageBaseURL == "" {
+		v.StorageBaseURL = storage.DefaultBaseURL
+	}
+	v.azClient, err = storage.NewClient(v.StorageAccountName, accountKey, v.StorageBaseURL, storage.DefaultAPIVersion, true)
 	if err != nil {
 		return fmt.Errorf("creating Azure storage client: %s", err)
 	}
+	v.azClient.Sender = &singleSender{}
 
 	if v.RequestTimeout == 0 {
 		v.RequestTimeout = azureDefaultRequestTimeout
@@ -147,21 +186,31 @@ func (v *AzureBlobVolume) Start() error {
 	v.azClient.HTTPClient = &http.Client{
 		Timeout: time.Duration(v.RequestTimeout),
 	}
-	v.bsClient = v.azClient.GetBlobService()
+	bs := v.azClient.GetBlobService()
+	v.container = &azureContainer{
+		ctr: bs.GetContainerReference(v.ContainerName),
+	}
 
-	ok, err := v.bsClient.ContainerExists(v.ContainerName)
-	if err != nil {
+	if ok, err := v.container.Exists(); err != nil {
 		return err
-	}
-	if !ok {
+	} else if !ok {
 		return fmt.Errorf("Azure container %q does not exist", v.ContainerName)
 	}
+	// Set up prometheus metrics
+	lbls := prometheus.Labels{"device_id": v.DeviceID()}
+	v.container.stats.opsCounters, v.container.stats.errCounters, v.container.stats.ioBytes = vm.getCounterVecsFor(lbls)
+
 	return nil
 }
 
+// DeviceID returns a globally unique ID for the storage container.
+func (v *AzureBlobVolume) DeviceID() string {
+	return "azure://" + v.StorageBaseURL + "/" + v.StorageAccountName + "/" + v.ContainerName
+}
+
 // Return true if expires_at metadata attribute is found on the block
 func (v *AzureBlobVolume) checkTrashed(loc string) (bool, map[string]string, error) {
-	metadata, err := v.bsClient.GetBlobMetadata(v.ContainerName, loc)
+	metadata, err := v.container.GetBlobMetadata(loc)
 	if err != nil {
 		return false, metadata, v.translateError(err)
 	}
@@ -187,7 +236,7 @@ func (v *AzureBlobVolume) Get(ctx context.Context, loc string, buf []byte) (int,
 	}
 	var deadline time.Time
 	haveDeadline := false
-	size, err := v.get(loc, buf)
+	size, err := v.get(ctx, loc, buf)
 	for err == nil && size == 0 && loc != "d41d8cd98f00b204e9800998ecf8427e" {
 		// Seeing a brand new empty block probably means we're
 		// in a race with CreateBlob, which under the hood
@@ -208,8 +257,12 @@ func (v *AzureBlobVolume) Get(ctx context.Context, loc string, buf []byte) (int,
 		} else if time.Now().After(deadline) {
 			break
 		}
-		time.Sleep(azureWriteRacePollTime)
-		size, err = v.get(loc, buf)
+		select {
+		case <-ctx.Done():
+			return 0, ctx.Err()
+		case <-time.After(azureWriteRacePollTime):
+		}
+		size, err = v.get(ctx, loc, buf)
 	}
 	if haveDeadline {
 		log.Printf("Race ended with size==%d", size)
@@ -217,12 +270,14 @@ func (v *AzureBlobVolume) Get(ctx context.Context, loc string, buf []byte) (int,
 	return size, err
 }
 
-func (v *AzureBlobVolume) get(loc string, buf []byte) (int, error) {
+func (v *AzureBlobVolume) get(ctx context.Context, loc string, buf []byte) (int, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
 	expectSize := len(buf)
 	if azureMaxGetBytes < BlockSize {
 		// Unfortunately the handler doesn't tell us how long the blob
 		// is expected to be, so we have to ask Azure.
-		props, err := v.bsClient.GetBlobProperties(v.ContainerName, loc)
+		props, err := v.container.GetBlobProperties(loc)
 		if err != nil {
 			return 0, v.translateError(err)
 		}
@@ -239,10 +294,18 @@ func (v *AzureBlobVolume) get(loc string, buf []byte) (int, error) {
 	// We'll update this actualSize if/when we get the last piece.
 	actualSize := -1
 	pieces := (expectSize + azureMaxGetBytes - 1) / azureMaxGetBytes
-	errors := make([]error, pieces)
+	errors := make(chan error, pieces)
 	var wg sync.WaitGroup
 	wg.Add(pieces)
 	for p := 0; p < pieces; p++ {
+		// Each goroutine retrieves one piece. If we hit an
+		// error, it is sent to the errors chan so get() can
+		// return it -- but only if the error happens before
+		// ctx is done. This way, if ctx is done before we hit
+		// any other error (e.g., requesting client has hung
+		// up), we return the original ctx.Err() instead of
+		// the secondary errors from the transfers that got
+		// interrupted as a result.
 		go func(p int) {
 			defer wg.Done()
 			startPos := p * azureMaxGetBytes
@@ -252,23 +315,51 @@ func (v *AzureBlobVolume) get(loc string, buf []byte) (int, error) {
 			}
 			var rdr io.ReadCloser
 			var err error
-			if startPos == 0 && endPos == expectSize {
-				rdr, err = v.bsClient.GetBlob(v.ContainerName, loc)
-			} else {
-				rdr, err = v.bsClient.GetBlobRange(v.ContainerName, loc, fmt.Sprintf("%d-%d", startPos, endPos-1), nil)
+			gotRdr := make(chan struct{})
+			go func() {
+				defer close(gotRdr)
+				if startPos == 0 && endPos == expectSize {
+					rdr, err = v.container.GetBlob(loc)
+				} else {
+					rdr, err = v.container.GetBlobRange(loc, startPos, endPos-1, nil)
+				}
+			}()
+			select {
+			case <-ctx.Done():
+				go func() {
+					<-gotRdr
+					if err == nil {
+						rdr.Close()
+					}
+				}()
+				return
+			case <-gotRdr:
 			}
 			if err != nil {
-				errors[p] = err
+				errors <- err
+				cancel()
 				return
 			}
-			defer rdr.Close()
+			go func() {
+				// Close the reader when the client
+				// hangs up or another piece fails
+				// (possibly interrupting ReadFull())
+				// or when all pieces succeed and
+				// get() returns.
+				<-ctx.Done()
+				rdr.Close()
+			}()
 			n, err := io.ReadFull(rdr, buf[startPos:endPos])
 			if pieces == 1 && (err == io.ErrUnexpectedEOF || err == io.EOF) {
 				// If we don't know the actual size,
 				// and just tried reading 64 MiB, it's
 				// normal to encounter EOF.
 			} else if err != nil {
-				errors[p] = err
+				if ctx.Err() == nil {
+					errors <- err
+				}
+				cancel()
+				return
 			}
 			if p == pieces-1 {
 				actualSize = startPos + n
@@ -276,10 +367,12 @@ func (v *AzureBlobVolume) get(loc string, buf []byte) (int, error) {
 		}(p)
 	}
 	wg.Wait()
-	for _, err := range errors {
-		if err != nil {
-			return 0, v.translateError(err)
-		}
+	close(errors)
+	if len(errors) > 0 {
+		return 0, v.translateError(<-errors)
+	}
+	if ctx.Err() != nil {
+		return 0, ctx.Err()
 	}
 	return actualSize, nil
 }
@@ -293,7 +386,23 @@ func (v *AzureBlobVolume) Compare(ctx context.Context, loc string, expect []byte
 	if trashed {
 		return os.ErrNotExist
 	}
-	rdr, err := v.bsClient.GetBlob(v.ContainerName, loc)
+	var rdr io.ReadCloser
+	gotRdr := make(chan struct{})
+	go func() {
+		defer close(gotRdr)
+		rdr, err = v.container.GetBlob(loc)
+	}()
+	select {
+	case <-ctx.Done():
+		go func() {
+			<-gotRdr
+			if err == nil {
+				rdr.Close()
+			}
+		}()
+		return ctx.Err()
+	case <-gotRdr:
+	}
 	if err != nil {
 		return v.translateError(err)
 	}
@@ -306,7 +415,46 @@ func (v *AzureBlobVolume) Put(ctx context.Context, loc string, block []byte) err
 	if v.ReadOnly {
 		return MethodDisabledError
 	}
-	return v.bsClient.CreateBlockBlobFromReader(v.ContainerName, loc, uint64(len(block)), bytes.NewReader(block), nil)
+	// Send the block data through a pipe, so that (if we need to)
+	// we can close the pipe early and abandon our
+	// CreateBlockBlobFromReader() goroutine, without worrying
+	// about CreateBlockBlobFromReader() accessing our block
+	// buffer after we release it.
+	bufr, bufw := io.Pipe()
+	go func() {
+		io.Copy(bufw, bytes.NewReader(block))
+		bufw.Close()
+	}()
+	errChan := make(chan error)
+	go func() {
+		var body io.Reader = bufr
+		if len(block) == 0 {
+			// We must send a "Content-Length: 0" header,
+			// but the http client interprets
+			// ContentLength==0 as "unknown" unless it can
+			// confirm by introspection that Body will
+			// read 0 bytes.
+			body = http.NoBody
+			bufr.Close()
+		}
+		errChan <- v.container.CreateBlockBlobFromReader(loc, len(block), body, nil)
+	}()
+	select {
+	case <-ctx.Done():
+		theConfig.debugLogf("%s: taking CreateBlockBlobFromReader's input away: %s", v, ctx.Err())
+		// Our pipe might be stuck in Write(), waiting for
+		// io.Copy() to read. If so, un-stick it. This means
+		// CreateBlockBlobFromReader will get corrupt data,
+		// but that's OK: the size won't match, so the write
+		// will fail.
+		go io.Copy(ioutil.Discard, bufr)
+		// CloseWithError() will return once pending I/O is done.
+		bufw.CloseWithError(ctx.Err())
+		theConfig.debugLogf("%s: abandoning CreateBlockBlobFromReader goroutine", v)
+		return ctx.Err()
+	case err := <-errChan:
+		return err
+	}
 }
 
 // Touch updates the last-modified property of a block blob.
@@ -322,8 +470,8 @@ func (v *AzureBlobVolume) Touch(loc string) error {
 		return os.ErrNotExist
 	}
 
-	metadata["touch"] = fmt.Sprintf("%d", time.Now())
-	return v.bsClient.SetBlobMetadata(v.ContainerName, loc, metadata, nil)
+	metadata["touch"] = fmt.Sprintf("%d", time.Now().Unix())
+	return v.container.SetBlobMetadata(loc, metadata, nil)
 }
 
 // Mtime returns the last-modified property of a block blob.
@@ -336,11 +484,11 @@ func (v *AzureBlobVolume) Mtime(loc string) (time.Time, error) {
 		return time.Time{}, os.ErrNotExist
 	}
 
-	props, err := v.bsClient.GetBlobProperties(v.ContainerName, loc)
+	props, err := v.container.GetBlobProperties(loc)
 	if err != nil {
 		return time.Time{}, err
 	}
-	return time.Parse(time.RFC1123, props.LastModified)
+	return time.Time(props.LastModified), nil
 }
 
 // IndexTo writes a list of Keep blocks that are stored in the
@@ -348,22 +496,19 @@ func (v *AzureBlobVolume) Mtime(loc string) (time.Time, error) {
 func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 	params := storage.ListBlobsParameters{
 		Prefix:  prefix,
-		Include: "metadata",
+		Include: &storage.IncludeBlobDataset{Metadata: true},
 	}
-	for {
-		resp, err := v.bsClient.ListBlobs(v.ContainerName, params)
+	for page := 1; ; page++ {
+		resp, err := v.listBlobs(page, params)
 		if err != nil {
 			return err
 		}
 		for _, b := range resp.Blobs {
-			t, err := time.Parse(time.RFC1123, b.Properties.LastModified)
-			if err != nil {
-				return err
-			}
 			if !v.isKeepBlock(b.Name) {
 				continue
 			}
-			if b.Properties.ContentLength == 0 && t.Add(azureWriteRaceInterval).After(time.Now()) {
+			modtime := time.Time(b.Properties.LastModified)
+			if b.Properties.ContentLength == 0 && modtime.Add(azureWriteRaceInterval).After(time.Now()) {
 				// A new zero-length blob is probably
 				// just a new non-empty blob that
 				// hasn't committed its data yet (see
@@ -375,7 +520,7 @@ func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 				// Trashed blob; exclude it from response
 				continue
 			}
-			fmt.Fprintf(writer, "%s+%d %d\n", b.Name, b.Properties.ContentLength, t.UnixNano())
+			fmt.Fprintf(writer, "%s+%d %d\n", b.Name, b.Properties.ContentLength, modtime.UnixNano())
 		}
 		if resp.NextMarker == "" {
 			return nil
@@ -384,6 +529,22 @@ func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 	}
 }
 
+// call v.container.ListBlobs, retrying if needed.
+func (v *AzureBlobVolume) listBlobs(page int, params storage.ListBlobsParameters) (resp storage.BlobListResponse, err error) {
+	for i := 0; i < v.ListBlobsMaxAttempts; i++ {
+		resp, err = v.container.ListBlobs(params)
+		err = v.translateError(err)
+		if err == VolumeBusyError {
+			log.Printf("ListBlobs: will retry page %d in %s after error: %s", page, v.ListBlobsRetryDelay, err)
+			time.Sleep(time.Duration(v.ListBlobsRetryDelay))
+			continue
+		} else {
+			break
+		}
+	}
+	return
+}
+
 // Trash a Keep block.
 func (v *AzureBlobVolume) Trash(loc string) error {
 	if v.ReadOnly {
@@ -395,7 +556,7 @@ func (v *AzureBlobVolume) Trash(loc string) error {
 	// we get the Etag before checking Mtime, and use If-Match to
 	// ensure we don't delete data if Put() or Touch() happens
 	// between our calls to Mtime() and DeleteBlob().
-	props, err := v.bsClient.GetBlobProperties(v.ContainerName, loc)
+	props, err := v.container.GetBlobProperties(loc)
 	if err != nil {
 		return err
 	}
@@ -407,16 +568,16 @@ func (v *AzureBlobVolume) Trash(loc string) error {
 
 	// If TrashLifetime == 0, just delete it
 	if theConfig.TrashLifetime == 0 {
-		return v.bsClient.DeleteBlob(v.ContainerName, loc, map[string]string{
-			"If-Match": props.Etag,
+		return v.container.DeleteBlob(loc, &storage.DeleteBlobOptions{
+			IfMatch: props.Etag,
 		})
 	}
 
 	// Otherwise, mark as trash
-	return v.bsClient.SetBlobMetadata(v.ContainerName, loc, map[string]string{
+	return v.container.SetBlobMetadata(loc, storage.BlobMetadata{
 		"expires_at": fmt.Sprintf("%d", time.Now().Add(theConfig.TrashLifetime.Duration()).Unix()),
-	}, map[string]string{
-		"If-Match": props.Etag,
+	}, &storage.SetBlobMetadataOptions{
+		IfMatch: props.Etag,
 	})
 }
 
@@ -424,7 +585,7 @@ func (v *AzureBlobVolume) Trash(loc string) error {
 // Delete the expires_at metadata attribute
 func (v *AzureBlobVolume) Untrash(loc string) error {
 	// if expires_at does not exist, return NotFoundError
-	metadata, err := v.bsClient.GetBlobMetadata(v.ContainerName, loc)
+	metadata, err := v.container.GetBlobMetadata(loc)
 	if err != nil {
 		return v.translateError(err)
 	}
@@ -434,7 +595,7 @@ func (v *AzureBlobVolume) Untrash(loc string) error {
 
 	// reset expires_at metadata attribute
 	metadata["expires_at"] = ""
-	err = v.bsClient.SetBlobMetadata(v.ContainerName, loc, metadata, nil)
+	err = v.container.SetBlobMetadata(loc, metadata, nil)
 	return v.translateError(err)
 }
 
@@ -464,12 +625,20 @@ func (v *AzureBlobVolume) Replication() int {
 	return v.AzureReplication
 }
 
+// GetStorageClasses implements Volume
+func (v *AzureBlobVolume) GetStorageClasses() []string {
+	return v.StorageClasses
+}
+
 // If possible, translate an Azure SDK error to a recognizable error
 // like os.ErrNotExist.
 func (v *AzureBlobVolume) translateError(err error) error {
 	switch {
 	case err == nil:
 		return err
+	case strings.Contains(err.Error(), "StatusCode=503"):
+		// "storage: service returned error: StatusCode=503, ErrorCode=ServerBusy, ErrorMessage=The server is busy" (See #14804)
+		return VolumeBusyError
 	case strings.Contains(err.Error(), "Not Found"):
 		// "storage: service returned without a response body (404 Not Found)"
 		return os.ErrNotExist
@@ -488,49 +657,209 @@ func (v *AzureBlobVolume) isKeepBlock(s string) bool {
 // and deletes them from the volume.
 func (v *AzureBlobVolume) EmptyTrash() {
 	var bytesDeleted, bytesInTrash int64
-	var blocksDeleted, blocksInTrash int
-	params := storage.ListBlobsParameters{Include: "metadata"}
+	var blocksDeleted, blocksInTrash int64
 
-	for {
-		resp, err := v.bsClient.ListBlobs(v.ContainerName, params)
+	doBlob := func(b storage.Blob) {
+		// Check whether the block is flagged as trash
+		if b.Metadata["expires_at"] == "" {
+			return
+		}
+
+		atomic.AddInt64(&blocksInTrash, 1)
+		atomic.AddInt64(&bytesInTrash, b.Properties.ContentLength)
+
+		expiresAt, err := strconv.ParseInt(b.Metadata["expires_at"], 10, 64)
 		if err != nil {
-			log.Printf("EmptyTrash: ListBlobs: %v", err)
-			break
+			log.Printf("EmptyTrash: ParseInt(%v): %v", b.Metadata["expires_at"], err)
+			return
 		}
-		for _, b := range resp.Blobs {
-			// Check if the block is expired
-			if b.Metadata["expires_at"] == "" {
-				continue
-			}
 
-			blocksInTrash++
-			bytesInTrash += b.Properties.ContentLength
+		if expiresAt > time.Now().Unix() {
+			return
+		}
 
-			expiresAt, err := strconv.ParseInt(b.Metadata["expires_at"], 10, 64)
-			if err != nil {
-				log.Printf("EmptyTrash: ParseInt(%v): %v", b.Metadata["expires_at"], err)
-				continue
-			}
+		err = v.container.DeleteBlob(b.Name, &storage.DeleteBlobOptions{
+			IfMatch: b.Properties.Etag,
+		})
+		if err != nil {
+			log.Printf("EmptyTrash: DeleteBlob(%v): %v", b.Name, err)
+			return
+		}
+		atomic.AddInt64(&blocksDeleted, 1)
+		atomic.AddInt64(&bytesDeleted, b.Properties.ContentLength)
+	}
 
-			if expiresAt > time.Now().Unix() {
-				continue
+	var wg sync.WaitGroup
+	todo := make(chan storage.Blob, theConfig.EmptyTrashWorkers)
+	for i := 0; i < 1 || i < theConfig.EmptyTrashWorkers; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for b := range todo {
+				doBlob(b)
 			}
+		}()
+	}
 
-			err = v.bsClient.DeleteBlob(v.ContainerName, b.Name, map[string]string{
-				"If-Match": b.Properties.Etag,
-			})
-			if err != nil {
-				log.Printf("EmptyTrash: DeleteBlob(%v): %v", b.Name, err)
-				continue
-			}
-			blocksDeleted++
-			bytesDeleted += b.Properties.ContentLength
+	params := storage.ListBlobsParameters{Include: &storage.IncludeBlobDataset{Metadata: true}}
+	for page := 1; ; page++ {
+		resp, err := v.listBlobs(page, params)
+		if err != nil {
+			log.Printf("EmptyTrash: ListBlobs: %v", err)
+			break
+		}
+		for _, b := range resp.Blobs {
+			todo <- b
 		}
 		if resp.NextMarker == "" {
 			break
 		}
 		params.Marker = resp.NextMarker
 	}
+	close(todo)
+	wg.Wait()
 
 	log.Printf("EmptyTrash stats for %v: Deleted %v bytes in %v blocks. Remaining in trash: %v bytes in %v blocks.", v.String(), bytesDeleted, blocksDeleted, bytesInTrash-bytesDeleted, blocksInTrash-blocksDeleted)
 }
+
+// InternalStats returns bucket I/O and API call counters.
+func (v *AzureBlobVolume) InternalStats() interface{} {
+	return &v.container.stats
+}
+
+type azureBlobStats struct {
+	statsTicker
+	Ops              uint64
+	GetOps           uint64
+	GetRangeOps      uint64
+	GetMetadataOps   uint64
+	GetPropertiesOps uint64
+	CreateOps        uint64
+	SetMetadataOps   uint64
+	DelOps           uint64
+	ListOps          uint64
+}
+
+func (s *azureBlobStats) TickErr(err error) {
+	if err == nil {
+		return
+	}
+	errType := fmt.Sprintf("%T", err)
+	if err, ok := err.(storage.AzureStorageServiceError); ok {
+		errType = errType + fmt.Sprintf(" %d (%s)", err.StatusCode, err.Code)
+	}
+	log.Printf("errType %T, err %s", err, err)
+	s.statsTicker.TickErr(err, errType)
+}
+
+// azureContainer wraps storage.Container in order to count I/O and
+// API usage stats.
+type azureContainer struct {
+	ctr   *storage.Container
+	stats azureBlobStats
+}
+
+func (c *azureContainer) Exists() (bool, error) {
+	c.stats.TickOps("exists")
+	c.stats.Tick(&c.stats.Ops)
+	ok, err := c.ctr.Exists()
+	c.stats.TickErr(err)
+	return ok, err
+}
+
+func (c *azureContainer) GetBlobMetadata(bname string) (storage.BlobMetadata, error) {
+	c.stats.TickOps("get_metadata")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetMetadataOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.GetMetadata(nil)
+	c.stats.TickErr(err)
+	return b.Metadata, err
+}
+
+func (c *azureContainer) GetBlobProperties(bname string) (*storage.BlobProperties, error) {
+	c.stats.TickOps("get_properties")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetPropertiesOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.GetProperties(nil)
+	c.stats.TickErr(err)
+	return &b.Properties, err
+}
+
+func (c *azureContainer) GetBlob(bname string) (io.ReadCloser, error) {
+	c.stats.TickOps("get")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetOps)
+	b := c.ctr.GetBlobReference(bname)
+	rdr, err := b.Get(nil)
+	c.stats.TickErr(err)
+	return NewCountingReader(rdr, c.stats.TickInBytes), err
+}
+
+func (c *azureContainer) GetBlobRange(bname string, start, end int, opts *storage.GetBlobOptions) (io.ReadCloser, error) {
+	c.stats.TickOps("get_range")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetRangeOps)
+	b := c.ctr.GetBlobReference(bname)
+	rdr, err := b.GetRange(&storage.GetBlobRangeOptions{
+		Range: &storage.BlobRange{
+			Start: uint64(start),
+			End:   uint64(end),
+		},
+		GetBlobOptions: opts,
+	})
+	c.stats.TickErr(err)
+	return NewCountingReader(rdr, c.stats.TickInBytes), err
+}
+
+// If we give it an io.Reader that doesn't also have a Len() int
+// method, the Azure SDK determines data size by copying the data into
+// a new buffer, which is not a good use of memory.
+type readerWithAzureLen struct {
+	io.Reader
+	len int
+}
+
+// Len satisfies the private lener interface in azure-sdk-for-go.
+func (r *readerWithAzureLen) Len() int {
+	return r.len
+}
+
+func (c *azureContainer) CreateBlockBlobFromReader(bname string, size int, rdr io.Reader, opts *storage.PutBlobOptions) error {
+	c.stats.TickOps("create")
+	c.stats.Tick(&c.stats.Ops, &c.stats.CreateOps)
+	if size != 0 {
+		rdr = &readerWithAzureLen{
+			Reader: NewCountingReader(rdr, c.stats.TickOutBytes),
+			len:    size,
+		}
+	}
+	b := c.ctr.GetBlobReference(bname)
+	err := b.CreateBlockBlobFromReader(rdr, opts)
+	c.stats.TickErr(err)
+	return err
+}
+
+func (c *azureContainer) SetBlobMetadata(bname string, m storage.BlobMetadata, opts *storage.SetBlobMetadataOptions) error {
+	c.stats.TickOps("set_metadata")
+	c.stats.Tick(&c.stats.Ops, &c.stats.SetMetadataOps)
+	b := c.ctr.GetBlobReference(bname)
+	b.Metadata = m
+	err := b.SetMetadata(opts)
+	c.stats.TickErr(err)
+	return err
+}
+
+func (c *azureContainer) ListBlobs(params storage.ListBlobsParameters) (storage.BlobListResponse, error) {
+	c.stats.TickOps("list")
+	c.stats.Tick(&c.stats.Ops, &c.stats.ListOps)
+	resp, err := c.ctr.ListBlobs(params)
+	c.stats.TickErr(err)
+	return resp, err
+}
+
+func (c *azureContainer) DeleteBlob(bname string, opts *storage.DeleteBlobOptions) error {
+	c.stats.TickOps("delete")
+	c.stats.Tick(&c.stats.Ops, &c.stats.DelOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.Delete(opts)
+	c.stats.TickErr(err)
+	return err
+}