Merge pull request #5379 from ktock/fix-push-race

Fix PushHandler cannot push image that contains duplicated blobs

go.mod

@@ -35,6 +35,7 @@ require (
 	github.com/hashicorp/go-multierror v1.0.0
 	github.com/imdario/mergo v0.3.11
 	github.com/klauspost/compress v1.11.13
+	github.com/moby/locker v1.0.1
 	github.com/moby/sys/mountinfo v0.4.1
 	github.com/moby/sys/symlink v0.1.0
 	github.com/opencontainers/go-digest v1.0.0

go.sum

@@ -420,6 +420,8 @@ github.com/mistifyio/go-zfs v2.1.2-0.20190413222219-f784269be439+incompatible/go
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mitchellh/osext v0.0.0-20151018003038-5e2d6d41470f/go.mod h1:OkQIRizQZAeMln+1tSwduZz7+Af5oFlKirV/MSYes2A=
+github.com/moby/locker v1.0.1 h1:fOXqR41zeveg4fFODix+1Ch4mj/gT0NE1XJbp/epuBg=
+github.com/moby/locker v1.0.1/go.mod h1:S7SDdo5zpBK84bzzVlKr2V0hz+7x9hWbYC/kq7oQppc=
 github.com/moby/sys/mountinfo v0.4.0/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=
 github.com/moby/sys/mountinfo v0.4.1 h1:1O+1cHA1aujwEwwVMa2Xm2l+gIpUHyd3+D+d7LZh1kM=
 github.com/moby/sys/mountinfo v0.4.1/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=

remotes/docker/pusher.go

@@ -44,17 +44,47 @@ type dockerPusher struct {
 	tracker StatusTracker
 }
 
+// Writer implements Ingester API of content store. This allows the client
+// to receive ErrUnavailable when there is already an on-going upload.
+// Note that the tracker MUST implement StatusTrackLocker interface to avoid
+// race condition on StatusTracker.
+func (p dockerPusher) Writer(ctx context.Context, opts ...content.WriterOpt) (content.Writer, error) {
+	var wOpts content.WriterOpts
+	for _, opt := range opts {
+		if err := opt(&wOpts); err != nil {
+			return nil, err
+		}
+	}
+	if wOpts.Ref == "" {
+		return nil, errors.Wrap(errdefs.ErrInvalidArgument, "ref must not be empty")
+	}
+	return p.push(ctx, wOpts.Desc, wOpts.Ref, true)
+}
+
 func (p dockerPusher) Push(ctx context.Context, desc ocispec.Descriptor) (content.Writer, error) {
+	return p.push(ctx, desc, remotes.MakeRefKey(ctx, desc), false)
+}
+
+func (p dockerPusher) push(ctx context.Context, desc ocispec.Descriptor, ref string, unavailableOnFail bool) (content.Writer, error) {
+	if l, ok := p.tracker.(StatusTrackLocker); ok {
+		l.Lock(ref)
+		defer l.Unlock(ref)
+	}
 	ctx, err := ContextWithRepositoryScope(ctx, p.refspec, true)
 	if err != nil {
 		return nil, err
 	}
-	ref := remotes.MakeRefKey(ctx, desc)
 	status, err := p.tracker.GetStatus(ref)
 	if err == nil {
 		if status.Committed && status.Offset == status.Total {
 			return nil, errors.Wrapf(errdefs.ErrAlreadyExists, "ref %v", ref)
 		}
+		if unavailableOnFail {
+			// Another push of this ref is happening elsewhere. The rest of function
+			// will continue only when `errdefs.IsNotFound(err) == true` (i.e. there
+			// is no actively-tracked ref already).
+			return nil, errors.Wrap(errdefs.ErrUnavailable, "push is on-going")
+		}
 		// TODO: Handle incomplete status
 	} else if !errdefs.IsNotFound(err) {
 		return nil, errors.Wrap(err, "failed to get status")
@@ -105,8 +135,11 @@ func (p dockerPusher) Push(ctx context.Context, desc ocispec.Descriptor) (conten
 
 			if exists {
 				p.tracker.SetStatus(ref, Status{
+					Committed: true,
 					Status: content.Status{
-						Ref: ref,
+						Ref:    ref,
+						Total:  desc.Size,
+						Offset: desc.Size,
 						// TODO: Set updated time?
 					},
 				})
@@ -162,8 +195,11 @@ func (p dockerPusher) Push(ctx context.Context, desc ocispec.Descriptor) (conten
 		case http.StatusOK, http.StatusAccepted, http.StatusNoContent:
 		case http.StatusCreated:
 			p.tracker.SetStatus(ref, Status{
+				Committed: true,
 				Status: content.Status{
-					Ref: ref,
+					Ref:    ref,
+					Total:  desc.Size,
+					Offset: desc.Size,
 				},
 			})
 			return nil, errors.Wrapf(errdefs.ErrAlreadyExists, "content %v on remote", desc.Digest)

remotes/docker/status.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
+	"github.com/moby/locker"
 	"github.com/pkg/errors"
 )
 
@@ -40,15 +41,24 @@ type StatusTracker interface {
 	SetStatus(string, Status)
 }
 
+// StatusTrackLocker to track status of operations with lock
+type StatusTrackLocker interface {
+	StatusTracker
+	Lock(string)
+	Unlock(string)
+}
+
 type memoryStatusTracker struct {
 	statuses map[string]Status
 	m        sync.Mutex
+	locker   *locker.Locker
 }
 
 // NewInMemoryTracker returns a StatusTracker that tracks content status in-memory
-func NewInMemoryTracker() StatusTracker {
+func NewInMemoryTracker() StatusTrackLocker {
 	return &memoryStatusTracker{
 		statuses: map[string]Status{},
+		locker:   locker.New(),
 	}
 }
 
@@ -67,3 +77,11 @@ func (t *memoryStatusTracker) SetStatus(ref string, status Status) {
 	t.statuses[ref] = status
 	t.m.Unlock()
 }
+
+func (t *memoryStatusTracker) Lock(ref string) {
+	t.locker.Lock(ref)
+}
+
+func (t *memoryStatusTracker) Unlock(ref string) {
+	t.locker.Unlock(ref)
+}

remotes/handlers.go

@@ -165,7 +165,15 @@ func PushHandler(pusher Pusher, provider content.Provider) images.HandlerFunc {
 func push(ctx context.Context, provider content.Provider, pusher Pusher, desc ocispec.Descriptor) error {
 	log.G(ctx).Debug("push")
 
-	cw, err := pusher.Push(ctx, desc)
+	var (
+		cw  content.Writer
+		err error
+	)
+	if cs, ok := pusher.(content.Ingester); ok {
+		cw, err = content.OpenWriter(ctx, cs, content.WithRef(MakeRefKey(ctx, desc)), content.WithDescriptor(desc))
+	} else {
+		cw, err = pusher.Push(ctx, desc)
+	}
 	if err != nil {
 		if !errdefs.IsAlreadyExists(err) {
 			return err

remotes/resolver.go

@@ -45,6 +45,8 @@ type Resolver interface {
 	Fetcher(ctx context.Context, ref string) (Fetcher, error)
 
 	// Pusher returns a new pusher for the provided reference
+	// The returned Pusher should satisfy content.Ingester and concurrent attempts
+	// to push the same blob using the Ingester API should result in ErrUnavailable.
 	Pusher(ctx context.Context, ref string) (Pusher, error)
 }
 

vendor/github.com/moby/locker/LICENSE

@@ -0,0 +1,190 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        https://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
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+      transformation or translation of a Source form, including but
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+
+      "Work" shall mean the work of authorship, whether in Source or
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+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
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+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
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+      the terms of any separate license agreement you may have executed
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+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
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+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
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+      implied, including, without limitation, any warranties or conditions
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+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
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+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
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+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
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+      on Your own behalf and on Your sole responsibility, not on behalf
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+      defend, and hold each Contributor harmless for any liability
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+      of your accepting any such warranty or additional liability.
+
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+   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.

vendor/github.com/moby/locker/README.md

@@ -0,0 +1,65 @@
+Locker
+=====
+
+locker provides a mechanism for creating finer-grained locking to help
+free up more global locks to handle other tasks.
+
+The implementation looks close to a sync.Mutex, however, the user must provide a
+reference to use to refer to the underlying lock when locking and unlocking,
+and unlock may generate an error.
+
+If a lock with a given name does not exist when `Lock` is called, one is
+created.
+Lock references are automatically cleaned up on `Unlock` if nothing else is
+waiting for the lock.
+
+
+## Usage
+
+```go
+package important
+
+import (
+	"sync"
+	"time"
+
+	"github.com/moby/locker"
+)
+
+type important struct {
+	locks *locker.Locker
+	data  map[string]interface{}
+	mu    sync.Mutex
+}
+
+func (i *important) Get(name string) interface{} {
+	i.locks.Lock(name)
+	defer i.locks.Unlock(name)
+	return i.data[name]
+}
+
+func (i *important) Create(name string, data interface{}) {
+	i.locks.Lock(name)
+	defer i.locks.Unlock(name)
+
+	i.createImportant(data)
+
+	i.mu.Lock()
+	i.data[name] = data
+	i.mu.Unlock()
+}
+
+func (i *important) createImportant(data interface{}) {
+	time.Sleep(10 * time.Second)
+}
+```
+
+For functions dealing with a given name, always lock at the beginning of the
+function (or before doing anything with the underlying state), this ensures any
+other function that is dealing with the same name will block.
+
+When needing to modify the underlying data, use the global lock to ensure nothing
+else is modifying it at the same time.
+Since name lock is already in place, no reads will occur while the modification
+is being performed.
+

vendor/github.com/moby/locker/go.mod

@@ -0,0 +1,3 @@
+module github.com/moby/locker
+
+go 1.13

vendor/github.com/moby/locker/locker.go

@@ -0,0 +1,112 @@
+/*
+Package locker provides a mechanism for creating finer-grained locking to help
+free up more global locks to handle other tasks.
+
+The implementation looks close to a sync.Mutex, however the user must provide a
+reference to use to refer to the underlying lock when locking and unlocking,
+and unlock may generate an error.
+
+If a lock with a given name does not exist when `Lock` is called, one is
+created.
+Lock references are automatically cleaned up on `Unlock` if nothing else is
+waiting for the lock.
+*/
+package locker
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+)
+
+// ErrNoSuchLock is returned when the requested lock does not exist
+var ErrNoSuchLock = errors.New("no such lock")
+
+// Locker provides a locking mechanism based on the passed in reference name
+type Locker struct {
+	mu    sync.Mutex
+	locks map[string]*lockCtr
+}
+
+// lockCtr is used by Locker to represent a lock with a given name.
+type lockCtr struct {
+	mu sync.Mutex
+	// waiters is the number of waiters waiting to acquire the lock
+	// this is int32 instead of uint32 so we can add `-1` in `dec()`
+	waiters int32
+}
+
+// inc increments the number of waiters waiting for the lock
+func (l *lockCtr) inc() {
+	atomic.AddInt32(&l.waiters, 1)
+}
+
+// dec decrements the number of waiters waiting on the lock
+func (l *lockCtr) dec() {
+	atomic.AddInt32(&l.waiters, -1)
+}
+
+// count gets the current number of waiters
+func (l *lockCtr) count() int32 {
+	return atomic.LoadInt32(&l.waiters)
+}
+
+// Lock locks the mutex
+func (l *lockCtr) Lock() {
+	l.mu.Lock()
+}
+
+// Unlock unlocks the mutex
+func (l *lockCtr) Unlock() {
+	l.mu.Unlock()
+}
+
+// New creates a new Locker
+func New() *Locker {
+	return &Locker{
+		locks: make(map[string]*lockCtr),
+	}
+}
+
+// Lock locks a mutex with the given name. If it doesn't exist, one is created
+func (l *Locker) Lock(name string) {
+	l.mu.Lock()
+	if l.locks == nil {
+		l.locks = make(map[string]*lockCtr)
+	}
+
+	nameLock, exists := l.locks[name]
+	if !exists {
+		nameLock = &lockCtr{}
+		l.locks[name] = nameLock
+	}
+
+	// increment the nameLock waiters while inside the main mutex
+	// this makes sure that the lock isn't deleted if `Lock` and `Unlock` are called concurrently
+	nameLock.inc()
+	l.mu.Unlock()
+
+	// Lock the nameLock outside the main mutex so we don't block other operations
+	// once locked then we can decrement the number of waiters for this lock
+	nameLock.Lock()
+	nameLock.dec()
+}
+
+// Unlock unlocks the mutex with the given name
+// If the given lock is not being waited on by any other callers, it is deleted
+func (l *Locker) Unlock(name string) error {
+	l.mu.Lock()
+	nameLock, exists := l.locks[name]
+	if !exists {
+		l.mu.Unlock()
+		return ErrNoSuchLock
+	}
+
+	if nameLock.count() == 0 {
+		delete(l.locks, name)
+	}
+	nameLock.Unlock()
+
+	l.mu.Unlock()
+	return nil
+}

vendor/modules.txt

@@ -246,6 +246,9 @@ github.com/matttproud/golang_protobuf_extensions/pbutil
 github.com/miekg/pkcs11
 # github.com/mistifyio/go-zfs v2.1.2-0.20190413222219-f784269be439+incompatible
 github.com/mistifyio/go-zfs
+# github.com/moby/locker v1.0.1
+## explicit
+github.com/moby/locker
 # github.com/moby/sys/mountinfo v0.4.1
 ## explicit
 github.com/moby/sys/mountinfo