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Merge pull request moby#43183 from thaJeztah/cleanup_distribution
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distribution/xfer: refactor to reduce public api/interface
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@AkihiroSuda
AkihiroSuda authored Feb 26, 2022
2 parents c549116 + 79ea1b1 commit d809ad9
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Showing 5 changed files with 198 additions and 202 deletions.
107 changes: 56 additions & 51 deletions distribution/xfer/download.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,21 +23,21 @@ const maxDownloadAttempts = 5
// layers.
type LayerDownloadManager struct {
layerStore layer.Store
tm TransferManager
tm *transferManager
waitDuration time.Duration
maxDownloadAttempts int
}

// SetConcurrency sets the max concurrent downloads for each pull
func (ldm *LayerDownloadManager) SetConcurrency(concurrency int) {
ldm.tm.SetConcurrency(concurrency)
ldm.tm.setConcurrency(concurrency)
}

// NewLayerDownloadManager returns a new LayerDownloadManager.
func NewLayerDownloadManager(layerStore layer.Store, concurrencyLimit int, options ...func(*LayerDownloadManager)) *LayerDownloadManager {
func NewLayerDownloadManager(layerStore layer.Store, concurrencyLimit int, options ...DownloadOption) *LayerDownloadManager {
manager := LayerDownloadManager{
layerStore: layerStore,
tm: NewTransferManager(concurrencyLimit),
tm: newTransferManager(concurrencyLimit),
waitDuration: time.Second,
maxDownloadAttempts: maxDownloadAttempts,
}
Expand All @@ -47,16 +47,19 @@ func NewLayerDownloadManager(layerStore layer.Store, concurrencyLimit int, optio
return &manager
}

// DownloadOption set options for the LayerDownloadManager.
type DownloadOption func(*LayerDownloadManager)

// WithMaxDownloadAttempts configures the maximum number of download
// attempts for a download manager.
func WithMaxDownloadAttempts(max int) func(*LayerDownloadManager) {
func WithMaxDownloadAttempts(max int) DownloadOption {
return func(dlm *LayerDownloadManager) {
dlm.maxDownloadAttempts = max
}
}

type downloadTransfer struct {
Transfer
transfer

layerStore layer.Store
layer layer.Layer
Expand Down Expand Up @@ -87,13 +90,17 @@ type DownloadDescriptor interface {
Close()
}

// DownloadDescriptorWithRegistered is a DownloadDescriptor that has an
// additional Registered method which gets called after a downloaded layer is
// registered. This allows the user of the download manager to know the DiffID
// of each registered layer. This method is called if a cast to
// DownloadDescriptorWithRegistered is successful.
type DownloadDescriptorWithRegistered interface {
DownloadDescriptor
// DigestRegisterer can be implemented by a DownloadDescriptor, and provides a
// Registered method which gets called after a downloaded layer is registered.
// This allows the user of the download manager to know the DiffID of each
// registered layer. This method is called if a cast to DigestRegisterer is
// successful.
type DigestRegisterer interface {

// TODO existing implementations in distribution and builder-next swallow errors
// when registering the diffID. Consider changing the Registered signature
// to return the error.

Registered(diffID layer.DiffID)
}

Expand All @@ -108,7 +115,7 @@ func (ldm *LayerDownloadManager) Download(ctx context.Context, initialRootFS ima
var (
topLayer layer.Layer
topDownload *downloadTransfer
watcher *Watcher
watcher *watcher
missingLayer bool
transferKey = ""
downloadsByKey = make(map[string]*downloadTransfer)
Expand Down Expand Up @@ -137,8 +144,7 @@ func (ldm *LayerDownloadManager) Download(ctx context.Context, initialRootFS ima
missingLayer = false
rootFS.Append(diffID)
// Register this repository as a source of this layer.
withRegistered, hasRegistered := descriptor.(DownloadDescriptorWithRegistered)
if hasRegistered { // As layerstore may set the driver
if withRegistered, ok := descriptor.(DigestRegisterer); ok { // As layerstore may set the driver
withRegistered.Registered(diffID)
}
continue
Expand All @@ -148,26 +154,26 @@ func (ldm *LayerDownloadManager) Download(ctx context.Context, initialRootFS ima

// Does this layer have the same data as a previous layer in
// the stack? If so, avoid downloading it more than once.
var topDownloadUncasted Transfer
var topDownloadUncasted transfer
if existingDownload, ok := downloadsByKey[key]; ok {
xferFunc := ldm.makeDownloadFuncFromDownload(descriptor, existingDownload, topDownload)
defer topDownload.Transfer.Release(watcher)
topDownloadUncasted, watcher = ldm.tm.Transfer(transferKey, xferFunc, progressOutput)
defer topDownload.transfer.release(watcher)
topDownloadUncasted, watcher = ldm.tm.transfer(transferKey, xferFunc, progressOutput)
topDownload = topDownloadUncasted.(*downloadTransfer)
continue
}

// Layer is not known to exist - download and register it.
progress.Update(progressOutput, descriptor.ID(), "Pulling fs layer")

var xferFunc DoFunc
var xferFunc doFunc
if topDownload != nil {
xferFunc = ldm.makeDownloadFunc(descriptor, "", topDownload)
defer topDownload.Transfer.Release(watcher)
defer topDownload.transfer.release(watcher)
} else {
xferFunc = ldm.makeDownloadFunc(descriptor, rootFS.ChainID(), nil)
}
topDownloadUncasted, watcher = ldm.tm.Transfer(transferKey, xferFunc, progressOutput)
topDownloadUncasted, watcher = ldm.tm.transfer(transferKey, xferFunc, progressOutput)
topDownload = topDownloadUncasted.(*downloadTransfer)
downloadsByKey[key] = topDownload
}
Expand All @@ -192,40 +198,40 @@ func (ldm *LayerDownloadManager) Download(ctx context.Context, initialRootFS ima

select {
case <-ctx.Done():
topDownload.Transfer.Release(watcher)
topDownload.transfer.release(watcher)
return rootFS, func() {}, ctx.Err()
case <-topDownload.Done():
case <-topDownload.done():
break
}

l, err := topDownload.result()
if err != nil {
topDownload.Transfer.Release(watcher)
topDownload.transfer.release(watcher)
return rootFS, func() {}, err
}

// Must do this exactly len(layers) times, so we don't include the
// base layer on Windows.
for range layers {
if l == nil {
topDownload.Transfer.Release(watcher)
topDownload.transfer.release(watcher)
return rootFS, func() {}, errors.New("internal error: too few parent layers")
}
rootFS.DiffIDs = append([]layer.DiffID{l.DiffID()}, rootFS.DiffIDs...)
l = l.Parent()
}
return rootFS, func() { topDownload.Transfer.Release(watcher) }, err
return rootFS, func() { topDownload.transfer.release(watcher) }, err
}

// makeDownloadFunc returns a function that performs the layer download and
// registration. If parentDownload is non-nil, it waits for that download to
// complete before the registration step, and registers the downloaded data
// on top of parentDownload's resulting layer. Otherwise, it registers the
// layer on top of the ChainID given by parentLayer.
func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor, parentLayer layer.ChainID, parentDownload *downloadTransfer) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor, parentLayer layer.ChainID, parentDownload *downloadTransfer) doFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) transfer {
d := &downloadTransfer{
Transfer: NewTransfer(),
transfer: newTransfer(),
layerStore: ldm.layerStore,
}

Expand All @@ -247,7 +253,7 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
// Did the parent download already fail or get
// cancelled?
select {
case <-parentDownload.Done():
case <-parentDownload.done():
_, err := parentDownload.result()
if err != nil {
d.err = err
Expand All @@ -267,15 +273,15 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
defer descriptor.Close()

for {
downloadReader, size, err = descriptor.Download(d.Transfer.Context(), progressOutput)
downloadReader, size, err = descriptor.Download(d.transfer.context(), progressOutput)
if err == nil {
break
}

// If an error was returned because the context
// was cancelled, we shouldn't retry.
select {
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
d.err = err
return
default:
Expand All @@ -302,7 +308,7 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
ticker.Stop()
break selectLoop
}
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
ticker.Stop()
d.err = errors.New("download cancelled during retry delay")
return
Expand All @@ -315,11 +321,11 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,

if parentDownload != nil {
select {
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
d.err = errors.New("layer registration cancelled")
downloadReader.Close()
return
case <-parentDownload.Done():
case <-parentDownload.done():
}

l, err := parentDownload.result()
Expand All @@ -331,7 +337,7 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
parentLayer = l.ChainID()
}

reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(d.Transfer.Context(), downloadReader), progressOutput, size, descriptor.ID(), "Extracting")
reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(d.transfer.context(), downloadReader), progressOutput, size, descriptor.ID(), "Extracting")
defer reader.Close()

inflatedLayerData, err := archive.DecompressStream(reader)
Expand All @@ -351,7 +357,7 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
}
if err != nil {
select {
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
d.err = errors.New("layer registration cancelled")
default:
d.err = fmt.Errorf("failed to register layer: %v", err)
Expand All @@ -360,15 +366,15 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
}

progress.Update(progressOutput, descriptor.ID(), "Pull complete")
withRegistered, hasRegistered := descriptor.(DownloadDescriptorWithRegistered)
if hasRegistered {

if withRegistered, ok := descriptor.(DigestRegisterer); ok {
withRegistered.Registered(d.layer.DiffID())
}

// Doesn't actually need to be its own goroutine, but
// done like this so we can defer close(c).
go func() {
<-d.Transfer.Released()
<-d.transfer.released()
if d.layer != nil {
layer.ReleaseAndLog(d.layerStore, d.layer)
}
Expand All @@ -386,10 +392,10 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
// parentDownload. This function does not log progress output because it would
// interfere with the progress reporting for sourceDownload, which has the same
// Key.
func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor DownloadDescriptor, sourceDownload *downloadTransfer, parentDownload *downloadTransfer) DoFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) Transfer {
func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor DownloadDescriptor, sourceDownload *downloadTransfer, parentDownload *downloadTransfer) doFunc {
return func(progressChan chan<- progress.Progress, start <-chan struct{}, inactive chan<- struct{}) transfer {
d := &downloadTransfer{
Transfer: NewTransfer(),
transfer: newTransfer(),
layerStore: ldm.layerStore,
}

Expand All @@ -403,10 +409,10 @@ func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor Downloa
close(inactive)

select {
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
d.err = errors.New("layer registration cancelled")
return
case <-parentDownload.Done():
case <-parentDownload.done():
}

l, err := parentDownload.result()
Expand All @@ -420,10 +426,10 @@ func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor Downloa
// parentDownload finished, but wait for it explicitly
// to be sure.
select {
case <-d.Transfer.Context().Done():
case <-d.transfer.context().Done():
d.err = errors.New("layer registration cancelled")
return
case <-sourceDownload.Done():
case <-sourceDownload.done():
}

l, err = sourceDownload.result()
Expand Down Expand Up @@ -453,15 +459,14 @@ func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor Downloa
return
}

withRegistered, hasRegistered := descriptor.(DownloadDescriptorWithRegistered)
if hasRegistered {
if withRegistered, ok := descriptor.(DigestRegisterer); ok {
withRegistered.Registered(d.layer.DiffID())
}

// Doesn't actually need to be its own goroutine, but
// done like this so we can defer close(c).
go func() {
<-d.Transfer.Released()
<-d.transfer.released()
if d.layer != nil {
layer.ReleaseAndLog(d.layerStore, d.layer)
}
Expand Down
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