forked from TrueCloudLab/distribution
Open cache interface
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
This commit is contained in:
Derek McGowan
parent
60b314ade5
commit
568df315ff
4 changed files with 142 additions and 92 deletions
60
docs/storage/blobcachemetrics.go
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60
docs/storage/blobcachemetrics.go
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@ -0,0 +1,60 @@
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package storage
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import (
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"expvar"
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"sync/atomic"
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"github.com/docker/distribution/registry/storage/cache"
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)
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type blobStatCollector struct {
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metrics cache.Metrics
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}
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func (bsc *blobStatCollector) Hit() {
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atomic.AddUint64(&bsc.metrics.Requests, 1)
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atomic.AddUint64(&bsc.metrics.Hits, 1)
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}
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func (bsc *blobStatCollector) Miss() {
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atomic.AddUint64(&bsc.metrics.Requests, 1)
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atomic.AddUint64(&bsc.metrics.Misses, 1)
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}
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func (bsc *blobStatCollector) Metrics() cache.Metrics {
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return bsc.metrics
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}
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// blobStatterCacheMetrics keeps track of cache metrics for blob descriptor
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// cache requests. Note this is kept globally and made available via expvar.
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// For more detailed metrics, its recommend to instrument a particular cache
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// implementation.
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var blobStatterCacheMetrics cache.MetricsTracker = &blobStatCollector{}
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func init() {
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registry := expvar.Get("registry")
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if registry == nil {
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registry = expvar.NewMap("registry")
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}
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cache := registry.(*expvar.Map).Get("cache")
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if cache == nil {
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cache = &expvar.Map{}
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cache.(*expvar.Map).Init()
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registry.(*expvar.Map).Set("cache", cache)
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}
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storage := cache.(*expvar.Map).Get("storage")
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if storage == nil {
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storage = &expvar.Map{}
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storage.(*expvar.Map).Init()
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cache.(*expvar.Map).Set("storage", storage)
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}
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storage.(*expvar.Map).Set("blobdescriptor", expvar.Func(func() interface{} {
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// no need for synchronous access: the increments are atomic and
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// during reading, we don't care if the data is up to date. The
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// numbers will always *eventually* be reported correctly.
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return blobStatterCacheMetrics
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}))
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}
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80
docs/storage/cache/cachedblobdescriptorstore.go
vendored
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80
docs/storage/cache/cachedblobdescriptorstore.go
vendored
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@ -0,0 +1,80 @@
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package cache
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import (
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"github.com/docker/distribution/context"
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"github.com/docker/distribution/digest"
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"github.com/docker/distribution"
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)
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// Metrics is used to hold metric counters
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// related to the number of times a cache was
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// hit or missed.
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type Metrics struct {
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Requests uint64
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Hits uint64
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Misses uint64
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}
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// MetricsTracker represents a metric tracker
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// which simply counts the number of hits and misses.
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type MetricsTracker interface {
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Hit()
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Miss()
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Metrics() Metrics
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}
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type cachedBlobStatter struct {
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cache distribution.BlobDescriptorService
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backend distribution.BlobStatter
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tracker MetricsTracker
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}
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// NewCachedBlobStatter creates a new statter which prefers a cache and
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// falls back to a backend.
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func NewCachedBlobStatter(cache distribution.BlobDescriptorService, backend distribution.BlobStatter) distribution.BlobStatter {
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return &cachedBlobStatter{
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cache: cache,
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backend: backend,
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}
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}
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// NewCachedBlobStatterWithMetrics creates a new statter which prefers a cache and
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// falls back to a backend. Hits and misses will send to the tracker.
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func NewCachedBlobStatterWithMetrics(cache distribution.BlobDescriptorService, backend distribution.BlobStatter, tracker MetricsTracker) distribution.BlobStatter {
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return &cachedBlobStatter{
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cache: cache,
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backend: backend,
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tracker: tracker,
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}
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}
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func (cbds *cachedBlobStatter) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
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desc, err := cbds.cache.Stat(ctx, dgst)
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if err != nil {
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if err != distribution.ErrBlobUnknown {
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context.GetLogger(ctx).Errorf("error retrieving descriptor from cache: %v", err)
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}
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goto fallback
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}
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if cbds.tracker != nil {
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cbds.tracker.Hit()
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}
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return desc, nil
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fallback:
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if cbds.tracker != nil {
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cbds.tracker.Miss()
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}
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desc, err = cbds.backend.Stat(ctx, dgst)
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if err != nil {
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return desc, err
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}
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if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
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context.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
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}
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return desc, err
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}
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@ -1,84 +0,0 @@
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package storage
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import (
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"expvar"
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"sync/atomic"
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"github.com/docker/distribution/context"
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"github.com/docker/distribution/digest"
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"github.com/docker/distribution"
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)
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type cachedBlobStatter struct {
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cache distribution.BlobDescriptorService
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backend distribution.BlobStatter
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}
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func (cbds *cachedBlobStatter) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
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atomic.AddUint64(&blobStatterCacheMetrics.Stat.Requests, 1)
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desc, err := cbds.cache.Stat(ctx, dgst)
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if err != nil {
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if err != distribution.ErrBlobUnknown {
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context.GetLogger(ctx).Errorf("error retrieving descriptor from cache: %v", err)
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}
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goto fallback
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}
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atomic.AddUint64(&blobStatterCacheMetrics.Stat.Hits, 1)
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return desc, nil
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fallback:
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atomic.AddUint64(&blobStatterCacheMetrics.Stat.Misses, 1)
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desc, err = cbds.backend.Stat(ctx, dgst)
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if err != nil {
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return desc, err
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}
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if err := cbds.cache.SetDescriptor(ctx, dgst, desc); err != nil {
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context.GetLogger(ctx).Errorf("error adding descriptor %v to cache: %v", desc.Digest, err)
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}
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return desc, err
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}
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// blobStatterCacheMetrics keeps track of cache metrics for blob descriptor
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// cache requests. Note this is kept globally and made available via expvar.
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// For more detailed metrics, its recommend to instrument a particular cache
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// implementation.
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var blobStatterCacheMetrics struct {
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// Stat tracks calls to the caches.
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Stat struct {
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Requests uint64
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Hits uint64
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Misses uint64
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}
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}
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func init() {
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registry := expvar.Get("registry")
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if registry == nil {
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registry = expvar.NewMap("registry")
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}
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cache := registry.(*expvar.Map).Get("cache")
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if cache == nil {
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cache = &expvar.Map{}
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cache.(*expvar.Map).Init()
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registry.(*expvar.Map).Set("cache", cache)
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}
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storage := cache.(*expvar.Map).Get("storage")
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if storage == nil {
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storage = &expvar.Map{}
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storage.(*expvar.Map).Init()
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cache.(*expvar.Map).Set("storage", storage)
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}
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storage.(*expvar.Map).Set("blobdescriptor", expvar.Func(func() interface{} {
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// no need for synchronous access: the increments are atomic and
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// during reading, we don't care if the data is up to date. The
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// numbers will always *eventually* be reported correctly.
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return blobStatterCacheMetrics
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}))
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}
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@ -29,10 +29,7 @@ func NewRegistryWithDriver(ctx context.Context, driver storagedriver.StorageDriv
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}
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if blobDescriptorCacheProvider != nil {
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statter = &cachedBlobStatter{
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cache: blobDescriptorCacheProvider,
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backend: statter,
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}
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statter = cache.NewCachedBlobStatter(blobDescriptorCacheProvider, statter)
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}
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bs := &blobStore{
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@ -143,10 +140,7 @@ func (repo *repository) Blobs(ctx context.Context) distribution.BlobStore {
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}
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if repo.descriptorCache != nil {
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statter = &cachedBlobStatter{
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cache: repo.descriptorCache,
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backend: statter,
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}
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statter = cache.NewCachedBlobStatter(repo.descriptorCache, statter)
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}
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return &linkedBlobStore{
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