Merge pull request #742 from BrianBland/ng-push-pull

Adds sliding-window parallelization to Push/Pull operations

client/pull.go

@@ -4,9 +4,16 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/docker/docker-registry"
+
 	log "github.com/Sirupsen/logrus"
 )
 
+// simultaneousLayerPullWindow is the size of the parallel layer pull window.
+// A layer may not be pulled until the layer preceeding it by the length of the
+// pull window has been successfully pulled.
+const simultaneousLayerPullWindow = 4
+
 // Pull implements a client pull workflow for the image defined by the given
 // name and tag pair, using the given ObjectStore for local manifest and layer
 // storage
@@ -24,7 +31,46 @@ func Pull(c Client, objectStore ObjectStore, name, tag string) error {
 		return fmt.Errorf("Image has no layers")
 	}
 
-	for _, fsLayer := range manifest.FSLayers {
+	errChans := make([]chan error, len(manifest.FSLayers))
+	for i := range manifest.FSLayers {
+		errChans[i] = make(chan error)
+	}
+
+	// Iterate over each layer in the manifest, simultaneously pulling no more
+	// than simultaneousLayerPullWindow layers at a time. If an error is
+	// received from a layer pull, we abort the push.
+	for i := 0; i < len(manifest.FSLayers)+simultaneousLayerPullWindow; i++ {
+		dependentLayer := i - simultaneousLayerPullWindow
+		if dependentLayer >= 0 {
+			err := <-errChans[dependentLayer]
+			if err != nil {
+				log.WithField("error", err).Warn("Pull aborted")
+				return err
+			}
+		}
+
+		if i < len(manifest.FSLayers) {
+			go func(i int) {
+				errChans[i] <- pullLayer(c, objectStore, name, manifest.FSLayers[i])
+			}(i)
+		}
+	}
+
+	err = objectStore.WriteManifest(name, tag, manifest)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"error":    err,
+			"manifest": manifest,
+		}).Warn("Unable to write image manifest")
+		return err
+	}
+
+	return nil
+}
+
+func pullLayer(c Client, objectStore ObjectStore, name string, fsLayer registry.FSLayer) error {
+	log.WithField("layer", fsLayer).Info("Pulling layer")
+
 	layer, err := objectStore.Layer(fsLayer.BlobSum)
 	if err != nil {
 		log.WithFields(log.Fields{
@@ -37,12 +83,12 @@ func Pull(c Client, objectStore ObjectStore, name, tag string) error {
 	writer, err := layer.Writer()
 	if err == ErrLayerAlreadyExists {
 		log.WithField("layer", fsLayer).Info("Layer already exists")
-			continue
+		return nil
 	}
 	if err == ErrLayerLocked {
 		log.WithField("layer", fsLayer).Info("Layer download in progress, waiting")
 		layer.Wait()
-			continue
+		return nil
 	}
 	if err != nil {
 		log.WithFields(log.Fields{
@@ -77,17 +123,10 @@ func Pull(c Client, objectStore ObjectStore, name, tag string) error {
 			"written":  copied,
 			"layer":    fsLayer,
 		}).Warn("Wrote incorrect number of bytes for layer")
+		return fmt.Errorf(
+			"Wrote incorrect number of bytes for layer %v. Expected %d, Wrote %d",
+			fsLayer, length, copied,
+		)
 	}
-	}
-
-	err = objectStore.WriteManifest(name, tag, manifest)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"error":    err,
-			"manifest": manifest,
-		}).Warn("Unable to write image manifest")
-		return err
-	}
-
 	return nil
 }

client/push.go

@@ -11,6 +11,13 @@ import (
 	log "github.com/Sirupsen/logrus"
 )
 
+// simultaneousLayerPushWindow is the size of the parallel layer push window.
+// A layer may not be pushed until the layer preceeding it by the length of the
+// push window has been successfully pushed.
+const simultaneousLayerPushWindow = 4
+
+type pushFunction func(fsLayer registry.FSLayer) error
+
 // Push implements a client push workflow for the image defined by the given
 // name and tag pair, using the given ObjectStore for local manifest and layer
 // storage
@@ -25,7 +32,46 @@ func Push(c Client, objectStore ObjectStore, name, tag string) error {
 		return err
 	}
 
-	for _, fsLayer := range manifest.FSLayers {
+	errChans := make([]chan error, len(manifest.FSLayers))
+	for i := range manifest.FSLayers {
+		errChans[i] = make(chan error)
+	}
+
+	// Iterate over each layer in the manifest, simultaneously pushing no more
+	// than simultaneousLayerPushWindow layers at a time. If an error is
+	// received from a layer push, we abort the push.
+	for i := 0; i < len(manifest.FSLayers)+simultaneousLayerPushWindow; i++ {
+		dependentLayer := i - simultaneousLayerPushWindow
+		if dependentLayer >= 0 {
+			err := <-errChans[dependentLayer]
+			if err != nil {
+				log.WithField("error", err).Warn("Push aborted")
+				return err
+			}
+		}
+
+		if i < len(manifest.FSLayers) {
+			go func(i int) {
+				errChans[i] <- pushLayer(c, objectStore, name, manifest.FSLayers[i])
+			}(i)
+		}
+	}
+
+	err = c.PutImageManifest(name, tag, manifest)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"error":    err,
+			"manifest": manifest,
+		}).Warn("Unable to upload manifest")
+		return err
+	}
+
+	return nil
+}
+
+func pushLayer(c Client, objectStore ObjectStore, name string, fsLayer registry.FSLayer) error {
+	log.WithField("layer", fsLayer).Info("Pushing layer")
+
 	layer, err := objectStore.Layer(fsLayer.BlobSum)
 	if err != nil {
 		log.WithFields(log.Fields{
@@ -47,7 +93,7 @@ func Push(c Client, objectStore ObjectStore, name, tag string) error {
 	location, err := c.InitiateLayerUpload(name, fsLayer.BlobSum)
 	if _, ok := err.(*registry.LayerAlreadyExistsError); ok {
 		log.WithField("layer", fsLayer).Info("Layer already exists")
-			continue
+		return nil
 	}
 	if err != nil {
 		log.WithFields(log.Fields{
@@ -80,16 +126,6 @@ func Push(c Client, objectStore ObjectStore, name, tag string) error {
 		}).Warn("Unable to upload layer")
 		return err
 	}
-	}
-
-	err = c.PutImageManifest(name, tag, manifest)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"error":    err,
-			"manifest": manifest,
-		}).Warn("Unable to upload manifest")
-		return err
-	}
 
 	return nil
 }