Cache the result of sorting images by timestamp

Much of the time, the images returned from the ListImagesWithOptions
API are sorted according to timestamp. As a cheap and simple
optimisation for this case, when we're constructing a result, cache
both the slice of image.Info records and those records sorted by
timestamp.

This means, for any given request, images that occur in more than one
container will be sorted by timestamp only once.

api/v6/container.go

@@ -26,8 +26,16 @@ type Container struct {
 	NewFilteredImagesCount int `json:",omitempty"`
 }
 
+type imageSorter interface {
+	// SortedImages returns the known images, sorted according to the
+	// pattern given
+	SortedImages(policy.Pattern) update.SortedImageInfos
+	// Images returns the images in no defined order
+	Images() []image.Info
+}
+
 // NewContainer creates a Container given a list of images and the current image
-func NewContainer(name string, images []image.Info, currentImage image.Info, tagPattern policy.Pattern, fields []string) (Container, error) {
+func NewContainer(name string, images imageSorter, currentImage image.Info, tagPattern policy.Pattern, fields []string) (Container, error) {
 	// Default fields
 	if len(fields) == 0 {
 		fields = []string{
@@ -57,7 +65,7 @@ func NewContainer(name string, images []image.Info, currentImage image.Info, tag
 
 	getFilteredImages := func() []image.Info {
 		if filteredImages == nil {
-			filteredImages = update.FilterImages(images, tagPattern)
+			filteredImages = update.FilterImages(images.Images(), tagPattern)
 		}
 		return filteredImages
 	}
@@ -71,7 +79,7 @@ func NewContainer(name string, images []image.Info, currentImage image.Info, tag
 
 	getSortedImages := func() update.SortedImageInfos {
 		if sortedImages == nil {
-			sortedImages = update.SortImages(images, tagPattern)
+			sortedImages = images.SortedImages(tagPattern)
 			// now that we have the sorted images anyway, the fastest
 			// way to get sorted, filtered images will be to filter
 			// the already sorted images
@@ -104,7 +112,7 @@ func NewContainer(name string, images []image.Info, currentImage image.Info, tag
 				c.AvailableError = registry.ErrNoImageData.Error()
 			}
 		case "AvailableImagesCount":
-			c.AvailableImagesCount = len(images)
+			c.AvailableImagesCount = len(images.Images())
 
 		// these required the sorted images, which we can get
 		// straight away

api/v6/container_test.go

@@ -7,8 +7,19 @@ import (
 
 	"github.com/weaveworks/flux/image"
 	"github.com/weaveworks/flux/policy"
+	"github.com/weaveworks/flux/update"
 )
 
+type justSlice []image.Info
+
+func (j justSlice) Images() []image.Info {
+	return []image.Info(j)
+}
+
+func (j justSlice) SortedImages(p policy.Pattern) update.SortedImageInfos {
+	return update.SortImages(j.Images(), p)
+}
+
 func TestNewContainer(t *testing.T) {
 
 	testImage := image.Info{ImageID: "test"}
@@ -127,7 +138,7 @@ func TestNewContainer(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := NewContainer(tt.args.name, tt.args.images, tt.args.currentImage, tt.args.tagPattern, tt.args.fields)
+			got, err := NewContainer(tt.args.name, justSlice(tt.args.images), tt.args.currentImage, tt.args.tagPattern, tt.args.fields)
 			assert.Equal(t, tt.wantErr, err != nil)
 			assert.Equal(t, tt.want, got)
 		})

daemon/daemon.go

@@ -670,30 +670,69 @@ func containers2containers(cs []resource.Container) []v6.Container {
 	return res
 }
 
+// Much of the time, images will be sorted by timestamp. At marginal
+// cost, we cache the result of sorting, so that other uses of the
+// image can reuse it (if they are also sorted by timestamp).
+
+type repo struct {
+	images                []image.Info
+	imagesByTag           map[string]image.Info
+	imagesSortedByCreated update.SortedImageInfos
+}
+
+func (r *repo) SortedImages(p policy.Pattern) update.SortedImageInfos {
+	// RequiresTimestamp means "ordered by timestamp" (it's required
+	// because no comparison to see which image is newer can be made
+	// if a timestamp is missing)
+	if p.RequiresTimestamp() {
+		if r.imagesSortedByCreated == nil {
+			r.imagesSortedByCreated = update.SortImages(r.images, p)
+		}
+		return r.imagesSortedByCreated
+	}
+	return update.SortImages(r.images, p)
+}
+
+func (r *repo) Images() []image.Info {
+	return r.images
+}
+
+func (r *repo) ImageByTag(tag string) image.Info {
+	return r.imagesByTag[tag]
+}
+
 func getWorkloadContainers(workload cluster.Workload, imageRepos update.ImageRepos, resource resource.Resource, fields []string) (res []v6.Container, err error) {
+	repos := map[image.Name]*repo{}
+
 	for _, c := range workload.ContainersOrNil() {
-		imageRepo := c.Image.Name
+		imageName := c.Image.Name
 		var policies policy.Set
 		if resource != nil {
 			policies = resource.Policies()
 		}
 		tagPattern := policy.GetTagPattern(policies, c.Name)
 
-		repoMetadata := imageRepos.GetRepositoryMetadata(imageRepo)
-		var images []image.Info
-		// Build images, tolerating tags with missing metadata
-		for _, tag := range repoMetadata.Tags {
-			info, ok := repoMetadata.Images[tag]
-			if !ok {
-				info = image.Info{
-					ID: image.Ref{Tag: tag},
+		imageRepo, ok := repos[imageName]
+		if !ok {
+			repoMetadata := imageRepos.GetRepositoryMetadata(imageName)
+			var images []image.Info
+			// Build images, tolerating tags with missing metadata
+			for _, tag := range repoMetadata.Tags {
+				info, ok := repoMetadata.Images[tag]
+				if !ok {
+					info = image.Info{
+						ID: image.Ref{Tag: tag},
+					}
 				}
+				images = append(images, info)
 			}
-			images = append(images, info)
+			imageRepo = &repo{images: images, imagesByTag: repoMetadata.Images}
+			repos[imageName] = imageRepo
 		}
-		currentImage := repoMetadata.FindImageWithRef(c.Image)
 
-		container, err := v6.NewContainer(c.Name, images, currentImage, tagPattern, fields)
+		currentImage := imageRepo.ImageByTag(c.Image.Tag)
+
+		container, err := v6.NewContainer(c.Name, imageRepo, currentImage, tagPattern, fields)
 		if err != nil {
 			return res, err
 		}

remote/rpc/compat.go

@@ -9,6 +9,7 @@ import (
 	"github.com/weaveworks/flux/api/v11"
 	"github.com/weaveworks/flux/api/v6"
 	"github.com/weaveworks/flux/cluster"
+	"github.com/weaveworks/flux/image"
 	"github.com/weaveworks/flux/policy"
 	"github.com/weaveworks/flux/remote"
 	"github.com/weaveworks/flux/resource"
@@ -138,6 +139,16 @@ type listImagesWithoutOptionsClient interface {
 	ListImages(ctx context.Context, spec update.ResourceSpec) ([]v6.ImageStatus, error)
 }
 
+type alreadySorted update.SortedImageInfos
+
+func (infos alreadySorted) Images() []image.Info {
+	return []image.Info(infos)
+}
+
+func (infos alreadySorted) SortedImages(_ policy.Pattern) update.SortedImageInfos {
+	return update.SortedImageInfos(infos)
+}
+
 // listImagesWithOptions is called by ListImagesWithOptions so we can use an
 // interface to dispatch .ListImages() and .ListServices() to the correct
 // API version.
@@ -177,7 +188,7 @@ func listImagesWithOptions(ctx context.Context, client listImagesWithoutOptionsC
 			}
 			tagPattern := policy.GetTagPattern(p, container.Name)
 			// Create a new container using the same function used in v10
-			newContainer, err := v6.NewContainer(container.Name, container.Available, container.Current, tagPattern, opts.OverrideContainerFields)
+			newContainer, err := v6.NewContainer(container.Name, alreadySorted(container.Available), container.Current, tagPattern, opts.OverrideContainerFields)
 			if err != nil {
 				return statuses, err
 			}