Split out the summary of a review into a separate struct.

This new struct is then returned by all of the methods that list the
reviews in a repo, and is what the "list" subcommand operates on.

By making this split, we can separate the data that is cheap to look up
from the data that is expensive to look up, and forgoe the expensive
look ups when we are operating on multiple reviews.

This change improves the performance of listing the open reviews in the
git-appraise repo by more than three fold (dropping the run time from
more than 7 seconds to less than 2).

Author: ojarjur

commands/list.go

@@ -34,7 +34,7 @@ var (
 // TODO(ojarjur): Add more flags for filtering the output (e.g. filtering by reviewer or status).
 func listReviews(repo repository.Repo, args []string) {
 	listFlagSet.Parse(args)
-	var reviews []review.Review
+	var reviews []review.ReviewSummary
 	if *listAll {
 		reviews = review.ListAll(repo)
 		fmt.Printf("Loaded %d reviews:\n", len(reviews))

commands/output/output.go

@@ -54,7 +54,7 @@ status: %s
 
 // getStatusString returns a human friendly string encapsulating both the review's
 // resolved status, and its submitted status.
-func getStatusString(r *review.Review) string {
+func getStatusString(r *review.ReviewSummary) string {
 	if r.Resolved == nil && r.Submitted {
 		return "tbr"
 	}
@@ -74,7 +74,7 @@ func getStatusString(r *review.Review) string {
 }
 
 // PrintSummary prints a single-line summary of a review.
-func PrintSummary(r *review.Review) {
+func PrintSummary(r *review.ReviewSummary) {
 	statusString := getStatusString(r)
 	indentedDescription := strings.Replace(r.Request.Description, "\n", "\n  ", -1)
 	fmt.Printf(reviewSummaryTemplate, statusString, r.Revision, indentedDescription)
@@ -176,7 +176,7 @@ func printComments(r *review.Review) error {
 
 // PrintDetails prints a multi-line overview of a review, including all comments.
 func PrintDetails(r *review.Review) error {
-	PrintSummary(r)
+	PrintSummary(r.ReviewSummary)
 	fmt.Printf(reviewDetailsTemplate, r.Request.ReviewRef, r.Request.TargetRef,
 		strings.Join(r.Request.Reviewers, ", "),
 		r.Request.Requester, r.GetBuildStatusMessage())

review/review.go

@@ -44,24 +44,35 @@ type CommentThread struct {
 	Resolved *bool           `json:"resolved,omitempty"`
 }
 
-// Review represents the entire state of a code review.
+// ReviewSummary represents the high-level state of a code review.
+//
+// This high-level state corresponds to the data that can be quickly read
+// directly from the repo, so other methods that need to operate on a lot
+// of reviews (such as listing the open reviews) should prefer operating on
+// the summary rather than the details.
 //
-// Reviews have two status fields which are orthogonal:
+// Review summaries have two status fields which are orthogonal:
 // 1. Resolved indicates if a reviewer has accepted or rejected the change.
 // 2. Submitted indicates if the change has been incorporated into the target.
+type ReviewSummary struct {
+	Repo      repository.Repo `json:"-"`
+	Revision  string          `json:"revision"`
+	Request   request.Request `json:"request"`
+	Comments  []CommentThread `json:"comments,omitempty"`
+	Resolved  *bool           `json:"resolved,omitempty"`
+	Submitted bool            `json:"submitted"`
+}
+
+// Review represents the entire state of a code review.
 //
-// Reviews also include a list of build-and-test status reports. Those
+// This extends ReviewSummary to also include a list of reports for both the
+// continuous integration status, and the static analysis runs. Those reports
 // correspond to either the current commit in the review ref (for pending
 // reviews), or to the last commented-upon commit (for submitted reviews).
 type Review struct {
-	Repo      repository.Repo   `json:"-"`
-	Revision  string            `json:"revision"`
-	Request   request.Request   `json:"request"`
-	Comments  []CommentThread   `json:"comments,omitempty"`
-	Resolved  *bool             `json:"resolved,omitempty"`
-	Submitted bool              `json:"submitted"`
-	Reports   []ci.Report       `json:"reports,omitempty"`
-	Analyses  []analyses.Report `json:"analyses,omitempty"`
+	*ReviewSummary
+	Reports  []ci.Report       `json:"reports,omitempty"`
+	Analyses []analyses.Report `json:"analyses,omitempty"`
 }
 
 type byTimestamp []CommentThread
@@ -173,46 +184,68 @@ func buildCommentThreads(commentsByHash map[string]comment.Comment) []CommentThr
 
 // loadComments reads in the log-structured sequence of comments for a review,
 // and then builds the corresponding tree-structured comment threads.
-func (r *Review) loadComments() []CommentThread {
+func (r *ReviewSummary) loadComments() []CommentThread {
 	commentNotes := r.Repo.GetNotes(comment.Ref, r.Revision)
 	commentsByHash := comment.ParseAllValid(commentNotes)
 	return buildCommentThreads(commentsByHash)
 }
 
-// Get returns the specified code review.
+// Get returns the summary of the specified code review.
 //
-// If no review request exists, the returned review is nil.
-func Get(repo repository.Repo, revision string) (*Review, error) {
+// If no review request exists, the returned review summary is nil.
+func GetSummary(repo repository.Repo, revision string) (*ReviewSummary, error) {
 	requestNotes := repo.GetNotes(request.Ref, revision)
 	requests := request.ParseAllValid(requestNotes)
 	if requests == nil {
 		return nil, nil
 	}
-	review := Review{
+	reviewSummary := ReviewSummary{
 		Repo:     repo,
 		Revision: revision,
 		Request:  requests[len(requests)-1],
 	}
-	review.Comments = review.loadComments()
-	review.Resolved = updateThreadsStatus(review.Comments)
-	submitted, err := repo.IsAncestor(revision, review.Request.TargetRef)
+	reviewSummary.Comments = reviewSummary.loadComments()
+	reviewSummary.Resolved = updateThreadsStatus(reviewSummary.Comments)
+	submitted, err := repo.IsAncestor(revision, reviewSummary.Request.TargetRef)
 	if err != nil {
 		return nil, err
 	}
-	review.Submitted = submitted
+	reviewSummary.Submitted = submitted
+	return &reviewSummary, nil
+}
+
+// Details returns the detailed review for the given summary.
+func (r *ReviewSummary) Details() (*Review, error) {
+	review := Review{
+		ReviewSummary: r,
+	}
 	currentCommit, err := review.GetHeadCommit()
 	if err == nil {
-		review.Reports = ci.ParseAllValid(repo.GetNotes(ci.Ref, currentCommit))
-		review.Analyses = analyses.ParseAllValid(repo.GetNotes(analyses.Ref, currentCommit))
+		review.Reports = ci.ParseAllValid(review.Repo.GetNotes(ci.Ref, currentCommit))
+		review.Analyses = analyses.ParseAllValid(review.Repo.GetNotes(analyses.Ref, currentCommit))
 	}
 	return &review, nil
 }
 
+// Get returns the specified code review.
+//
+// If no review request exists, the returned review is nil.
+func Get(repo repository.Repo, revision string) (*Review, error) {
+	summary, err := GetSummary(repo, revision)
+	if err != nil {
+		return nil, err
+	}
+	if summary == nil {
+		return nil, nil
+	}
+	return summary.Details()
+}
+
 // ListAll returns all reviews stored in the git-notes.
-func ListAll(repo repository.Repo) []Review {
-	var reviews []Review
+func ListAll(repo repository.Repo) []ReviewSummary {
+	var reviews []ReviewSummary
 	for _, revision := range repo.ListNotedRevisions(request.Ref) {
-		review, err := Get(repo, revision)
+		review, err := GetSummary(repo, revision)
 		if err == nil && review != nil {
 			reviews = append(reviews, *review)
 		}
@@ -221,8 +254,8 @@ func ListAll(repo repository.Repo) []Review {
 }
 
 // ListOpen returns all reviews that are not yet incorporated into their target refs.
-func ListOpen(repo repository.Repo) []Review {
-	var openReviews []Review
+func ListOpen(repo repository.Repo) []ReviewSummary {
+	var openReviews []ReviewSummary
 	for _, review := range ListAll(repo) {
 		if !review.Submitted {
 			openReviews = append(openReviews, review)
@@ -239,7 +272,7 @@ func GetCurrent(repo repository.Repo) (*Review, error) {
 	if err != nil {
 		return nil, err
 	}
-	var matchingReviews []Review
+	var matchingReviews []ReviewSummary
 	for _, review := range ListOpen(repo) {
 		if review.Request.ReviewRef == reviewRef {
 			matchingReviews = append(matchingReviews, review)
@@ -251,8 +284,7 @@ func GetCurrent(repo repository.Repo) (*Review, error) {
 	if len(matchingReviews) != 1 {
 		return nil, fmt.Errorf("There are %d open reviews for the ref \"%s\"", len(matchingReviews), reviewRef)
 	}
-	r := &matchingReviews[0]
-	return r, nil
+	return matchingReviews[0].Details()
 }
 
 // GetBuildStatusMessage returns a string of the current build-and-test status