Divergence from base branch display

docs/Config.md

@@ -187,6 +187,10 @@ gui:
   # If true, show commit hashes alongside branch names in the branches view.
   showBranchCommitHash: false
 
+  # Whether to show the divergence from the base branch in the branches view.
+  # One of: 'none' | 'onlyArrow'  | 'arrowAndNumber'
+  showDivergenceFromBaseBranch: none
+
   # Height of the command log view
   commandLogSize: 8
 

pkg/commands/git_commands/branch_loader.go

@@ -5,6 +5,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/jesseduffield/generics/set"
 	"github.com/jesseduffield/go-git/v5/config"
@@ -14,6 +15,7 @@ import (
 	"github.com/jesseduffield/lazygit/pkg/utils"
 	"github.com/samber/lo"
 	"golang.org/x/exp/slices"
+	"golang.org/x/sync/errgroup"
 )
 
 // context:
@@ -63,7 +65,13 @@ func NewBranchLoader(
 }
 
 // Load the list of branches for the current repo
-func (self *BranchLoader) Load(reflogCommits []*models.Commit) ([]*models.Branch, error) {
+func (self *BranchLoader) Load(reflogCommits []*models.Commit,
+	mainBranches *MainBranches,
+	oldBranches []*models.Branch,
+	loadBehindCounts bool,
+	onWorker func(func() error),
+	renderFunc func(),
+) ([]*models.Branch, error) {
 	branches := self.obtainBranches(self.version.IsAtLeast(2, 22, 0))
 
 	if self.AppState.LocalBranchSortOrder == "recency" {
@@ -122,11 +130,108 @@ func (self *BranchLoader) Load(reflogCommits []*models.Commit) ([]*models.Branch
 			branch.UpstreamRemote = match.Remote
 			branch.UpstreamBranch = match.Merge.Short()
 		}
+
+		// If the branch already existed, take over its BehindBaseBranch value
+		// to reduce flicker
+		if oldBranch, found := lo.Find(oldBranches, func(b *models.Branch) bool {
+			return b.Name == branch.Name
+		}); found {
+			branch.BehindBaseBranch.Store(oldBranch.BehindBaseBranch.Load())
+		}
+	}
+
+	if loadBehindCounts && self.UserConfig.Gui.ShowDivergenceFromBaseBranch != "none" {
+		onWorker(func() error {
+			return self.GetBehindBaseBranchValuesForAllBranches(branches, mainBranches, renderFunc)
+		})
 	}
 
 	return branches, nil
 }
 
+func (self *BranchLoader) GetBehindBaseBranchValuesForAllBranches(
+	branches []*models.Branch,
+	mainBranches *MainBranches,
+	renderFunc func(),
+) error {
+	mainBranchRefs := mainBranches.Get()
+	if len(mainBranchRefs) == 0 {
+		return nil
+	}
+
+	t := time.Now()
+	errg := errgroup.Group{}
+
+	for _, branch := range branches {
+		errg.Go(func() error {
+			baseBranch, err := self.GetBaseBranch(branch, mainBranches)
+			if err != nil {
+				return err
+			}
+			behind := 0 // prime it in case something below fails
+			if baseBranch != "" {
+				output, err := self.cmd.New(
+					NewGitCmd("rev-list").
+						Arg("--left-right").
+						Arg("--count").
+						Arg(fmt.Sprintf("%s...%s", branch.FullRefName(), baseBranch)).
+						ToArgv(),
+				).DontLog().RunWithOutput()
+				if err != nil {
+					return err
+				}
+				// The format of the output is "<ahead>\t<behind>"
+				aheadBehindStr := strings.Split(strings.TrimSpace(output), "\t")
+				if len(aheadBehindStr) == 2 {
+					if value, err := strconv.Atoi(aheadBehindStr[1]); err == nil {
+						behind = value
+					}
+				}
+			}
+			branch.BehindBaseBranch.Store(int32(behind))
+			return nil
+		})
+	}
+
+	err := errg.Wait()
+	self.Log.Debugf("time to get behind base branch values for all branches: %s", time.Since(t))
+	renderFunc()
+	return err
+}
+
+// Find the base branch for the given branch (i.e. the main branch that the
+// given branch was forked off of)
+//
+// Note that this function may return an empty string even if the returned error
+// is nil, e.g. when none of the configured main branches exist. This is not
+// considered an error condition, so callers need to check both the returned
+// error and whether the returned base branch is empty (and possibly react
+// differently in both cases).
+func (self *BranchLoader) GetBaseBranch(branch *models.Branch, mainBranches *MainBranches) (string, error) {
+	mergeBase := mainBranches.GetMergeBase(branch.FullRefName())
+	if mergeBase == "" {
+		return "", nil
+	}
+
+	output, err := self.cmd.New(
+		NewGitCmd("for-each-ref").
+			Arg("--contains").
+			Arg(mergeBase).
+			Arg("--format=%(refname)").
+			Arg(mainBranches.Get()...).
+			ToArgv(),
+	).DontLog().RunWithOutput()
+	if err != nil {
+		return "", err
+	}
+	trimmedOutput := strings.TrimSpace(output)
+	split := strings.Split(trimmedOutput, "\n")
+	if len(split) == 0 || split[0] == "" {
+		return "", nil
+	}
+	return split[0], nil
+}
+
 func (self *BranchLoader) obtainBranches(canUsePushTrack bool) []*models.Branch {
 	output, err := self.getRawBranches()
 	if err != nil {

pkg/commands/git_commands/commit_loader.go

@@ -35,11 +35,6 @@ type CommitLoader struct {
 	readFile      func(filename string) ([]byte, error)
 	walkFiles     func(root string, fn filepath.WalkFunc) error
 	dotGitDir     string
-	// List of main branches that exist in the repo.
-	// We use these to obtain the merge base of the branch.
-	// When nil, we're yet to obtain the list of existing main branches.
-	// When an empty slice, we've obtained the list and it's empty.
-	mainBranches []string
 	*GitCommon
 }
 
@@ -56,7 +51,6 @@ func NewCommitLoader(
 		getRebaseMode: getRebaseMode,
 		readFile:      os.ReadFile,
 		walkFiles:     filepath.Walk,
-		mainBranches:  nil,
 		GitCommon:     gitCommon,
 	}
 }
@@ -72,6 +66,7 @@ type GetCommitsOptions struct {
 	All bool
 	// If non-empty, show divergence from this ref (left-right log)
 	RefToShowDivergenceFrom string
+	MainBranches            *MainBranches
 }
 
 // GetCommits obtains the commits of the current branch
@@ -108,9 +103,9 @@ func (self *CommitLoader) GetCommits(opts GetCommitsOptions) ([]*models.Commit,
 	go utils.Safe(func() {
 		defer wg.Done()
 
-		ancestor = self.getMergeBase(opts.RefName)
+		ancestor = opts.MainBranches.GetMergeBase(opts.RefName)
 		if opts.RefToShowDivergenceFrom != "" {
-			remoteAncestor = self.getMergeBase(opts.RefToShowDivergenceFrom)
+			remoteAncestor = opts.MainBranches.GetMergeBase(opts.RefToShowDivergenceFrom)
 		}
 	})
 
@@ -471,82 +466,6 @@ func setCommitMergedStatuses(ancestor string, commits []*models.Commit) {
 	}
 }
 
-func (self *CommitLoader) getMergeBase(refName string) string {
-	if self.mainBranches == nil {
-		self.mainBranches = self.getExistingMainBranches()
-	}
-
-	if len(self.mainBranches) == 0 {
-		return ""
-	}
-
-	// We pass all configured main branches to the merge-base call; git will
-	// return the base commit for the closest one.
-
-	output, err := self.cmd.New(
-		NewGitCmd("merge-base").Arg(refName).Arg(self.mainBranches...).
-			ToArgv(),
-	).DontLog().RunWithOutput()
-	if err != nil {
-		// If there's an error, it must be because one of the main branches that
-		// used to exist when we called getExistingMainBranches() was deleted
-		// meanwhile. To fix this for next time, throw away our cache.
-		self.mainBranches = nil
-	}
-	return ignoringWarnings(output)
-}
-
-func (self *CommitLoader) getExistingMainBranches() []string {
-	var existingBranches []string
-	var wg sync.WaitGroup
-
-	mainBranches := self.UserConfig.Git.MainBranches
-	existingBranches = make([]string, len(mainBranches))
-
-	for i, branchName := range mainBranches {
-		wg.Add(1)
-		go utils.Safe(func() {
-			defer wg.Done()
-
-			// Try to determine upstream of local main branch
-			if ref, err := self.cmd.New(
-				NewGitCmd("rev-parse").Arg("--symbolic-full-name", branchName+"@{u}").ToArgv(),
-			).DontLog().RunWithOutput(); err == nil {
-				existingBranches[i] = strings.TrimSpace(ref)
-				return
-			}
-
-			// If this failed, a local branch for this main branch doesn't exist or it
-			// has no upstream configured. Try looking for one in the "origin" remote.
-			ref := "refs/remotes/origin/" + branchName
-			if err := self.cmd.New(
-				NewGitCmd("rev-parse").Arg("--verify", "--quiet", ref).ToArgv(),
-			).DontLog().Run(); err == nil {
-				existingBranches[i] = ref
-				return
-			}
-
-			// If this failed as well, try if we have the main branch as a local
-			// branch. This covers the case where somebody is using git locally
-			// for something, but never pushing anywhere.
-			ref = "refs/heads/" + branchName
-			if err := self.cmd.New(
-				NewGitCmd("rev-parse").Arg("--verify", "--quiet", ref).ToArgv(),
-			).DontLog().Run(); err == nil {
-				existingBranches[i] = ref
-			}
-		})
-	}
-
-	wg.Wait()
-
-	existingBranches = lo.Filter(existingBranches, func(branch string, _ int) bool {
-		return branch != ""
-	})
-
-	return existingBranches
-}
-
 func ignoringWarnings(commandOutput string) string {
 	trimmedOutput := strings.TrimSpace(commandOutput)
 	split := strings.Split(trimmedOutput, "\n")

pkg/commands/git_commands/commit_loader_test.go

@@ -307,10 +307,11 @@ func TestGetCommits(t *testing.T) {
 			common := utils.NewDummyCommon()
 			common.AppState = &config.AppState{}
 			common.AppState.GitLogOrder = scenario.logOrder
+			cmd := oscommands.NewDummyCmdObjBuilder(scenario.runner)
 
 			builder := &CommitLoader{
 				Common:        common,
-				cmd:           oscommands.NewDummyCmdObjBuilder(scenario.runner),
+				cmd:           cmd,
 				getRebaseMode: func() (enums.RebaseMode, error) { return scenario.rebaseMode, nil },
 				dotGitDir:     ".git",
 				readFile: func(filename string) ([]byte, error) {
@@ -322,7 +323,9 @@ func TestGetCommits(t *testing.T) {
 			}
 
 			common.UserConfig.Git.MainBranches = scenario.mainBranches
-			commits, err := builder.GetCommits(scenario.opts)
+			opts := scenario.opts
+			opts.MainBranches = NewMainBranches(scenario.mainBranches, cmd)
+			commits, err := builder.GetCommits(opts)
 
 			assert.Equal(t, scenario.expectedCommits, commits)
 			assert.Equal(t, scenario.expectedError, err)