Store Commit.Hash by pointer (kept in a pool of hashes)

This in itself is not an improvement, because hashes are unique (they are shared
between real commits and rebase todos, but there are so few of those that it
doesn't matter). However, it becomes an improvement once we also store parent
hashes in the same pool; but the real motivation for this change is to also
reuse the hash pointers in Pipe objects later in the branch. This will be a big
win because in a merge-heavy git repo there are many more Pipe instances than
commits.

pkg/commands/git_commands/commit_loader.go

@@ -66,6 +66,7 @@ type GetCommitsOptions struct {
 	// If non-empty, show divergence from this ref (left-right log)
 	RefToShowDivergenceFrom string
 	MainBranches            *MainBranches
+	HashPool                *utils.StringPool
 }
 
 // GetCommits obtains the commits of the current branch
@@ -74,7 +75,7 @@ func (self *CommitLoader) GetCommits(opts GetCommitsOptions) ([]*models.Commit,
 
 	if opts.IncludeRebaseCommits && opts.FilterPath == "" {
 		var err error
-		commits, err = self.MergeRebasingCommits(commits)
+		commits, err = self.MergeRebasingCommits(opts.HashPool, commits)
 		if err != nil {
 			return nil, err
 		}
@@ -89,7 +90,7 @@ func (self *CommitLoader) GetCommits(opts GetCommitsOptions) ([]*models.Commit,
 		defer wg.Done()
 
 		logErr = self.getLogCmd(opts).RunAndProcessLines(func(line string) (bool, error) {
-			commit := self.extractCommitFromLine(line, opts.RefToShowDivergenceFrom != "")
+			commit := self.extractCommitFromLine(opts.HashPool, line, opts.RefToShowDivergenceFrom != "")
 			commits = append(commits, commit)
 			return false, nil
 		})
@@ -159,7 +160,7 @@ func (self *CommitLoader) GetCommits(opts GetCommitsOptions) ([]*models.Commit,
 	return commits, nil
 }
 
-func (self *CommitLoader) MergeRebasingCommits(commits []*models.Commit) ([]*models.Commit, error) {
+func (self *CommitLoader) MergeRebasingCommits(hashPool *utils.StringPool, commits []*models.Commit) ([]*models.Commit, error) {
 	// chances are we have as many commits as last time so we'll set the capacity to be the old length
 	result := make([]*models.Commit, 0, len(commits))
 	for i, commit := range commits {
@@ -172,7 +173,7 @@ func (self *CommitLoader) MergeRebasingCommits(commits []*models.Commit) ([]*mod
 	workingTreeState := self.getWorkingTreeState()
 	addConflictedRebasingCommit := true
 	if workingTreeState.CherryPicking || workingTreeState.Reverting {
-		sequencerCommits, err := self.getHydratedSequencerCommits(workingTreeState)
+		sequencerCommits, err := self.getHydratedSequencerCommits(hashPool, workingTreeState)
 		if err != nil {
 			return nil, err
 		}
@@ -181,7 +182,7 @@ func (self *CommitLoader) MergeRebasingCommits(commits []*models.Commit) ([]*mod
 	}
 
 	if workingTreeState.Rebasing {
-		rebasingCommits, err := self.getHydratedRebasingCommits(addConflictedRebasingCommit)
+		rebasingCommits, err := self.getHydratedRebasingCommits(hashPool, addConflictedRebasingCommit)
 		if err != nil {
 			return nil, err
 		}
@@ -196,7 +197,7 @@ func (self *CommitLoader) MergeRebasingCommits(commits []*models.Commit) ([]*mod
 // then puts them into a commit object
 // example input:
 // 8ad01fe32fcc20f07bc6693f87aa4977c327f1e1|10 hours ago|Jesse Duffield| (HEAD -> master, tag: v0.15.2)|refresh commits when adding a tag
-func (self *CommitLoader) extractCommitFromLine(line string, showDivergence bool) *models.Commit {
+func (self *CommitLoader) extractCommitFromLine(hashPool *utils.StringPool, line string, showDivergence bool) *models.Commit {
 	split := strings.SplitN(line, "\x00", 8)
 
 	hash := split[0]
@@ -234,7 +235,7 @@ func (self *CommitLoader) extractCommitFromLine(line string, showDivergence bool
 		parents = strings.Split(parentHashes, " ")
 	}
 
-	return models.NewCommit(models.NewCommitOpts{
+	return models.NewCommit(hashPool, models.NewCommitOpts{
 		Hash:          hash,
 		Name:          message,
 		Tags:          tags,
@@ -247,13 +248,13 @@ func (self *CommitLoader) extractCommitFromLine(line string, showDivergence bool
 	})
 }
 
-func (self *CommitLoader) getHydratedRebasingCommits(addConflictingCommit bool) ([]*models.Commit, error) {
+func (self *CommitLoader) getHydratedRebasingCommits(hashPool *utils.StringPool, addConflictingCommit bool) ([]*models.Commit, error) {
 	todoFileHasShortHashes := self.version.IsOlderThan(2, 25, 2)
-	return self.getHydratedTodoCommits(self.getRebasingCommits(addConflictingCommit), todoFileHasShortHashes)
+	return self.getHydratedTodoCommits(hashPool, self.getRebasingCommits(hashPool, addConflictingCommit), todoFileHasShortHashes)
 }
 
-func (self *CommitLoader) getHydratedSequencerCommits(workingTreeState models.WorkingTreeState) ([]*models.Commit, error) {
+func (self *CommitLoader) getHydratedSequencerCommits(hashPool *utils.StringPool, workingTreeState models.WorkingTreeState) ([]*models.Commit, error) {
-	commits := self.getSequencerCommits()
+	commits := self.getSequencerCommits(hashPool)
 	if len(commits) > 0 {
 		// If we have any commits in .git/sequencer/todo, then the last one of
 		// those is the conflicting one.
@@ -262,16 +263,16 @@ func (self *CommitLoader) getHydratedSequencerCommits(workingTreeState models.Wo
 		// For single-commit cherry-picks and reverts, git apparently doesn't
 		// use the sequencer; in that case, CHERRY_PICK_HEAD or REVERT_HEAD is
 		// our conflicting commit, so synthesize it here.
-		conflicedCommit := self.getConflictedSequencerCommit(workingTreeState)
+		conflicedCommit := self.getConflictedSequencerCommit(hashPool, workingTreeState)
 		if conflicedCommit != nil {
 			commits = append(commits, conflicedCommit)
 		}
 	}
 
-	return self.getHydratedTodoCommits(commits, true)
+	return self.getHydratedTodoCommits(hashPool, commits, true)
 }
 
-func (self *CommitLoader) getHydratedTodoCommits(todoCommits []*models.Commit, todoFileHasShortHashes bool) ([]*models.Commit, error) {
+func (self *CommitLoader) getHydratedTodoCommits(hashPool *utils.StringPool, todoCommits []*models.Commit, todoFileHasShortHashes bool) ([]*models.Commit, error) {
 	if len(todoCommits) == 0 {
 		return nil, nil
 	}
@@ -292,7 +293,7 @@ func (self *CommitLoader) getHydratedTodoCommits(todoCommits []*models.Commit, t
 
 	fullCommits := map[string]*models.Commit{}
 	err := cmdObj.RunAndProcessLines(func(line string) (bool, error) {
-		commit := self.extractCommitFromLine(line, false)
+		commit := self.extractCommitFromLine(hashPool, line, false)
 		fullCommits[commit.Hash()] = commit
 		return false, nil
 	})
@@ -331,7 +332,7 @@ func (self *CommitLoader) getHydratedTodoCommits(todoCommits []*models.Commit, t
 // git-rebase-todo example:
 // pick ac446ae94ee560bdb8d1d057278657b251aaef17 ac446ae
 // pick afb893148791a2fbd8091aeb81deba4930c73031 afb8931
-func (self *CommitLoader) getRebasingCommits(addConflictingCommit bool) []*models.Commit {
+func (self *CommitLoader) getRebasingCommits(hashPool *utils.StringPool, addConflictingCommit bool) []*models.Commit {
 	bytesContent, err := self.readFile(filepath.Join(self.repoPaths.WorktreeGitDirPath(), "rebase-merge/git-rebase-todo"))
 	if err != nil {
 		self.Log.Error(fmt.Sprintf("error occurred reading git-rebase-todo: %s", err.Error()))
@@ -350,7 +351,7 @@ func (self *CommitLoader) getRebasingCommits(addConflictingCommit bool) []*model
 	// See if the current commit couldn't be applied because it conflicted; if
 	// so, add a fake entry for it
 	if addConflictingCommit {
-		if conflictedCommit := self.getConflictedCommit(todos); conflictedCommit != nil {
+		if conflictedCommit := self.getConflictedCommit(hashPool, todos); conflictedCommit != nil {
 			commits = append(commits, conflictedCommit)
 		}
 	}
@@ -364,7 +365,7 @@ func (self *CommitLoader) getRebasingCommits(addConflictingCommit bool) []*model
 			// Command does not have a commit associated, skip
 			continue
 		}
-		commits = utils.Prepend(commits, models.NewCommit(models.NewCommitOpts{
+		commits = utils.Prepend(commits, models.NewCommit(hashPool, models.NewCommitOpts{
 			Hash:   t.Commit,
 			Name:   t.Msg,
 			Status: models.StatusRebasing,
@@ -375,7 +376,7 @@ func (self *CommitLoader) getRebasingCommits(addConflictingCommit bool) []*model
 	return commits
 }
 
-func (self *CommitLoader) getConflictedCommit(todos []todo.Todo) *models.Commit {
+func (self *CommitLoader) getConflictedCommit(hashPool *utils.StringPool, todos []todo.Todo) *models.Commit {
 	bytesContent, err := self.readFile(filepath.Join(self.repoPaths.WorktreeGitDirPath(), "rebase-merge/done"))
 	if err != nil {
 		self.Log.Error(fmt.Sprintf("error occurred reading rebase-merge/done: %s", err.Error()))
@@ -391,10 +392,10 @@ func (self *CommitLoader) getConflictedCommit(todos []todo.Todo) *models.Commit
 	amendFileExists, _ := self.os.FileExists(filepath.Join(self.repoPaths.WorktreeGitDirPath(), "rebase-merge/amend"))
 	messageFileExists, _ := self.os.FileExists(filepath.Join(self.repoPaths.WorktreeGitDirPath(), "rebase-merge/message"))
 
-	return self.getConflictedCommitImpl(todos, doneTodos, amendFileExists, messageFileExists)
+	return self.getConflictedCommitImpl(hashPool, todos, doneTodos, amendFileExists, messageFileExists)
 }
 
-func (self *CommitLoader) getConflictedCommitImpl(todos []todo.Todo, doneTodos []todo.Todo, amendFileExists bool, messageFileExists bool) *models.Commit {
+func (self *CommitLoader) getConflictedCommitImpl(hashPool *utils.StringPool, todos []todo.Todo, doneTodos []todo.Todo, amendFileExists bool, messageFileExists bool) *models.Commit {
 	// Should never be possible, but just to be safe:
 	if len(doneTodos) == 0 {
 		self.Log.Error("no done entries in rebase-merge/done file")
@@ -465,14 +466,14 @@ func (self *CommitLoader) getConflictedCommitImpl(todos []todo.Todo, doneTodos [
 
 	// Any other todo that has a commit associated with it must have failed with
 	// a conflict, otherwise we wouldn't have stopped the rebase:
-	return models.NewCommit(models.NewCommitOpts{
+	return models.NewCommit(hashPool, models.NewCommitOpts{
 		Hash:   lastTodo.Commit,
 		Action: lastTodo.Command,
 		Status: models.StatusConflicted,
 	})
 }
 
-func (self *CommitLoader) getSequencerCommits() []*models.Commit {
+func (self *CommitLoader) getSequencerCommits(hashPool *utils.StringPool) []*models.Commit {
 	bytesContent, err := self.readFile(filepath.Join(self.repoPaths.WorktreeGitDirPath(), "sequencer/todo"))
 	if err != nil {
 		self.Log.Error(fmt.Sprintf("error occurred reading sequencer/todo: %s", err.Error()))
@@ -493,7 +494,7 @@ func (self *CommitLoader) getSequencerCommits() []*models.Commit {
 			// Command does not have a commit associated, skip
 			continue
 		}
-		commits = utils.Prepend(commits, models.NewCommit(models.NewCommitOpts{
+		commits = utils.Prepend(commits, models.NewCommit(hashPool, models.NewCommitOpts{
 			Hash:   t.Commit,
 			Name:   t.Msg,
 			Status: models.StatusCherryPickingOrReverting,
@@ -504,7 +505,7 @@ func (self *CommitLoader) getSequencerCommits() []*models.Commit {
 	return commits
 }
 
-func (self *CommitLoader) getConflictedSequencerCommit(workingTreeState models.WorkingTreeState) *models.Commit {
+func (self *CommitLoader) getConflictedSequencerCommit(hashPool *utils.StringPool, workingTreeState models.WorkingTreeState) *models.Commit {
 	var shaFile string
 	var action todo.TodoCommand
 	if workingTreeState.CherryPicking {
@@ -526,7 +527,7 @@ func (self *CommitLoader) getConflictedSequencerCommit(workingTreeState models.W
 	if len(lines) == 0 {
 		return nil
 	}
-	return models.NewCommit(models.NewCommitOpts{
+	return models.NewCommit(hashPool, models.NewCommitOpts{
 		Hash:   lines[0],
 		Status: models.StatusConflicted,
 		Action: action,

pkg/commands/git_commands/commit_loader_test.go

@@ -314,13 +314,16 @@ func TestGetCommits(t *testing.T) {
 				},
 			}
 
+			hashPool := &utils.StringPool{}
+
 			common.UserConfig().Git.MainBranches = scenario.mainBranches
 			opts := scenario.opts
 			opts.MainBranches = NewMainBranches(common, cmd)
+			opts.HashPool = hashPool
 			commits, err := builder.GetCommits(opts)
 
 			expectedCommits := lo.Map(scenario.expectedCommitOpts,
-				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 			assert.Equal(t, expectedCommits, commits)
 			assert.Equal(t, scenario.expectedError, err)
 
@@ -330,6 +333,8 @@ func TestGetCommits(t *testing.T) {
 }
 
 func TestCommitLoader_getConflictedCommitImpl(t *testing.T) {
+	hashPool := &utils.StringPool{}
+
 	scenarios := []struct {
 		testName          string
 		todos             []todo.Todo
@@ -359,7 +364,7 @@ func TestCommitLoader_getConflictedCommitImpl(t *testing.T) {
 				},
 			},
 			amendFileExists: false,
-			expectedResult: models.NewCommit(models.NewCommitOpts{
+			expectedResult: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:   "fa1afe1",
 				Action: todo.Pick,
 				Status: models.StatusConflicted,
@@ -460,7 +465,7 @@ func TestCommitLoader_getConflictedCommitImpl(t *testing.T) {
 				},
 			},
 			amendFileExists: false,
-			expectedResult: models.NewCommit(models.NewCommitOpts{
+			expectedResult: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:   "fa1afe1",
 				Action: todo.Pick,
 				Status: models.StatusConflicted,
@@ -489,7 +494,7 @@ func TestCommitLoader_getConflictedCommitImpl(t *testing.T) {
 			},
 			amendFileExists:   false,
 			messageFileExists: true,
-			expectedResult: models.NewCommit(models.NewCommitOpts{
+			expectedResult: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:   "fa1afe1",
 				Action: todo.Edit,
 				Status: models.StatusConflicted,
@@ -526,7 +531,7 @@ func TestCommitLoader_getConflictedCommitImpl(t *testing.T) {
 				},
 			}
 
-			hash := builder.getConflictedCommitImpl(scenario.todos, scenario.doneTodos, scenario.amendFileExists, scenario.messageFileExists)
+			hash := builder.getConflictedCommitImpl(hashPool, scenario.todos, scenario.doneTodos, scenario.amendFileExists, scenario.messageFileExists)
 			assert.Equal(t, scenario.expectedResult, hash)
 		})
 	}
@@ -573,11 +578,13 @@ func TestCommitLoader_setCommitMergedStatuses(t *testing.T) {
 
 	for _, scenario := range scenarios {
 		t.Run(scenario.testName, func(t *testing.T) {
+			hashPool := &utils.StringPool{}
+
 			commits := lo.Map(scenario.commitOpts,
-				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 			setCommitMergedStatuses(scenario.ancestor, commits)
 			expectedCommits := lo.Map(scenario.expectedCommitOpts,
-				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 			assert.Equal(t, expectedCommits, commits)
 		})
 	}

pkg/commands/git_commands/rebase_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
+	"github.com/jesseduffield/lazygit/pkg/utils"
 	"github.com/samber/lo"
 	"github.com/stretchr/testify/assert"
 )
@@ -158,8 +159,9 @@ func TestRebaseDiscardOldFileChanges(t *testing.T) {
 				gitConfig:  git_config.NewFakeGitConfig(s.gitConfigMockResponses),
 			})
 
+			hashPool := &utils.StringPool{}
 			commits := lo.Map(s.commitOpts,
-				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 
 			s.test(instance.DiscardOldFileChanges(commits, s.commitIndex, s.fileName))
 			s.runner.CheckForMissingCalls()

pkg/commands/git_commands/reflog_commit_loader.go

@@ -7,6 +7,7 @@ import (
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 	"github.com/jesseduffield/lazygit/pkg/common"
+	"github.com/jesseduffield/lazygit/pkg/utils"
 )
 
 type ReflogCommitLoader struct {
@@ -23,7 +24,7 @@ func NewReflogCommitLoader(common *common.Common, cmd oscommands.ICmdObjBuilder)
 
 // GetReflogCommits only returns the new reflog commits since the given lastReflogCommit
 // if none is passed (i.e. it's value is nil) then we get all the reflog commits
-func (self *ReflogCommitLoader) GetReflogCommits(lastReflogCommit *models.Commit, filterPath string, filterAuthor string) ([]*models.Commit, bool, error) {
+func (self *ReflogCommitLoader) GetReflogCommits(hashPool *utils.StringPool, lastReflogCommit *models.Commit, filterPath string, filterAuthor string) ([]*models.Commit, bool, error) {
 	commits := make([]*models.Commit, 0)
 
 	cmdArgs := NewGitCmd("log").
@@ -39,7 +40,7 @@ func (self *ReflogCommitLoader) GetReflogCommits(lastReflogCommit *models.Commit
 
 	onlyObtainedNewReflogCommits := false
 	err := cmdObj.RunAndProcessLines(func(line string) (bool, error) {
-		commit, ok := self.parseLine(line)
+		commit, ok := self.parseLine(hashPool, line)
 		if !ok {
 			return false, nil
 		}
@@ -68,7 +69,7 @@ func (self *ReflogCommitLoader) sameReflogCommit(a *models.Commit, b *models.Com
 	return a.Hash() == b.Hash() && a.UnixTimestamp == b.UnixTimestamp && a.Name == b.Name
 }
 
-func (self *ReflogCommitLoader) parseLine(line string) (*models.Commit, bool) {
+func (self *ReflogCommitLoader) parseLine(hashPool *utils.StringPool, line string) (*models.Commit, bool) {
 	fields := strings.SplitN(line, "\x00", 4)
 	if len(fields) <= 3 {
 		return nil, false
@@ -82,7 +83,7 @@ func (self *ReflogCommitLoader) parseLine(line string) (*models.Commit, bool) {
 		parents = strings.Split(parentHashes, " ")
 	}
 
-	return models.NewCommit(models.NewCommitOpts{
+	return models.NewCommit(hashPool, models.NewCommitOpts{
 		Hash:          fields[0],
 		Name:          fields[2],
 		UnixTimestamp: int64(unixTimestamp),

pkg/commands/git_commands/reflog_commit_loader_test.go

@@ -32,6 +32,8 @@ func TestGetReflogCommits(t *testing.T) {
 		expectedError           error
 	}
 
+	hashPool := &utils.StringPool{}
+
 	scenarios := []scenario{
 		{
 			testName: "no reflog entries",
@@ -94,7 +96,7 @@ func TestGetReflogCommits(t *testing.T) {
 			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"-c", "log.showSignature=false", "log", "-g", "--abbrev=40", "--format=%h%x00%ct%x00%gs%x00%p"}, reflogOutput, nil),
 
-			lastReflogCommit: models.NewCommit(models.NewCommitOpts{
+			lastReflogCommit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:          "c3c4b66b64c97ffeecde",
 				Name:          "checkout: moving from B to A",
 				Status:        models.StatusReflog,
@@ -118,7 +120,7 @@ func TestGetReflogCommits(t *testing.T) {
 			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"-c", "log.showSignature=false", "log", "-g", "--abbrev=40", "--format=%h%x00%ct%x00%gs%x00%p", "--follow", "--", "path"}, reflogOutput, nil),
 
-			lastReflogCommit: models.NewCommit(models.NewCommitOpts{
+			lastReflogCommit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:          "c3c4b66b64c97ffeecde",
 				Name:          "checkout: moving from B to A",
 				Status:        models.StatusReflog,
@@ -143,7 +145,7 @@ func TestGetReflogCommits(t *testing.T) {
 			runner: oscommands.NewFakeRunner(t).
 				ExpectGitArgs([]string{"-c", "log.showSignature=false", "log", "-g", "--abbrev=40", "--format=%h%x00%ct%x00%gs%x00%p", "--author=John Doe <john@doe.com>"}, reflogOutput, nil),
 
-			lastReflogCommit: models.NewCommit(models.NewCommitOpts{
+			lastReflogCommit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:          "c3c4b66b64c97ffeecde",
 				Name:          "checkout: moving from B to A",
 				Status:        models.StatusReflog,
@@ -183,14 +185,14 @@ func TestGetReflogCommits(t *testing.T) {
 				cmd:    oscommands.NewDummyCmdObjBuilder(scenario.runner),
 			}
 
-			commits, onlyObtainednew, err := builder.GetReflogCommits(scenario.lastReflogCommit, scenario.filterPath, scenario.filterAuthor)
+			commits, onlyObtainednew, err := builder.GetReflogCommits(hashPool, scenario.lastReflogCommit, scenario.filterPath, scenario.filterAuthor)
 			assert.Equal(t, scenario.expectedOnlyObtainedNew, onlyObtainednew)
 			assert.Equal(t, scenario.expectedError, err)
 			t.Logf("actual commits: \n%s", litter.Sdump(commits))
 			var expectedCommits []*models.Commit
 			if scenario.expectedCommitOpts != nil {
 				expectedCommits = lo.Map(scenario.expectedCommitOpts,
-					func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+					func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 			}
 			assert.Equal(t, expectedCommits, commits)
 

pkg/commands/models/commit.go

@@ -42,7 +42,7 @@ const (
 
 // Commit : A git commit
 type Commit struct {
-	hash          string
+	hash          *string
 	Name          string
 	Status        CommitStatus
 	Action        todo.TodoCommand
@@ -71,9 +71,9 @@ type NewCommitOpts struct {
 	Parents       []string
 }
 
-func NewCommit(opts NewCommitOpts) *Commit {
+func NewCommit(hashPool *utils.StringPool, opts NewCommitOpts) *Commit {
 	return &Commit{
-		hash:          opts.Hash,
+		hash:          hashPool.Add(opts.Hash),
 		Name:          opts.Name,
 		Status:        opts.Status,
 		Action:        opts.Action,
@@ -88,7 +88,7 @@ func NewCommit(opts NewCommitOpts) *Commit {
 }
 
 func (c *Commit) Hash() string {
-	return c.hash
+	return *c.hash
 }
 
 func (c *Commit) ShortHash() string {

pkg/gui/controllers/helpers/refresh_helper.go

@@ -332,6 +332,7 @@ func (self *RefreshHelper) refreshCommitsWithLimit() error {
 			RefForPushedStatus:   checkedOutBranchName,
 			All:                  self.c.Contexts().LocalCommits.GetShowWholeGitGraph(),
 			MainBranches:         self.c.Model().MainBranches,
+			HashPool:             self.c.Model().HashPool,
 		},
 	)
 	if err != nil {
@@ -360,6 +361,7 @@ func (self *RefreshHelper) refreshSubCommitsWithLimit() error {
 			RefToShowDivergenceFrom: self.c.Contexts().SubCommits.GetRefToShowDivergenceFrom(),
 			RefForPushedStatus:      self.c.Contexts().SubCommits.GetRef().FullRefName(),
 			MainBranches:            self.c.Model().MainBranches,
+			HashPool:                self.c.Model().HashPool,
 		},
 	)
 	if err != nil {
@@ -406,7 +408,7 @@ func (self *RefreshHelper) refreshRebaseCommits() error {
 	self.c.Mutexes().LocalCommitsMutex.Lock()
 	defer self.c.Mutexes().LocalCommitsMutex.Unlock()
 
-	updatedCommits, err := self.c.Git().Loaders.CommitLoader.MergeRebasingCommits(self.c.Model().Commits)
+	updatedCommits, err := self.c.Git().Loaders.CommitLoader.MergeRebasingCommits(self.c.Model().HashPool, self.c.Model().Commits)
 	if err != nil {
 		return err
 	}
@@ -455,7 +457,7 @@ func (self *RefreshHelper) refreshBranches(refreshWorktrees bool, keepBranchSele
 		// which allows us to order them correctly. So if we're filtering we'll just
 		// manually load all the reflog commits here
 		var err error
-		reflogCommits, _, err = self.c.Git().Loaders.ReflogCommitLoader.GetReflogCommits(nil, "", "")
+		reflogCommits, _, err = self.c.Git().Loaders.ReflogCommitLoader.GetReflogCommits(self.c.Model().HashPool, nil, "", "")
 		if err != nil {
 			self.c.Log.Error(err)
 		}
@@ -624,7 +626,7 @@ func (self *RefreshHelper) refreshReflogCommits() error {
 
 	refresh := func(stateCommits *[]*models.Commit, filterPath string, filterAuthor string) error {
 		commits, onlyObtainedNewReflogCommits, err := self.c.Git().Loaders.ReflogCommitLoader.
-			GetReflogCommits(lastReflogCommit, filterPath, filterAuthor)
+			GetReflogCommits(self.c.Model().HashPool, lastReflogCommit, filterPath, filterAuthor)
 		if err != nil {
 			return err
 		}

pkg/gui/controllers/helpers/sub_commits_helper.go

@@ -45,6 +45,7 @@ func (self *SubCommitsHelper) ViewSubCommits(opts ViewSubCommitsOpts) error {
 			RefForPushedStatus:      opts.Ref.FullRefName(),
 			RefToShowDivergenceFrom: opts.RefToShowDivergenceFrom,
 			MainBranches:            self.c.Model().MainBranches,
+			HashPool:                self.c.Model().HashPool,
 		},
 	)
 	if err != nil {

pkg/gui/controllers/local_commits_controller.go

@@ -564,7 +564,7 @@ func (self *LocalCommitsController) startInteractiveRebaseWithEdit(
 				for _, c := range commitsToEdit[:len(commitsToEdit)-1] {
 					// Merge commits can't be set to "edit", so just skip them
 					if !c.IsMerge() {
-						todos = append(todos, models.NewCommit(models.NewCommitOpts{Hash: c.Hash(), Action: todo.Pick}))
+						todos = append(todos, models.NewCommit(self.c.Model().HashPool, models.NewCommitOpts{Hash: c.Hash(), Action: todo.Pick}))
 					}
 				}
 				if len(todos) > 0 {

pkg/gui/gui.go

@@ -558,6 +558,7 @@ func (gui *Gui) resetState(startArgs appTypes.StartArgs) types.Context {
 			FilesTrie:             patricia.NewTrie(),
 			Authors:               map[string]*models.Author{},
 			MainBranches:          git_commands.NewMainBranches(gui.c.Common, gui.os.Cmd),
+			HashPool:              &utils.StringPool{},
 		},
 		Modes: &types.Modes{
 			Filtering:        filtering.New(startArgs.FilterPath, ""),

pkg/gui/presentation/commits_test.go

@@ -544,8 +544,10 @@ func TestGetCommitListDisplayStrings(t *testing.T) {
 	for _, s := range scenarios {
 		if !focusing || s.focus {
 			t.Run(s.testName, func(t *testing.T) {
+				hashPool := &utils.StringPool{}
+
 				commits := lo.Map(s.commitOpts,
-					func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+					func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 
 				result := GetCommitListDisplayStrings(
 					common,

pkg/gui/presentation/files_test.go

@@ -149,8 +149,10 @@ func TestRenderCommitFileTree(t *testing.T) {
 
 	for _, s := range scenarios {
 		t.Run(s.name, func(t *testing.T) {
+			hashPool := &utils.StringPool{}
+
 			viewModel := filetree.NewCommitFileTreeViewModel(func() []*models.CommitFile { return s.files }, utils.NewDummyLog(), true)
-			viewModel.SetRef(&models.Commit{})
+			viewModel.SetRef(models.NewCommit(hashPool, models.NewCommitOpts{Hash: "1234"}))
 			viewModel.SetTree()
 			for _, path := range s.collapsedPaths {
 				viewModel.ToggleCollapsed(path)

pkg/gui/presentation/graph/graph_test.go

@@ -219,9 +219,11 @@ func TestRenderCommitGraph(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
+			hashPool := &utils.StringPool{}
+
 			getStyle := func(c *models.Commit) style.TextStyle { return style.FgDefault }
 			commits := lo.Map(test.commitOpts,
-				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(opts) })
+				func(opts models.NewCommitOpts, _ int) *models.Commit { return models.NewCommit(hashPool, opts) })
 			lines := RenderCommitGraph(commits, "blah", getStyle)
 
 			trimmedExpectedOutput := ""
@@ -254,6 +256,8 @@ func TestRenderPipeSet(t *testing.T) {
 	magenta := style.FgMagenta
 	nothing := style.Nothing
 
+	hashPool := &utils.StringPool{}
+
 	tests := []struct {
 		name           string
 		pipes          []*Pipe
@@ -268,7 +272,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "a", toHash: "b", kind: TERMINATES, style: cyan},
 				{fromPos: 0, toPos: 0, fromHash: "b", toHash: "c", kind: STARTS, style: green},
 			},
-			prevCommit:     models.NewCommit(models.NewCommitOpts{Hash: "a"}),
+			prevCommit:     models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
 			expectedStr:    "◯",
 			expectedStyles: []style.TextStyle{green},
 		},
@@ -278,7 +282,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "a", toHash: "selected", kind: TERMINATES, style: cyan},
 				{fromPos: 0, toPos: 0, fromHash: "selected", toHash: "c", kind: STARTS, style: green},
 			},
-			prevCommit:     models.NewCommit(models.NewCommitOpts{Hash: "a"}),
+			prevCommit:     models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
 			expectedStr:    "◯",
 			expectedStyles: []style.TextStyle{highlightStyle},
 		},
@@ -290,7 +294,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "selected", toHash: "d", kind: STARTS, style: green},
 				{fromPos: 0, toPos: 1, fromHash: "selected", toHash: "e", kind: STARTS, style: green},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
 			expectedStr: "⏣─╮",
 			expectedStyles: []style.TextStyle{
 				highlightStyle, highlightStyle, highlightStyle,
@@ -304,7 +308,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "b", toHash: "d", kind: STARTS, style: green},
 				{fromPos: 0, toPos: 1, fromHash: "b", toHash: "e", kind: STARTS, style: green},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a"}),
 			expectedStr: "⏣─│",
 			expectedStyles: []style.TextStyle{
 				green, green, magenta,
@@ -319,7 +323,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 3, toPos: 0, fromHash: "e1", toHash: "a2", kind: TERMINATES, style: green},
 				{fromPos: 0, toPos: 2, fromHash: "a2", toHash: "c3", kind: STARTS, style: yellow},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "⏣─│─┬─╯",
 			expectedStyles: []style.TextStyle{
 				yellow, yellow, magenta, yellow, yellow, green, green,
@@ -334,7 +338,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 3, toPos: 0, fromHash: "e1", toHash: "selected", kind: TERMINATES, style: green},
 				{fromPos: 0, toPos: 2, fromHash: "selected", toHash: "c3", kind: STARTS, style: yellow},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "⏣───╮ ╯",
 			expectedStyles: []style.TextStyle{
 				highlightStyle, highlightStyle, highlightStyle, highlightStyle, highlightStyle, nothing, green,
@@ -348,7 +352,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 1, toPos: 0, fromHash: "b1", toHash: "a2", kind: TERMINATES, style: magenta},
 				{fromPos: 2, toPos: 0, fromHash: "c1", toHash: "a2", kind: TERMINATES, style: green},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "◯─┴─╯",
 			expectedStyles: []style.TextStyle{
 				yellow, magenta, magenta, green, green,
@@ -363,7 +367,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 1, toPos: 1, fromHash: "b1", toHash: "b3", kind: CONTINUES, style: magenta},
 				{fromPos: 2, toPos: 2, fromHash: "c1", toHash: "c3", kind: CONTINUES, style: green},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "⏣─│─│─╮",
 			expectedStyles: []style.TextStyle{
 				yellow, yellow, magenta, yellow, green, yellow, yellow,
@@ -378,7 +382,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 1, toPos: 1, fromHash: "b1", toHash: "a2", kind: CONTINUES, style: green},
 				{fromPos: 2, toPos: 0, fromHash: "c1", toHash: "a2", kind: TERMINATES, style: magenta},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "⏣─│─╯",
 			expectedStyles: []style.TextStyle{
 				yellow, yellow, green, magenta, magenta,
@@ -393,7 +397,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 2, toPos: 2, fromHash: "c1", toHash: "c3", kind: CONTINUES, style: green},
 				{fromPos: 3, toPos: 0, fromHash: "d1", toHash: "a2", kind: TERMINATES, style: magenta},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "a1"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a1"}),
 			expectedStr: "⏣─┬─│─╯",
 			expectedStyles: []style.TextStyle{
 				yellow, yellow, yellow, magenta, green, magenta, magenta,
@@ -405,7 +409,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "selected", toHash: "a2", kind: TERMINATES, style: red},
 				{fromPos: 0, toPos: 0, fromHash: "a2", toHash: "a3", kind: STARTS, style: yellow},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "selected"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "selected"}),
 			expectedStr: "◯",
 			expectedStyles: []style.TextStyle{
 				yellow,
@@ -417,7 +421,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "selected", toHash: "a2", kind: TERMINATES, style: red},
 				{fromPos: 1, toPos: 1, fromHash: "selected", toHash: "b3", kind: CONTINUES, style: red},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "selected"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "selected"}),
 			expectedStr: "◯ │",
 			expectedStyles: []style.TextStyle{
 				highlightStyle, nothing, highlightStyle,
@@ -430,7 +434,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 1, toPos: 1, fromHash: "z1", toHash: "z3", kind: CONTINUES, style: green},
 				{fromPos: 2, toPos: 2, fromHash: "selected", toHash: "b3", kind: CONTINUES, style: red},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "selected"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "selected"}),
 			expectedStr: "◯ │ │",
 			expectedStyles: []style.TextStyle{
 				highlightStyle, nothing, green, nothing, highlightStyle,
@@ -444,7 +448,7 @@ func TestRenderPipeSet(t *testing.T) {
 				{fromPos: 0, toPos: 1, fromHash: "a2", toHash: "b3", kind: STARTS, style: green},
 				{fromPos: 1, toPos: 0, fromHash: "selected", toHash: "a2", kind: TERMINATES, style: yellow},
 			},
-			prevCommit:  models.NewCommit(models.NewCommitOpts{Hash: "selected"}),
+			prevCommit:  models.NewCommit(hashPool, models.NewCommitOpts{Hash: "selected"}),
 			expectedStr: "⏣─╯",
 			expectedStyles: []style.TextStyle{
 				highlightStyle, highlightStyle, highlightStyle,
@@ -477,6 +481,8 @@ func TestRenderPipeSet(t *testing.T) {
 }
 
 func TestGetNextPipes(t *testing.T) {
+	hashPool := &utils.StringPool{}
+
 	tests := []struct {
 		prevPipes []*Pipe
 		commit    *models.Commit
@@ -486,7 +492,7 @@ func TestGetNextPipes(t *testing.T) {
 			prevPipes: []*Pipe{
 				{fromPos: 0, toPos: 0, fromHash: "a", toHash: "b", kind: STARTS, style: style.FgDefault},
 			},
-			commit: models.NewCommit(models.NewCommitOpts{
+			commit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:    "b",
 				Parents: []string{"c"},
 			}),
@@ -501,7 +507,7 @@ func TestGetNextPipes(t *testing.T) {
 				{fromPos: 0, toPos: 0, fromHash: "b", toHash: "c", kind: STARTS, style: style.FgDefault},
 				{fromPos: 0, toPos: 1, fromHash: "b", toHash: "d", kind: STARTS, style: style.FgDefault},
 			},
-			commit: models.NewCommit(models.NewCommitOpts{
+			commit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:    "d",
 				Parents: []string{"e"},
 			}),
@@ -515,7 +521,7 @@ func TestGetNextPipes(t *testing.T) {
 			prevPipes: []*Pipe{
 				{fromPos: 0, toPos: 0, fromHash: "a", toHash: "root", kind: TERMINATES, style: style.FgDefault},
 			},
-			commit: models.NewCommit(models.NewCommitOpts{
+			commit: models.NewCommit(hashPool, models.NewCommitOpts{
 				Hash:    "root",
 				Parents: []string{},
 			}),
@@ -557,8 +563,10 @@ func BenchmarkRenderCommitGraph(b *testing.B) {
 }
 
 func generateCommits(count int) []*models.Commit {
+	hashPool := &utils.StringPool{}
+
 	rnd := rand.New(rand.NewSource(1234))
-	pool := []*models.Commit{models.NewCommit(models.NewCommitOpts{Hash: "a", AuthorName: "A"})}
+	pool := []*models.Commit{models.NewCommit(hashPool, models.NewCommitOpts{Hash: "a", AuthorName: "A"})}
 	commits := make([]*models.Commit, 0, count)
 	authorPool := []string{"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"}
 	for len(commits) < count {
@@ -575,7 +583,7 @@ func generateCommits(count int) []*models.Commit {
 			if reuseParent {
 				newParent = pool[j]
 			} else {
-				newParent = models.NewCommit(models.NewCommitOpts{
+				newParent = models.NewCommit(hashPool, models.NewCommitOpts{
 					Hash:       fmt.Sprintf("%s%d", currentCommit.Hash(), j),
 					AuthorName: authorPool[rnd.Intn(len(authorPool))],
 				})
@@ -584,7 +592,7 @@ func generateCommits(count int) []*models.Commit {
 			parentHashes = append(parentHashes, newParent.Hash())
 		}
 
-		changedCommit := models.NewCommit(models.NewCommitOpts{
+		changedCommit := models.NewCommit(hashPool, models.NewCommitOpts{
 			Hash:       currentCommit.Hash(),
 			AuthorName: currentCommit.AuthorName,
 			Parents:    parentHashes,

pkg/gui/types/common.go

@@ -305,6 +305,8 @@ type Model struct {
 	FilesTrie *patricia.Trie
 
 	Authors map[string]*models.Author
+
+	HashPool *utils.StringPool
 }
 
 // if you add a new mutex here be sure to instantiate it. We're using pointers to

pkg/utils/string_pool.go

@@ -0,0 +1,14 @@
+package utils
+
+import "sync"
+
+// A simple string pool implementation that can help reduce memory usage for
+// cases where the same string is used multiple times.
+type StringPool struct {
+	sync.Map
+}
+
+func (self *StringPool) Add(s string) *string {
+	poolEntry, _ := self.LoadOrStore(s, &s)
+	return poolEntry.(*string)
+}