knotserver: last commit for each file

This is a super trivial implementation last commit for each file. It's
slow and inefficient despite using ristretto for in-memory caching.

We should move this to storing in sqlite in the future.

go.mod

···
 	github.com/bluesky-social/jetstream v0.0.0-20241210005130-ea96859b93d1
 	github.com/casbin/casbin/v2 v2.103.0
 	github.com/cyphar/filepath-securejoin v0.3.3
+	github.com/dgraph-io/ristretto v0.2.0
 	github.com/dustin/go-humanize v1.0.1
 	github.com/gliderlabs/ssh v0.3.5
 	github.com/go-chi/chi/v5 v5.2.0
···
 	github.com/multiformats/go-varint v0.0.7 // indirect
 	github.com/opentracing/opentracing-go v1.2.0 // indirect
 	github.com/pjbgf/sha1cd v0.3.0 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/polydawn/refmt v0.89.1-0.20221221234430-40501e09de1f // indirect
 	github.com/prometheus/client_golang v1.19.1 // indirect

go.sum

···
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dgraph-io/ristretto v0.2.0 h1:XAfl+7cmoUDWW/2Lx8TGZQjjxIQ2Ley9DSf52dru4WE=
+github.com/dgraph-io/ristretto v0.2.0/go.mod h1:8uBHCU/PBV4Ag0CJrP47b9Ofby5dqWNh4FicAdoqFNU=
+github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 h1:fAjc9m62+UWV/WAFKLNi6ZS0675eEUC9y3AlwSbQu1Y=
+github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=

knotserver/git/git.go

···
 	"io/fs"
 	"path"
 	"sort"
+	"sync"
 	"time"
 
+	"github.com/dgraph-io/ristretto"
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/object"
 )
+
+var (
+	commitCache *ristretto.Cache
+	cacheMu     sync.RWMutex
+)
+
+func init() {
+	cache, _ := ristretto.NewCache(&ristretto.Config{
+		NumCounters: 1e7,
+		MaxCost:     1 << 30,
+		BufferItems: 64,
+	})
+	commitCache = cache
+}
 
 var (
 	ErrBinaryFile = fmt.Errorf("binary file")
···
 	}
 
 	return nil
+}
+
+func (g *GitRepo) LastCommitTime(filePath string) (*object.Commit, error) {
+	cacheMu.RLock()
+	if commit, exists := commitCache.Get(filePath); exists {
+		cacheMu.RUnlock()
+		return commit.(*object.Commit), nil
+	}
+	cacheMu.RUnlock()
+
+	commitIter, err := g.r.Log(&git.LogOptions{
+		From: g.h,
+		PathFilter: func(s string) bool {
+			return s == filePath
+		},
+		Order: git.LogOrderCommitterTime,
+	})
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to get commit log for %s: %w", filePath, err)
+	}
+
+	commit, err := commitIter.Next()
+	if err != nil {
+		return nil, fmt.Errorf("no commit found for %s", filePath)
+	}
+
+	cacheMu.Lock()
+	commitCache.Set(filePath, commit, 1)
+	cacheMu.Unlock()
+
+	return commit, nil
 }
 
 func newInfoWrapper(

knotserver/git/tree.go

···
 	}
 
 	if path == "" {
-		files = makeNiceTree(tree)
+		files = g.makeNiceTree(tree)
 	} else {
 		o, err := tree.FindEntry(path)
 		if err != nil {
···
 				return nil, err
 			}
 
-			files = makeNiceTree(subtree)
+			files = g.makeNiceTree(subtree)
 		}
 	}
 
 	return files, nil
 }
 
-func makeNiceTree(t *object.Tree) []types.NiceTree {
+func (g *GitRepo) makeNiceTree(t *object.Tree) []types.NiceTree {
 	nts := []types.NiceTree{}
 
 	for _, e := range t.Entries {
 		mode, _ := e.Mode.ToOSFileMode()
 		sz, _ := t.Size(e.Name)
+
+		lastCommit, err := g.LastCommitTime(e.Name)
+		if err != nil {
+			continue
+		}
+
 		nts = append(nts, types.NiceTree{
-			Name:   e.Name,
-			Mode:   mode.String(),
-			IsFile: e.Mode.IsFile(),
-			Size:   sz,
+			Name:       e.Name,
+			Mode:       mode.String(),
+			IsFile:     e.Mode.IsFile(),
+			Size:       sz,
+			LastCommit: lastCommit,
 		})
+
 	}
 
 	return nts

types/tree.go

···
 package types
 
+import (
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
 // A nicer git tree representation.
 type NiceTree struct {
 	Name      string `json:"name"`
···
 	Size      int64  `json:"size"`
 	IsFile    bool   `json:"is_file"`
 	IsSubtree bool   `json:"is_subtree"`
+
+	LastCommit *object.Commit `json:"last_commit,omitempty"`
 }