refactor: fold dataset into gitshallow, caller owns atomic.Pointer

fs/dataset deleted — generic File[T] wrapper didn't earn its abstraction layer
gitshallow.ShallowRepo → Repo (redundant with package name)
gitshallow.Repo.Register(func() error) — callbacks fire after each sync
gitshallow.Repo.Init/Run — full lifecycle in one package
caller (check-ip-blacklist) holds atomic.Pointer[Cohort] directly

fs/dataset/dataset.go

@@ -1,134 +0,0 @@
-package dataset
-
-import (
-	"context"
-	"fmt"
-	"os"
-	"path/filepath"
-	"sync/atomic"
-	"time"
-
-	"github.com/therootcompany/golib/net/gitshallow"
-)
-
-// File holds an atomically-swappable pointer to a value loaded from a file.
-// Reads are lock-free. Use NewFile for file-only use, or AddFile to attach
-// to a GitRepo so the value refreshes whenever the repo is updated.
-type File[T any] struct {
-	atomic.Pointer[T]
-	path     string
-	loadFile func(string) (*T, error)
-}
-
-// NewFile creates a file-backed dataset with no git dependency.
-// Call Reload to do the initial load and after any file change.
-func NewFile[T any](path string, loadFile func(string) (*T, error)) *File[T] {
-	d := &File[T]{
-		path:     path,
-		loadFile: loadFile,
-	}
-	d.Store(new(T))
-	return d
-}
-
-// Reload reads the file and atomically replaces the stored value.
-func (d *File[T]) Reload() error {
-	v, err := d.loadFile(d.path)
-	if err != nil {
-		return err
-	}
-	d.Store(v)
-	return nil
-}
-
-func (d *File[T]) reloadFile() error {
-	return d.Reload()
-}
-
-// reloader is the internal interface GitRepo uses to trigger file reloads.
-type reloader interface {
-	reloadFile() error
-}
-
-// GitRepo manages a shallow git clone and reloads all registered files
-// whenever the repo is updated. Multiple files from the same repo share
-// one clone and one pull, avoiding git file-lock conflicts.
-type GitRepo struct {
-	path        string
-	shallowRepo *gitshallow.ShallowRepo
-	files       []reloader
-}
-
-// NewRepo creates a GitRepo backed by the given git URL, cloning into repoPath.
-func NewRepo(gitURL, repoPath string) *GitRepo {
-	return &GitRepo{
-		path:        repoPath,
-		shallowRepo: gitshallow.New(gitURL, repoPath, 1, ""),
-	}
-}
-
-// AddFile registers a file inside this repo and returns its handle.
-// relPath is relative to the repo root. The file is reloaded automatically
-// whenever the repo is synced via Init or Run.
-func AddFile[T any](repo *GitRepo, relPath string, loadFile func(string) (*T, error)) *File[T] {
-	d := NewFile(filepath.Join(repo.path, relPath), loadFile)
-	repo.files = append(repo.files, d)
-	return d
-}
-
-// Init clones the repo if missing, syncs once, and loads all registered files.
-// Always runs aggressive GC — acceptable as a one-time startup cost.
-func (r *GitRepo) Init() error {
-	gitDir := filepath.Join(r.path, ".git")
-	if _, err := os.Stat(gitDir); err != nil {
-		if _, err := r.shallowRepo.Clone(); err != nil {
-			return err
-		}
-	}
-	_, err := r.sync(false, true)
-	return err
-}
-
-// Run periodically syncs the repo and reloads files. Blocks until ctx is done.
-// lightGC=false (zero value) runs aggressive GC with immediate pruning to keep footprint minimal.
-// Pass true to skip both when the periodic GC is too slow for your workload.
-func (r *GitRepo) Run(ctx context.Context, lightGC bool) {
-	ticker := time.NewTicker(47 * time.Minute)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-ticker.C:
-			if updated, err := r.sync(lightGC, false); err != nil {
-				fmt.Fprintf(os.Stderr, "error: git repo sync: %v\n", err)
-			} else if updated {
-				fmt.Fprintf(os.Stderr, "git repo: files reloaded\n")
-			}
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
-// Sync pulls the latest commits and reloads all files if HEAD changed.
-// lightGC=false (zero value) runs aggressive GC with immediate pruning to keep footprint minimal.
-func (r *GitRepo) Sync(lightGC bool) (bool, error) {
-	return r.sync(lightGC, false)
-}
-
-func (r *GitRepo) sync(lightGC, force bool) (bool, error) {
-	updated, err := r.shallowRepo.Sync(lightGC)
-	if err != nil {
-		return false, fmt.Errorf("git sync: %w", err)
-	}
-	if !updated && !force {
-		return false, nil
-	}
-
-	for _, f := range r.files {
-		if err := f.reloadFile(); err != nil {
-			fmt.Fprintf(os.Stderr, "error: reload file: %v\n", err)
-		}
-	}
-	return true, nil
-}

net/gitshallow/gitshallow.go

@@ -1,30 +1,33 @@
 package gitshallow
 
 import (
+	"context"
 	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"sync"
+	"time"
 )
 
-// ShallowRepo represents a shallow Git repository manager.
-type ShallowRepo struct {
+// Repo manages a shallow git clone used as a periodically-updated data source.
+type Repo struct {
 	URL    string
 	Path   string
 	Depth  int    // 0 defaults to 1, -1 for all
 	Branch string // Optional: specific branch to clone/pull
 
-	mu sync.Mutex
+	mu        sync.Mutex
+	callbacks []func() error
 }
 
-// New creates a new ShallowRepo instance.
-func New(url, path string, depth int, branch string) *ShallowRepo {
+// New creates a new Repo instance.
+func New(url, path string, depth int, branch string) *Repo {
 	if depth == 0 {
 		depth = 1
 	}
-	return &ShallowRepo{
+	return &Repo{
 		URL:    url,
 		Path:   path,
 		Depth:  depth,
@@ -32,15 +35,60 @@ func New(url, path string, depth int, branch string) *ShallowRepo {
 	}
 }
 
+// Register adds a callback invoked after each successful clone or pull.
+// Use this to reload files and update atomic pointers when the repo changes.
+func (r *Repo) Register(fn func() error) {
+	r.callbacks = append(r.callbacks, fn)
+}
+
+// Init clones the repo if missing, syncs once, then invokes all callbacks
+// regardless of whether git had new commits — ensuring files are loaded on startup.
+func (r *Repo) Init(lightGC bool) error {
+	gitDir := filepath.Join(r.Path, ".git")
+	if _, err := os.Stat(gitDir); err != nil {
+		if _, err := r.Clone(); err != nil {
+			return err
+		}
+	}
+
+	if _, err := r.syncGit(lightGC); err != nil {
+		return err
+	}
+
+	return r.invokeCallbacks()
+}
+
+// Run periodically syncs the repo and invokes callbacks when HEAD changes.
+// Blocks until ctx is done.
+// lightGC=false (zero value) runs aggressive GC with immediate pruning to minimize disk use.
+// Pass true to skip both when the periodic GC is too slow for your workload.
+func (r *Repo) Run(ctx context.Context, lightGC bool) {
+	ticker := time.NewTicker(47 * time.Minute)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			if updated, err := r.Sync(lightGC); err != nil {
+				fmt.Fprintf(os.Stderr, "error: git sync: %v\n", err)
+			} else if updated {
+				fmt.Fprintf(os.Stderr, "git: repo updated\n")
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
 // Clone performs a shallow clone (--depth N --single-branch --no-tags).
-func (r *ShallowRepo) Clone() (bool, error) {
+func (r *Repo) Clone() (bool, error) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
 	return r.clone()
 }
 
-func (r *ShallowRepo) clone() (bool, error) {
+func (r *Repo) clone() (bool, error) {
 	if r.exists() {
 		return false, nil
 	}
@@ -70,13 +118,13 @@ func (r *ShallowRepo) clone() (bool, error) {
 }
 
 // exists checks if the directory contains a .git folder.
-func (r *ShallowRepo) exists() bool {
+func (r *Repo) exists() bool {
 	_, err := os.Stat(filepath.Join(r.Path, ".git"))
 	return err == nil
 }
 
 // runGit executes a git command in the repo directory (or parent for clone).
-func (r *ShallowRepo) runGit(args ...string) (string, error) {
+func (r *Repo) runGit(args ...string) (string, error) {
 	cmd := exec.Command("git", args...)
 
 	if _, err := os.Stat(r.Path); err == nil && r.exists() {
@@ -94,14 +142,14 @@ func (r *ShallowRepo) runGit(args ...string) (string, error) {
 }
 
 // Pull performs a shallow pull (--ff-only) and reports whether HEAD changed.
-func (r *ShallowRepo) Pull() (updated bool, err error) {
+func (r *Repo) Pull() (updated bool, err error) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
 	return r.pull()
 }
 
-func (r *ShallowRepo) pull() (updated bool, err error) {
+func (r *Repo) pull() (updated bool, err error) {
 	if !r.exists() {
 		return false, fmt.Errorf("repository does not exist at %s", r.Path)
 	}
@@ -134,14 +182,14 @@ func (r *ShallowRepo) pull() (updated bool, err error) {
 }
 
 // GC runs git gc. aggressiveGC adds --aggressive; pruneNow adds --prune=now.
-func (r *ShallowRepo) GC(aggressiveGC, pruneNow bool) error {
+func (r *Repo) GC(aggressiveGC, pruneNow bool) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
 	return r.gc(aggressiveGC, pruneNow)
 }
 
-func (r *ShallowRepo) gc(aggressiveGC, pruneNow bool) error {
+func (r *Repo) gc(aggressiveGC, pruneNow bool) error {
 	if !r.exists() {
 		return fmt.Errorf("repository does not exist at %s", r.Path)
 	}
@@ -158,10 +206,19 @@ func (r *ShallowRepo) gc(aggressiveGC, pruneNow bool) error {
 	return err
 }
 
-// Sync clones if missing, pulls, and runs GC.
-// lightGC=false (zero value) runs --aggressive GC with --prune=now to minimize disk use.
-// Pass true to skip both when speed matters more than footprint.
-func (r *ShallowRepo) Sync(lightGC bool) (updated bool, err error) {
+// Sync clones if missing, pulls, runs GC, and invokes callbacks if HEAD changed.
+// Returns whether HEAD changed.
+// lightGC=false (zero value) runs aggressive GC with --prune=now to minimize disk use.
+func (r *Repo) Sync(lightGC bool) (updated bool, err error) {
+	updated, err = r.syncGit(lightGC)
+	if err != nil || !updated {
+		return updated, err
+	}
+
+	return true, r.invokeCallbacks()
+}
+
+func (r *Repo) syncGit(lightGC bool) (updated bool, err error) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
@@ -172,16 +229,18 @@ func (r *ShallowRepo) Sync(lightGC bool) (updated bool, err error) {
 	}
 
 	updated, err = r.pull()
-	if err != nil {
-		return false, err
-	}
-	if !updated {
-		return false, nil
+	if err != nil || !updated {
+		return updated, err
 	}
 
-	if err := r.gc(!lightGC, !lightGC); err != nil {
-		return true, fmt.Errorf("gc failed but pull succeeded: %w", err)
-	}
-
-	return true, nil
+	return true, r.gc(!lightGC, !lightGC)
+}
+
+func (r *Repo) invokeCallbacks() error {
+	for _, fn := range r.callbacks {
+		if err := fn(); err != nil {
+			fmt.Fprintf(os.Stderr, "error: reload callback: %v\n", err)
+		}
+	}
+	return nil
 }

net/ipcohort/cmd/check-ip-blacklist/main.go

@@ -4,8 +4,9 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sync/atomic"
 
-	"github.com/therootcompany/golib/fs/dataset"
+	"github.com/therootcompany/golib/net/gitshallow"
 	"github.com/therootcompany/golib/net/ipcohort"
 )
 
@@ -22,28 +23,35 @@ func main() {
 		gitURL = os.Args[3]
 	}
 
-	var blacklist *dataset.File[ipcohort.Cohort]
+	var cohort atomic.Pointer[ipcohort.Cohort]
+
+	load := func() error {
+		c, err := ipcohort.LoadFile(dataPath)
+		if err != nil {
+			return err
+		}
+		cohort.Store(c)
+		return nil
+	}
 
 	if gitURL != "" {
 		repoDir := filepath.Dir(dataPath)
-		relPath := filepath.Base(dataPath)
-		repo := dataset.NewRepo(gitURL, repoDir)
-		blacklist = dataset.AddFile(repo, relPath, ipcohort.LoadFile)
+		repo := gitshallow.New(gitURL, repoDir, 1, "")
+		repo.Register(load)
 		fmt.Fprintf(os.Stderr, "Syncing %q ...\n", repoDir)
-		if err := repo.Init(); err != nil {
+		if err := repo.Init(false); err != nil {
 			fmt.Fprintf(os.Stderr, "error: git sync: %v\n", err)
 			os.Exit(1)
 		}
 	} else {
-		blacklist = dataset.NewFile(dataPath, ipcohort.LoadFile)
 		fmt.Fprintf(os.Stderr, "Loading %q ...\n", dataPath)
-		if err := blacklist.Reload(); err != nil {
+		if err := load(); err != nil {
 			fmt.Fprintf(os.Stderr, "error: load: %v\n", err)
 			os.Exit(1)
 		}
 	}
 
-	c := blacklist.Load()
+	c := cohort.Load()
 	fmt.Fprintf(os.Stderr, "Loaded %d entries\n", c.Size())
 
 	if c.Contains(ipStr) {