Artifact [082c8a50e9]

Artifact 082c8a50e9df61455641a95de00c5e964bab833304f79594fa12e16e47b98c13:

• File internal/branch/branch.go — part of check-in [9c071c7c22] at 2026-10-12 19:37:25 on branch main — fix(branch): check the open branch name in the check-in transaction (#316) (#346)

  branch.Create refused a name an open leaf carries (fossil's branch_is_open), but checked before manifest.Checkin opened its transaction, and Checkin applied the branch tags, parent propagation and leaf state in later transactions. Concurrent creates of one name could all pass the check and all commit.

  Checkin now derives its tags and leaf state inside its own transaction and runs an optional Precheck first in it. Create checks the name there, so check and write are one transaction: with BEGIN IMMEDIATE the second writer sees the first's open leaf and is refused. Create's redundant second tag pass after the check-in goes away. (user: [email protected], size: 7304) [annotate] [blame] [check-ins using]

package branch

import (
	"database/sql"
	"errors"
	"fmt"
	"time"

	"github.com/danmestas/go-libfossil/db"
	"github.com/danmestas/go-libfossil/internal/content"
	"github.com/danmestas/go-libfossil/internal/deck"
	libfossil "github.com/danmestas/go-libfossil/internal/fsltype"
	"github.com/danmestas/go-libfossil/internal/manifest"
	"github.com/danmestas/go-libfossil/internal/repo"
	"github.com/danmestas/go-libfossil/internal/tag"
)

type CreateOpts struct {
	Name   string
	Parent libfossil.FslID
	User   string
	Time   time.Time
	Color  string
}

type Branch struct {
	Name         string
	LastMTime    float64
	IsClosed     bool
	CheckinCount int
	LatestUUID   string
}

func Create(r *repo.Repo, opts CreateOpts) (libfossil.FslID, string, error) {
	if r == nil {
		panic("branch.Create: r must not be nil")
	}
	if opts.Name == "" {
		panic("branch.Create: opts.Name must not be empty")
	}
	if opts.Parent <= 0 {
		panic("branch.Create: opts.Parent must be positive")
	}
	if opts.User == "" {
		panic("branch.Create: opts.User must not be empty")
	}
	if opts.Time.IsZero() {
		opts.Time = time.Now().UTC()
	}

	// 1. Get parent's file list.
	entries, err := manifest.ListFiles(r, opts.Parent)
	if err != nil {
		return 0, "", fmt.Errorf("branch.Create list files: %w", err)
	}
	var files []manifest.File
	for _, e := range entries {
		frid, ok := content.AvailableByUUID(r.DB(), e.UUID)
		if !ok {
			return 0, "", fmt.Errorf("branch.Create: file blob %s not found", e.UUID)
		}
		// Bare Expand: each file of the single parent checkin is expanded
		// exactly once to seed the new branch commit. There is no repeated or
		// overlapping-chain access here for a cache to amortize.
		data, err := content.Expand(r.DB(), frid)
		if err != nil {
			return 0, "", fmt.Errorf("branch.Create: expand %s: %w", e.Name, err)
		}
		files = append(files, manifest.File{Name: e.Name, Content: data, Perm: e.Perm})
	}

	// 2. Query existing sym-* tags on parent for cancel cards.
	rows, err := r.DB().Query(
		"SELECT tag.tagname FROM tagxref JOIN tag USING(tagid) WHERE tagxref.rid=? AND tagxref.tagtype>0 AND tag.tagname GLOB 'sym-*'",
		opts.Parent,
	)
	if err != nil {
		return 0, "", fmt.Errorf("branch.Create query sym tags: %w", err)
	}
	defer rows.Close()
	var oldSyms []string
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			return 0, "", err
		}
		oldSyms = append(oldSyms, name)
	}
	if err := rows.Err(); err != nil {
		return 0, "", err
	}

	// 3. Build T-cards.
	var tags []deck.TagCard
	tags = append(tags, deck.TagCard{Type: deck.TagPropagating, Name: "branch", UUID: "*", Value: opts.Name})
	tags = append(tags, deck.TagCard{Type: deck.TagPropagating, Name: "sym-" + opts.Name, UUID: "*"})
	for _, old := range oldSyms {
		tags = append(tags, deck.TagCard{Type: deck.TagCancel, Name: old, UUID: "*"})
	}
	if opts.Color != "" {
		tags = append(tags, deck.TagCard{Type: deck.TagPropagating, Name: "bgcolor", UUID: "*", Value: opts.Color})
	}

	// 4. Create the checkin with its branch tags. Checkin applies them in its
	// own transaction, and refuses there a name an open branch already
	// carries, as `fossil branch new` does (src/branch.c branch_is_open): the
	// check and the write are one transaction, so of two concurrent Creates of
	// one name only the first commits, and a refused Create stores nothing.
	rid, uuid, err := manifest.Checkin(r, manifest.CheckinOpts{
		Files:   files,
		Comment: fmt.Sprintf("Create branch %s", opts.Name),
		User:    opts.User,
		Parent:  opts.Parent,
		Time:    opts.Time,
		Tags:    tags,
		Precheck: func(q db.Querier) error {
			open, err := branchIsOpen(q, opts.Name)
			if err != nil {
				return err
			}
			if open {
				return fmt.Errorf("an open branch named %q already exists", opts.Name)
			}
			return nil
		},
	})
	if err != nil {
		return 0, "", fmt.Errorf("branch.Create: %w", err)
	}
	return rid, uuid, nil
}

// branchIsOpen reports whether some open leaf's active branch tag is name:
// a leaf (in the leaf table) whose propagating branch tag (tagtype=2) has the
// value name and that carries no singleton closed tag (tagtype=1). This is
// fossil's branch_is_open (src/branch.c), which uses those exact tag types.
//
// Create runs it on the check-in's own transaction (CheckinOpts.Precheck), so
// the check and the new branch's write see one state.
func branchIsOpen(q db.Querier, name string) (bool, error) {
	var one int
	err := q.QueryRow(`
		SELECT 1 FROM tagxref ox
		JOIN tag t ON t.tagid = ox.tagid
		WHERE t.tagname = 'branch'
		  AND ox.value = ?
		  AND ox.tagtype = 2
		  AND ox.rid IN (SELECT rid FROM leaf)
		  AND NOT EXISTS (
		    SELECT 1 FROM tagxref ix
		    JOIN tag ct ON ct.tagid = ix.tagid
		    WHERE ct.tagname = 'closed'
		      AND ix.rid = ox.rid
		      AND ix.tagtype = 1
		  )
		LIMIT 1`, name).Scan(&one)
	if errors.Is(err, sql.ErrNoRows) {
		return false, nil
	}
	if err != nil {
		return false, fmt.Errorf("branch.branchIsOpen %q: %w", name, err)
	}
	return true, nil
}

func List(r *repo.Repo) ([]Branch, error) {
	if r == nil {
		panic("branch.List: r must not be nil")
	}

	rows, err := r.DB().Query(`
		SELECT
			tagxref.value AS branch_name,
			max(event.mtime) AS last_mtime,
			count(*) AS checkin_count,
			(SELECT EXISTS(SELECT 1 FROM tagxref cx JOIN tag ct ON cx.tagid=ct.tagid
				 WHERE ct.tagname='closed' AND cx.rid=ev.objid AND cx.tagtype>0)
			 FROM tagxref bx JOIN tag bt ON bx.tagid=bt.tagid
			 JOIN event ev ON ev.objid=bx.rid
			 WHERE bt.tagname='branch' AND bx.value=tagxref.value AND bx.tagtype>0
			 ORDER BY ev.mtime DESC LIMIT 1) AS isclosed,
			(SELECT b.uuid FROM blob b
			 JOIN tagxref tx4 ON b.rid=tx4.rid
			 JOIN tag t4 ON tx4.tagid=t4.tagid
			 JOIN event e ON e.objid=tx4.rid
			 WHERE t4.tagname='branch' AND tx4.value=tagxref.value AND tx4.tagtype>0
			 ORDER BY e.mtime DESC LIMIT 1) AS latest
		FROM tagxref JOIN tag ON tagxref.tagid=tag.tagid
		JOIN event ON event.objid=tagxref.rid
		WHERE tag.tagname='branch' AND tagxref.tagtype>0
		GROUP BY tagxref.value
	`)
	if err != nil {
		return nil, fmt.Errorf("branch.List: %w", err)
	}
	defer rows.Close()

	var branches []Branch
	for rows.Next() {
		var b Branch
		var isClosed *int
		if err := rows.Scan(&b.Name, &b.LastMTime, &b.CheckinCount, &isClosed, &b.LatestUUID); err != nil {
			return nil, fmt.Errorf("branch.List scan: %w", err)
		}
		b.IsClosed = isClosed != nil && *isClosed == 1
		branches = append(branches, b)
	}
	return branches, rows.Err()
}

func Close(r *repo.Repo, name string, user string) error {
	if r == nil {
		panic("branch.Close: r must not be nil")
	}
	if name == "" {
		panic("branch.Close: name must not be empty")
	}

	var tipRID int64
	err := r.DB().QueryRow(`
		SELECT tagxref.rid FROM tagxref
		JOIN tag ON tagxref.tagid=tag.tagid
		JOIN event ON event.objid=tagxref.rid
		WHERE tag.tagname='branch' AND tagxref.value=? AND tagxref.tagtype>0
		ORDER BY event.mtime DESC LIMIT 1`,
		name,
	).Scan(&tipRID)
	if err != nil {
		return fmt.Errorf("branch.Close: find tip for %q: %w", name, err)
	}

	_, err = tag.AddTag(r, tag.TagOpts{
		TargetRID: libfossil.FslID(tipRID),
		TagName:   "closed",
		TagType:   tag.TagSingleton,
		User:      user,
	})
	if err != nil {
		return fmt.Errorf("branch.Close: add closed tag: %w", err)
	}
	return nil
}