From dce5c4442fdc6b11f3377e8d79b0cf507e99d925 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@parabola.nu>
Date: Sat, 1 May 2021 15:31:15 -0600
Subject: improve

---
 fi-prune-empty2/main.go   |  1 +
 fi-prune-empty2/prune.go  | 40 +++++++++++++++++++++++++++-------------
 fi-prune-empty2/stream.go | 24 +++++++++++++++++++++++-
 go.mod                    |  2 +-
 go.sum                    |  4 ++--
 5 files changed, 54 insertions(+), 17 deletions(-)

diff --git a/fi-prune-empty2/main.go b/fi-prune-empty2/main.go
index f09af64..0278a66 100644
--- a/fi-prune-empty2/main.go
+++ b/fi-prune-empty2/main.go
@@ -64,6 +64,7 @@ func main() {
 		fmt.Println()
 		fmt.Println("Requirements for the input stream:")
 		fmt.Println(" - Every commit must have a 'mark' (this is the default from `git fast-export`)")
+		fmt.Println(" - Every tag must have a 'mark' (eg: `git fast-export --mark-tags`)")
 		fmt.Println(" - Every commit must have an 'original-oid' (eg: `git fast-export --show-original-ids`)")
 		fmt.Println("   if any of (note that several of these are the default):")
 		fmt.Println("     --prune-empty=auto")
diff --git a/fi-prune-empty2/prune.go b/fi-prune-empty2/prune.go
index ff0119b..e3181b2 100644
--- a/fi-prune-empty2/prune.go
+++ b/fi-prune-empty2/prune.go
@@ -75,8 +75,8 @@ type Pruner struct {
 
 	replace map[Mark]Mark
 
-	ancestors map[Mark]map[Mark]struct{} // all ancestors, not just immediate parents
-	tree      map[Mark]Tree
+	parents map[Mark]map[Mark]struct{}
+	tree    map[Mark]Tree
 
 	newhash2mark map[Hash]Mark
 }
@@ -94,8 +94,8 @@ func NewPruner(
 
 		replace: make(map[Mark]Mark),
 
-		ancestors: make(map[Mark]map[Mark]struct{}),
-		tree:      make(map[Mark]Tree),
+		parents: make(map[Mark]map[Mark]struct{}),
+		tree:    make(map[Mark]Tree),
 
 		newhash2mark: make(map[Hash]Mark),
 	}
@@ -156,14 +156,13 @@ func (p *Pruner) ProcessCommit(commit Commit) (*Commit, error) {
 		return nil, nil
 	}
 
-	ancestors := map[Mark]struct{}{}
-	for _, parent := range commit.Parents {
-		ancestors[parent] = struct{}{}
-		for ancestor := range p.ancestors[parent] {
-			ancestors[ancestor] = struct{}{}
+	p.parents[commit.Mark] = func() map[Mark]struct{} {
+		parents := make(map[Mark]struct{}, len(commit.Parents))
+		for _, parent := range commit.Parents {
+			parents[parent] = struct{}{}
 		}
-	}
-	p.ancestors[commit.Mark] = ancestors
+		return parents
+	}()
 	p.tree[commit.Mark] = commit.Tree
 
 	return &commit, nil
@@ -241,8 +240,23 @@ func (p *Pruner) isEmpty(commit Commit) (bool, error) {
 }
 
 func (p *Pruner) isAncestor(ancestor, descendant Mark) bool {
-	_, ret := p.ancestors[descendant][ancestor]
-	return ret
+	isDescendentMemo := make(map[Mark]bool)
+	var isDescendent func(desc Mark) bool
+	isDescendent = func(desc Mark) bool {
+		if ret, ok := isDescendentMemo[desc]; ok {
+			return ret
+		}
+		ret := false
+		for descParent := range p.parents[desc] {
+			if descParent == ancestor || isDescendent(descParent) {
+				ret = true
+				break
+			}
+		}
+		isDescendentMemo[desc] = ret
+		return ret
+	}
+	return isDescendent(descendant)
 }
 
 // pruneParents prunes "duplicate" parents of a commit.  It is
diff --git a/fi-prune-empty2/stream.go b/fi-prune-empty2/stream.go
index da4b7be..be36d54 100644
--- a/fi-prune-empty2/stream.go
+++ b/fi-prune-empty2/stream.go
@@ -357,7 +357,29 @@ func (h *Handler) CmdReset(cmd libfastimport.CmdReset) error {
 }
 func (h *Handler) CmdTag(cmd libfastimport.CmdTag) error {
 	cmd.CommitIsh = h.driver.FixCommitIsh(cmd.CommitIsh)
-	return h.backend.Do(cmd)
+
+	// emit the tag
+	if err := h.backend.Do(cmd); err != nil {
+		return err
+	}
+
+	// tell the driver about the emitted tag
+	sha1, err := h.backend.GetMark(libfastimport.CmdGetMark{
+		Mark: cmd.Mark,
+	})
+	if err != nil {
+		return err
+	}
+	hash, err := AsHash(sha1)
+	if err != nil {
+		return err
+	}
+	h.driver.GotMark(Mark(cmd.Mark), hash)
+
+	// remember the tag
+	h.refs[cmd.RefName] = Mark(cmd.Mark)
+
+	return nil
 }
 
 func (h *Handler) CmdCatBlob(cmd libfastimport.CmdCatBlob) (sha1 string, data string, err error) {
diff --git a/go.mod b/go.mod
index 6472c43..393dffb 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module git.parabola.nu/~lukeshu/fastimport-go-utils
 go 1.15
 
 require (
-	git.lukeshu.com/go/libfastimport v0.0.0-20210430013857-225cc75c0ab0
+	git.lukeshu.com/go/libfastimport v0.0.0-20210501213144-c022dea68713
 	github.com/pkg/errors v0.9.1
 	github.com/spf13/pflag v1.0.5
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
diff --git a/go.sum b/go.sum
index 7c2935d..c576616 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,5 @@
-git.lukeshu.com/go/libfastimport v0.0.0-20210430013857-225cc75c0ab0 h1:9AcUO9xEdDXWYZLWiPL5HVp8bBc3OgENRdCF4GCS1w4=
-git.lukeshu.com/go/libfastimport v0.0.0-20210430013857-225cc75c0ab0/go.mod h1:S+paUkL2Xjs2Kjg+r+pIkbWDnYZDKuzkaQ4mJ5cKTgM=
+git.lukeshu.com/go/libfastimport v0.0.0-20210501213144-c022dea68713 h1:kLaRwGQRmMBX5f9ArfQL6trCXgaO84N5YU8F13ISrdU=
+git.lukeshu.com/go/libfastimport v0.0.0-20210501213144-c022dea68713/go.mod h1:S+paUkL2Xjs2Kjg+r+pIkbWDnYZDKuzkaQ4mJ5cKTgM=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
-- 
cgit v1.2.2