rebuildnodes/btrees: Refactor to split the forrest from the trees

1 files changed, 299 insertions, 0 deletions

diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/btrees/tree.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/btrees/tree.go
new file mode 100644
index 0000000..1fc1f52
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/btrees/tree.go
@@ -0,0 +1,299 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package btrees
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/datawire/dlib/dlog"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	pkggraph "git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect/rebuildnodes/keyio"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
+	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
+)
+
+type RebuiltTree struct {
+	// static
+	ID        btrfsprim.ObjID
+	UUID      btrfsprim.UUID
+	Parent    *RebuiltTree
+	ParentGen btrfsprim.Generation // offset of this tree's root item
+	forrest   *RebuiltForrest
+
+	// all leafs (lvl=0) that pass .isOwnerOK, even if not in the tree
+	leafToRoots map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr]
+	keys        containers.SortedMap[btrfsprim.Key, keyio.ItemPtr]
+
+	// mutable
+	Roots containers.Set[btrfsvol.LogicalAddr]
+	Leafs containers.Set[btrfsvol.LogicalAddr]
+	Items containers.SortedMap[btrfsprim.Key, keyio.ItemPtr]
+}
+
+// initializaton (called by `RebuiltForrest.Tree()`) ///////////////////////////////////////////////////////////////////
+
+func (tree *RebuiltTree) indexLeafs(ctx context.Context) {
+	ctx = dlog.WithField(ctx, "btrfsinspect.rebuild-nodes.rebuild.add-tree.substep", "index-nodes")
+
+	nodeToRoots := make(map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr])
+
+	var stats textui.Portion[int]
+	stats.D = len(tree.forrest.graph.Nodes)
+	progressWriter := textui.NewProgress[textui.Portion[int]](ctx, dlog.LogLevelInfo, textui.Tunable(1*time.Second))
+	progress := func() {
+		stats.N = len(nodeToRoots)
+		progressWriter.Set(stats)
+	}
+
+	progress()
+	for _, node := range maps.SortedKeys(tree.forrest.graph.Nodes) {
+		tree.indexNode(ctx, node, nodeToRoots, progress, nil)
+	}
+	progressWriter.Done()
+
+	tree.leafToRoots = make(map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr])
+	for node, roots := range nodeToRoots {
+		if tree.forrest.graph.Nodes[node].Level == 0 && len(roots) > 0 {
+			tree.leafToRoots[node] = roots
+		}
+	}
+}
+
+func (tree *RebuiltTree) indexNode(ctx context.Context, node btrfsvol.LogicalAddr, index map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr], progress func(), stack []btrfsvol.LogicalAddr) {
+	defer progress()
+	if err := ctx.Err(); err != nil {
+		return
+	}
+	if _, done := index[node]; done {
+		return
+	}
+	if slices.Contains(node, stack) {
+		// This is a panic because tree.forrest.graph.FinalCheck() should
+		// have already checked for loops.
+		panic("loop")
+	}
+	if !tree.isOwnerOK(tree.forrest.graph.Nodes[node].Owner, tree.forrest.graph.Nodes[node].Generation) {
+		index[node] = nil
+		return
+	}
+
+	// tree.leafToRoots
+	stack = append(stack, node)
+	var roots containers.Set[btrfsvol.LogicalAddr]
+	kps := slices.RemoveAllFunc(tree.forrest.graph.EdgesTo[node], func(kp *pkggraph.Edge) bool {
+		return !tree.isOwnerOK(tree.forrest.graph.Nodes[kp.FromNode].Owner, tree.forrest.graph.Nodes[kp.FromNode].Generation)
+	})
+	for _, kp := range kps {
+		tree.indexNode(ctx, kp.FromNode, index, progress, stack)
+		if len(index[kp.FromNode]) > 0 {
+			if roots == nil {
+				roots = make(containers.Set[btrfsvol.LogicalAddr])
+			}
+			roots.InsertFrom(index[kp.FromNode])
+		}
+	}
+	if roots == nil {
+		roots = containers.NewSet[btrfsvol.LogicalAddr](node)
+	}
+	index[node] = roots
+
+	// tree.keys
+	for i, key := range tree.forrest.graph.Nodes[node].Items {
+		if oldPtr, ok := tree.keys.Load(key); !ok || tree.shouldReplace(oldPtr.Node, node) {
+			tree.keys.Store(key, keyio.ItemPtr{
+				Node: node,
+				Idx:  i,
+			})
+		}
+	}
+}
+
+// isOwnerOK returns whether it is permissible for a node with
+// .Head.Owner=owner to be in this tree.
+func (tree *RebuiltTree) isOwnerOK(owner btrfsprim.ObjID, gen btrfsprim.Generation) bool {
+	for {
+		if owner == tree.ID {
+			return true
+		}
+		if tree.Parent == nil || gen >= tree.ParentGen {
+			return false
+		}
+		tree = tree.Parent
+	}
+}
+
+// .AddRoot() //////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+type rootStats struct {
+	Leafs         textui.Portion[int]
+	AddedItems    int
+	ReplacedItems int
+}
+
+func (s rootStats) String() string {
+	return textui.Sprintf("%v (added %v items, replaced %v items)",
+		s.Leafs, s.AddedItems, s.ReplacedItems)
+}
+
+// AddRoot adds an additional root node to the tree.  It is useful to
+// call .AddRoot() to re-attach part of the tree that has been broken
+// off.
+func (tree *RebuiltTree) AddRoot(ctx context.Context, rootNode btrfsvol.LogicalAddr) {
+	ctx = dlog.WithField(ctx, "btrfsinspect.rebuild-nodes.rebuild.add-root", fmt.Sprintf("tree=%v rootNode=%v", tree.ID, rootNode))
+	tree.Roots.Insert(rootNode)
+
+	var stats rootStats
+	stats.Leafs.D = len(tree.leafToRoots)
+	progressWriter := textui.NewProgress[rootStats](ctx, dlog.LogLevelInfo, textui.Tunable(1*time.Second))
+	for i, leaf := range maps.SortedKeys(tree.leafToRoots) {
+		stats.Leafs.N = i
+		progressWriter.Set(stats)
+		if tree.Leafs.Has(leaf) || !tree.leafToRoots[leaf].Has(rootNode) {
+			continue
+		}
+		tree.Leafs.Insert(leaf)
+		for j, itemKey := range tree.forrest.graph.Nodes[leaf].Items {
+			newPtr := keyio.ItemPtr{
+				Node: leaf,
+				Idx:  j,
+			}
+			if oldPtr, exists := tree.Items.Load(itemKey); !exists {
+				tree.Items.Store(itemKey, newPtr)
+				stats.AddedItems++
+			} else if tree.shouldReplace(oldPtr.Node, newPtr.Node) {
+				tree.Items.Store(itemKey, newPtr)
+				stats.ReplacedItems++
+			}
+			tree.forrest.cbAddedItem(ctx, tree.ID, itemKey)
+			progressWriter.Set(stats)
+		}
+	}
+	stats.Leafs.N = len(tree.leafToRoots)
+	progressWriter.Set(stats)
+	progressWriter.Done()
+}
+
+func (tree *RebuiltTree) shouldReplace(oldNode, newNode btrfsvol.LogicalAddr) bool {
+	oldDist, _ := tree.COWDistance(tree.forrest.graph.Nodes[oldNode].Owner)
+	newDist, _ := tree.COWDistance(tree.forrest.graph.Nodes[newNode].Owner)
+	switch {
+	case newDist < oldDist:
+		// Replace the old one with the new lower-dist one.
+		return true
+	case newDist > oldDist:
+		// Retain the old lower-dist one.
+		return false
+	default:
+		oldGen := tree.forrest.graph.Nodes[oldNode].Generation
+		newGen := tree.forrest.graph.Nodes[newNode].Generation
+		switch {
+		case newGen > oldGen:
+			// Replace the old one with the new higher-gen one.
+			return true
+		case newGen < oldGen:
+			// Retain the old higher-gen one.
+			return false
+		default:
+			// This is a panic because I'm not really sure what the best way to
+			// handle this is, and so if this happens I want the program to crash
+			// and force me to figure out how to handle it.
+			panic(fmt.Errorf("dup nodes in tree=%v: old=%v=%v ; new=%v=%v",
+				tree.ID,
+				oldNode, tree.forrest.graph.Nodes[oldNode],
+				newNode, tree.forrest.graph.Nodes[newNode]))
+		}
+	}
+}
+
+// main public API /////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// COWDistance returns how many COW-snapshots down the 'tree' is from
+// the 'parent'.
+func (tree *RebuiltTree) COWDistance(parentID btrfsprim.ObjID) (dist int, ok bool) {
+	for {
+		if parentID == tree.ID {
+			return dist, true
+		}
+		if tree.Parent == nil {
+			return 0, false
+		}
+		tree = tree.Parent
+		dist++
+	}
+}
+
+// Resolve a key to a keyio.ItemPtr.
+func (tree *RebuiltTree) Resolve(key btrfsprim.Key) (ptr keyio.ItemPtr, ok bool) {
+	return tree.Items.Load(key)
+}
+
+// Load reads an item from a tree.
+func (tree *RebuiltTree) Load(ctx context.Context, key btrfsprim.Key) (item btrfsitem.Item, ok bool) {
+	ptr, ok := tree.Resolve(key)
+	if !ok {
+		return nil, false
+	}
+	return tree.forrest.keyIO.ReadItem(ctx, ptr)
+}
+
+// Search searches for an item from a tree.
+func (tree *RebuiltTree) Search(fn func(btrfsprim.Key) int) (key btrfsprim.Key, ok bool) {
+	k, _, ok := tree.Items.Search(func(k btrfsprim.Key, _ keyio.ItemPtr) int {
+		return fn(k)
+	})
+	return k, ok
+}
+
+// Search searches for a range of items from a tree.
+func (tree *RebuiltTree) SearchAll(fn func(btrfsprim.Key) int) []btrfsprim.Key {
+	kvs := tree.Items.SearchAll(func(k btrfsprim.Key, _ keyio.ItemPtr) int {
+		return fn(k)
+	})
+	if len(kvs) == 0 {
+		return nil
+	}
+	ret := make([]btrfsprim.Key, len(kvs))
+	for i := range kvs {
+		ret[i] = kvs[i].K
+	}
+	return ret
+}
+
+// LeafToRoots returns the list of potential roots (to pass to
+// .AddRoot) that include a given leaf-node.
+func (tree *RebuiltTree) LeafToRoots(leaf btrfsvol.LogicalAddr) containers.Set[btrfsvol.LogicalAddr] {
+	if tree.forrest.graph.Nodes[leaf].Level != 0 {
+		panic(fmt.Errorf("should not happen: (tree=%v).LeafToRoots(leaf=%v): not a leaf",
+			tree.ID, leaf))
+	}
+	ret := make(containers.Set[btrfsvol.LogicalAddr])
+	for root := range tree.leafToRoots[leaf] {
+		if tree.Roots.Has(root) {
+			panic(fmt.Errorf("should not happen: (tree=%v).LeafToRoots(leaf=%v): tree contains root=%v but not leaf",
+				tree.ID, leaf, root))
+		}
+		ret.Insert(root)
+	}
+	if len(ret) == 0 {
+		return nil
+	}
+	return ret
+}
+
+// Keys returns a map of all keys in node that would be valid in this tree.
+//
+// Do not mutate the returned map; it is a pointer to the
+// RebuiltTree's internal map!
+func (tree *RebuiltTree) Keys() *containers.SortedMap[btrfsprim.Key, keyio.ItemPtr] {
+	return &tree.keys
+}