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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsutil
import (
"fmt"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
)
func maybeSet[K, V comparable](name string, m map[K]V, k K, v V) {
if other, conflict := m[k]; conflict && other != v {
panic(fmt.Errorf("conflict: %s %v can't have both %v and %v", name, k, other, v))
}
m[k] = v
}
type skinnyKP struct {
src, dst btrfsvol.LogicalAddr
}
type skinnyItem struct {
node btrfsvol.LogicalAddr
item int
}
type SkinnyPathArena struct {
fatKPs map[skinnyKP]btrfstree.TreePathElem
fatItems map[skinnyItem]btrfstree.TreePathElem
}
type SkinnyPath struct {
Nodes []btrfsvol.LogicalAddr
Item int
}
func (a *SkinnyPathArena) init() {
if a.fatKPs == nil {
a.fatKPs = make(map[skinnyKP]btrfstree.TreePathElem)
a.fatItems = make(map[skinnyItem]btrfstree.TreePathElem)
}
}
func (a *SkinnyPathArena) Deflate(fat btrfstree.TreePath) SkinnyPath {
a.init()
var ret SkinnyPath
ret.Item = -1
var prevNode btrfsvol.LogicalAddr
for _, elem := range fat {
if elem.ToNodeAddr > 0 {
maybeSet("SkinnyPathArena.fatKPs", a.fatKPs, skinnyKP{
src: prevNode,
dst: elem.ToNodeAddr,
}, elem)
ret.Nodes = append(ret.Nodes, elem.ToNodeAddr)
} else {
maybeSet("SkinnyPathArena.fatItems", a.fatItems, skinnyItem{
node: prevNode,
item: elem.FromItemIdx,
}, elem)
ret.Item = elem.FromItemIdx
}
prevNode = elem.ToNodeAddr
}
return ret
}
func (a *SkinnyPathArena) Inflate(skinny SkinnyPath) btrfstree.TreePath {
a.init()
var ret btrfstree.TreePath
var prevNode btrfsvol.LogicalAddr
for _, node := range skinny.Nodes {
elem, ok := a.fatKPs[skinnyKP{
src: prevNode,
dst: node,
}]
if !ok {
panic(fmt.Errorf("SkinnyPathArena.Inflate: no stored TreePathElem for %v->%v",
prevNode, node))
}
ret = append(ret, elem)
prevNode = node
}
if skinny.Item >= 0 {
elem, ok := a.fatItems[skinnyItem{
node: prevNode,
item: skinny.Item,
}]
if !ok {
panic(fmt.Errorf("SkinnyPathArena.Inflate: no stored TreePathElem for %v[%d]",
prevNode, skinny.Item))
}
ret = append(ret, elem)
}
return ret
}
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