summaryrefslogtreecommitdiff
path: root/cmd/btrfs-rec/inspect/rebuildmappings/sumrunwithgaps.go
blob: f79e2be6696cdabbdda9e5a4c2f0c7a6a807e9ce (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later

package rebuildmappings

import (
	"context"
	"fmt"
	"io"
	"math"

	"git.lukeshu.com/go/lowmemjson"

	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfssum"
	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
)

type SumRunWithGaps[Addr btrfsvol.IntAddr[Addr]] struct {
	// Store the start address and size, in order to facilitate
	// leading and trailing gaps.
	Addr Addr
	Size btrfsvol.AddrDelta

	Runs []btrfssum.SumRun[Addr]
}

var (
	_ lowmemjson.Encodable = SumRunWithGaps[btrfsvol.LogicalAddr]{}
	_ lowmemjson.Decodable = (*SumRunWithGaps[btrfsvol.LogicalAddr])(nil)
)

// PatLen implements kmpPattern[int, ShortSum].
func (sg SumRunWithGaps[Addr]) PatLen() int {
	return int(sg.Size / btrfssum.BlockSize)
}

func (sg SumRunWithGaps[Addr]) PctFull() float64 {
	total := sg.PatLen()
	var full int
	for _, run := range sg.Runs {
		full += run.SeqLen()
	}
	return float64(full) / float64(total)
}

func (sg SumRunWithGaps[Addr]) RunForAddr(addr Addr) (btrfssum.SumRun[Addr], Addr, bool) {
	for _, run := range sg.Runs {
		if run.Addr > addr {
			return btrfssum.SumRun[Addr]{}, run.Addr, false
		}
		if run.Addr.Add(run.Size()) <= addr {
			continue
		}
		return run, 0, true
	}
	return btrfssum.SumRun[Addr]{}, math.MaxInt64, false
}

func (sg SumRunWithGaps[Addr]) SumForAddr(addr Addr) (btrfssum.ShortSum, bool) {
	if addr < sg.Addr || addr >= sg.Addr.Add(sg.Size) {
		return "", false
	}
	runIdx, ok := slices.Search(sg.Runs, func(run btrfssum.SumRun[Addr]) int {
		switch {
		case addr < run.Addr:
			return -1
		case addr >= run.Addr.Add(run.Size()):
			return 1
		default:
			return 0
		}
	})
	if !ok {
		return "", false
	}
	run := sg.Runs[runIdx]
	off := int((addr-run.Addr)/btrfssum.BlockSize) * run.ChecksumSize
	return run.Sums[off : off+run.ChecksumSize], true
}

func (sg SumRunWithGaps[Addr]) Walk(ctx context.Context, fn func(Addr, btrfssum.ShortSum) error) error {
	for _, run := range sg.Runs {
		if err := run.Walk(ctx, fn); err != nil {
			return err
		}
	}
	return nil
}

// PatGet implements kmpPattern[int, ShortSum].
func (sg SumRunWithGaps[Addr]) PatGet(sumIdx int) (btrfssum.ShortSum, bool) {
	addr := sg.Addr.Add(btrfsvol.AddrDelta(sumIdx) * btrfssum.BlockSize)
	return sg.SumForAddr(addr)
}

func (sg SumRunWithGaps[Addr]) EncodeJSON(w io.Writer) error {
	if _, err := fmt.Fprintf(w, `{"Addr":%d,"Size":%d,"Runs":[`, sg.Addr, sg.Size); err != nil {
		return err
	}
	cur := sg.Addr
	for i, run := range sg.Runs {
		if i > 0 {
			if _, err := w.Write([]byte{','}); err != nil {
				return err
			}
		}
		switch {
		case run.Addr < cur:
			return fmt.Errorf("invalid %T: addr went backwards: %v < %v", sg, run.Addr, cur)
		case run.Addr > cur:
			if _, err := fmt.Fprintf(w, `{"Gap":%d},`, run.Addr.Sub(cur)); err != nil {
				return err
			}
			fallthrough
		default:
			if err := lowmemjson.NewEncoder(w).Encode(run); err != nil {
				return err
			}
			cur = run.Addr.Add(run.Size())
		}
	}
	end := sg.Addr.Add(sg.Size)
	switch {
	case end < cur:
		return fmt.Errorf("invalid %T: addr went backwards: %v < %v", sg, end, cur)
	case end > cur:
		if _, err := fmt.Fprintf(w, `,{"Gap":%d}`, end.Sub(cur)); err != nil {
			return err
		}
	}
	if _, err := w.Write([]byte("]}")); err != nil {
		return err
	}
	return nil
}

func (sg *SumRunWithGaps[Addr]) DecodeJSON(r io.RuneScanner) error {
	*sg = SumRunWithGaps[Addr]{}
	var name string
	return lowmemjson.DecodeObject(r,
		func(r io.RuneScanner) error {
			return lowmemjson.NewDecoder(r).Decode(&name)
		},
		func(r io.RuneScanner) error {
			switch name {
			case "Addr":
				return lowmemjson.NewDecoder(r).Decode(&sg.Addr)
			case "Size":
				return lowmemjson.NewDecoder(r).Decode(&sg.Size)
			case "Runs":
				return lowmemjson.DecodeArray(r, func(r io.RuneScanner) error {
					var run btrfssum.SumRun[Addr]
					if err := lowmemjson.NewDecoder(r).Decode(&run); err != nil {
						return err
					}
					if run.ChecksumSize > 0 {
						sg.Runs = append(sg.Runs, run)
					}
					return nil
				})
			default:
				return fmt.Errorf("unknown key %q", name)
			}
		})
}