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// 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)
}
})
}
|
