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restic/internal/archiver/scanner.go
Alexander Neumann 1140950d7b scanner: Use context only for cancellation
When the scanner is slower than the actual backup, the tomb cancels the
context passed to Scan(), which then returns ctx.Err(). In the end, the
main function prints an error message that is not helpful ("Context
cancelled") and exits with an error code although no error occurred.

The code now ignores the error in the context and just uses it for
cancellation. The scanner is not supposed to return an error anyway.

Closes #1978
2018-09-08 18:53:12 +02:00

108 lines
2.4 KiB
Go

package archiver
import (
"context"
"os"
"path/filepath"
"github.com/restic/restic/internal/fs"
)
// Scanner traverses the targets and calls the function Result with cumulated
// stats concerning the files and folders found. Select is used to decide which
// items should be included. Error is called when an error occurs.
type Scanner struct {
FS fs.FS
SelectByName SelectByNameFunc
Select SelectFunc
Error ErrorFunc
Result func(item string, s ScanStats)
}
// NewScanner initializes a new Scanner.
func NewScanner(fs fs.FS) *Scanner {
return &Scanner{
FS: fs,
SelectByName: func(item string) bool { return true },
Select: func(item string, fi os.FileInfo) bool { return true },
Error: func(item string, fi os.FileInfo, err error) error { return err },
Result: func(item string, s ScanStats) {},
}
}
// ScanStats collect statistics.
type ScanStats struct {
Files, Dirs, Others uint
Bytes uint64
}
// Scan traverses the targets. The function Result is called for each new item
// found, the complete result is also returned by Scan.
func (s *Scanner) Scan(ctx context.Context, targets []string) error {
var stats ScanStats
for _, target := range targets {
abstarget, err := s.FS.Abs(target)
if err != nil {
return err
}
stats, err = s.scan(ctx, stats, abstarget)
if err != nil {
return err
}
if ctx.Err() != nil {
return nil
}
}
s.Result("", stats)
return nil
}
func (s *Scanner) scan(ctx context.Context, stats ScanStats, target string) (ScanStats, error) {
if ctx.Err() != nil {
return stats, nil
}
// exclude files by path before running stat to reduce number of lstat calls
if !s.SelectByName(target) {
return stats, nil
}
// get file information
fi, err := s.FS.Lstat(target)
if err != nil {
return stats, s.Error(target, fi, err)
}
// run remaining select functions that require file information
if !s.Select(target, fi) {
return stats, nil
}
switch {
case fi.Mode().IsRegular():
stats.Files++
stats.Bytes += uint64(fi.Size())
case fi.Mode().IsDir():
names, err := readdirnames(s.FS, target)
if err != nil {
return stats, s.Error(target, fi, err)
}
for _, name := range names {
stats, err = s.scan(ctx, stats, filepath.Join(target, name))
if err != nil {
return stats, err
}
}
stats.Dirs++
default:
stats.Others++
}
s.Result(target, stats)
return stats, nil
}