restic/internal/repository/index_parallel.go

78 lines
1.8 KiB
Go

package repository
import (
"context"
"sync"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
"golang.org/x/sync/errgroup"
)
const loadIndexParallelism = 5
// ForAllIndexes loads all index files in parallel and calls the given callback.
// It is guaranteed that the function is not run concurrently. If the callback
// returns an error, this function is cancelled and also returns that error.
func ForAllIndexes(ctx context.Context, repo restic.Repository,
fn func(id restic.ID, index *Index, oldFormat bool, err error) error) error {
debug.Log("Start")
type FileInfo struct {
restic.ID
Size int64
}
var m sync.Mutex
// track spawned goroutines using wg, create a new context which is
// cancelled as soon as an error occurs.
wg, ctx := errgroup.WithContext(ctx)
ch := make(chan FileInfo)
// send list of index files through ch, which is closed afterwards
wg.Go(func() error {
defer close(ch)
return repo.List(ctx, restic.IndexFile, func(id restic.ID, size int64) error {
select {
case <-ctx.Done():
return ctx.Err()
case ch <- FileInfo{id, size}:
}
return nil
})
})
// a worker receives an index ID from ch, loads the index, and sends it to indexCh
worker := func() error {
var buf []byte
for fi := range ch {
debug.Log("worker got file %v", fi.ID.Str())
var err error
var idx *Index
oldFormat := false
buf, err = repo.LoadUnpacked(ctx, buf[:0], restic.IndexFile, fi.ID)
if err == nil {
idx, oldFormat, err = DecodeIndex(buf, fi.ID)
}
m.Lock()
err = fn(fi.ID, idx, oldFormat, err)
m.Unlock()
if err != nil {
return err
}
}
return nil
}
// run workers on ch
for i := 0; i < loadIndexParallelism; i++ {
wg.Go(worker)
}
return wg.Wait()
}