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restic/internal/archiver/blob_saver.go
Michael Eischer b4de902596 archiver: Asynchronously complete FutureFile
After reading and chunking all data in a file, the FutureFile still has
to wait until the FutureBlobs are completed. This was done synchronously
which results in blocking the file saver and prevents the next file from
being read.

By replacing the FutureBlob with a callback, it becomes possible to
complete the FutureFile asynchronously.
2022-10-30 10:29:11 +01:00

103 lines
2.3 KiB
Go

package archiver
import (
"context"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
"golang.org/x/sync/errgroup"
)
// Saver allows saving a blob.
type Saver interface {
SaveBlob(ctx context.Context, t restic.BlobType, data []byte, id restic.ID, storeDuplicate bool) (restic.ID, bool, int, error)
}
// BlobSaver concurrently saves incoming blobs to the repo.
type BlobSaver struct {
repo Saver
ch chan<- saveBlobJob
}
// NewBlobSaver returns a new blob. A worker pool is started, it is stopped
// when ctx is cancelled.
func NewBlobSaver(ctx context.Context, wg *errgroup.Group, repo Saver, workers uint) *BlobSaver {
ch := make(chan saveBlobJob)
s := &BlobSaver{
repo: repo,
ch: ch,
}
for i := uint(0); i < workers; i++ {
wg.Go(func() error {
return s.worker(ctx, ch)
})
}
return s
}
func (s *BlobSaver) TriggerShutdown() {
close(s.ch)
}
// Save stores a blob in the repo. It checks the index and the known blobs
// before saving anything. It takes ownership of the buffer passed in.
func (s *BlobSaver) Save(ctx context.Context, t restic.BlobType, buf *Buffer, cb func(res SaveBlobResponse)) {
select {
case s.ch <- saveBlobJob{BlobType: t, buf: buf, cb: cb}:
case <-ctx.Done():
debug.Log("not sending job, context is cancelled")
}
}
type saveBlobJob struct {
restic.BlobType
buf *Buffer
cb func(res SaveBlobResponse)
}
type SaveBlobResponse struct {
id restic.ID
length int
sizeInRepo int
known bool
}
func (s *BlobSaver) saveBlob(ctx context.Context, t restic.BlobType, buf []byte) (SaveBlobResponse, error) {
id, known, sizeInRepo, err := s.repo.SaveBlob(ctx, t, buf, restic.ID{}, false)
if err != nil {
return SaveBlobResponse{}, err
}
return SaveBlobResponse{
id: id,
length: len(buf),
sizeInRepo: sizeInRepo,
known: known,
}, nil
}
func (s *BlobSaver) worker(ctx context.Context, jobs <-chan saveBlobJob) error {
for {
var job saveBlobJob
var ok bool
select {
case <-ctx.Done():
return nil
case job, ok = <-jobs:
if !ok {
return nil
}
}
res, err := s.saveBlob(ctx, job.BlobType, job.buf.Data)
if err != nil {
debug.Log("saveBlob returned error, exiting: %v", err)
return err
}
job.cb(res)
job.buf.Release()
}
}