package archiver import ( "context" "sync" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/restic" ) // Saver allows saving a blob. type Saver interface { SaveBlob(ctx context.Context, t restic.BlobType, data []byte, id restic.ID) (restic.ID, error) Index() restic.Index } // BlobSaver concurrently saves incoming blobs to the repo. type BlobSaver struct { repo Saver m sync.Mutex knownBlobs restic.BlobSet 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, g Goer, repo Saver, workers uint) *BlobSaver { ch := make(chan saveBlobJob) s := &BlobSaver{ repo: repo, knownBlobs: restic.NewBlobSet(), ch: ch, } for i := uint(0); i < workers; i++ { g.Go(func() error { return s.worker(ctx, ch) }) } return s } // Save stores a blob in the repo. It checks the index and the known blobs // before saving anything. The second return parameter is true if the blob was // previously unknown. func (s *BlobSaver) Save(ctx context.Context, t restic.BlobType, buf *Buffer) FutureBlob { ch := make(chan saveBlobResponse, 1) select { case s.ch <- saveBlobJob{BlobType: t, buf: buf, ch: ch}: case <-ctx.Done(): debug.Log("not sending job, context is cancelled") close(ch) return FutureBlob{ch: ch} } return FutureBlob{ch: ch, length: len(buf.Data)} } // FutureBlob is returned by SaveBlob and will return the data once it has been processed. type FutureBlob struct { ch <-chan saveBlobResponse length int res saveBlobResponse } // Wait blocks until the result is available or the context is cancelled. func (s *FutureBlob) Wait(ctx context.Context) { select { case <-ctx.Done(): return case res, ok := <-s.ch: if ok { s.res = res } } } // ID returns the ID of the blob after it has been saved. func (s *FutureBlob) ID() restic.ID { return s.res.id } // Known returns whether or not the blob was already known. func (s *FutureBlob) Known() bool { return s.res.known } // Length returns the length of the blob. func (s *FutureBlob) Length() int { return s.length } type saveBlobJob struct { restic.BlobType buf *Buffer ch chan<- saveBlobResponse } type saveBlobResponse struct { id restic.ID known bool } func (s *BlobSaver) saveBlob(ctx context.Context, t restic.BlobType, buf []byte) (saveBlobResponse, error) { id := restic.Hash(buf) h := restic.BlobHandle{ID: id, Type: t} // check if another goroutine has already saved this blob known := false s.m.Lock() if s.knownBlobs.Has(h) { known = true } else { s.knownBlobs.Insert(h) known = false } s.m.Unlock() // blob is already known, nothing to do if known { return saveBlobResponse{ id: id, known: true, }, nil } // check if the repo knows this blob if s.repo.Index().Has(id, t) { return saveBlobResponse{ id: id, known: true, }, nil } // otherwise we're responsible for saving it _, err := s.repo.SaveBlob(ctx, t, buf, id) if err != nil { return saveBlobResponse{}, errors.Fatalf("unable to save data: %v", err) } return saveBlobResponse{ id: id, known: false, }, nil } func (s *BlobSaver) worker(ctx context.Context, jobs <-chan saveBlobJob) error { for { var job saveBlobJob select { case <-ctx.Done(): debug.Log("context is cancelled, exiting: %v", ctx.Err()) return nil case job = <-jobs: } res, err := s.saveBlob(ctx, job.BlobType, job.buf.Data) if err != nil { debug.Log("saveBlob returned error: %v", err) close(job.ch) return err } job.ch <- res close(job.ch) job.buf.Release() } }