mirror of
https://github.com/restic/restic.git
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6f53ecc1ae
Use runtime.GOMAXPROCS(0) as worker count for CPU-bound tasks, repo.Connections() for IO-bound task and a combination if a task can be both. Streaming packs is treated as IO-bound as adding more worker cannot provide a speedup. Typical IO-bound tasks are download / uploading / deleting files. Decoding / Encoding / Verifying are usually CPU-bound. Several tasks are a combination of both, e.g. for combined download and decode functions. In the latter case add both limits together. As the backends have their own concurrency limits restic still won't download more than repo.Connections() files in parallel, but the additional workers can decode already downloaded data in parallel.
124 lines
3.3 KiB
Go
124 lines
3.3 KiB
Go
package repository
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import (
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"context"
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"sync"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/restic"
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"github.com/restic/restic/internal/ui/progress"
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"golang.org/x/sync/errgroup"
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)
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// Repack takes a list of packs together with a list of blobs contained in
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// these packs. Each pack is loaded and the blobs listed in keepBlobs is saved
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// into a new pack. Returned is the list of obsolete packs which can then
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// be removed.
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//
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// The map keepBlobs is modified by Repack, it is used to keep track of which
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// blobs have been processed.
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func Repack(ctx context.Context, repo restic.Repository, dstRepo restic.Repository, packs restic.IDSet, keepBlobs restic.BlobSet, p *progress.Counter) (obsoletePacks restic.IDSet, err error) {
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debug.Log("repacking %d packs while keeping %d blobs", len(packs), len(keepBlobs))
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if repo == dstRepo && dstRepo.Backend().Connections() < 2 {
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return nil, errors.Fatal("repack step requires a backend connection limit of at least two")
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}
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wg, wgCtx := errgroup.WithContext(ctx)
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dstRepo.StartPackUploader(wgCtx, wg)
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wg.Go(func() error {
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var err error
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obsoletePacks, err = repack(wgCtx, repo, dstRepo, packs, keepBlobs, p)
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return err
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})
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if err := wg.Wait(); err != nil {
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return nil, err
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}
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return obsoletePacks, nil
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}
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func repack(ctx context.Context, repo restic.Repository, dstRepo restic.Repository, packs restic.IDSet, keepBlobs restic.BlobSet, p *progress.Counter) (obsoletePacks restic.IDSet, err error) {
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wg, wgCtx := errgroup.WithContext(ctx)
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var keepMutex sync.Mutex
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downloadQueue := make(chan restic.PackBlobs)
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wg.Go(func() error {
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defer close(downloadQueue)
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for pbs := range repo.Index().ListPacks(wgCtx, packs) {
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var packBlobs []restic.Blob
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keepMutex.Lock()
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// filter out unnecessary blobs
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for _, entry := range pbs.Blobs {
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h := restic.BlobHandle{ID: entry.ID, Type: entry.Type}
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if keepBlobs.Has(h) {
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packBlobs = append(packBlobs, entry)
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}
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}
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keepMutex.Unlock()
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select {
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case downloadQueue <- restic.PackBlobs{PackID: pbs.PackID, Blobs: packBlobs}:
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case <-wgCtx.Done():
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return wgCtx.Err()
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}
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}
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return nil
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})
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worker := func() error {
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for t := range downloadQueue {
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err := StreamPack(wgCtx, repo.Backend().Load, repo.Key(), t.PackID, t.Blobs, func(blob restic.BlobHandle, buf []byte, err error) error {
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if err != nil {
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return err
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}
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keepMutex.Lock()
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// recheck whether some other worker was faster
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shouldKeep := keepBlobs.Has(blob)
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if shouldKeep {
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keepBlobs.Delete(blob)
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}
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keepMutex.Unlock()
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if !shouldKeep {
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return nil
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}
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// We do want to save already saved blobs!
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_, _, _, err = dstRepo.SaveBlob(wgCtx, blob.Type, buf, blob.ID, true)
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if err != nil {
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return err
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}
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debug.Log(" saved blob %v", blob.ID)
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return nil
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})
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if err != nil {
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return err
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}
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p.Add(1)
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}
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return nil
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}
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// as packs are streamed the concurrency is limited by IO
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// reduce by one to ensure that uploading is always possible
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repackWorkerCount := int(repo.Connections() - 1)
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for i := 0; i < repackWorkerCount; i++ {
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wg.Go(worker)
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}
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if err := wg.Wait(); err != nil {
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return nil, err
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}
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if err := dstRepo.Flush(ctx); err != nil {
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return nil, err
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}
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return packs, nil
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}
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