forked from TrueCloudLab/restic
repository: Limit to a single pending pack file
Use only a single not completed pack file to keep the number of open and active pack files low. The main change here is to defer hashing the pack file to the upload step. This prevents the pack assembly step to become a bottleneck as the only task is now to write data to the temporary pack file. The tests are cleaned up to no longer reimplement packer manager functions.
This commit is contained in:
Michael Eischer
parent
fa25d6118e
commit
753e56ee29
3 changed files with 95 additions and 171 deletions
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@ -1,9 +1,10 @@
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package repository
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import (
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"bufio"
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"context"
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"hash"
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"io"
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"io/ioutil"
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"os"
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"runtime"
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"sync"
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@ -23,32 +24,29 @@ import (
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// Packer holds a pack.Packer together with a hash writer.
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type Packer struct {
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*pack.Packer
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hw *hashing.Writer
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beHw *hashing.Writer
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tmpfile *os.File
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bufWr *bufio.Writer
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}
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// packerManager keeps a list of open packs and creates new on demand.
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type packerManager struct {
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tpe restic.BlobType
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key *crypto.Key
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hasherFn func() hash.Hash
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queueFn func(ctx context.Context, t restic.BlobType, p *Packer) error
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tpe restic.BlobType
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key *crypto.Key
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queueFn func(ctx context.Context, t restic.BlobType, p *Packer) error
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pm sync.Mutex
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packers []*Packer
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pm sync.Mutex
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packer *Packer
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}
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const minPackSize = 4 * 1024 * 1024
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// newPackerManager returns an new packer manager which writes temporary files
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// to a temporary directory
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func newPackerManager(key *crypto.Key, hasherFn func() hash.Hash, tpe restic.BlobType, queueFn func(ctx context.Context, t restic.BlobType, p *Packer) error) *packerManager {
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func newPackerManager(key *crypto.Key, tpe restic.BlobType, queueFn func(ctx context.Context, t restic.BlobType, p *Packer) error) *packerManager {
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return &packerManager{
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tpe: tpe,
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key: key,
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hasherFn: hasherFn,
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queueFn: queueFn,
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tpe: tpe,
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key: key,
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queueFn: queueFn,
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}
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}
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@ -56,24 +54,34 @@ func (r *packerManager) Flush(ctx context.Context) error {
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r.pm.Lock()
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defer r.pm.Unlock()
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debug.Log("manually flushing %d packs", len(r.packers))
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for _, packer := range r.packers {
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err := r.queueFn(ctx, r.tpe, packer)
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if r.packer != nil {
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debug.Log("manually flushing pending pack")
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err := r.queueFn(ctx, r.tpe, r.packer)
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if err != nil {
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return err
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}
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r.packer = nil
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}
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r.packers = r.packers[:0]
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return nil
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}
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func (r *packerManager) SaveBlob(ctx context.Context, t restic.BlobType, id restic.ID, ciphertext []byte, uncompressedLength int) (int, error) {
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packer, err := r.findPacker()
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if err != nil {
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return 0, err
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r.pm.Lock()
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defer r.pm.Unlock()
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var err error
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packer := r.packer
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if r.packer == nil {
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packer, err = r.newPacker()
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if err != nil {
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return 0, err
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}
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}
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// remember packer
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r.packer = packer
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// save ciphertext
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// Add only appends bytes in memory to avoid being a scaling bottleneck
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size, err := packer.Add(t, id, ciphertext, uncompressedLength)
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if err != nil {
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return 0, err
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@ -82,10 +90,12 @@ func (r *packerManager) SaveBlob(ctx context.Context, t restic.BlobType, id rest
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// if the pack is not full enough, put back to the list
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if packer.Size() < minPackSize {
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debug.Log("pack is not full enough (%d bytes)", packer.Size())
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r.insertPacker(packer)
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return size, nil
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}
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// forget full packer
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r.packer = nil
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// call while holding lock to prevent findPacker from creating new packers if the uploaders are busy
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// else write the pack to the backend
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err = r.queueFn(ctx, t, packer)
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if err != nil {
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@ -97,56 +107,24 @@ func (r *packerManager) SaveBlob(ctx context.Context, t restic.BlobType, id rest
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// findPacker returns a packer for a new blob of size bytes. Either a new one is
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// created or one is returned that already has some blobs.
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func (r *packerManager) findPacker() (packer *Packer, err error) {
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r.pm.Lock()
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defer r.pm.Unlock()
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// search for a suitable packer
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if len(r.packers) > 0 {
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p := r.packers[0]
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last := len(r.packers) - 1
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r.packers[0] = r.packers[last]
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r.packers[last] = nil // Allow GC of stale reference.
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r.packers = r.packers[:last]
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return p, nil
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}
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// no suitable packer found, return new
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func (r *packerManager) newPacker() (packer *Packer, err error) {
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debug.Log("create new pack")
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tmpfile, err := fs.TempFile("", "restic-temp-pack-")
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if err != nil {
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return nil, errors.Wrap(err, "fs.TempFile")
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}
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w := io.Writer(tmpfile)
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beHasher := r.hasherFn()
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var beHw *hashing.Writer
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if beHasher != nil {
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beHw = hashing.NewWriter(w, beHasher)
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w = beHw
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}
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hw := hashing.NewWriter(w, sha256.New())
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p := pack.NewPacker(r.key, hw)
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bufWr := bufio.NewWriter(tmpfile)
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p := pack.NewPacker(r.key, bufWr)
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packer = &Packer{
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Packer: p,
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beHw: beHw,
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hw: hw,
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tmpfile: tmpfile,
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bufWr: bufWr,
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}
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return packer, nil
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}
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// insertPacker appends p to s.packs.
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func (r *packerManager) insertPacker(p *Packer) {
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r.pm.Lock()
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defer r.pm.Unlock()
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r.packers = append(r.packers, p)
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debug.Log("%d packers\n", len(r.packers))
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}
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// savePacker stores p in the backend.
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func (r *Repository) savePacker(ctx context.Context, t restic.BlobType, p *Packer) error {
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debug.Log("save packer for %v with %d blobs (%d bytes)\n", t, p.Packer.Count(), p.Packer.Size())
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@ -154,20 +132,43 @@ func (r *Repository) savePacker(ctx context.Context, t restic.BlobType, p *Packe
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if err != nil {
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return err
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}
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id := restic.IDFromHash(p.hw.Sum(nil))
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h := restic.Handle{Type: restic.PackFile, Name: id.String(),
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ContainedBlobType: t}
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var beHash []byte
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if p.beHw != nil {
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beHash = p.beHw.Sum(nil)
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}
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rd, err := restic.NewFileReader(p.tmpfile, beHash)
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err = p.bufWr.Flush()
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if err != nil {
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return err
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}
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err = r.be.Save(ctx, h, rd)
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// calculate sha256 hash in a second pass
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var rd io.Reader
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rd, err = restic.NewFileReader(p.tmpfile, nil)
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if err != nil {
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return err
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}
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beHasher := r.be.Hasher()
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var beHr *hashing.Reader
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if beHasher != nil {
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beHr = hashing.NewReader(rd, beHasher)
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rd = beHr
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}
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hr := hashing.NewReader(rd, sha256.New())
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_, err = io.Copy(ioutil.Discard, hr)
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if err != nil {
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return err
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}
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id := restic.IDFromHash(hr.Sum(nil))
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h := restic.Handle{Type: restic.PackFile, Name: id.String(),
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ContainedBlobType: t}
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var beHash []byte
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if beHr != nil {
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beHash = beHr.Sum(nil)
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}
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rrd, err := restic.NewFileReader(p.tmpfile, beHash)
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if err != nil {
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return err
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}
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err = r.be.Save(ctx, h, rrd)
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if err != nil {
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debug.Log("Save(%v) error: %v", h, err)
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return err
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@ -198,11 +199,3 @@ func (r *Repository) savePacker(ctx context.Context, t restic.BlobType, p *Packe
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}
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return r.idx.SaveFullIndex(ctx, r)
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}
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// countPacker returns the number of open (unfinished) packers.
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func (r *packerManager) countPacker() int {
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r.pm.Lock()
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defer r.pm.Unlock()
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return len(r.packers)
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}
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@ -2,26 +2,16 @@ package repository
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import (
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"context"
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"hash"
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"io"
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"math/rand"
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"os"
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"sync"
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"testing"
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"github.com/restic/restic/internal/backend/mem"
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"github.com/restic/restic/internal/crypto"
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"github.com/restic/restic/internal/fs"
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"github.com/restic/restic/internal/mock"
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"github.com/restic/restic/internal/restic"
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"github.com/restic/restic/internal/test"
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)
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// Saver implements saving data in a backend.
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type Saver interface {
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Save(context.Context, restic.Handle, restic.RewindReader) error
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Hasher() hash.Hash
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}
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func randomID(rd io.Reader) restic.ID {
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id := restic.ID{}
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_, err := io.ReadFull(rd, id[:])
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@ -40,91 +30,27 @@ func min(a, b int) int {
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return b
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}
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func saveFile(t testing.TB, be Saver, length int, f *os.File, id restic.ID, hash []byte) {
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h := restic.Handle{Type: restic.PackFile, Name: id.String()}
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t.Logf("save file %v", h)
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rd, err := restic.NewFileReader(f, hash)
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if err != nil {
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t.Fatal(err)
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}
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err = be.Save(context.TODO(), h, rd)
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if err != nil {
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t.Fatal(err)
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}
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if err := f.Close(); err != nil {
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t.Fatal(err)
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}
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if err := fs.RemoveIfExists(f.Name()); err != nil {
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t.Fatal(err)
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}
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}
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func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager, buf []byte) (bytes int) {
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func fillPacks(t testing.TB, rnd *rand.Rand, pm *packerManager, buf []byte) (bytes int) {
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for i := 0; i < 100; i++ {
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l := rnd.Intn(maxBlobSize)
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packer, err := pm.findPacker()
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if err != nil {
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t.Fatal(err)
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}
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id := randomID(rnd)
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buf = buf[:l]
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// Only change a few bytes so we know we're not benchmarking the RNG.
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rnd.Read(buf[:min(l, 4)])
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n, err := packer.Add(restic.DataBlob, id, buf, 0)
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n, err := pm.SaveBlob(context.TODO(), restic.DataBlob, id, buf, 0)
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if err != nil {
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t.Fatal(err)
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}
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if n != l+37 {
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if n != l+37 && n != l+37+36 {
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t.Errorf("Add() returned invalid number of bytes: want %v, got %v", l, n)
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}
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bytes += l
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if packer.Size() < minPackSize {
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pm.insertPacker(packer)
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continue
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}
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err = packer.Finalize()
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if err != nil {
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t.Fatal(err)
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}
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packID := restic.IDFromHash(packer.hw.Sum(nil))
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var beHash []byte
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if packer.beHw != nil {
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beHash = packer.beHw.Sum(nil)
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}
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saveFile(t, be, int(packer.Size()), packer.tmpfile, packID, beHash)
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bytes += n
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}
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return bytes
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}
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func flushRemainingPacks(t testing.TB, be Saver, pm *packerManager) (bytes int) {
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if pm.countPacker() > 0 {
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for _, packer := range pm.packers {
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err := packer.Finalize()
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if err != nil {
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t.Fatal(err)
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}
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bytes += packer.HeaderOverhead()
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packID := restic.IDFromHash(packer.hw.Sum(nil))
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var beHash []byte
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if packer.beHw != nil {
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beHash = packer.beHw.Sum(nil)
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}
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saveFile(t, be, int(packer.Size()), packer.tmpfile, packID, beHash)
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}
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err := pm.Flush(context.TODO())
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if err != nil {
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t.Fatal(err)
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}
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return bytes
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}
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@ -143,13 +69,21 @@ func TestPackerManager(t *testing.T) {
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func testPackerManager(t testing.TB) int64 {
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rnd := rand.New(rand.NewSource(randomSeed))
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be := mem.New()
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pm := newPackerManager(crypto.NewRandomKey(), be.Hasher, restic.DataBlob, nil)
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savedBytes := int(0)
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pm := newPackerManager(crypto.NewRandomKey(), restic.DataBlob, func(ctx context.Context, tp restic.BlobType, p *Packer) error {
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err := p.Finalize()
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if err != nil {
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return err
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}
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savedBytes += int(p.Size())
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return nil
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})
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blobBuf := make([]byte, maxBlobSize)
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bytes := fillPacks(t, rnd, be, pm, blobBuf)
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bytes += flushRemainingPacks(t, be, pm)
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bytes := fillPacks(t, rnd, pm, blobBuf)
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// bytes does not include the last packs header
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test.Equals(t, savedBytes, bytes+36)
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t.Logf("saved %d bytes", bytes)
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return int64(bytes)
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@ -162,10 +96,6 @@ func BenchmarkPackerManager(t *testing.B) {
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})
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rnd := rand.New(rand.NewSource(randomSeed))
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be := &mock.Backend{
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SaveFn: func(context.Context, restic.Handle, restic.RewindReader) error { return nil },
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}
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blobBuf := make([]byte, maxBlobSize)
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t.ReportAllocs()
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@ -174,8 +104,9 @@ func BenchmarkPackerManager(t *testing.B) {
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for i := 0; i < t.N; i++ {
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rnd.Seed(randomSeed)
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pm := newPackerManager(crypto.NewRandomKey(), be.Hasher, restic.DataBlob, nil)
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fillPacks(t, rnd, be, pm, blobBuf)
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flushRemainingPacks(t, be, pm)
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pm := newPackerManager(crypto.NewRandomKey(), restic.DataBlob, func(ctx context.Context, t restic.BlobType, p *Packer) error {
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return nil
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})
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fillPacks(t, rnd, pm, blobBuf)
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}
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}
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@ -520,8 +520,8 @@ func (r *Repository) StartPackUploader(ctx context.Context, wg *errgroup.Group)
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innerWg, ctx := errgroup.WithContext(ctx)
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r.packerWg = innerWg
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r.uploader = newPackerUploader(ctx, innerWg, r, r.be.Connections())
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r.treePM = newPackerManager(r.key, r.be.Hasher, restic.TreeBlob, r.uploader.QueuePacker)
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r.dataPM = newPackerManager(r.key, r.be.Hasher, restic.DataBlob, r.uploader.QueuePacker)
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r.treePM = newPackerManager(r.key, restic.TreeBlob, r.uploader.QueuePacker)
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r.dataPM = newPackerManager(r.key, restic.DataBlob, r.uploader.QueuePacker)
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wg.Go(func() error {
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return innerWg.Wait()
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