storj/pkg/audit/cursor.go

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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.
package audit
import (
"context"
"crypto/rand"
"math/big"
"sync"
"github.com/vivint/infectious"
"storj.io/storj/pkg/eestream"
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"storj.io/storj/pkg/identity"
"storj.io/storj/pkg/pb"
"storj.io/storj/pkg/pointerdb"
"storj.io/storj/pkg/storage/meta"
"storj.io/storj/pkg/storj"
)
// Stripe keeps track of a stripe's index and its parent segment
type Stripe struct {
Index int
Segment *pb.Pointer
PBA *pb.OrderLimit
}
// Cursor keeps track of audit location in pointer db
type Cursor struct {
pointers *pointerdb.Service
allocation *pointerdb.AllocationSigner
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identity *identity.FullIdentity
lastPath storj.Path
mutex sync.Mutex
}
// NewCursor creates a Cursor which iterates over pointer db
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func NewCursor(pointers *pointerdb.Service, allocation *pointerdb.AllocationSigner, identity *identity.FullIdentity) *Cursor {
return &Cursor{pointers: pointers, allocation: allocation, identity: identity}
}
// NextStripe returns a random stripe to be audited
func (cursor *Cursor) NextStripe(ctx context.Context) (stripe *Stripe, err error) {
cursor.mutex.Lock()
defer cursor.mutex.Unlock()
var pointerItems []*pb.ListResponse_Item
var path storj.Path
var more bool
pointerItems, more, err = cursor.pointers.List("", cursor.lastPath, "", true, 0, meta.None)
if err != nil {
return nil, err
}
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if len(pointerItems) == 0 {
return nil, nil
}
pointerItem, err := getRandomPointer(pointerItems)
if err != nil {
return nil, err
}
path = pointerItem.Path
// keep track of last path listed
if !more {
cursor.lastPath = ""
} else {
cursor.lastPath = pointerItems[len(pointerItems)-1].Path
}
// get pointer info
pointer, err := cursor.pointers.Get(path)
if err != nil {
return nil, err
}
peerIdentity := &identity.PeerIdentity{ID: cursor.identity.ID, Leaf: cursor.identity.Leaf}
pba, err := cursor.allocation.PayerBandwidthAllocation(ctx, peerIdentity, pb.BandwidthAction_GET_AUDIT)
if err != nil {
return nil, err
}
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if pointer.GetType() != pb.Pointer_REMOTE {
return nil, nil
}
// create the erasure scheme so we can get the stripe size
es, err := makeErasureScheme(pointer.GetRemote().GetRedundancy())
if err != nil {
return nil, err
}
if pointer.GetSegmentSize() == 0 {
return nil, nil
}
index, err := getRandomStripe(es, pointer)
if err != nil {
return nil, err
}
return &Stripe{
Index: index,
Segment: pointer,
PBA: pba,
}, nil
}
func makeErasureScheme(rs *pb.RedundancyScheme) (eestream.ErasureScheme, error) {
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required := int(rs.GetMinReq())
total := int(rs.GetTotal())
fc, err := infectious.NewFEC(required, total)
if err != nil {
return nil, err
}
es := eestream.NewRSScheme(fc, int(rs.GetErasureShareSize()))
return es, nil
}
func getRandomStripe(es eestream.ErasureScheme, pointer *pb.Pointer) (index int, err error) {
stripeSize := es.StripeSize()
// the last segment could be smaller than stripe size
if pointer.GetSegmentSize() < int64(stripeSize) {
return 0, nil
}
randomStripeIndex, err := rand.Int(rand.Reader, big.NewInt(pointer.GetSegmentSize()/int64(stripeSize)))
if err != nil {
return -1, err
}
return int(randomStripeIndex.Int64()), nil
}
func getRandomPointer(pointerItems []*pb.ListResponse_Item) (pointer *pb.ListResponse_Item, err error) {
randomNum, err := rand.Int(rand.Reader, big.NewInt(int64(len(pointerItems))))
if err != nil {
return &pb.ListResponse_Item{}, err
}
randomNumInt64 := randomNum.Int64()
pointerItem := pointerItems[randomNumInt64]
return pointerItem, nil
}