path: root/swarm/network/stream/syncer.go

// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package stream

import (
    "context"
    "fmt"
    "strconv"
    "time"

    "github.com/ethereum/go-ethereum/metrics"
    "github.com/ethereum/go-ethereum/swarm/chunk"
    "github.com/ethereum/go-ethereum/swarm/log"
    "github.com/ethereum/go-ethereum/swarm/storage"
)

const (
    BatchSize = 128
)

// SwarmSyncerServer implements an Server for history syncing on bins
// offered streams:
// * live request delivery with or without checkback
// * (live/non-live historical) chunk syncing per proximity bin
type SwarmSyncerServer struct {
    correlateId string //used for logging
    po          uint8
    netStore    *storage.NetStore
    quit        chan struct{}
}

// NewSwarmSyncerServer is constructor for SwarmSyncerServer
func NewSwarmSyncerServer(po uint8, netStore *storage.NetStore, correlateId string) (*SwarmSyncerServer, error) {
    return &SwarmSyncerServer{
        correlateId: correlateId,
        po:          po,
        netStore:    netStore,
        quit:        make(chan struct{}),
    }, nil
}

func RegisterSwarmSyncerServer(streamer *Registry, netStore *storage.NetStore) {
    streamer.RegisterServerFunc("SYNC", func(p *Peer, t string, _ bool) (Server, error) {
        po, err := ParseSyncBinKey(t)
        if err != nil {
            return nil, err
        }
        return NewSwarmSyncerServer(po, netStore, fmt.Sprintf("%s|%d", p.ID(), po))
    })
    // streamer.RegisterServerFunc(stream, func(p *Peer) (Server, error) {
    //  return NewOutgoingProvableSwarmSyncer(po, db)
    // })
}

// Close needs to be called on a stream server
func (s *SwarmSyncerServer) Close() {
    close(s.quit)
}

// GetData retrieves the actual chunk from netstore
func (s *SwarmSyncerServer) GetData(ctx context.Context, key []byte) ([]byte, error) {
    ch, err := s.netStore.Get(ctx, chunk.ModeGetSync, storage.Address(key))
    if err != nil {
        return nil, err
    }
    return ch.Data(), nil
}

// SessionIndex returns current storage bin (po) index.
func (s *SwarmSyncerServer) SessionIndex() (uint64, error) {
    return s.netStore.LastPullSubscriptionBinID(s.po)
}

// SetNextBatch retrieves the next batch of hashes from the localstore.
// It expects a range of bin IDs, both ends inclusive in syncing, and returns
// concatenated byte slice of chunk addresses and bin IDs of the first and
// the last one in that slice. The batch may have up to BatchSize number of
// chunk addresses. If at least one chunk is added to the batch and no new chunks
// are added in batchTimeout period, the batch will be returned. This function
// will block until new chunks are received from localstore pull subscription.
func (s *SwarmSyncerServer) SetNextBatch(from, to uint64) ([]byte, uint64, uint64, *HandoverProof, error) {
    //TODO: maybe add unit test for intervals usage in netstore/localstore together with SwarmSyncerServer?
    if from > 0 {
        from--
    }
    batchStart := time.Now()
    descriptors, stop := s.netStore.SubscribePull(context.Background(), s.po, from, to)
    defer stop()

    const batchTimeout = 2 * time.Second

    var (
        batch        []byte
        batchSize    int
        batchStartID *uint64
        batchEndID   uint64
        timer        *time.Timer
        timerC       <-chan time.Time
    )

    defer func(start time.Time) {
        metrics.GetOrRegisterResettingTimer("syncer.set-next-batch.total-time", nil).UpdateSince(start)
        metrics.GetOrRegisterCounter("syncer.set-next-batch.batch-size", nil).Inc(int64(batchSize))
        if timer != nil {
            timer.Stop()
        }
    }(batchStart)

    for iterate := true; iterate; {
        select {
        case d, ok := <-descriptors:
            if !ok {
                iterate = false
                break
            }
            batch = append(batch, d.Address[:]...)
            // This is the most naive approach to label the chunk as synced
            // allowing it to be garbage collected. A proper way requires
            // validating that the chunk is successfully stored by the peer.
            err := s.netStore.Set(context.Background(), chunk.ModeSetSync, d.Address)
            if err != nil {
                metrics.GetOrRegisterCounter("syncer.set-next-batch.set-sync-err", nil).Inc(1)
                log.Debug("syncer pull subscription - err setting chunk as synced", "correlateId", s.correlateId, "err", err)
                return nil, 0, 0, nil, err
            }
            batchSize++
            if batchStartID == nil {
                // set batch start id only if
                // this is the first iteration
                batchStartID = &d.BinID
            }
            batchEndID = d.BinID
            if batchSize >= BatchSize {
                iterate = false
                metrics.GetOrRegisterCounter("syncer.set-next-batch.full-batch", nil).Inc(1)
                log.Trace("syncer pull subscription - batch size reached", "correlateId", s.correlateId, "batchSize", batchSize, "batchStartID", batchStartID, "batchEndID", batchEndID)
            }
            if timer == nil {
                timer = time.NewTimer(batchTimeout)
            } else {
                log.Trace("syncer pull subscription - stopping timer", "correlateId", s.correlateId)
                if !timer.Stop() {
                    <-timer.C
                }
                log.Trace("syncer pull subscription - channel drained, resetting timer", "correlateId", s.correlateId)
                timer.Reset(batchTimeout)
            }
            timerC = timer.C
        case <-timerC:
            // return batch if new chunks are not
            // received after some time
            iterate = false
            metrics.GetOrRegisterCounter("syncer.set-next-batch.timer-expire", nil).Inc(1)
            log.Trace("syncer pull subscription timer expired", "correlateId", s.correlateId, "batchSize", batchSize, "batchStartID", batchStartID, "batchEndID", batchEndID)
        case <-s.quit:
            iterate = false
            log.Trace("syncer pull subscription - quit received", "correlateId", s.correlateId, "batchSize", batchSize, "batchStartID", batchStartID, "batchEndID", batchEndID)
        }
    }
    if batchStartID == nil {
        // if batch start id is not set, return 0
        batchStartID = new(uint64)
    }
    return batch, *batchStartID, batchEndID, nil, nil
}

// SwarmSyncerClient
type SwarmSyncerClient struct {
    netStore *storage.NetStore
    peer     *Peer
    stream   Stream
}

// NewSwarmSyncerClient is a contructor for provable data exchange syncer
func NewSwarmSyncerClient(p *Peer, netStore *storage.NetStore, stream Stream) (*SwarmSyncerClient, error) {
    return &SwarmSyncerClient{
        netStore: netStore,
        peer:     p,
        stream:   stream,
    }, nil
}

// RegisterSwarmSyncerClient registers the client constructor function for
// to handle incoming sync streams
func RegisterSwarmSyncerClient(streamer *Registry, netStore *storage.NetStore) {
    streamer.RegisterClientFunc("SYNC", func(p *Peer, t string, live bool) (Client, error) {
        return NewSwarmSyncerClient(p, netStore, NewStream("SYNC", t, live))
    })
}

// NeedData
func (s *SwarmSyncerClient) NeedData(ctx context.Context, key []byte) (wait func(context.Context) error) {
    return s.netStore.FetchFunc(ctx, key)
}

// BatchDone
func (s *SwarmSyncerClient) BatchDone(stream Stream, from uint64, hashes []byte, root []byte) func() (*TakeoverProof, error) {
    // TODO: reenable this with putter/getter refactored code
    // if s.chunker != nil {
    //  return func() (*TakeoverProof, error) { return s.TakeoverProof(stream, from, hashes, root) }
    // }
    return nil
}

func (s *SwarmSyncerClient) Close() {}

// base for parsing and formating sync bin key
// it must be 2 <= base <= 36
const syncBinKeyBase = 36

// FormatSyncBinKey returns a string representation of
// Kademlia bin number to be used as key for SYNC stream.
func FormatSyncBinKey(bin uint8) string {
    return strconv.FormatUint(uint64(bin), syncBinKeyBase)
}

// ParseSyncBinKey parses the string representation
// and returns the Kademlia bin number.
func ParseSyncBinKey(s string) (uint8, error) {
    bin, err := strconv.ParseUint(s, syncBinKeyBase, 8)
    if err != nil {
        return 0, err
    }
    return uint8(bin), nil
}