Official Go implementation of the Ethereum protocol
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go-ethereum/eth/downloader/fetchers.go

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3.9 KiB

// Copyright 2021 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 downloader
import (
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/protocols/eth"
)
// fetchHeadersByHash is a blocking version of Peer.RequestHeadersByHash which
// handles all the cancellation, interruption and timeout mechanisms of a data
// retrieval to allow blocking API calls.
func (d *Downloader) fetchHeadersByHash(p *peerConnection, hash common.Hash, amount int, skip int, reverse bool) ([]*types.Header, []common.Hash, error) {
// Create the response sink and send the network request
start := time.Now()
resCh := make(chan *eth.Response)
req, err := p.peer.RequestHeadersByHash(hash, amount, skip, reverse, resCh)
if err != nil {
return nil, nil, err
}
defer req.Close()
// Wait until the response arrives, the request is cancelled or times out
ttl := d.peers.rates.TargetTimeout()
timeoutTimer := time.NewTimer(ttl)
defer timeoutTimer.Stop()
select {
case <-d.cancelCh:
return nil, nil, errCanceled
case <-timeoutTimer.C:
// Header retrieval timed out, update the metrics
p.log.Debug("Header request timed out", "elapsed", ttl)
headerTimeoutMeter.Mark(1)
return nil, nil, errTimeout
case res := <-resCh:
// Headers successfully retrieved, update the metrics
headerReqTimer.Update(time.Since(start))
headerInMeter.Mark(int64(len(*res.Res.(*eth.BlockHeadersRequest))))
// Don't reject the packet even if it turns out to be bad, downloader will
// disconnect the peer on its own terms. Simply delivery the headers to
// be processed by the caller
res.Done <- nil
return *res.Res.(*eth.BlockHeadersRequest), res.Meta.([]common.Hash), nil
}
}
// fetchHeadersByNumber is a blocking version of Peer.RequestHeadersByNumber which
// handles all the cancellation, interruption and timeout mechanisms of a data
// retrieval to allow blocking API calls.
func (d *Downloader) fetchHeadersByNumber(p *peerConnection, number uint64, amount int, skip int, reverse bool) ([]*types.Header, []common.Hash, error) {
// Create the response sink and send the network request
start := time.Now()
resCh := make(chan *eth.Response)
req, err := p.peer.RequestHeadersByNumber(number, amount, skip, reverse, resCh)
if err != nil {
return nil, nil, err
}
defer req.Close()
// Wait until the response arrives, the request is cancelled or times out
ttl := d.peers.rates.TargetTimeout()
timeoutTimer := time.NewTimer(ttl)
defer timeoutTimer.Stop()
select {
case <-d.cancelCh:
return nil, nil, errCanceled
case <-timeoutTimer.C:
// Header retrieval timed out, update the metrics
p.log.Debug("Header request timed out", "elapsed", ttl)
headerTimeoutMeter.Mark(1)
return nil, nil, errTimeout
case res := <-resCh:
// Headers successfully retrieved, update the metrics
headerReqTimer.Update(time.Since(start))
headerInMeter.Mark(int64(len(*res.Res.(*eth.BlockHeadersRequest))))
// Don't reject the packet even if it turns out to be bad, downloader will
// disconnect the peer on its own terms. Simply delivery the headers to
// be processed by the caller
res.Done <- nil
return *res.Res.(*eth.BlockHeadersRequest), res.Meta.([]common.Hash), nil
}
}