github.1485827954.workers.dev/ethereum/go-ethereum@v1.14.3/eth/downloader/fetchers.go (about)

     1  // Copyright 2021 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package downloader
    18  
    19  import (
    20  	"time"
    21  
    22  	"github.com/ethereum/go-ethereum/common"
    23  	"github.com/ethereum/go-ethereum/core/types"
    24  	"github.com/ethereum/go-ethereum/eth/protocols/eth"
    25  )
    26  
    27  // fetchHeadersByHash is a blocking version of Peer.RequestHeadersByHash which
    28  // handles all the cancellation, interruption and timeout mechanisms of a data
    29  // retrieval to allow blocking API calls.
    30  func (d *Downloader) fetchHeadersByHash(p *peerConnection, hash common.Hash, amount int, skip int, reverse bool) ([]*types.Header, []common.Hash, error) {
    31  	// Create the response sink and send the network request
    32  	start := time.Now()
    33  	resCh := make(chan *eth.Response)
    34  
    35  	req, err := p.peer.RequestHeadersByHash(hash, amount, skip, reverse, resCh)
    36  	if err != nil {
    37  		return nil, nil, err
    38  	}
    39  	defer req.Close()
    40  
    41  	// Wait until the response arrives, the request is cancelled or times out
    42  	ttl := d.peers.rates.TargetTimeout()
    43  
    44  	timeoutTimer := time.NewTimer(ttl)
    45  	defer timeoutTimer.Stop()
    46  
    47  	select {
    48  	case <-d.cancelCh:
    49  		return nil, nil, errCanceled
    50  
    51  	case <-timeoutTimer.C:
    52  		// Header retrieval timed out, update the metrics
    53  		p.log.Debug("Header request timed out", "elapsed", ttl)
    54  		headerTimeoutMeter.Mark(1)
    55  
    56  		return nil, nil, errTimeout
    57  
    58  	case res := <-resCh:
    59  		// Headers successfully retrieved, update the metrics
    60  		headerReqTimer.Update(time.Since(start))
    61  		headerInMeter.Mark(int64(len(*res.Res.(*eth.BlockHeadersRequest))))
    62  
    63  		// Don't reject the packet even if it turns out to be bad, downloader will
    64  		// disconnect the peer on its own terms. Simply delivery the headers to
    65  		// be processed by the caller
    66  		res.Done <- nil
    67  
    68  		return *res.Res.(*eth.BlockHeadersRequest), res.Meta.([]common.Hash), nil
    69  	}
    70  }