Downloader.fetchHeadersByNumber¶
| Source (upstream pre-purge) | Current | |
|---|---|---|
| File | eth/downloader/fetchers.go |
downloader_pow.go |
| Symbol | Downloader.fetchHeadersByNumber |
Downloader.fetchHeadersByNumber |
| Ref | f4d53133f~1 |
etc/v1.17.3-full-node |
3-way merge — purge → getc ← upstream¶
pre-purge
↗// 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
}
}