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downloader: extract findAncestor search functions (#21744)

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This is a simple refactoring, extracting common ancestor
negotiation logic to named function
This commit is contained in:
meowsbits 2021-01-20 15:45:01 -06:00 committed by GitHub
parent 7da8f75d5b
commit 81bf9f97c9
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1 changed files with 27 additions and 0 deletions
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27
eth/downloader/downloader.go
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@ -90,6 +90,7 @@ var (
errCanceled = errors.New("syncing canceled (requested)") errCanceled = errors.New("syncing canceled (requested)")
errNoSyncActive = errors.New("no sync active") errNoSyncActive = errors.New("no sync active")
errTooOld = errors.New("peer's protocol version too old") errTooOld = errors.New("peer's protocol version too old")
errNoAncestorFound = errors.New("no common ancestor found")
) )
type Downloader struct { type Downloader struct {
@ -814,6 +815,26 @@ func (d *Downloader) findAncestor(p *peerConnection, remoteHeader *types.Header)
} }
} }
ancestor, err := d.findAncestorSpanSearch(p, mode, remoteHeight, localHeight, floor)
if err == nil {
return ancestor, nil
}
// The returned error was not nil.
// If the error returned does not reflect that a common ancestor was not found, return it.
// If the error reflects that a common ancestor was not found, continue to binary search,
// where the error value will be reassigned.
if !errors.Is(err, errNoAncestorFound) {
return 0, err
}
ancestor, err = d.findAncestorBinarySearch(p, mode, remoteHeight, floor)
if err != nil {
return 0, err
}
return ancestor, nil
}
func (d *Downloader) findAncestorSpanSearch(p *peerConnection, mode SyncMode, remoteHeight, localHeight uint64, floor int64) (commonAncestor uint64, err error) {
from, count, skip, max := calculateRequestSpan(remoteHeight, localHeight) from, count, skip, max := calculateRequestSpan(remoteHeight, localHeight)
p.log.Trace("Span searching for common ancestor", "count", count, "from", from, "skip", skip) p.log.Trace("Span searching for common ancestor", "count", count, "from", from, "skip", skip)
@ -894,6 +915,12 @@ func (d *Downloader) findAncestor(p *peerConnection, remoteHeader *types.Header)
p.log.Debug("Found common ancestor", "number", number, "hash", hash) p.log.Debug("Found common ancestor", "number", number, "hash", hash)
return number, nil return number, nil
} }
return 0, errNoAncestorFound
}
func (d *Downloader) findAncestorBinarySearch(p *peerConnection, mode SyncMode, remoteHeight uint64, floor int64) (commonAncestor uint64, err error) {
hash := common.Hash{}
// Ancestor not found, we need to binary search over our chain // Ancestor not found, we need to binary search over our chain
start, end := uint64(0), remoteHeight start, end := uint64(0), remoteHeight
if floor > 0 { if floor > 0 {