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eth/downloader: prevent pivot moves after state commit (#28126)

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Péter Szilágyi 2023-09-15 15:06:25 +03:00 committed by GitHub
parent 48fdb79de5
commit 4fa3db49a1
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1 changed files with 26 additions and 11 deletions
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31
eth/downloader/downloader.go
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@ -1606,17 +1606,30 @@ func (d *Downloader) processSnapSyncContent() error {
// To cater for moving pivot points, track the pivot block and subsequently
// accumulated download results separately.
//
// These will be nil up to the point where we reach the pivot, and will only
// be set temporarily if the synced blocks are piling up, but the pivot is
// still busy downloading. In that case, we need to occasionally check for
// pivot moves, so need to unblock the loop. These fields will accumulate
// the results in the meantime.
//
// Note, there's no issue with memory piling up since after 64 blocks the
// pivot will forcefully move so these accumulators will be dropped.
var (
oldPivot *fetchResult // Locked in pivot block, might change eventually
oldTail []*fetchResult // Downloaded content after the pivot
)
for {
// Wait for the next batch of downloaded data to be available, and if the pivot
// block became stale, move the goalpost
results := d.queue.Results(oldPivot == nil) // Block if we're not monitoring pivot staleness
// Wait for the next batch of downloaded data to be available. If we have
// not yet reached the pivot point, wait blockingly as there's no need to
// spin-loop check for pivot moves. If we reached the pivot but have not
// yet processed it, check for results async, so we might notice pivot
// moves while state syncing. If the pivot was passed fully, block again
// as there's no more reason to check for pivot moves at all.
results := d.queue.Results(oldPivot == nil)
if len(results) == 0 {
// If pivot sync is done, stop
if oldPivot == nil {
if d.committed.Load() {
d.reportSnapSyncProgress(true)
return sync.Cancel()
}
@ -1639,21 +1652,23 @@ func (d *Downloader) processSnapSyncContent() error {
pivot := d.pivotHeader
d.pivotLock.RUnlock()
if oldPivot == nil {
if pivot.Root != sync.root {
if oldPivot == nil { // no results piling up, we can move the pivot
if !d.committed.Load() { // not yet passed the pivot, we can move the pivot
if pivot.Root != sync.root { // pivot position changed, we can move the pivot
sync.Cancel()
sync = d.syncState(pivot.Root)
go closeOnErr(sync)
}
} else {
}
} else { // results already piled up, consume before handling pivot move
results = append(append([]*fetchResult{oldPivot}, oldTail...), results...)
}
// Split around the pivot block and process the two sides via snap/full sync
if !d.committed.Load() {
latest := results[len(results)-1].Header
// If the height is above the pivot block by 2 sets, it means the pivot
// become stale in the network and it was garbage collected, move to a
// become stale in the network, and it was garbage collected, move to a
// new pivot.
//
// Note, we have `reorgProtHeaderDelay` number of blocks withheld, Those