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authorFelföldi Zsolt <zsfelfoldi@gmail.com>2018-02-19 16:41:30 +0800
committerPéter Szilágyi <peterke@gmail.com>2018-02-19 16:41:30 +0800
commit1bdde620dad3c5fccb8e5de19fe7f42b1209a156 (patch)
tree952ec4a208b3ed2db4bde4487a0a368f6b7817a9 /les
parent06c5cae3158dfdd4c528ce17b6fc793f3198ee64 (diff)
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les: fix light fetcher database race (#16103)
* les: fix light fetcher database race * les: lightFetcher comments
Diffstat (limited to 'les')
-rw-r--r--les/fetcher.go30
1 files changed, 21 insertions, 9 deletions
diff --git a/les/fetcher.go b/les/fetcher.go
index 9d224176f..e12a2c78a 100644
--- a/les/fetcher.go
+++ b/les/fetcher.go
@@ -36,24 +36,26 @@ const (
maxNodeCount = 20 // maximum number of fetcherTreeNode entries remembered for each peer
)
-// lightFetcher
+// lightFetcher implements retrieval of newly announced headers. It also provides a peerHasBlock function for the
+// ODR system to ensure that we only request data related to a certain block from peers who have already processed
+// and announced that block.
type lightFetcher struct {
pm *ProtocolManager
odr *LesOdr
chain *light.LightChain
+ lock sync.Mutex // lock protects access to the fetcher's internal state variables except sent requests
maxConfirmedTd *big.Int
peers map[*peer]*fetcherPeerInfo
lastUpdateStats *updateStatsEntry
+ syncing bool
+ syncDone chan *peer
- lock sync.Mutex // qwerqwerqwe
- deliverChn chan fetchResponse
- reqMu sync.RWMutex
+ reqMu sync.RWMutex // reqMu protects access to sent header fetch requests
requested map[uint64]fetchRequest
+ deliverChn chan fetchResponse
timeoutChn chan uint64
requestChn chan bool // true if initiated from outside
- syncing bool
- syncDone chan *peer
}
// fetcherPeerInfo holds fetcher-specific information about each active peer
@@ -560,8 +562,13 @@ func (f *lightFetcher) checkAnnouncedHeaders(fp *fetcherPeerInfo, headers []*typ
return true
}
// we ran out of recently delivered headers but have not reached a node known by this peer yet, continue matching
- td = f.chain.GetTd(header.ParentHash, header.Number.Uint64()-1)
- header = f.chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
+ hash, number := header.ParentHash, header.Number.Uint64()-1
+ td = f.chain.GetTd(hash, number)
+ header = f.chain.GetHeader(hash, number)
+ if header == nil || td == nil {
+ log.Error("Missing parent of validated header", "hash", hash, "number", number)
+ return false
+ }
} else {
header = headers[i]
td = tds[i]
@@ -645,13 +652,18 @@ func (f *lightFetcher) checkKnownNode(p *peer, n *fetcherTreeNode) bool {
if td == nil {
return false
}
+ header := f.chain.GetHeader(n.hash, n.number)
+ // check the availability of both header and td because reads are not protected by chain db mutex
+ // Note: returning false is always safe here
+ if header == nil {
+ return false
+ }
fp := f.peers[p]
if fp == nil {
p.Log().Debug("Unknown peer to check known nodes")
return false
}
- header := f.chain.GetHeader(n.hash, n.number)
if !f.checkAnnouncedHeaders(fp, []*types.Header{header}, []*big.Int{td}) {
p.Log().Debug("Inconsistent announcement")
go f.pm.removePeer(p.id)