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Allow block announcements with headers

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This replaces using inv messages to announce new blocks, when a peer requests
(via the new "sendheaders" message) that blocks be announced with headers
instead of inv's.

Since headers-first was introduced, peers send getheaders messages in response
to an inv, which requires generating a block locator that is large compared to
the size of the header being requested, and requires an extra round-trip before
a reorg can be relayed.  Save time by tracking headers that a peer is likely to
know about, and send a headers chain that would connect to a peer's known
headers, unless the chain would be too big, in which case we revert to sending
an inv instead.

Based off of @sipa's commit to announce all blocks in a reorg via inv,
which has been squashed into this commit.

Rebased-by: Pieter Wuille
This commit is contained in:
Suhas Daftuar
2014-11-18 22:16:32 +01:00
committed by Pieter Wuille
parent c894fbbb1d
commit 50262d8953
8 changed files with 781 additions and 14 deletions
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223
src/main.cpp
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@@ -247,6 +247,8 @@ struct CNodeState {
uint256 hashLastUnknownBlock;
//! The last full block we both have.
CBlockIndex *pindexLastCommonBlock;
//! The best header we have sent our peer.
CBlockIndex *pindexBestHeaderSent;
//! Whether we've started headers synchronization with this peer.
bool fSyncStarted;
//! Since when we're stalling block download progress (in microseconds), or 0.
@@ -256,6 +258,8 @@ struct CNodeState {
int nBlocksInFlightValidHeaders;
//! Whether we consider this a preferred download peer.
bool fPreferredDownload;
//! Whether this peer wants invs or headers (when possible) for block announcements.
bool fPreferHeaders;
CNodeState() {
fCurrentlyConnected = false;
@@ -264,11 +268,13 @@ struct CNodeState {
pindexBestKnownBlock = NULL;
hashLastUnknownBlock.SetNull();
pindexLastCommonBlock = NULL;
pindexBestHeaderSent = NULL;
fSyncStarted = false;
nStallingSince = 0;
nBlocksInFlight = 0;
nBlocksInFlightValidHeaders = 0;
fPreferredDownload = false;
fPreferHeaders = false;
}
};
@@ -398,6 +404,22 @@ void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
}
}
// Requires cs_main
bool CanDirectFetch(const Consensus::Params &consensusParams)
{
return chainActive.Tip()->GetBlockTime() > GetAdjustedTime() - consensusParams.nPowTargetSpacing * 20;
}
// Requires cs_main
bool PeerHasHeader(CNodeState *state, CBlockIndex *pindex)
{
if (state->pindexBestKnownBlock && pindex == state->pindexBestKnownBlock->GetAncestor(pindex->nHeight))
return true;
if (state->pindexBestHeaderSent && pindex == state->pindexBestHeaderSent->GetAncestor(pindex->nHeight))
return true;
return false;
}
/** Find the last common ancestor two blocks have.
* Both pa and pb must be non-NULL. */
CBlockIndex* LastCommonAncestor(CBlockIndex* pa, CBlockIndex* pb) {
@@ -2557,16 +2579,17 @@ static bool ActivateBestChainStep(CValidationState& state, const CChainParams& c
* or an activated best chain. pblock is either NULL or a pointer to a block
* that is already loaded (to avoid loading it again from disk).
*/
bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams, const CBlock* pblock)
{
CBlockIndex *pindexNewTip = NULL;
bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, const CBlock *pblock) {
CBlockIndex *pindexMostWork = NULL;
do {
boost::this_thread::interruption_point();
CBlockIndex *pindexNewTip = NULL;
const CBlockIndex *pindexFork;
bool fInitialDownload;
{
LOCK(cs_main);
CBlockIndex *pindexOldTip = chainActive.Tip();
pindexMostWork = FindMostWorkChain();
// Whether we have anything to do at all.
@@ -2577,26 +2600,44 @@ bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams,
return false;
pindexNewTip = chainActive.Tip();
pindexFork = chainActive.FindFork(pindexOldTip);
fInitialDownload = IsInitialBlockDownload();
}
// When we reach this point, we switched to a new tip (stored in pindexNewTip).
// Notifications/callbacks that can run without cs_main
if (!fInitialDownload) {
uint256 hashNewTip = pindexNewTip->GetBlockHash();
// Find the hashes of all blocks that weren't previously in the best chain.
std::vector<uint256> vHashes;
CBlockIndex *pindexToAnnounce = pindexNewTip;
while (pindexToAnnounce != pindexFork) {
vHashes.push_back(pindexToAnnounce->GetBlockHash());
pindexToAnnounce = pindexToAnnounce->pprev;
if (vHashes.size() == MAX_BLOCKS_TO_ANNOUNCE) {
// Limit announcements in case of a huge reorganization.
// Rely on the peer's synchronization mechanism in that case.
break;
}
}
// Relay inventory, but don't relay old inventory during initial block download.
int nBlockEstimate = 0;
if (fCheckpointsEnabled)
nBlockEstimate = Checkpoints::GetTotalBlocksEstimate(chainparams.Checkpoints());
{
LOCK(cs_vNodes);
BOOST_FOREACH(CNode* pnode, vNodes)
if (chainActive.Height() > (pnode->nStartingHeight != -1 ? pnode->nStartingHeight - 2000 : nBlockEstimate))
pnode->PushInventory(CInv(MSG_BLOCK, hashNewTip));
BOOST_FOREACH(CNode* pnode, vNodes) {
if (chainActive.Height() > (pnode->nStartingHeight != -1 ? pnode->nStartingHeight - 2000 : nBlockEstimate)) {
BOOST_REVERSE_FOREACH(const uint256& hash, vHashes) {
pnode->PushBlockHash(hash);
}
}
}
}
// Notify external listeners about the new tip.
GetMainSignals().UpdatedBlockTip(pindexNewTip);
uiInterface.NotifyBlockTip(hashNewTip);
if (!vHashes.empty()) {
GetMainSignals().UpdatedBlockTip(pindexNewTip);
uiInterface.NotifyBlockTip(vHashes.front());
}
}
} while(pindexMostWork != chainActive.Tip());
CheckBlockIndex(chainparams.GetConsensus());
@@ -4333,6 +4374,14 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
LOCK(cs_main);
State(pfrom->GetId())->fCurrentlyConnected = true;
}
if (pfrom->nVersion >= SENDHEADERS_VERSION) {
// Tell our peer we prefer to receive headers rather than inv's
// We send this to non-NODE NETWORK peers as well, because even
// non-NODE NETWORK peers can announce blocks (such as pruning
// nodes)
pfrom->PushMessage("sendheaders");
}
}
@@ -4402,6 +4451,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
pfrom->fDisconnect = true;
}
else if (strCommand == "sendheaders")
{
LOCK(cs_main);
State(pfrom->GetId())->fPreferHeaders = true;
}
else if (strCommand == "inv")
{
@@ -4446,7 +4501,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
// not a direct successor.
pfrom->PushMessage("getheaders", chainActive.GetLocator(pindexBestHeader), inv.hash);
CNodeState *nodestate = State(pfrom->GetId());
if (chainActive.Tip()->GetBlockTime() > GetAdjustedTime() - chainparams.GetConsensus().nPowTargetSpacing * 20 &&
if (CanDirectFetch(chainparams.GetConsensus()) &&
nodestate->nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
vToFetch.push_back(inv);
// Mark block as in flight already, even though the actual "getdata" message only goes out
@@ -4554,6 +4609,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
LogPrint("net", "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom->id);
return true;
}
CNodeState *nodestate = State(pfrom->GetId());
CBlockIndex* pindex = NULL;
if (locator.IsNull())
{
@@ -4581,6 +4638,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
if (--nLimit <= 0 || pindex->GetBlockHash() == hashStop)
break;
}
// pindex can be NULL either if we sent chainActive.Tip() OR
// if our peer has chainActive.Tip() (and thus we are sending an empty
// headers message). In both cases it's safe to update
// pindexBestHeaderSent to be our tip.
nodestate->pindexBestHeaderSent = pindex ? pindex : chainActive.Tip();
pfrom->PushMessage("headers", vHeaders);
}
@@ -4772,6 +4834,53 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
pfrom->PushMessage("getheaders", chainActive.GetLocator(pindexLast), uint256());
}
bool fCanDirectFetch = CanDirectFetch(chainparams.GetConsensus());
CNodeState *nodestate = State(pfrom->GetId());
// If this set of headers is valid and ends in a block with at least as
// much work as our tip, download as much as possible.
if (fCanDirectFetch && pindexLast->IsValid(BLOCK_VALID_TREE) && chainActive.Tip()->nChainWork <= pindexLast->nChainWork) {
vector<CBlockIndex *> vToFetch;
CBlockIndex *pindexWalk = pindexLast;
// Calculate all the blocks we'd need to switch to pindexLast, up to a limit.
while (pindexWalk && !chainActive.Contains(pindexWalk) && vToFetch.size() <= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
if (!(pindexWalk->nStatus & BLOCK_HAVE_DATA) &&
!mapBlocksInFlight.count(pindexWalk->GetBlockHash())) {
// We don't have this block, and it's not yet in flight.
vToFetch.push_back(pindexWalk);
}
pindexWalk = pindexWalk->pprev;
}
// If pindexWalk still isn't on our main chain, we're looking at a
// very large reorg at a time we think we're close to caught up to
// the main chain -- this shouldn't really happen. Bail out on the
// direct fetch and rely on parallel download instead.
if (!chainActive.Contains(pindexWalk)) {
LogPrint("net", "Large reorg, won't direct fetch to %s (%d)\n",
pindexLast->GetBlockHash().ToString(),
pindexLast->nHeight);
} else {
vector<CInv> vGetData;
// Download as much as possible, from earliest to latest.
BOOST_REVERSE_FOREACH(CBlockIndex *pindex, vToFetch) {
if (nodestate->nBlocksInFlight >= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
// Can't download any more from this peer
break;
}
vGetData.push_back(CInv(MSG_BLOCK, pindex->GetBlockHash()));
MarkBlockAsInFlight(pfrom->GetId(), pindex->GetBlockHash(), chainparams.GetConsensus(), pindex);
LogPrint("net", "Requesting block %s from peer=%d\n",
pindex->GetBlockHash().ToString(), pfrom->id);
}
if (vGetData.size() > 1) {
LogPrint("net", "Downloading blocks toward %s (%d) via headers direct fetch\n",
pindexLast->GetBlockHash().ToString(), pindexLast->nHeight);
}
if (vGetData.size() > 0) {
pfrom->PushMessage("getdata", vGetData);
}
}
}
CheckBlockIndex(chainparams.GetConsensus());
}
@@ -5297,6 +5406,100 @@ bool SendMessages(CNode* pto, bool fSendTrickle)
GetMainSignals().Broadcast(nTimeBestReceived);
}
//
// Try sending block announcements via headers
//
{
// If we have less than MAX_BLOCKS_TO_ANNOUNCE in our
// list of block hashes we're relaying, and our peer wants
// headers announcements, then find the first header
// not yet known to our peer but would connect, and send.
// If no header would connect, or if we have too many
// blocks, or if the peer doesn't want headers, just
// add all to the inv queue.
LOCK(pto->cs_inventory);
vector<CBlock> vHeaders;
bool fRevertToInv = (!state.fPreferHeaders || pto->vBlockHashesToAnnounce.size() > MAX_BLOCKS_TO_ANNOUNCE);
CBlockIndex *pBestIndex = NULL; // last header queued for delivery
ProcessBlockAvailability(pto->id); // ensure pindexBestKnownBlock is up-to-date
if (!fRevertToInv) {
bool fFoundStartingHeader = false;
// Try to find first header that our peer doesn't have, and
// then send all headers past that one. If we come across any
// headers that aren't on chainActive, give up.
BOOST_FOREACH(const uint256 &hash, pto->vBlockHashesToAnnounce) {
BlockMap::iterator mi = mapBlockIndex.find(hash);
assert(mi != mapBlockIndex.end());
CBlockIndex *pindex = mi->second;
if (chainActive[pindex->nHeight] != pindex) {
// Bail out if we reorged away from this block
fRevertToInv = true;
break;
}
assert(pBestIndex == NULL || pindex->pprev == pBestIndex);
pBestIndex = pindex;
if (fFoundStartingHeader) {
// add this to the headers message
vHeaders.push_back(pindex->GetBlockHeader());
} else if (PeerHasHeader(&state, pindex)) {
continue; // keep looking for the first new block
} else if (pindex->pprev == NULL || PeerHasHeader(&state, pindex->pprev)) {
// Peer doesn't have this header but they do have the prior one.
// Start sending headers.
fFoundStartingHeader = true;
vHeaders.push_back(pindex->GetBlockHeader());
} else {
// Peer doesn't have this header or the prior one -- nothing will
// connect, so bail out.
fRevertToInv = true;
break;
}
}
}
if (fRevertToInv) {
// If falling back to using an inv, just try to inv the tip.
// The last entry in vBlockHashesToAnnounce was our tip at some point
// in the past.
if (!pto->vBlockHashesToAnnounce.empty()) {
const uint256 &hashToAnnounce = pto->vBlockHashesToAnnounce.back();
BlockMap::iterator mi = mapBlockIndex.find(hashToAnnounce);
assert(mi != mapBlockIndex.end());
CBlockIndex *pindex = mi->second;
// Warn if we're announcing a block that is not on the main chain.
// This should be very rare and could be optimized out.
// Just log for now.
if (chainActive[pindex->nHeight] != pindex) {
LogPrint("net", "Announcing block %s not on main chain (tip=%s)\n",
hashToAnnounce.ToString(), chainActive.Tip()->GetBlockHash().ToString());
}
// If the peer announced this block to us, don't inv it back.
// (Since block announcements may not be via inv's, we can't solely rely on
// setInventoryKnown to track this.)
if (!PeerHasHeader(&state, pindex)) {
pto->PushInventory(CInv(MSG_BLOCK, hashToAnnounce));
LogPrint("net", "%s: sending inv peer=%d hash=%s\n", __func__,
pto->id, hashToAnnounce.ToString());
}
}
} else if (!vHeaders.empty()) {
if (vHeaders.size() > 1) {
LogPrint("net", "%s: %u headers, range (%s, %s), to peer=%d\n", __func__,
vHeaders.size(),
vHeaders.front().GetHash().ToString(),
vHeaders.back().GetHash().ToString(), pto->id);
} else {
LogPrint("net", "%s: sending header %s to peer=%d\n", __func__,
vHeaders.front().GetHash().ToString(), pto->id);
}
pto->PushMessage("headers", vHeaders);
state.pindexBestHeaderSent = pBestIndex;
}
pto->vBlockHashesToAnnounce.clear();
}
//
// Message: inventory
//