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Add rewind logic to deal with post-fork software updates

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Includes logic for dealing with pruning by Suhas Daftuar.
This commit is contained in:
Pieter Wuille 2016-03-18 17:20:12 +01:00
parent b7dbeb24eb
commit 6032f6930a
4 changed files with 124 additions and 17 deletions
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2
src/chain.h
View file

@ -144,6 +144,8 @@ enum BlockStatus: uint32_t {
BLOCK_FAILED_VALID = 32, //! stage after last reached validness failed
BLOCK_FAILED_CHILD = 64, //! descends from failed block
BLOCK_FAILED_MASK = BLOCK_FAILED_VALID | BLOCK_FAILED_CHILD,
BLOCK_OPT_WITNESS = 128, //! block data in blk*.data was received with a witness-enforcing client
};
/** The block chain is a tree shaped structure starting with the

8
src/init.cpp
View file

@ -1284,6 +1284,14 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
break;
}
if (!fReindex) {
uiInterface.InitMessage(_("Rewinding blocks..."));
if (!RewindBlockIndex(chainparams)) {
strLoadError = _("Unable to rewind the database to a pre-fork state. You will need to redownload the blockchain");
break;
}
}
uiInterface.InitMessage(_("Verifying blocks..."));
if (fHavePruned && GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) > MIN_BLOCKS_TO_KEEP) {
LogPrintf("Prune: pruned datadir may not have more than %d blocks; only checking available blocks",

96
src/main.cpp
View file

@ -658,6 +658,9 @@ CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& loc
CBlockIndex* pindex = (*mi).second;
if (chain.Contains(pindex))
return pindex;
if (pindex->GetAncestor(chain.Height()) == chain.Tip()) {
return chain.Tip();
}
}
}
return chain.Genesis();
@ -2777,7 +2780,7 @@ void static UpdateTip(CBlockIndex *pindexNew, const CChainParams& chainParams) {
}
/** Disconnect chainActive's tip. You probably want to call mempool.removeForReorg and manually re-limit mempool size after this, with cs_main held. */
bool static DisconnectTip(CValidationState& state, const CChainParams& chainparams)
bool static DisconnectTip(CValidationState& state, const CChainParams& chainparams, bool fBare = false)
{
CBlockIndex *pindexDelete = chainActive.Tip();
assert(pindexDelete);
@ -2797,6 +2800,8 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
// Write the chain state to disk, if necessary.
if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
return false;
if (!fBare) {
// Resurrect mempool transactions from the disconnected block.
std::vector<uint256> vHashUpdate;
BOOST_FOREACH(const CTransaction &tx, block.vtx) {
@ -2815,6 +2820,8 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
// UpdateTransactionsFromBlock finds descendants of any transactions in this
// block that were added back and cleans up the mempool state.
mempool.UpdateTransactionsFromBlock(vHashUpdate);
}
// Update chainActive and related variables.
UpdateTip(pindexDelete->pprev, chainparams);
// Let wallets know transactions went from 1-confirmed to
@ -3266,6 +3273,9 @@ bool ReceivedBlockTransactions(const CBlock &block, CValidationState& state, CBl
pindexNew->nDataPos = pos.nPos;
pindexNew->nUndoPos = 0;
pindexNew->nStatus |= BLOCK_HAVE_DATA;
if (IsWitnessEnabled(pindexNew->pprev, Params().GetConsensus())) {
pindexNew->nStatus |= BLOCK_OPT_WITNESS;
}
pindexNew->RaiseValidity(BLOCK_VALID_TRANSACTIONS);
setDirtyBlockIndex.insert(pindexNew);
@ -4214,6 +4224,90 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
return true;
}
bool RewindBlockIndex(const CChainParams& params)
{
LOCK(cs_main);
int nHeight = 1;
while (nHeight <= chainActive.Height()) {
if (IsWitnessEnabled(chainActive[nHeight - 1], params.GetConsensus()) && !(chainActive[nHeight]->nStatus & BLOCK_OPT_WITNESS)) {
break;
}
nHeight++;
}
// nHeight is now the height of the first insufficiently-validated block, or tipheight + 1
CValidationState state;
CBlockIndex* pindex = chainActive.Tip();
while (chainActive.Height() >= nHeight) {
if (fPruneMode && !(chainActive.Tip()->nStatus & BLOCK_HAVE_DATA)) {
// If pruning, don't try rewinding past the HAVE_DATA point;
// since older blocks can't be served anyway, there's
// no need to walk further, and trying to DisconnectTip()
// will fail (and require a needless reindex/redownload
// of the blockchain).
break;
}
if (!DisconnectTip(state, params, true)) {
return error("RewindBlockIndex: unable to disconnect block at height %i", pindex->nHeight);
}
// Occasionally flush state to disk.
if (!FlushStateToDisk(state, FLUSH_STATE_PERIODIC))
return false;
}
// Reduce validity flag and have-data flags.
// We do this after actual disconnecting, otherwise we'll end up writing the lack of data
// to disk before writing the chainstate, resulting in a failure to continue if interrupted.
for (BlockMap::iterator it = mapBlockIndex.begin(); it != mapBlockIndex.end(); it++) {
CBlockIndex* pindexIter = it->second;
// Note: If we encounter an insufficiently validated block that
// is on chainActive, it must be because we are a pruning node, and
// this block or some successor doesn't HAVE_DATA, so we were unable to
// rewind all the way. Blocks remaining on chainActive at this point
// must not have their validity reduced.
if (IsWitnessEnabled(pindexIter->pprev, params.GetConsensus()) && !(pindexIter->nStatus & BLOCK_OPT_WITNESS) && !chainActive.Contains(pindexIter)) {
// Reduce validity
pindexIter->nStatus = std::min<unsigned int>(pindexIter->nStatus & BLOCK_VALID_MASK, BLOCK_VALID_TREE) | (pindexIter->nStatus & ~BLOCK_VALID_MASK);
// Remove have-data flags.
pindexIter->nStatus &= ~(BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO);
// Remove storage location.
pindexIter->nFile = 0;
pindexIter->nDataPos = 0;
pindexIter->nUndoPos = 0;
// Remove various other things
pindexIter->nTx = 0;
pindexIter->nChainTx = 0;
pindexIter->nSequenceId = 0;
// Make sure it gets written.
setDirtyBlockIndex.insert(pindexIter);
// Update indexes
setBlockIndexCandidates.erase(pindexIter);
std::pair<std::multimap<CBlockIndex*, CBlockIndex*>::iterator, std::multimap<CBlockIndex*, CBlockIndex*>::iterator> ret = mapBlocksUnlinked.equal_range(pindexIter->pprev);
while (ret.first != ret.second) {
if (ret.first->second == pindexIter) {
mapBlocksUnlinked.erase(ret.first++);
} else {
++ret.first;
}
}
} else if (pindexIter->IsValid(BLOCK_VALID_TRANSACTIONS) && pindexIter->nChainTx) {
setBlockIndexCandidates.insert(pindexIter);
}
}
PruneBlockIndexCandidates();
CheckBlockIndex(params.GetConsensus());
if (!FlushStateToDisk(state, FLUSH_STATE_ALWAYS)) {
return false;
}
return true;
}
void UnloadBlockIndex()
{
LOCK(cs_main);

3
src/main.h
View file

@ -459,6 +459,9 @@ bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams,
/** Check whether witness commitments are required for block. */
bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& params);
/** When there are blocks in the active chain with missing data, rewind the chainstate and remove them from the block index */
bool RewindBlockIndex(const CChainParams& params);
/** Update uncommitted block structures (currently: only the witness nonce). This is safe for submitted blocks. */
void UpdateUncommittedBlockStructures(CBlock& block, const CBlockIndex* pindexPrev, const Consensus::Params& consensusParams);