Non-atomic flushing using the blockchain as replay journal

This commit is contained in:
Pieter Wuille
2017-04-19 09:34:30 -07:00
parent b3a279cd58
commit 013a56aa1a
7 changed files with 186 additions and 16 deletions

View File

@@ -96,7 +96,7 @@ namespace {
struct CBlockIndexWorkComparator
{
bool operator()(CBlockIndex *pa, CBlockIndex *pb) const {
bool operator()(const CBlockIndex *pa, const CBlockIndex *pb) const {
// First sort by most total work, ...
if (pa->nChainWork > pb->nChainWork) return false;
if (pa->nChainWork < pb->nChainWork) return true;
@@ -1331,17 +1331,19 @@ int ApplyTxInUndo(Coin&& undo, CCoinsViewCache& view, const COutPoint& out)
return DISCONNECT_FAILED; // adding output for transaction without known metadata
}
}
view.AddCoin(out, std::move(undo), undo.fCoinBase);
// The potential_overwrite parameter to AddCoin is only allowed to be false if we know for
// sure that the coin did not already exist in the cache. As we have queried for that above
// using HaveCoin, we don't need to guess. When fClean is false, a coin already existed and
// it is an overwrite.
view.AddCoin(out, std::move(undo), !fClean);
return fClean ? DISCONNECT_OK : DISCONNECT_UNCLEAN;
}
/** Undo the effects of this block (with given index) on the UTXO set represented by coins.
* When UNCLEAN or FAILED is returned, view is left in an indeterminate state. */
* When FAILED is returned, view is left in an indeterminate state. */
static DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)
{
assert(pindex->GetBlockHash() == view.GetBestBlock());
bool fClean = true;
CBlockUndo blockUndo;
@@ -1946,6 +1948,7 @@ bool static DisconnectTip(CValidationState& state, const CChainParams& chainpara
int64_t nStart = GetTimeMicros();
{
CCoinsViewCache view(pcoinsTip);
assert(view.GetBestBlock() == pindexDelete->GetBlockHash());
if (DisconnectBlock(block, pindexDelete, view) != DISCONNECT_OK)
return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
bool flushed = view.Flush();
@@ -3417,20 +3420,26 @@ bool static LoadBlockIndexDB(const CChainParams& chainparams)
pblocktree->ReadFlag("txindex", fTxIndex);
LogPrintf("%s: transaction index %s\n", __func__, fTxIndex ? "enabled" : "disabled");
LoadChainTip(chainparams);
return true;
}
void LoadChainTip(const CChainParams& chainparams)
{
if (chainActive.Tip() && chainActive.Tip()->GetBlockHash() == pcoinsTip->GetBestBlock()) return;
// Load pointer to end of best chain
BlockMap::iterator it = mapBlockIndex.find(pcoinsTip->GetBestBlock());
if (it == mapBlockIndex.end())
return true;
return;
chainActive.SetTip(it->second);
PruneBlockIndexCandidates();
LogPrintf("%s: hashBestChain=%s height=%d date=%s progress=%f\n", __func__,
LogPrintf("Loaded best chain: hashBestChain=%s height=%d date=%s progress=%f\n",
chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(),
DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
GuessVerificationProgress(chainparams.TxData(), chainActive.Tip()));
return true;
}
CVerifyDB::CVerifyDB()
@@ -3499,6 +3508,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
}
// check level 3: check for inconsistencies during memory-only disconnect of tip blocks
if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
assert(coins.GetBestBlock() == pindex->GetBlockHash());
DisconnectResult res = DisconnectBlock(block, pindex, coins);
if (res == DISCONNECT_FAILED) {
return error("VerifyDB(): *** irrecoverable inconsistency in block data at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
@@ -3538,6 +3548,92 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
return true;
}
/** Apply the effects of a block on the utxo cache, ignoring that it may already have been applied. */
static bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params)
{
// TODO: merge with ConnectBlock
CBlock block;
if (!ReadBlockFromDisk(block, pindex, params.GetConsensus())) {
return error("ReplayBlock(): ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
}
for (const CTransactionRef& tx : block.vtx) {
if (!tx->IsCoinBase()) {
for (const CTxIn &txin : tx->vin) {
inputs.SpendCoin(txin.prevout);
}
}
// Pass check = true as every addition may be an overwrite.
AddCoins(inputs, *tx, pindex->nHeight, true);
}
return true;
}
bool ReplayBlocks(const CChainParams& params, CCoinsView* view)
{
LOCK(cs_main);
CCoinsViewCache cache(view);
std::vector<uint256> hashHeads = view->GetHeadBlocks();
if (hashHeads.empty()) return true; // We're already in a consistent state.
if (hashHeads.size() != 2) return error("ReplayBlocks(): unknown inconsistent state");
uiInterface.ShowProgress(_("Replaying blocks..."), 0);
LogPrintf("Replaying blocks\n");
const CBlockIndex* pindexOld = nullptr; // Old tip during the interrupted flush.
const CBlockIndex* pindexNew; // New tip during the interrupted flush.
const CBlockIndex* pindexFork = nullptr; // Latest block common to both the old and the new tip.
if (mapBlockIndex.count(hashHeads[0]) == 0) {
return error("ReplayBlocks(): reorganization to unknown block requested");
}
pindexNew = mapBlockIndex[hashHeads[0]];
if (!hashHeads[1].IsNull()) { // The old tip is allowed to be 0, indicating it's the first flush.
if (mapBlockIndex.count(hashHeads[1]) == 0) {
return error("ReplayBlocks(): reorganization from unknown block requested");
}
pindexOld = mapBlockIndex[hashHeads[1]];
pindexFork = LastCommonAncestor(pindexOld, pindexNew);
assert(pindexFork != nullptr);
}
// Rollback along the old branch.
while (pindexOld != pindexFork) {
if (pindexOld->nHeight > 0) { // Never disconnect the genesis block.
CBlock block;
if (!ReadBlockFromDisk(block, pindexOld, params.GetConsensus())) {
return error("RollbackBlock(): ReadBlockFromDisk() failed at %d, hash=%s", pindexOld->nHeight, pindexOld->GetBlockHash().ToString());
}
LogPrintf("Rolling back %s (%i)\n", pindexOld->GetBlockHash().ToString(), pindexOld->nHeight);
DisconnectResult res = DisconnectBlock(block, pindexOld, cache);
if (res == DISCONNECT_FAILED) {
return error("RollbackBlock(): DisconnectBlock failed at %d, hash=%s", pindexOld->nHeight, pindexOld->GetBlockHash().ToString());
}
// If DISCONNECT_UNCLEAN is returned, it means a non-existing UTXO was deleted, or an existing UTXO was
// overwritten. It corresponds to cases where the block-to-be-disconnect never had all its operations
// applied to the UTXO set. However, as both writing a UTXO and deleting a UTXO are idempotent operations,
// the result is still a version of the UTXO set with the effects of that block undone.
}
pindexOld = pindexOld->pprev;
}
// Roll forward from the forking point to the new tip.
int nForkHeight = pindexFork ? pindexFork->nHeight : 0;
for (int nHeight = nForkHeight + 1; nHeight <= pindexNew->nHeight; ++nHeight) {
const CBlockIndex* pindex = pindexNew->GetAncestor(nHeight);
LogPrintf("Rolling forward %s (%i)\n", pindex->GetBlockHash().ToString(), nHeight);
if (!RollforwardBlock(pindex, cache, params)) return false;
}
cache.SetBestBlock(pindexNew->GetBlockHash());
cache.Flush();
uiInterface.ShowProgress("", 100);
return true;
}
bool RewindBlockIndex(const CChainParams& params)
{
LOCK(cs_main);