bool InitializeAccumulators(const int nHeight, int& nHeightCheckpoint, AccumulatorMap& mapAccumulators)
{
if (nHeight < Params().Zerocoin_StartHeight())
return error("%s: height is below zerocoin activated", __func__);
//On a specific block, a recalculation of the accumulators will be forced
if (nHeight == Params().Zerocoin_Block_RecalculateAccumulators() && Params().NetworkID() != CBaseChainParams::REGTEST) {
mapAccumulators.Reset();
if (!mapAccumulators.Load(chainActive[Params().Zerocoin_Block_LastGoodCheckpoint()]->nAccumulatorCheckpoint))
return error("%s: failed to reset to previous checkpoint when recalculating accumulators", __func__);
// Erase the checkpoints from the period of time that bad mints were being made
if (!EraseCheckpoints(Params().Zerocoin_Block_LastGoodCheckpoint() + 1, nHeight))
return error("%s : failed to erase Checkpoints while recalculating checkpoints", __func__);
nHeightCheckpoint = Params().Zerocoin_Block_LastGoodCheckpoint();
return true;
}
if (nHeight >= Params().Zerocoin_Block_V2_Start()) {
//after v2_start, accumulators need to use v2 params
mapAccumulators.Reset(Params().Zerocoin_Params(false));
// 20 after v2 start is when the new checkpoints will be in the block, so don't need to load hard checkpoints
if (nHeight <= Params().Zerocoin_Block_V2_Start() + 20 && Params().NetworkID() != CBaseChainParams::REGTEST) {
//Load hard coded checkpointed value
AccumulatorCheckpoints::Checkpoint checkpoint = AccumulatorCheckpoints::GetClosestCheckpoint(nHeight,
nHeightCheckpoint);
if (nHeightCheckpoint < 0)
return error("%s: failed to load hard-checkpoint for block %s", __func__, nHeight);
mapAccumulators.Load(checkpoint);
return true;
}
}
//Use the previous block's checkpoint to initialize the accumulator's state
uint256 nCheckpointPrev = chainActive[nHeight - 1]->nAccumulatorCheckpoint;
if (nCheckpointPrev == 0)
mapAccumulators.Reset();
else if (!mapAccumulators.Load(nCheckpointPrev))
return error("%s: failed to reset to previous checkpoint", __func__);
nHeightCheckpoint = nHeight;
return true;
}
//Get checkpoint value for a specific block height
bool CalculateAccumulatorCheckpoint(int nHeight, uint256& nCheckpoint)
{
if (nHeight < Params().Zerocoin_StartHeight()) {
nCheckpoint = 0;
return true;
}
//the checkpoint is updated every ten blocks, return current active checkpoint if not update block
if (nHeight % 10 != 0) {
nCheckpoint = chainActive[nHeight - 1]->nAccumulatorCheckpoint;
return true;
}
//set the accumulators to last checkpoint value
AccumulatorMap mapAccumulators;
if (!mapAccumulators.Load(chainActive[nHeight - 1]->nAccumulatorCheckpoint)) {
if (chainActive[nHeight - 1]->nAccumulatorCheckpoint == 0) {
//Before zerocoin is fully activated so set to init state
mapAccumulators.Reset();
} else {
LogPrintf("%s: failed to reset to previous checkpoint\n", __func__);
return false;
}
}
//Whether this should filter out invalid/fraudulent outpoints
bool fFilterInvalid = nHeight >= Params().Zerocoin_Block_RecalculateAccumulators();
//Accumulate all coins over the last ten blocks that havent been accumulated (height - 20 through height - 11)
int nTotalMintsFound = 0;
CBlockIndex *pindex = chainActive[nHeight - 20];
//On a specific block, a recalculation of the accumulators will be forced
if (nHeight == Params().Zerocoin_Block_RecalculateAccumulators()) {
pindex = chainActive[Params().Zerocoin_Block_LastGoodCheckpoint() - 10];
mapAccumulators.Reset();
if (!mapAccumulators.Load(chainActive[Params().Zerocoin_Block_LastGoodCheckpoint()]->nAccumulatorCheckpoint)) {
LogPrintf("%s: failed to reset to previous checkpoint when recalculating accumulators\n", __func__);
return false;
}
LogPrintf("*** %s recalculating checkpoint\n", __func__);
// Erase the checkpoints from the period of time that bad mints were being made
if (!EraseCheckpoints(Params().Zerocoin_Block_LastGoodCheckpoint() + 1, nHeight)) {
LogPrintf("%s : failed to erase Checkpoints while recalculating checkpoints\n", __func__);
return false;
}
}
while (pindex->nHeight < nHeight - 10) {
// checking whether we should stop this process due to a shutdown request
if (ShutdownRequested()) {
return false;
}
//make sure this block is eligible for accumulation
if (pindex->nHeight < Params().Zerocoin_StartHeight()) {
pindex = chainActive[pindex->nHeight + 1];
continue;
}
//grab mints from this block
CBlock block;
if(!ReadBlockFromDisk(block, pindex)) {
LogPrint("zero","%s: failed to read block from disk\n", __func__);
return false;
}
std::list<PublicCoin> listPubcoins;
if (!BlockToPubcoinList(block, listPubcoins, fFilterInvalid)) {
LogPrint("zero","%s: failed to get zerocoin mintlist from block %n\n", __func__, pindex->nHeight);
return false;
}
nTotalMintsFound += listPubcoins.size();
LogPrint("zero", "%s found %d mints\n", __func__, listPubcoins.size());
//add the pubcoins to accumulator
for (const PublicCoin pubcoin : listPubcoins) {
if(!mapAccumulators.Accumulate(pubcoin, true)) {
LogPrintf("%s: failed to add pubcoin to accumulator at height %n\n", __func__, pindex->nHeight);
return false;
}
}
pindex = chainActive.Next(pindex);
}
// if there were no new mints found, the accumulator checkpoint will be the same as the last checkpoint
if (nTotalMintsFound == 0) {
nCheckpoint = chainActive[nHeight - 1]->nAccumulatorCheckpoint;
}
else
nCheckpoint = mapAccumulators.GetCheckpoint();
// make sure that these values are databased because reorgs may have deleted the checksums from DB
DatabaseChecksums(mapAccumulators);
LogPrint("zero", "%s checkpoint=%s\n", __func__, nCheckpoint.GetHex());
return true;
}
bool GenerateAccumulatorWitness(CoinWitnessData* coinWitness, AccumulatorMap& mapAccumulators, CBlockIndex* pindexCheckpoint)
{
try {
// Lock
LogPrint("zero", "%s: generating\n", __func__);
if (!LockMethod()) return false;
LogPrint("zero", "%s: after lock\n", __func__);
int64_t nTimeStart = GetTimeMicros();
//If there is a Acc End height filled in, then this has already been partially accumulated.
if (!coinWitness->nHeightAccEnd) {
LogPrintf("RESET ACC\n");
coinWitness->pAccumulator = std::unique_ptr<Accumulator>(new Accumulator(Params().Zerocoin_Params(false), coinWitness->denom));
coinWitness->pWitness = std::unique_ptr<AccumulatorWitness>(new AccumulatorWitness(Params().Zerocoin_Params(false), *coinWitness->pAccumulator, *coinWitness->coin));
}
// Mint added height
coinWitness->SetHeightMintAdded(SearchMintHeightOf(coinWitness->coin->getValue()));
// Set the initial state of the witness accumulator for this coin.
CBigNum bnAccValue = 0;
if (!coinWitness->nHeightAccEnd && GetAccumulatorValue(coinWitness->nHeightCheckpoint, coinWitness->coin->getDenomination(), bnAccValue)) {
libzerocoin::Accumulator witnessAccumulator(Params().Zerocoin_Params(false), coinWitness->denom, bnAccValue);
coinWitness->pAccumulator->setValue(witnessAccumulator.getValue());
}
//add the pubcoins from the blockchain up to the next checksum starting from the block
int nChainHeight = chainActive.Height();
int nHeightMax = nChainHeight % 10;
nHeightMax = nChainHeight - nHeightMax - 20; // at least two checkpoints deep
// Determine the height to stop at
int nHeightStop;
if (pindexCheckpoint) {
nHeightStop = pindexCheckpoint->nHeight - 10;
nHeightStop -= nHeightStop % 10;
LogPrint("zero", "%s: using checkpoint height %d\n", __func__, pindexCheckpoint->nHeight);
} else {
nHeightStop = nHeightMax;
}
if (nHeightStop > coinWitness->nHeightAccEnd)
AccumulateRange(coinWitness, nHeightStop - 1);
mapAccumulators.Load(chainActive[nHeightStop + 10]->nAccumulatorCheckpoint);
coinWitness->pWitness->resetValue(*coinWitness->pAccumulator, *coinWitness->coin);
if(!coinWitness->pWitness->VerifyWitness(mapAccumulators.GetAccumulator(coinWitness->denom), *coinWitness->coin))
return error("%s: failed to verify witness", __func__);
// A certain amount of accumulated coins are required
if (coinWitness->nMintsAdded < Params().Zerocoin_RequiredAccumulation())
return error("%s : Less than %d mints added, unable to create spend. %s", __func__, Params().Zerocoin_RequiredAccumulation(), coinWitness->ToString());
// calculate how many mints of this denomination existed in the accumulator we initialized
coinWitness->nMintsAdded += ComputeAccumulatedCoins(coinWitness->nHeightAccStart, coinWitness->denom);
LogPrint("zero", "%s : %d mints added to witness\n", __func__, coinWitness->nMintsAdded);
int64_t nTime1 = GetTimeMicros();
LogPrint("bench", " - Witness generated in %.2fms\n", 0.001 * (nTime1 - nTimeStart));
return true;
// TODO: I know that could merge all of this exception but maybe it's not really good.. think if we should have a different treatment for each one
} catch (searchMintHeightException e) {
return error("%s: searchMintHeightException: %s", __func__, e.message);
} catch (ChecksumInDbNotFoundException e) {
return error("%s: ChecksumInDbNotFoundException: %s", __func__, e.message);
} catch (GetPubcoinException e) {
return error("%s: GetPubcoinException: %s", __func__, e.message);
}
}