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Fix removal of last liquidity on empty used pool (#1287)
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* Move end of block processes to functions

* Migrate last amount to burn address on empty used pool

* Handle case of burnaddress in pool split

Co-authored-by: Prasanna Loganathar <[email protected]>
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@Bushstar @prasannavl
Bushstar and prasannavl authored May 25, 2022
1 parent d229e92 commit ed4efea
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Showing 2 changed files with 117 additions and 87 deletions.
200 changes: 113 additions & 87 deletions src/validation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2203,6 +2203,69 @@ Res AddNonTxToBurnIndex(const CScript& from, const CBalances& amounts)
return mapBurnAmounts[from].AddBalances(amounts.balances);
}

void CChainState::ProcessEunosEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams) {
if (pindex->nHeight != chainparams.GetConsensus().EunosHeight) {
return;
}

// Move funds from old burn address to new one
CBalances burnAmounts;
cache.ForEachBalance([&burnAmounts](CScript const & owner, CTokenAmount balance) {
if (owner != Params().GetConsensus().retiredBurnAddress) {
return false;
}

burnAmounts.Add({balance.nTokenId, balance.nValue});

return true;
}, BalanceKey{chainparams.GetConsensus().retiredBurnAddress, DCT_ID{}});

AddNonTxToBurnIndex(chainparams.GetConsensus().retiredBurnAddress, burnAmounts);

// Zero foundation balances
for (const auto& script : chainparams.GetConsensus().accountDestruction)
{
CBalances zeroAmounts;
cache.ForEachBalance([&zeroAmounts, script](CScript const & owner, CTokenAmount balance) {
if (owner != script) {
return false;
}

zeroAmounts.Add({balance.nTokenId, balance.nValue});

return true;
}, BalanceKey{script, DCT_ID{}});

cache.SubBalances(script, zeroAmounts);
}

// Add any non-Tx burns to index as phantom Txs
for (const auto& item : mapBurnAmounts)
{
for (const auto& subItem : item.second.balances)
{
// If amount cannot be deducted then burn skipped.
auto result = cache.SubBalance(item.first, {subItem.first, subItem.second});
if (result.ok)
{
cache.AddBalance(chainparams.GetConsensus().burnAddress, {subItem.first, subItem.second});

// Add transfer as additional TX in block
pburnHistoryDB->WriteAccountHistory({Params().GetConsensus().burnAddress, static_cast<uint32_t>(pindex->nHeight), GetNextBurnPosition()},
{uint256{}, static_cast<uint8_t>(CustomTxType::AccountToAccount), {{subItem.first, subItem.second}}});
}
else // Log burn failure
{
CTxDestination dest;
ExtractDestination(item.first, dest);
LogPrintf("Burn failed: %s Address: %s Token: %d Amount: %d\n", result.msg, EncodeDestination(dest), subItem.first.v, subItem.second);
}
}
}

mapBurnAmounts.clear();
}

template<typename GovVar>
static void UpdateDailyGovVariables(const std::map<CommunityAccountType, uint32_t>::const_iterator& incentivePair, CCustomCSView& cache, int nHeight) {
if (incentivePair != Params().GetConsensus().newNonUTXOSubsidies.end())
Expand Down Expand Up @@ -2921,92 +2984,20 @@ bool CChainState::ConnectBlock(const CBlock& block, CValidationState& state, CBl
cache.BayfrontFlagsCleanup();
}

if (pindex->nHeight == chainparams.GetConsensus().EunosHeight)
{
// Move funds from old burn address to new one
CBalances burnAmounts;
cache.ForEachBalance([&burnAmounts](CScript const & owner, CTokenAmount balance) {
if (owner != Params().GetConsensus().retiredBurnAddress) {
return false;
}

burnAmounts.Add({balance.nTokenId, balance.nValue});

return true;
}, BalanceKey{chainparams.GetConsensus().retiredBurnAddress, DCT_ID{}});

AddNonTxToBurnIndex(chainparams.GetConsensus().retiredBurnAddress, burnAmounts);

// Zero foundation balances
for (const auto& script : chainparams.GetConsensus().accountDestruction)
{
CBalances zeroAmounts;
cache.ForEachBalance([&zeroAmounts, script](CScript const & owner, CTokenAmount balance) {
if (owner != script) {
return false;
}

zeroAmounts.Add({balance.nTokenId, balance.nValue});

return true;
}, BalanceKey{script, DCT_ID{}});

cache.SubBalances(script, zeroAmounts);
}
}

// Add any non-Tx burns to index as phantom Txs
for (const auto& item : mapBurnAmounts)
{
for (const auto& subItem : item.second.balances)
{
// If amount cannot be deducted then burn skipped.
auto result = cache.SubBalance(item.first, {subItem.first, subItem.second});
if (result.ok)
{
cache.AddBalance(chainparams.GetConsensus().burnAddress, {subItem.first, subItem.second});

// Add transfer as additional TX in block
pburnHistoryDB->WriteAccountHistory({Params().GetConsensus().burnAddress, static_cast<uint32_t>(pindex->nHeight), GetNextBurnPosition()},
{uint256{}, static_cast<uint8_t>(CustomTxType::AccountToAccount), {{subItem.first, subItem.second}}});
}
else // Log burn failure
{
CTxDestination dest;
ExtractDestination(item.first, dest);
LogPrintf("Burn failed: %s Address: %s Token: %d Amount: %d\n", result.msg, EncodeDestination(dest), subItem.first.v, subItem.second);
}
}
}

mapBurnAmounts.clear();
// burn DFI on Eunos height
ProcessEunosEvents(pindex, cache, chainparams);

// set oracle prices
ProcessOracleEvents(pindex, cache, chainparams);

// loan scheme, collateral ratio, liquidations
ProcessLoanEvents(pindex, cache, chainparams);

// Must be before set gov by height to clear futures in case there's a disabling of loan token in v3+
ProcessFutures(pindex, cache, chainparams);

if (pindex->nHeight >= chainparams.GetConsensus().FortCanningHeight) {
// Apply any pending GovVariable changes. Will come into effect on the next block.
auto storedGovVars = cache.GetStoredVariables(static_cast<uint32_t>(pindex->nHeight));
for (const auto& var : storedGovVars) {
if (var) {
CCustomCSView govCache(cache);
// Add to existing ATTRIBUTES instead of overwriting.
if (var->GetName() == "ATTRIBUTES") {
auto govVar = mnview.GetAttributes();
govVar->time = pindex->GetBlockTime();
if (govVar->Import(var->Export()) && govVar->Validate(govCache) && govVar->Apply(govCache, pindex->nHeight) && govCache.SetVariable(*govVar)) {
govCache.Flush();
}
} else if (var->Validate(govCache) && var->Apply(govCache, pindex->nHeight) && govCache.SetVariable(*var)) {
govCache.Flush();
}
}
}
cache.EraseStoredVariables(static_cast<uint32_t>(pindex->nHeight));
}
// update governance variables
ProcessGovEvents(pindex, cache, chainparams);

// Migrate loan and collateral tokens to Gov vars.
ProcessTokenToGovVar(pindex, cache, chainparams);
Expand Down Expand Up @@ -3709,6 +3700,31 @@ void CChainState::ProcessOracleEvents(const CBlockIndex* pindex, CCustomCSView&
});
}

void CChainState::ProcessGovEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams) {
if (pindex->nHeight < chainparams.GetConsensus().FortCanningHeight) {
return;
}

// Apply any pending GovVariable changes. Will come into effect on the next block.
auto storedGovVars = cache.GetStoredVariables(pindex->nHeight);
for (const auto& var : storedGovVars) {
if (var) {
CCustomCSView govCache(cache);
// Add to existing ATTRIBUTES instead of overwriting.
if (var->GetName() == "ATTRIBUTES") {
auto govVar = cache.GetAttributes();
govVar->time = pindex->GetBlockTime();
if (govVar->Import(var->Export()) && govVar->Validate(govCache) && govVar->Apply(govCache, pindex->nHeight) && govCache.SetVariable(*govVar)) {
govCache.Flush();
}
} else if (var->Validate(govCache) && var->Apply(govCache, pindex->nHeight) && govCache.SetVariable(*var)) {
govCache.Flush();
}
}
}
cache.EraseStoredVariables(static_cast<uint32_t>(pindex->nHeight));
}

void CChainState::ProcessTokenToGovVar(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams) {

// Migrate at +1 height so that GetLastHeight() in Gov var
Expand Down Expand Up @@ -3930,18 +3946,28 @@ static Res PoolSplits(CCustomCSView& view, CAmount& totalBalance, ATTRIBUTES& at
return a.second > b.second;
});

// Special case. No liquidity providers in a previously used pool.
if (balancesToMigrate.empty() && oldPoolPair->totalLiquidity == CPoolPair::MINIMUM_LIQUIDITY) {
balancesToMigrate.emplace_back(Params().GetConsensus().burnAddress, CAmount{CPoolPair::MINIMUM_LIQUIDITY});
}

for (auto& [owner, amount] : balancesToMigrate) {
if (oldPoolPair->totalLiquidity < CPoolPair::MINIMUM_LIQUIDITY) {
throw std::runtime_error("totalLiquidity less than minimum.");
}

view.CalculateOwnerRewards(owner, pindex->nHeight);
if (owner != Params().GetConsensus().burnAddress) {
view.CalculateOwnerRewards(owner, pindex->nHeight);

res = view.SubBalance(owner, CTokenAmount{oldPoolId, amount});
if (!res.ok) {
throw std::runtime_error(strprintf("SubBalance failed: %s", res.msg));
res = view.SubBalance(owner, CTokenAmount{oldPoolId, amount});
if (!res.ok) {
throw std::runtime_error(strprintf("SubBalance failed: %s", res.msg));
}
}

if (oldPoolPair->totalLiquidity < CPoolPair::MINIMUM_LIQUIDITY) {
throw std::runtime_error("totalLiquidity less than minimum.");
}

// First deposit to the pool has MINIMUM_LIQUIDITY removed and does not
// belong to anyone. Give this to the last person leaving the pool.
if (oldPoolPair->totalLiquidity - amount == CPoolPair::MINIMUM_LIQUIDITY) {
amount += CPoolPair::MINIMUM_LIQUIDITY;
}
Expand All @@ -3968,7 +3994,7 @@ static Res PoolSplits(CCustomCSView& view, CAmount& totalBalance, ATTRIBUTES& at
view.AddBalance(owner, {newPoolPair.idTokenB, amountB});
};

if (amountA <= 0 || amountB <= 0) {
if (amountA <= 0 || amountB <= 0 || owner == Params().GetConsensus().burnAddress) {
refundBalances();
continue;
}
Expand Down
4 changes: 4 additions & 0 deletions src/validation.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -765,6 +765,10 @@ class CChainState {

static void ProcessLoanEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams);

static void ProcessEunosEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams);

static void ProcessGovEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams);

static void ProcessOracleEvents(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams);

static void ProcessFutures(const CBlockIndex* pindex, CCustomCSView& cache, const CChainParams& chainparams);
Expand Down

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