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Use a boost::optional for nCachedBranchId

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This enables us to distinguish between it being unset vs. being set to zero.
This commit is contained in:
Jack Grigg
2018-02-06 12:39:20 +00:00
parent 149d69e36b
commit 828940b163
3 changed files with 36 additions and 18 deletions
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32
src/main.cpp
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@@ -2223,15 +2223,15 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
pindex->nStatus |= BLOCK_HAVE_UNDO;
}
// Now that all consensus rules have been validated, set nConsensusBranchId.
// Now that all consensus rules have been validated, set nCachedBranchId.
// Move this if BLOCK_VALID_CONSENSUS is ever altered.
static_assert(BLOCK_VALID_CONSENSUS == BLOCK_VALID_SCRIPTS,
"nConsensusBranchId must be set after all consensus rules have been validated.");
"nCachedBranchId must be set after all consensus rules have been validated.");
if (IsActivationHeightForAnyUpgrade(pindex->nHeight, Params().GetConsensus())) {
pindex->nStatus |= BLOCK_ACTIVATES_UPGRADE;
pindex->nConsensusBranchId = CurrentEpochBranchId(pindex->nHeight, chainparams.GetConsensus());
pindex->nCachedBranchId = CurrentEpochBranchId(pindex->nHeight, chainparams.GetConsensus());
} else if (pindex->pprev) {
pindex->nConsensusBranchId = pindex->pprev->nConsensusBranchId;
pindex->nCachedBranchId = pindex->pprev->nCachedBranchId;
}
pindex->RaiseValidity(BLOCK_VALID_SCRIPTS);
@@ -3577,9 +3577,15 @@ bool static LoadBlockIndexDB()
// Construct in-memory chain of branch IDs.
// Relies on invariant: a block that does not activate a network upgrade
// will always be valid under the same consensus rules as its parent.
// Activation blocks will have non-zero branch IDs (read from disk).
if (pindex->IsValid(BLOCK_VALID_CONSENSUS) && pindex->nConsensusBranchId == 0 && pindex->pprev) {
pindex->nConsensusBranchId = pindex->pprev->nConsensusBranchId;
// Genesis block has a branch ID of zero by definition, but has no
// validity status because it is side-loaded into a fresh chain.
// Activation blocks will have branch IDs set (read from disk).
if (pindex->pprev) {
if (pindex->IsValid(BLOCK_VALID_CONSENSUS) && !pindex->nCachedBranchId) {
pindex->nCachedBranchId = pindex->pprev->nCachedBranchId;
}
} else {
pindex->nCachedBranchId = NetworkUpgradeInfo[Consensus::BASE_SPROUT].nBranchId;
}
if (pindex->IsValid(BLOCK_VALID_TRANSACTIONS) && (pindex->nChainTx || pindex->pprev == NULL))
setBlockIndexCandidates.insert(pindex);
@@ -3769,19 +3775,21 @@ bool RewindBlockIndex(const CChainParams& params)
LOCK(cs_main);
// RewindBlockIndex is called after LoadBlockIndex, so at this point every block
// index will have nConsensusBranchId set based on the values previously persisted
// to disk. By definition, a non-zero nConsensusBranchId means that the block was
// index will have nCachedBranchId set based on the values previously persisted
// to disk. By definition, a set nCachedBranchId means that the block was
// fully-validated under the corresponding consensus rules. Thus we can quickly
// identify whether the current active chain matches our expected sequence of
// consensus rule changes, with two checks:
//
// - BLOCK_ACTIVATES_UPGRADE is set only on blocks that activate upgrades.
// - nConsensusBranchId for each block matches what we expect.
// - nCachedBranchId for each block matches what we expect.
auto sufficientlyValidated = [&params](const CBlockIndex* pindex) {
auto consensus = params.GetConsensus();
bool fFlagSet = pindex->nStatus & BLOCK_ACTIVATES_UPGRADE;
bool fFlagExpected = IsActivationHeightForAnyUpgrade(pindex->nHeight, consensus);
return fFlagSet == fFlagExpected && pindex->nConsensusBranchId == CurrentEpochBranchId(pindex->nHeight, consensus);
return fFlagSet == fFlagExpected &&
pindex->nCachedBranchId &&
*pindex->nCachedBranchId == CurrentEpochBranchId(pindex->nHeight, consensus);
};
int nHeight = 1;
@@ -3832,7 +3840,7 @@ bool RewindBlockIndex(const CChainParams& params)
pindexIter->nStatus &= ~(BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO);
// Remove branch ID
pindexIter->nStatus &= ~BLOCK_ACTIVATES_UPGRADE;
pindexIter->nConsensusBranchId = 0;
pindexIter->nCachedBranchId = boost::none;
// Remove storage location
pindexIter->nFile = 0;
pindexIter->nDataPos = 0;