diff options
Diffstat (limited to 'src/versionbits.h')
| -rw-r--r-- | src/versionbits.h | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/src/versionbits.h b/src/versionbits.h index cdc947cd9e..d8dda7d95b 100644 --- a/src/versionbits.h +++ b/src/versionbits.h @@ -17,12 +17,17 @@ static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL; /** Total bits available for versionbits */ static const int32_t VERSIONBITS_NUM_BITS = 29; +/** BIP 9 defines a finite-state-machine to deploy a softfork in multiple stages. + * State transitions happen during retarget period if conditions are met + * In case of reorg, transitions can go backward. Without transition, state is + * inherited between periods. All blocks of a period share the same state. + */ enum class ThresholdState { - DEFINED, - STARTED, - LOCKED_IN, - ACTIVE, - FAILED, + DEFINED, // First state that each softfork starts out as. The genesis block is by definition in this state for each deployment. + STARTED, // For blocks past the starttime. + LOCKED_IN, // For one retarget period after the first retarget period with STARTED blocks of which at least threshold have the associated bit set in nVersion. + ACTIVE, // For all blocks after the LOCKED_IN retarget period (final state) + FAILED, // For all blocks once the first retarget period after the timeout time is hit, if LOCKED_IN wasn't already reached (final state) }; // A map that gives the state for blocks whose height is a multiple of Period(). @@ -30,11 +35,17 @@ enum class ThresholdState { // will either be nullptr or a block with (height + 1) % Period() == 0. typedef std::map<const CBlockIndex*, ThresholdState> ThresholdConditionCache; +/** Display status of an in-progress BIP9 softfork */ struct BIP9Stats { + /** Length of blocks of the BIP9 signalling period */ int period; + /** Number of blocks with the version bit set required to activate the softfork */ int threshold; + /** Number of blocks elapsed since the beginning of the current period */ int elapsed; + /** Number of blocks with the version bit set since the beginning of the current period */ int count; + /** False if there are not enough blocks left in this period to pass activation threshold */ bool possible; }; @@ -50,12 +61,17 @@ protected: virtual int Threshold(const Consensus::Params& params) const =0; public: + /** Returns the numerical statistics of an in-progress BIP9 softfork in the current period */ BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const; - // Note that the functions below take a pindexPrev as input: they compute information for block B based on its parent. + /** Returns the state for pindex A based on parent pindexPrev B. Applies any state transition if conditions are present. + * Caches state from first block of period. */ ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const; + /** Returns the height since when the ThresholdState has started for pindex A based on parent pindexPrev B, all blocks of a period share the same */ int GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const; }; +/** BIP 9 allows multiple softforks to be deployed in parallel. We cache per-period state for every one of them + * keyed by the bit position used to signal support. */ struct VersionBitsCache { ThresholdConditionCache caches[Consensus::MAX_VERSION_BITS_DEPLOYMENTS]; |