src/versionbits.h

   1 // Copyright (c) 2016-2017 The Bitcoin Core developers
   2 // Distributed under the MIT software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #ifndef BITCOIN_CONSENSUS_VERSIONBITS
   6 #define BITCOIN_CONSENSUS_VERSIONBITS
   7
   8 #include <chain.h>
   9 #include <map>
  10
  11 /** What block version to use for new blocks (pre versionbits) */
  12 static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4;
  13 /** What bits to set in version for versionbits blocks */
  14 static const int32_t VERSIONBITS_TOP_BITS = 0x20000000UL;
  15 /** What bitmask determines whether versionbits is in use */
  16 static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL;
  17 /** Total bits available for versionbits */
  18 static const int32_t VERSIONBITS_NUM_BITS = 29;
  19
  20 enum ThresholdState {
  21     THRESHOLD_DEFINED,
  22     THRESHOLD_STARTED,
  23     THRESHOLD_LOCKED_IN,
  24     THRESHOLD_ACTIVE,
  25     THRESHOLD_FAILED,
  26 };
  27
  28 // A map that gives the state for blocks whose height is a multiple of Period().
  29 // The map is indexed by the block's parent, however, so all keys in the map
  30 // will either be nullptr or a block with (height + 1) % Period() == 0.
  31 typedef std::map<const CBlockIndex*, ThresholdState> ThresholdConditionCache;
  32
  33 struct VBDeploymentInfo {
  34     /** Deployment name */
  35     const char *name;
  36     /** Whether GBT clients can safely ignore this rule in simplified usage */
  37     bool gbt_force;
  38 };
  39
  40 struct BIP9Stats {
  41     int period;
  42     int threshold;
  43     int elapsed;
  44     int count;
  45     bool possible;
  46 };
  47
  48 extern const struct VBDeploymentInfo VersionBitsDeploymentInfo[];
  49
  50 /**
  51  * Abstract class that implements BIP9-style threshold logic, and caches results.
  52  */
  53 class AbstractThresholdConditionChecker {
  54 protected:
  55     virtual bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const =0;
  56     virtual int64_t BeginTime(const Consensus::Params& params) const =0;
  57     virtual int64_t EndTime(const Consensus::Params& params) const =0;
  58     virtual int Period(const Consensus::Params& params) const =0;
  59     virtual int Threshold(const Consensus::Params& params) const =0;
  60
  61 public:
  62     BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const;
  63     // Note that the functions below take a pindexPrev as input: they compute information for block B based on its parent.
  64     ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
  65     int GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
  66 };
  67
  68 struct VersionBitsCache
  69 {
  70     ThresholdConditionCache caches[Consensus::MAX_VERSION_BITS_DEPLOYMENTS];
  71
  72     void Clear();
  73 };
  74
  75 ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
  76 BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos);
  77 int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
  78 uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);
  79
  80 #endif