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// Copyright (c) 2016-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_VERSIONBITS_H
#define BITCOIN_VERSIONBITS_H
#include <chain.h>
#include <sync.h>
#include <array>
#include <map>
#include <optional>
#include <vector>
class CChainParams;
/** What block version to use for new blocks (pre versionbits) */
static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4;
/** What bits to set in version for versionbits blocks */
static const int32_t VERSIONBITS_TOP_BITS = 0x20000000UL;
/** What bitmask determines whether versionbits is in use */
static const int32_t VERSIONBITS_TOP_MASK = 0xE0000000UL;
/** Total bits available for versionbits */
static const int32_t VERSIONBITS_NUM_BITS = 29;
/** Opaque type for BIP9 state. See versionbits_impl.h for details. */
enum class ThresholdState : uint8_t;
// A map that gives the state for blocks whose height is a multiple of Period().
// The map is indexed by the block's parent, however, so all keys in the map
// 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 */
uint32_t period{0};
/** Number of blocks with the version bit set required to activate the softfork */
uint32_t threshold{0};
/** Number of blocks elapsed since the beginning of the current period */
uint32_t elapsed{0};
/** Number of blocks with the version bit set since the beginning of the current period */
uint32_t count{0};
/** False if there are not enough blocks left in this period to pass activation threshold */
bool possible{false};
};
/** Detailed status of an enabled BIP9 deployment */
struct BIP9Info {
/** Height at which current_state started */
int since{0};
/** String representing the current state */
std::string current_state{};
/** String representing the next block's state */
std::string next_state{};
/** For states where signalling is applicable, information about the signalling */
std::optional<BIP9Stats> stats;
/** Which blocks signalled; empty if signalling is not applicable */
std::vector<bool> signalling_blocks;
/** Height at which the deployment is active, if known. May be in the future. */
std::optional<int> active_since;
};
struct BIP9GBTStatus {
struct Info {
int bit;
uint32_t mask;
bool gbt_optional_rule;
};
std::map<std::string, const Info, std::less<>> signalling, locked_in, active;
};
/** BIP 9 allows multiple softforks to be deployed in parallel. We cache
* per-period state for every one of them. */
class VersionBitsCache
{
private:
Mutex m_mutex;
std::array<ThresholdConditionCache,VERSIONBITS_NUM_BITS> m_warning_caches GUARDED_BY(m_mutex);
std::array<ThresholdConditionCache,Consensus::MAX_VERSION_BITS_DEPLOYMENTS> m_caches GUARDED_BY(m_mutex);
public:
BIP9Info Info(const CBlockIndex& block_index, const Consensus::Params& params, Consensus::DeploymentPos id) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
BIP9GBTStatus GBTStatus(const CBlockIndex& block_index, const Consensus::Params& params) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
/** Get the BIP9 state for a given deployment for the block after pindexPrev. */
bool IsActiveAfter(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
/** Determine what nVersion a new block should use */
int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
/** Check for unknown activations
* Returns a vector containing the bit number used for signalling and a bool
* indicating the deployment is likely to be ACTIVE, rather than merely LOCKED_IN. */
std::vector<std::pair<int,bool>> CheckUnknownActivations(const CBlockIndex* pindex, const CChainParams& chainparams) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
void Clear() EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
};
#endif // BITCOIN_VERSIONBITS_H