AmendmentTable.cpp

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.
 
    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#include <ripple/app/main/Application.h>
#include <ripple/app/misc/AmendmentTable.h>
#include <ripple/core/ConfigSections.h>
#include <ripple/core/DatabaseCon.h>
#include <ripple/protocol/STValidation.h>
#include <ripple/protocol/TxFlags.h>
#include <ripple/protocol/jss.h>
#include <boost/format.hpp>
#include <boost/regex.hpp>
#include <algorithm>
#include <mutex>
 
namespace ripple {
 
static std::vector<std::pair<uint256, std::string>>
parseSection(Section const& section)
{
    static boost::regex const re1(
        "^"                        // start of line
        "(?:\\s*)"                 // whitespace (optional)
        "([abcdefABCDEF0-9]{64})"  // <hexadecimal amendment ID>
        "(?:\\s+)"                 // whitespace
        "(\\S+)"                   // <description>
        ,
        boost::regex_constants::optimize);
 
    std::vector<std::pair<uint256, std::string>> names;
 
    for (auto const& line : section.lines())
    {
        boost::smatch match;
 
        if (!boost::regex_match(line, match, re1))
            Throw<std::runtime_error>(
                "Invalid entry '" + line + "' in [" + section.name() + "]");
 
        uint256 id;
 
        if (!id.SetHexExact(match[1]))
            Throw<std::runtime_error>(
                "Invalid amendment ID '" + match[1] + "' in [" +
                section.name() + "]");
 
        names.push_back(std::make_pair(id, match[2]));
    }
 
    return names;
}
 
struct AmendmentState
{
    bool vetoed = false;
 
    bool enabled = false;
 
    bool supported = false;
 
    std::string name;
 
    explicit AmendmentState() = default;
};
 
struct AmendmentSet
{
private:
    // How many yes votes each amendment received
    hash_map<uint256, int> votes_;
 
public:
    // number of trusted validations
    int mTrustedValidations = 0;
 
    // number of votes needed
    int mThreshold = 0;
 
    AmendmentSet() = default;
 
    void
    tally(std::set<uint256> const& amendments)
    {
        ++mTrustedValidations;
 
        for (auto const& amendment : amendments)
            ++votes_[amendment];
    }
 
    int
    votes(uint256 const& amendment) const
    {
        auto const& it = votes_.find(amendment);
 
        if (it == votes_.end())
            return 0;
 
        return it->second;
    }
};
 
//------------------------------------------------------------------------------
 
class AmendmentTableImpl final : public AmendmentTable
{
protected:
    mutable std::mutex mutex_;
 
    hash_map<uint256, AmendmentState> amendmentMap_;
    std::uint32_t lastUpdateSeq_;
 
    // Time that an amendment must hold a majority for
    std::chrono::seconds const majorityTime_;
 
    // The amount of support that an amendment must receive
    // 0 = 0% and 256 = 100%
    int const majorityFraction_;
 
    // The results of the last voting round - may be empty if
    // we haven't participated in one yet.
    std::unique_ptr<AmendmentSet> lastVote_;
 
    // True if an unsupported amendment is enabled
    bool unsupportedEnabled_;
 
    // Unset if no unsupported amendments reach majority,
    // else set to the earliest time an unsupported amendment
    // will be enabled.
    boost::optional<NetClock::time_point> firstUnsupportedExpected_;
 
    beast::Journal const j_;
 
    // Finds or creates state.  Must be called with mutex_ locked.
    AmendmentState*
    add(uint256 const& amendment, std::lock_guard<std::mutex> const& sl);
 
    // Finds existing state.  Must be called with mutex_ locked.
    AmendmentState*
    get(uint256 const& amendment, std::lock_guard<std::mutex> const& sl);
 
    AmendmentState const*
    get(uint256 const& amendment, std::lock_guard<std::mutex> const& sl) const;
 
    // Injects amendment json into v.  Must be called with mutex_ locked.
    void
    injectJson(
        Json::Value& v,
        uint256 const& amendment,
        AmendmentState const& state,
        std::lock_guard<std::mutex> const& sl) const;
 
public:
    AmendmentTableImpl(
        std::chrono::seconds majorityTime,
        int majorityFraction,
        Section const& supported,
        Section const& enabled,
        Section const& vetoed,
        beast::Journal journal);
 
    uint256
    find(std::string const& name) const override;
 
    bool
    veto(uint256 const& amendment) override;
    bool
    unVeto(uint256 const& amendment) override;
 
    bool
    enable(uint256 const& amendment) override;
 
    bool
    isEnabled(uint256 const& amendment) const override;
    bool
    isSupported(uint256 const& amendment) const override;
 
    bool
    hasUnsupportedEnabled() const override;
 
    boost::optional<NetClock::time_point>
    firstUnsupportedExpected() const override;
 
    Json::Value
    getJson() const override;
    Json::Value
    getJson(uint256 const&) const override;
 
    bool
    needValidatedLedger(LedgerIndex seq) const override;
 
    void
    doValidatedLedger(
        LedgerIndex seq,
        std::set<uint256> const& enabled,
        majorityAmendments_t const& majority) override;
 
    std::vector<uint256>
    doValidation(std::set<uint256> const& enabledAmendments) const override;
 
    std::vector<uint256>
    getDesired() const override;
 
    std::map<uint256, std::uint32_t>
    doVoting(
        NetClock::time_point closeTime,
        std::set<uint256> const& enabledAmendments,
        majorityAmendments_t const& majorityAmendments,
        std::vector<std::shared_ptr<STValidation>> const& validations) override;
};
 
//------------------------------------------------------------------------------
 
AmendmentTableImpl::AmendmentTableImpl(
    std::chrono::seconds majorityTime,
    int majorityFraction,
    Section const& supported,
    Section const& enabled,
    Section const& vetoed,
    beast::Journal journal)
    : lastUpdateSeq_(0)
    , majorityTime_(majorityTime)
    , majorityFraction_(majorityFraction)
    , unsupportedEnabled_(false)
    , j_(journal)
{
    assert(majorityFraction_ != 0);
 
    std::lock_guard sl(mutex_);
 
    for (auto const& a : parseSection(supported))
    {
        if (auto s = add(a.first, sl))
        {
            JLOG(j_.debug()) << "Amendment " << a.first << " is supported.";
 
            if (!a.second.empty())
                s->name = a.second;
 
            s->supported = true;
        }
    }
 
    for (auto const& a : parseSection(enabled))
    {
        if (auto s = add(a.first, sl))
        {
            JLOG(j_.debug()) << "Amendment " << a.first << " is enabled.";
 
            if (!a.second.empty())
                s->name = a.second;
 
            s->supported = true;
            s->enabled = true;
        }
    }
 
    for (auto const& a : parseSection(vetoed))
    {
        // Unknown amendments are effectively vetoed already
        if (auto s = get(a.first, sl))
        {
            JLOG(j_.info()) << "Amendment " << a.first << " is vetoed.";
 
            if (!a.second.empty())
                s->name = a.second;
 
            s->vetoed = true;
        }
    }
}
 
AmendmentState*
AmendmentTableImpl::add(
    uint256 const& amendmentHash,
    std::lock_guard<std::mutex> const&)
{
    // call with the mutex held
    return &amendmentMap_[amendmentHash];
}
 
AmendmentState*
AmendmentTableImpl::get(
    uint256 const& amendmentHash,
    std::lock_guard<std::mutex> const& sl)
{
    // Forward to the const version of get.
    return const_cast<AmendmentState*>(
        std::as_const(*this).get(amendmentHash, sl));
}
 
AmendmentState const*
AmendmentTableImpl::get(
    uint256 const& amendmentHash,
    std::lock_guard<std::mutex> const&) const
{
    // call with the mutex held
    auto ret = amendmentMap_.find(amendmentHash);
 
    if (ret == amendmentMap_.end())
        return nullptr;
 
    return &ret->second;
}
 
uint256
AmendmentTableImpl::find(std::string const& name) const
{
    std::lock_guard sl(mutex_);
 
    for (auto const& e : amendmentMap_)
    {
        if (name == e.second.name)
            return e.first;
    }
 
    return {};
}
 
bool
AmendmentTableImpl::veto(uint256 const& amendment)
{
    std::lock_guard sl(mutex_);
    auto s = add(amendment, sl);
 
    if (s->vetoed)
        return false;
    s->vetoed = true;
    return true;
}
 
bool
AmendmentTableImpl::unVeto(uint256 const& amendment)
{
    std::lock_guard sl(mutex_);
    auto s = get(amendment, sl);
 
    if (!s || !s->vetoed)
        return false;
    s->vetoed = false;
    return true;
}
 
bool
AmendmentTableImpl::enable(uint256 const& amendment)
{
    std::lock_guard sl(mutex_);
    auto s = add(amendment, sl);
 
    if (s->enabled)
        return false;
 
    s->enabled = true;
 
    if (!s->supported)
    {
        JLOG(j_.error()) << "Unsupported amendment " << amendment
                         << " activated.";
        unsupportedEnabled_ = true;
    }
 
    return true;
}
 
bool
AmendmentTableImpl::isEnabled(uint256 const& amendment) const
{
    std::lock_guard sl(mutex_);
    auto s = get(amendment, sl);
    return s && s->enabled;
}
 
bool
AmendmentTableImpl::isSupported(uint256 const& amendment) const
{
    std::lock_guard sl(mutex_);
    auto s = get(amendment, sl);
    return s && s->supported;
}
 
bool
AmendmentTableImpl::hasUnsupportedEnabled() const
{
    std::lock_guard sl(mutex_);
    return unsupportedEnabled_;
}
 
boost::optional<NetClock::time_point>
AmendmentTableImpl::firstUnsupportedExpected() const
{
    std::lock_guard sl(mutex_);
    return firstUnsupportedExpected_;
}
 
std::vector<uint256>
AmendmentTableImpl::doValidation(std::set<uint256> const& enabled) const
{
    // Get the list of amendments we support and do not
    // veto, but that are not already enabled
    std::vector<uint256> amendments;
 
    {
        std::lock_guard sl(mutex_);
        amendments.reserve(amendmentMap_.size());
        for (auto const& e : amendmentMap_)
        {
            if (e.second.supported && !e.second.vetoed &&
                (enabled.count(e.first) == 0))
            {
                amendments.push_back(e.first);
            }
        }
    }
 
    if (!amendments.empty())
        std::sort(amendments.begin(), amendments.end());
 
    return amendments;
}
 
std::vector<uint256>
AmendmentTableImpl::getDesired() const
{
    // Get the list of amendments we support and do not veto
    return doValidation({});
}
 
std::map<uint256, std::uint32_t>
AmendmentTableImpl::doVoting(
    NetClock::time_point closeTime,
    std::set<uint256> const& enabledAmendments,
    majorityAmendments_t const& majorityAmendments,
    std::vector<std::shared_ptr<STValidation>> const& valSet)
{
    JLOG(j_.trace()) << "voting at " << closeTime.time_since_epoch().count()
                     << ": " << enabledAmendments.size() << ", "
                     << majorityAmendments.size() << ", " << valSet.size();
 
    auto vote = std::make_unique<AmendmentSet>();
 
    // process validations for ledger before flag ledger
    for (auto const& val : valSet)
    {
        if (val->isTrusted())
        {
            std::set<uint256> ballot;
 
            if (val->isFieldPresent(sfAmendments))
            {
                auto const choices = val->getFieldV256(sfAmendments);
                ballot.insert(choices.begin(), choices.end());
            }
 
            vote->tally(ballot);
        }
    }
 
    vote->mThreshold =
        std::max(1, (vote->mTrustedValidations * majorityFraction_) / 256);
 
    JLOG(j_.debug()) << "Received " << vote->mTrustedValidations
                     << " trusted validations, threshold is: "
                     << vote->mThreshold;
 
    // Map of amendments to the action to be taken for each one. The action is
    // the value of the flags in the pseudo-transaction
    std::map<uint256, std::uint32_t> actions;
 
    std::lock_guard sl(mutex_);
 
    // process all amendments we know of
    for (auto const& entry : amendmentMap_)
    {
        NetClock::time_point majorityTime = {};
 
        bool const hasValMajority =
            (vote->votes(entry.first) >= vote->mThreshold);
 
        {
            auto const it = majorityAmendments.find(entry.first);
            if (it != majorityAmendments.end())
                majorityTime = it->second;
        }
 
        if (enabledAmendments.count(entry.first) != 0)
        {
            JLOG(j_.debug()) << entry.first << ": amendment already enabled";
        }
        else if (
            hasValMajority && (majorityTime == NetClock::time_point{}) &&
            !entry.second.vetoed)
        {
            // Ledger says no majority, validators say yes
            JLOG(j_.debug()) << entry.first << ": amendment got majority";
            actions[entry.first] = tfGotMajority;
        }
        else if (!hasValMajority && (majorityTime != NetClock::time_point{}))
        {
            // Ledger says majority, validators say no
            JLOG(j_.debug()) << entry.first << ": amendment lost majority";
            actions[entry.first] = tfLostMajority;
        }
        else if (
            (majorityTime != NetClock::time_point{}) &&
            ((majorityTime + majorityTime_) <= closeTime) &&
            !entry.second.vetoed)
        {
            // Ledger says majority held
            JLOG(j_.debug()) << entry.first << ": amendment majority held";
            actions[entry.first] = 0;
        }
    }
 
    // Stash for reporting
    lastVote_ = std::move(vote);
    return actions;
}
 
bool
AmendmentTableImpl::needValidatedLedger(LedgerIndex ledgerSeq) const
{
    std::lock_guard sl(mutex_);
 
    // Is there a ledger in which an amendment could have been enabled
    // between these two ledger sequences?
 
    return ((ledgerSeq - 1) / 256) != ((lastUpdateSeq_ - 1) / 256);
}
 
void
AmendmentTableImpl::doValidatedLedger(
    LedgerIndex ledgerSeq,
    std::set<uint256> const& enabled,
    majorityAmendments_t const& majority)
{
    for (auto& e : enabled)
        enable(e);
 
    std::lock_guard sl(mutex_);
 
    // Remember the ledger sequence of this update.
    lastUpdateSeq_ = ledgerSeq;
 
    // Since we have the whole list in `majority`, reset the time flag, even
    // if it's currently set. If it's not set when the loop is done, then any
    // prior unknown amendments have lost majority.
    firstUnsupportedExpected_.reset();
    for (auto const& [hash, time] : majority)
    {
        auto s = add(hash, sl);
 
        if (s->enabled)
            continue;
 
        if (!s->supported)
        {
            JLOG(j_.info()) << "Unsupported amendment " << hash
                            << " reached majority at " << to_string(time);
            if (!firstUnsupportedExpected_ || firstUnsupportedExpected_ > time)
                firstUnsupportedExpected_ = time;
        }
    }
    if (firstUnsupportedExpected_)
        firstUnsupportedExpected_ = *firstUnsupportedExpected_ + majorityTime_;
}
 
void
AmendmentTableImpl::injectJson(
    Json::Value& v,
    const uint256& id,
    const AmendmentState& fs,
    std::lock_guard<std::mutex> const&) const
{
    if (!fs.name.empty())
        v[jss::name] = fs.name;
 
    v[jss::supported] = fs.supported;
    v[jss::vetoed] = fs.vetoed;
    v[jss::enabled] = fs.enabled;
 
    if (!fs.enabled && lastVote_)
    {
        auto const votesTotal = lastVote_->mTrustedValidations;
        auto const votesNeeded = lastVote_->mThreshold;
        auto const votesFor = lastVote_->votes(id);
 
        v[jss::count] = votesFor;
        v[jss::validations] = votesTotal;
 
        if (votesNeeded)
        {
            v[jss::vote] = votesFor * 256 / votesNeeded;
            v[jss::threshold] = votesNeeded;
        }
    }
}
 
Json::Value
AmendmentTableImpl::getJson() const
{
    Json::Value ret(Json::objectValue);
    {
        std::lock_guard sl(mutex_);
        for (auto const& e : amendmentMap_)
        {
            injectJson(
                ret[to_string(e.first)] = Json::objectValue,
                e.first,
                e.second,
                sl);
        }
    }
    return ret;
}
 
Json::Value
AmendmentTableImpl::getJson(uint256 const& amendmentID) const
{
    Json::Value ret = Json::objectValue;
    Json::Value& jAmendment = (ret[to_string(amendmentID)] = Json::objectValue);
 
    {
        std::lock_guard sl(mutex_);
        auto a = get(amendmentID, sl);
        if (a)
            injectJson(jAmendment, amendmentID, *a, sl);
    }
 
    return ret;
}
 
std::unique_ptr<AmendmentTable>
make_AmendmentTable(
    std::chrono::seconds majorityTime,
    int majorityFraction,
    Section const& supported,
    Section const& enabled,
    Section const& vetoed,
    beast::Journal journal)
{
    return std::make_unique<AmendmentTableImpl>(
        majorityTime, majorityFraction, supported, enabled, vetoed, journal);
}
 
}  // namespace ripple