interaction_builder.hpp

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#pragma once
 
#include <array>
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <memory>
#include <utility>
#include <vector>
 
#include "barretenberg/common/tuple.hpp"
#include "barretenberg/vm2/common/field.hpp"
#include "barretenberg/vm2/generated/columns.hpp"
#include "barretenberg/vm2/tracegen/trace_container.hpp"
 
namespace bb::avm2::tracegen {
 
// Helper to generate a tuple type with N const FF& elements.
namespace detail {
template <size_t N, typename = std::make_index_sequence<N>> struct RefTupleHelper;
template <size_t N, size_t... Is> struct RefTupleHelper<N, std::index_sequence<Is...>> {
    template <size_t> using ConstFFRef = const FF&;
    using type = flat_tuple::tuple<ConstFFRef<Is>...>;
};
} // namespace detail
 
template <size_t N> using RefTuple = typename detail::RefTupleHelper<N>::type;
 
// Same as TraceContainer::get_multiple but copies the values into an owning std::array. Use when
// the result must outlive a subsequent column write (e.g. when stored as a hash-map key): the
// references returned by get_multiple point into column storage and can dangle on reallocation.
template <size_t N>
std::array<FF, N> get_multiple_as_array(const TraceContainer& trace,
                                        const std::array<ColumnAndShifts, N>& cols,
                                        uint32_t row)
{
    auto refs = trace.get_multiple(cols, row);
    return [&]<size_t... Is>(std::index_sequence<Is...>) {
        return std::array<FF, N>{ flat_tuple::get<Is>(refs)... };
    }(std::make_index_sequence<N>{});
}
 
class InteractionBuilderInterface {
  public:
    virtual ~InteractionBuilderInterface() = default;
    virtual void process(TraceContainer& trace) = 0;
    // Fingerprint of the destination columns.
    // Used to identify jobs that share the same destination columns and prevent them
    // from building the index at the same time.
    virtual size_t get_destination_columns_fingerprint() const { return 0; }
};
 
// A concatenate that works with movable objects.
template <typename T> std::vector<T> concatenate_jobs(std::vector<T>&& first, auto&&... rest)
{
    const size_t total_size = first.size() + (rest.size() + ...);
    std::vector<T> result = std::move(first);
    result.reserve(total_size);
    (std::move(rest.begin(), rest.end(), std::back_inserter(result)), ...);
    return result;
}
 
// Orders jobs to minimize index building contention.
// Jobs with first occurrences of each destination column key come first, followed by jobs that share
// destination column keys with previously seen ones.
// This ordering helps the SharedIndexCache by ensuring that when multiple jobs share
// the same destination, only the first one builds the index while others wait.
void order_jobs_by_destination_columns(std::vector<std::unique_ptr<InteractionBuilderInterface>>& jobs);
 
} // namespace bb::avm2::tracegen