search_handler.cpp

#include "search.hpp"

#include <iostream>
#include <ostream>
#include <fmt/format.h>

#include "common.hpp"
#include "move_generator.hpp"

void SearchHandler::search_thread_function() {
    int this_search_id;
    while (true) {
        barrier.wait();
        this_search_id = current_search_id;
        if (this->shutting_down) {
            return;
        }
        search_cancelled = false;
        in_search = true;
        {
            std::lock_guard<std::mutex> lock(search_mutex);
            if (should_perft) {
                Perft::run_perft(board_hist[board_hist.len() - 1], perft_depth, true);
                should_perft = false;
            } else {
                auto move = run_iterative_deepening_search();
                if (move.is_null_move()) {
                    // Unlikely, but possible!
                    move = Search::select_random_move(board_hist[board_hist.len() - 1]);
                    // Just choose a random move
                }
                if (this_search_id == current_search_id && print_info) {
                    fmt::println("bestmove {}", move);
                    std::fflush(stdout);
                }
                // We've had issues with stdout not being flushed in the past
            }
        }
        in_search = false;
        supervisor_cv.notify_all();
    }
}

void SearchHandler::shutdown() {
    this->shutting_down = true;
    this->search_cancelled = true;
    // If we're in a search, quit searching ASAP
    barrier.wait();
    this->search_thread.join();
}

SearchHandler::SearchHandler() { 
    this->search_thread = std::thread(&SearchHandler::search_thread_function, this);
    recompute_table();
}

void SearchHandler::search(const TimeControlInfo& tc) {
    current_search_id += 1;
    search_cancelled = true;
    // cancel a search if performing one
    in_search = true;
    this->tc = tc;
    barrier.wait();
    // We then wake up the search thread
    int id_to_cancel = current_search_id;
    const auto tc_search_time = TimeManagement::get_search_time(tc);
    const auto tc_end_time = std::chrono::steady_clock::now() + std::chrono::milliseconds(tc_search_time);
    if (TimeManagement::is_time_based_tc(tc)) {
        cancelFuture = std::async(std::launch::async, [this, id_to_cancel, tc_end_time]() {
            auto lk = std::unique_lock(supervisor_mutex);
            supervisor_cv.wait_until(lk, tc_end_time, [&]() {
                return !in_search || current_search_id != id_to_cancel || shutting_down;
            });
            if (this->get_current_search_id() == id_to_cancel) {
                // only cancel the current search
                this->EndSearch();
            }
        });
    }
}

void SearchHandler::run_perft(uint16_t depth) {
    search_cancelled = true;
    // cancel any existing search
    perft_depth = depth;
    should_perft = true;
    in_search = true;
    barrier.wait();
}

void SearchHandler::reset() {
    this->EndSearch();
    board_hist = BoardHistory();
    tt.clear();
    history_table.clear();
}

void SearchHandler::run_bench(uint16_t depth) {
    static constexpr std::array fens = {// taken from alexandria, originally from bitgenie
                                        "r3k2r/2pb1ppp/2pp1q2/p7/1nP1B3/1P2P3/P2N1PPP/R2QK2R w KQkq a6 0 14",
                                        "4rrk1/2p1b1p1/p1p3q1/4p3/2P2n1p/1P1NR2P/PB3PP1/3R1QK1 b - - 2 24",
                                        "r3qbrk/6p1/2b2pPp/p3pP1Q/PpPpP2P/3P1B2/2PB3K/R5R1 w - - 16 42",
                                        "6k1/1R3p2/6p1/2Bp3p/3P2q1/P7/1P2rQ1K/5R2 b - - 4 44",
                                        "8/8/1p2k1p1/3p3p/1p1P1P1P/1P2PK2/8/8 w - - 3 54",
                                        "7r/2p3k1/1p1p1qp1/1P1Bp3/p1P2r1P/P7/4R3/Q4RK1 w - - 0 36",
                                        "r1bq1rk1/pp2b1pp/n1pp1n2/3P1p2/2P1p3/2N1P2N/PP2BPPP/R1BQ1RK1 b - - 2 10",
                                        "3r3k/2r4p/1p1b3q/p4P2/P2Pp3/1B2P3/3BQ1RP/6K1 w - - 3 87",
                                        "2r4r/1p4k1/1Pnp4/3Qb1pq/8/4BpPp/5P2/2RR1BK1 w - - 0 42",
                                        "4q1bk/6b1/7p/p1p4p/PNPpP2P/KN4P1/3Q4/4R3 b - - 0 37",
                                        "2q3r1/1r2pk2/pp3pp1/2pP3p/P1Pb1BbP/1P4Q1/R3NPP1/4R1K1 w - - 2 34",
                                        "1r2r2k/1b4q1/pp5p/2pPp1p1/P3Pn2/1P1B1Q1P/2R3P1/4BR1K b - - 1 37",
                                        "r3kbbr/pp1n1p1P/3ppnp1/q5N1/1P1pP3/P1N1B3/2P1QP2/R3KB1R b KQkq b3 0 17",
                                        "8/6pk/2b1Rp2/3r4/1R1B2PP/P5K1/8/2r5 b - - 16 42",
                                        "1r4k1/4ppb1/2n1b1qp/pB4p1/1n1BP1P1/7P/2PNQPK1/3RN3 w - - 8 29",
                                        "8/p2B4/PkP5/4p1pK/4Pb1p/5P2/8/8 w - - 29 68",
                                        "3r4/ppq1ppkp/4bnp1/2pN4/2P1P3/1P4P1/PQ3PBP/R4K2 b - - 2 20",
                                        "5rr1/4n2k/4q2P/P1P2n2/3B1p2/4pP2/2N1P3/1RR1K2Q w - - 1 49",
                                        "1r5k/2pq2p1/3p3p/p1pP4/4QP2/PP1R3P/6PK/8 w - - 1 51",
                                        "q5k1/5ppp/1r3bn1/1B6/P1N2P2/BQ2P1P1/5K1P/8 b - - 2 34",
                                        "r1b2k1r/5n2/p4q2/1ppn1Pp1/3pp1p1/NP2P3/P1PPBK2/1RQN2R1 w - - 0 22",
                                        "r1bqk2r/pppp1ppp/5n2/4b3/4P3/P1N5/1PP2PPP/R1BQKB1R w KQkq - 0 5",
                                        "r1bqr1k1/pp1p1ppp/2p5/8/3N1Q2/P2BB3/1PP2PPP/R3K2n b Q - 1 12",
                                        "r1bq2k1/p4r1p/1pp2pp1/3p4/1P1B3Q/P2B1N2/2P3PP/4R1K1 b - - 2 19",
                                        "r4qk1/6r1/1p4p1/2ppBbN1/1p5Q/P7/2P3PP/5RK1 w - - 2 25",
                                        "r7/6k1/1p6/2pp1p2/7Q/8/p1P2K1P/8 w - - 0 32",
                                        "r3k2r/ppp1pp1p/2nqb1pn/3p4/4P3/2PP4/PP1NBPPP/R2QK1NR w KQkq - 1 5",
                                        "3r1rk1/1pp1pn1p/p1n1q1p1/3p4/Q3P3/2P5/PP1NBPPP/4RRK1 w - - 0 12",
                                        "5rk1/1pp1pn1p/p3Brp1/8/1n6/5N2/PP3PPP/2R2RK1 w - - 2 20",
                                        "8/1p2pk1p/p1p1r1p1/3n4/8/5R2/PP3PPP/4R1K1 b - - 3 27",
                                        "8/4pk2/1p1r2p1/p1p4p/Pn5P/3R4/1P3PP1/4RK2 w - - 1 33",
                                        "8/5k2/1pnrp1p1/p1p4p/P6P/4R1PK/1P3P2/4R3 b - - 1 38",
                                        "8/8/1p1kp1p1/p1pr1n1p/P6P/1R4P1/1P3PK1/1R6 b - - 15 45",
                                        "8/8/1p1k2p1/p1prp2p/P2n3P/6P1/1P1R1PK1/4R3 b - - 5 49",
                                        "8/8/1p4p1/p1p2k1p/P2npP1P/4K1P1/1P6/3R4 w - - 6 54",
                                        "8/8/1p4p1/p1p2k1p/P2n1P1P/4K1P1/1P6/6R1 b - - 6 59",
                                        "8/5k2/1p4p1/p1pK3p/P2n1P1P/6P1/1P6/4R3 b - - 14 63",
                                        "8/1R6/1p1K1kp1/p6p/P1p2P1P/6P1/1Pn5/8 w - - 0 67",
                                        "1rb1rn1k/p3q1bp/2p3p1/2p1p3/2P1P2N/PP1RQNP1/1B3P2/4R1K1 b - - 4 23",
                                        "4rrk1/pp1n1pp1/q5p1/P1pP4/2n3P1/7P/1P3PB1/R1BQ1RK1 w - - 3 22",
                                        "r2qr1k1/pb1nbppp/1pn1p3/2ppP3/3P4/2PB1NN1/PP3PPP/R1BQR1K1 w - - 4 12",
                                        "2r2k2/8/4P1R1/1p6/8/P4K1N/7b/2B5 b - - 0 55",
                                        "6k1/5pp1/8/2bKP2P/2P5/p4PNb/B7/8 b - - 1 44",
                                        "2rqr1k1/1p3p1p/p2p2p1/P1nPb3/2B1P3/5P2/1PQ2NPP/R1R4K w - - 3 25",
                                        "r1b2rk1/p1q1ppbp/6p1/2Q5/8/4BP2/PPP3PP/2KR1B1R b - - 2 14",
                                        "6r1/5k2/p1b1r2p/1pB1p1p1/1Pp3PP/2P1R1K1/2P2P2/3R4 w - - 1 36",
                                        "rnbqkb1r/pppppppp/5n2/8/2PP4/8/PP2PPPP/RNBQKBNR b KQkq c3 0 2",
                                        "2rr2k1/1p4bp/p1q1p1p1/4Pp1n/2PB4/1PN3P1/P3Q2P/2RR2K1 w - f6 0 20",
                                        "3br1k1/p1pn3p/1p3n2/5pNq/2P1p3/1PN3PP/P2Q1PB1/4R1K1 w - - 0 23",
                                        "2r2b2/5p2/5k2/p1r1pP2/P2pB3/1P3P2/K1P3R1/7R w - - 23 93",
                                        "8/P6p/2K1q1pk/2Q5/4p3/8/7P/8 w - - 4 44",
                                        "7k/8/7P/5B2/5K2/8/8/8 b - - 0 175"};
    print_info = false;
    uint64_t total_nodes = 0;
    const auto start = std::chrono::steady_clock::now();
    for (const auto& fen : fens) {
        this->reset();
        Position pos;
        pos.set_from_fen(fen);
        this->set_pos(pos);
        this->tc = DepthTC{depth};
        search_cancelled = false;
        run_iterative_deepening_search();
        // loop until search completes
        total_nodes += node_count;
        fmt::println("{} {}", fen, node_count);
    }
    const auto duration =
        std::max(std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::steady_clock::now() - start).count(), (int64_t) 1);
    fmt::println("{} nodes {} nps", total_nodes, (total_nodes / duration) * 1000);
}