#include "evaluate.h"
#include "history.h"
#include "misc.h"
-#include "move.h"
#include "movegen.h"
#include "movepick.h"
#include "search.h"
#include "tt.h"
#include "ucioption.h"
+namespace Search {
+
+ volatile SignalsType Signals;
+ LimitsType Limits;
+ std::vector<Move> RootMoves;
+ Position RootPosition;
+}
+
using std::cout;
using std::endl;
using std::string;
+using namespace Search;
namespace {
// RootMoveList struct is mainly a std::vector of RootMove objects
struct RootMoveList : public std::vector<RootMove> {
- void init(Position& pos, Move searchMoves[]);
+ void init(Position& pos, Move rootMoves[]);
RootMove* find(const Move& m, int startIndex = 0);
int bestMoveChanges;
int MultiPV, UCIMultiPV, MultiPVIdx;
// Time management variables
- volatile bool StopOnPonderhit, FirstRootMove, StopRequest, QuitRequest, AspirationFailLow;
TimeManager TimeMgr;
- SearchLimits Limits;
// Skill level adjustment
int SkillLevel;
/// Local functions
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove);
+ Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove);
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth);
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue);
bool connected_moves(const Position& pos, Move m1, Move m2);
void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void do_skill_level(Move* best, Move* ponder);
- int elapsed_search_time(int set = 0);
+ int elapsed_time(bool reset = false);
string score_to_uci(Value v, Value alpha = -VALUE_INFINITE, Value beta = VALUE_INFINITE);
string speed_to_uci(int64_t nodes);
string pv_to_uci(const Move pv[], int pvNum, bool chess960);
string pretty_pv(Position& pos, int depth, Value score, int time, Move pv[]);
string depth_to_uci(Depth depth);
- void wait_for_stop_or_ponderhit();
// MovePickerExt template class extends MovePicker and allows to choose at compile
// time the proper moves source according to the type of node. In the default case
// we simply create and use a standard MovePicker object.
template<bool SpNode> struct MovePickerExt : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b) {}
};
// In case of a SpNode we use split point's shared MovePicker object as moves source
template<> struct MovePickerExt<true> : public MovePicker {
- MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b)
+ MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, Stack* ss, Value b)
: MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {}
Move get_next_move() { return mp->get_next_move(); }
/// init_search() is called during startup to initialize various lookup tables
-void init_search() {
+void Search::init() {
int d; // depth (ONE_PLY == 2)
int hd; // half depth (ONE_PLY == 1)
/// perft() is our utility to verify move generation. All the leaf nodes up to
/// the given depth are generated and counted and the sum returned.
-int64_t perft(Position& pos, Depth depth) {
+int64_t Search::perft(Position& pos, Depth depth) {
StateInfo st;
int64_t sum = 0;
}
-/// think() is the external interface to Stockfish's search, and is called when
-/// the program receives the UCI 'go' command. It initializes various global
-/// variables, and calls id_loop(). It returns false when a "quit" command is
-/// received during the search.
+/// think() is the external interface to Stockfish's search, and is called by the
+/// main thread when the program receives the UCI 'go' command. It searches from
+/// RootPosition and at the end prints the "bestmove" to output.
-bool think(Position& pos, const SearchLimits& limits, Move searchMoves[]) {
+void Search::think() {
static Book book; // Defined static to initialize the PRNG only once
- // Save "search start" time and reset elapsed time to zero
- elapsed_search_time(get_system_time());
+ Position& pos = RootPosition;
- // Initialize global search-related variables
- StopOnPonderhit = StopRequest = QuitRequest = AspirationFailLow = false;
- Limits = limits;
+ // Reset elapsed search time
+ elapsed_time(true);
// Set output stream mode: normal or chess960. Castling notation is different
cout << set960(pos.is_chess960());
Move bookMove = book.probe(pos, Options["Best Book Move"].value<bool>());
if (bookMove != MOVE_NONE)
{
- if (Limits.ponder)
- wait_for_stop_or_ponderhit();
+ if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ Threads.wait_for_stop_or_ponderhit();
cout << "bestmove " << bookMove << endl;
- return !QuitRequest;
+ return;
}
}
else
Threads.set_timer(100);
- // Start async mode to catch UCI commands sent to us while searching,
- // like "quit", "stop", etc.
- Threads.start_listener();
-
// We're ready to start thinking. Call the iterative deepening loop function
Move ponderMove = MOVE_NONE;
- Move bestMove = id_loop(pos, searchMoves, &ponderMove);
-
- // From now on any UCI command will be read in-sync with Threads.getline()
- Threads.stop_listener();
+ Move bestMove = id_loop(pos, &RootMoves[0], &ponderMove);
// Stop timer, no need to check for available time any more
Threads.set_timer(0);
// Write current search final statistics to log file
if (Options["Use Search Log"].value<bool>())
{
- int e = elapsed_search_time();
+ int e = elapsed_time();
Log log(Options["Search Log Filename"].value<string>());
log << "Nodes: " << pos.nodes_searched()
// When we reach max depth we arrive here even without a StopRequest, but if
// we are pondering or in infinite search, we shouldn't print the best move
// before we are told to do so.
- if (!StopRequest && (Limits.ponder || Limits.infinite))
- wait_for_stop_or_ponderhit();
+ if (!Signals.stop && (Limits.ponder || Limits.infinite))
+ Threads.wait_for_stop_or_ponderhit();
// Could be MOVE_NONE when searching on a stalemate position
cout << "bestmove " << bestMove;
cout << " ponder " << ponderMove;
cout << endl;
-
- return !QuitRequest;
}
// with increasing depth until the allocated thinking time has been consumed,
// user stops the search, or the maximum search depth is reached.
- Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove) {
+ Move id_loop(Position& pos, Move rootMoves[], Move* ponderMove) {
- SearchStack ss[PLY_MAX_PLUS_2];
+ Stack ss[PLY_MAX_PLUS_2];
Value bestValues[PLY_MAX_PLUS_2];
int bestMoveChanges[PLY_MAX_PLUS_2];
int depth, aspirationDelta;
bool bestMoveNeverChanged = true;
// Initialize stuff before a new search
- memset(ss, 0, 4 * sizeof(SearchStack));
+ memset(ss, 0, 4 * sizeof(Stack));
TT.new_search();
H.clear();
*ponderMove = bestMove = skillBest = skillPonder = MOVE_NONE;
ss->currentMove = MOVE_NULL; // Hack to skip update gains
// Moves to search are verified and copied
- Rml.init(pos, searchMoves);
+ Rml.init(pos, rootMoves);
// Handle special case of searching on a mate/stalemate position
if (!Rml.size())
}
// Iterative deepening loop until requested to stop or target depth reached
- while (!StopRequest && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
+ while (!Signals.stop && ++depth <= PLY_MAX && (!Limits.maxDepth || depth <= Limits.maxDepth))
{
// Save now last iteration's scores, before Rml moves are reordered
for (size_t i = 0; i < Rml.size(); i++)
// If search has been stopped exit the aspiration window loop,
// note that sorting and writing PV back to TT is safe becuase
// Rml is still valid, although refers to the previous iteration.
- if (StopRequest)
+ if (Signals.stop)
break;
// Send full PV info to GUI if we are going to leave the loop or
// if we have a fail high/low and we are deep in the search. UCI
// protocol requires to send all the PV lines also if are still
// to be searched and so refer to the previous search's score.
- if ((bestValue > alpha && bestValue < beta) || elapsed_search_time() > 2000)
+ if ((bestValue > alpha && bestValue < beta) || elapsed_time() > 2000)
for (int i = 0; i < std::min(UCIMultiPV, (int)Rml.size()); i++)
{
bool updated = (i <= MultiPVIdx);
}
else if (bestValue <= alpha)
{
- AspirationFailLow = true;
- StopOnPonderhit = false;
+ Signals.failedLowAtRoot = true;
+ Signals.stopOnPonderhit = false;
alpha = std::max(alpha - aspirationDelta, -VALUE_INFINITE);
aspirationDelta += aspirationDelta / 2;
if (Options["Use Search Log"].value<bool>())
{
Log log(Options["Search Log Filename"].value<string>());
- log << pretty_pv(pos, depth, bestValue, elapsed_search_time(), &Rml[0].pv[0]) << endl;
+ log << pretty_pv(pos, depth, bestValue, elapsed_time(), &Rml[0].pv[0]) << endl;
}
// Filter out startup noise when monitoring best move stability
bestMoveNeverChanged = false;
// Do we have time for the next iteration? Can we stop searching now?
- if (!StopRequest && !StopOnPonderhit && Limits.useTimeManagement())
+ if (!Signals.stop && !Signals.stopOnPonderhit && Limits.useTimeManagement())
{
+ bool stop = false; // Local variable instead of the volatile Signals.stop
+
// Take in account some extra time if the best move has changed
if (depth > 4 && depth < 50)
TimeMgr.pv_instability(bestMoveChanges[depth], bestMoveChanges[depth - 1]);
// Stop search if most of available time is already consumed. We probably don't
// have enough time to search the first move at the next iteration anyway.
- if (elapsed_search_time() > (TimeMgr.available_time() * 62) / 100)
- StopRequest = true;
+ if (elapsed_time() > (TimeMgr.available_time() * 62) / 100)
+ stop = true;
// Stop search early if one move seems to be much better than others
if ( depth >= 10
- && !StopRequest
+ && !stop
&& ( bestMoveNeverChanged
- || elapsed_search_time() > (TimeMgr.available_time() * 40) / 100))
+ || elapsed_time() > (TimeMgr.available_time() * 40) / 100))
{
Value rBeta = bestValue - EasyMoveMargin;
(ss+1)->excludedMove = bestMove;
(ss+1)->excludedMove = MOVE_NONE;
if (v < rBeta)
- StopRequest = true;
+ stop = true;
}
- // If we are allowed to ponder do not stop the search now but keep pondering
- if (StopRequest && Limits.ponder) // FIXME Limits.ponder is racy
+ if (stop)
{
- StopRequest = false;
- StopOnPonderhit = true;
+ // If we are allowed to ponder do not stop the search now but
+ // keep pondering until GUI sends "ponderhit" or "stop".
+ if (Limits.ponder)
+ Signals.stopOnPonderhit = true;
+ else
+ Signals.stop = true;
}
}
}
// here: This is taken care of after we return from the split point.
template <NodeType NT>
- Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV || NT == SplitPointRoot);
const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV || NT == SplitPointRoot);
ValueType vt;
Value bestValue, value, oldAlpha;
Value refinedValue, nullValue, futilityBase, futilityValue;
- bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous;
+ bool isPvMove, inCheck, singularExtensionNode, givesCheck;
+ bool captureOrPromotion, dangerous, doFullDepthSearch;
int moveCount = 0, playedMoveCount = 0;
Thread& thread = Threads[pos.thread()];
SplitPoint* sp = NULL;
}
// Step 2. Check for aborted search and immediate draw
- if (( StopRequest
+ if (( Signals.stop
|| pos.is_draw<false>()
|| ss->ply > PLY_MAX) && !RootNode)
return VALUE_DRAW;
if (RootNode)
{
// This is used by time management
- FirstRootMove = (moveCount == 1);
+ Signals.firstRootMove = (moveCount == 1);
// Save the current node count before the move is searched
nodes = pos.nodes_searched();
// For long searches send current move info to GUI
- if (pos.thread() == 0 && elapsed_search_time() > 2000)
+ if (pos.thread() == 0 && elapsed_time() > 2000)
cout << "info" << depth_to_uci(depth)
<< " currmove " << move
<< " currmovenumber " << moveCount + MultiPVIdx << endl;
Value rBeta = ttValue - int(depth);
ss->excludedMove = move;
ss->skipNullMove = true;
- Value v = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
+ value = search<NonPV>(pos, ss, rBeta - 1, rBeta, depth / 2);
ss->skipNullMove = false;
ss->excludedMove = MOVE_NONE;
ss->bestMove = MOVE_NONE;
- if (v < rBeta)
+ if (value < rBeta)
ext = ONE_PLY;
}
}
// Step 14. Make the move
pos.do_move(move, st, ci, givesCheck);
- // Step extra. pv search (only in PV nodes)
- // The first move in list is the expected PV
- if (isPvMove)
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- else
+ // Step 15. Reduced depth search (LMR). If the move fails high will be
+ // re-searched at full depth.
+ if ( depth > 3 * ONE_PLY
+ && !isPvMove
+ && !captureOrPromotion
+ && !dangerous
+ && !is_castle(move)
+ && ss->killers[0] != move
+ && ss->killers[1] != move)
{
- // Step 15. Reduced depth search
- // If the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( depth > 3 * ONE_PLY
- && !captureOrPromotion
- && !dangerous
- && !is_castle(move)
- && ss->killers[0] != move
- && ss->killers[1] != move
- && (ss->reduction = reduction<PvNode>(depth, moveCount)) != DEPTH_ZERO)
- {
- Depth d = newDepth - ss->reduction;
- alpha = SpNode ? sp->alpha : alpha;
+ ss->reduction = reduction<PvNode>(depth, moveCount);
+ Depth d = newDepth - ss->reduction;
+ alpha = SpNode ? sp->alpha : alpha;
- value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
+ value = d < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, d);
- ss->reduction = DEPTH_ZERO;
- doFullDepthSearch = (value > alpha);
- }
+ doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
+ ss->reduction = DEPTH_ZERO;
+ }
+ else
+ doFullDepthSearch = !isPvMove;
- // Step 16. Full depth search
- if (doFullDepthSearch)
- {
- alpha = SpNode ? sp->alpha : alpha;
- value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
- : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
-
- // Step extra. pv search (only in PV nodes)
- // Search only for possible new PV nodes, if instead value >= beta then
- // parent node fails low with value <= alpha and tries another move.
- if (PvNode && value > alpha && (RootNode || value < beta))
- value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
- : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
- }
+ // Step 16. Full depth search, when LMR is skipped or fails high
+ if (doFullDepthSearch)
+ {
+ alpha = SpNode ? sp->alpha : alpha;
+ value = newDepth < ONE_PLY ? -qsearch<NonPV>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
+ : - search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth);
}
+ // Only for PV nodes do a full PV search on the first move or after a fail
+ // high, in the latter case search only if value < beta, otherwise let the
+ // parent node to fail low with value <= alpha and to try another move.
+ if (PvNode && (isPvMove || (value > alpha && (RootNode || value < beta))))
+ value = newDepth < ONE_PLY ? -qsearch<PV>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
+ : - search<PV>(pos, ss+1, -beta, -alpha, newDepth);
+
// Step 17. Undo move
pos.undo_move(move);
// was aborted because the user interrupted the search or because we
// ran out of time. In this case, the return value of the search cannot
// be trusted, and we don't update the best move and/or PV.
- if (RootNode && !StopRequest)
+ if (RootNode && !Signals.stop)
{
// Remember searched nodes counts for this move
RootMove* rm = Rml.find(move);
&& depth >= Threads.min_split_depth()
&& bestValue < beta
&& Threads.available_slave_exists(pos.thread())
- && !StopRequest
+ && !Signals.stop
&& !thread.cutoff_occurred())
bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, depth,
threatMove, moveCount, &mp, NT);
// Step 21. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (!SpNode && !StopRequest && !thread.cutoff_occurred())
+ if (!SpNode && !Signals.stop && !thread.cutoff_occurred())
{
move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
// less than ONE_PLY).
template <NodeType NT>
- Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) {
+ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
const bool PvNode = (NT == PV);
// current_search_time() returns the number of milliseconds which have passed
// since the beginning of the current search.
- int elapsed_search_time(int set) {
+ int elapsed_time(bool reset) {
static int searchStartTime;
- if (set)
- searchStartTime = set;
+ if (reset)
+ searchStartTime = get_system_time();
return get_system_time() - searchStartTime;
}
string speed_to_uci(int64_t nodes) {
std::stringstream s;
- int t = elapsed_search_time();
+ int t = elapsed_time();
s << " nodes " << nodes
<< " nps " << (t > 0 ? int(nodes * 1000 / t) : 0)
}
- // wait_for_stop_or_ponderhit() is called when the maximum depth is reached
- // while the program is pondering. The point is to work around a wrinkle in
- // the UCI protocol: When pondering, the engine is not allowed to give a
- // "bestmove" before the GUI sends it a "stop" or "ponderhit" command.
- // We simply wait here until one of these commands (that raise StopRequest) is
- // sent, and return, after which the bestmove and pondermove will be printed.
-
- void wait_for_stop_or_ponderhit() {
-
- string cmd;
- StopOnPonderhit = true;
-
- while (!StopRequest)
- {
- Threads.getline(cmd);
- do_uci_async_cmd(cmd);
- }
- }
-
-
// When playing with strength handicap choose best move among the MultiPV set
// using a statistical rule dependent on SkillLevel. Idea by Heinz van Saanen.
/// RootMove and RootMoveList method's definitions
- void RootMoveList::init(Position& pos, Move searchMoves[]) {
+ void RootMoveList::init(Position& pos, Move rootMoves[]) {
Move* sm;
bestMoveChanges = 0;
// Generate all legal moves and add them to RootMoveList
for (MoveList<MV_LEGAL> ml(pos); !ml.end(); ++ml)
{
- // If we have a searchMoves[] list then verify the move
+ // If we have a rootMoves[] list then verify the move
// is in the list before to add it.
- for (sm = searchMoves; *sm && *sm != ml.move(); sm++) {}
+ for (sm = rootMoves; *sm && *sm != ml.move(); sm++) {}
- if (sm != searchMoves && *sm != ml.move())
+ if (sm != rootMoves && *sm != ml.move())
continue;
RootMove rm;
assert(!do_terminate);
// Copy split point position and search stack and call search()
- SearchStack ss[PLY_MAX_PLUS_2];
+ Stack ss[PLY_MAX_PLUS_2];
SplitPoint* tsp = splitPoint;
Position pos(*tsp->pos, threadID);
- memcpy(ss, tsp->ss - 1, 4 * sizeof(SearchStack));
+ memcpy(ss, tsp->ss - 1, 4 * sizeof(Stack));
(ss+1)->sp = tsp;
if (tsp->nodeType == Root)
}
-// do_uci_async_cmd() is called by listener thread when in async mode and 'cmd'
-// input line is received from the GUI.
-
-void do_uci_async_cmd(const std::string& cmd) {
-
- if (cmd == "quit")
- QuitRequest = StopRequest = true;
-
- else if (cmd == "stop")
- StopRequest = true;
-
- else if (cmd == "ponderhit")
- {
- // The opponent has played the expected move. GUI sends "ponderhit" if
- // we were told to ponder on the same move the opponent has played. We
- // should continue searching but switching from pondering to normal search.
- Limits.ponder = false;
-
- if (StopOnPonderhit)
- StopRequest = true;
- }
-}
-
-
// do_timer_event() is called by the timer thread when the timer triggers
void do_timer_event() {
static int lastInfoTime;
- int e = elapsed_search_time();
+ int e = elapsed_time();
// Print debug information every one second
if (!lastInfoTime || get_system_time() - lastInfoTime >= 1000)
if (Limits.ponder)
return;
- bool stillAtFirstMove = FirstRootMove
- && !AspirationFailLow
+ bool stillAtFirstMove = Signals.firstRootMove
+ && !Signals.failedLowAtRoot
&& e > TimeMgr.available_time();
bool noMoreTime = e > TimeMgr.maximum_time()
if ( (Limits.useTimeManagement() && noMoreTime)
|| (Limits.maxTime && e >= Limits.maxTime)
/* missing nodes limit */ ) // FIXME
- StopRequest = true;
+ Signals.stop = true;
}
projects / stockfish / blobdiff