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BadFish/src/thread.h
Marco Costalba 5b35c149e8 Do not modify alpha in split()
When calling split or we immediately return because unable to
find available slaves, or we start searching on _all_ the moves
of the node or until a cut-off occurs, so that when returning
from split we immediately leave the moves loop.

Because of this we don't need to change alpha inside split() and
we can use a signature similar to search() so to better clarify
that split() is actually a search on the remaining node's moves.

No functional change with faked split.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
2011-08-07 15:10:41 +01:00

132 lines
4 KiB
C++

/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#if !defined(THREAD_H_INCLUDED)
#define THREAD_H_INCLUDED
#include <cstring>
#include "lock.h"
#include "material.h"
#include "movepick.h"
#include "pawns.h"
#include "position.h"
const int MAX_THREADS = 32;
const int MAX_ACTIVE_SPLIT_POINTS = 8;
struct SplitPoint {
// Const data after splitPoint has been setup
SplitPoint* parent;
const Position* pos;
Depth depth;
Value beta;
int nodeType;
int ply;
int master;
Move threatMove;
// Const pointers to shared data
MovePicker* mp;
SearchStack* ss;
// Shared data
Lock lock;
volatile int64_t nodes;
volatile Value alpha;
volatile Value bestValue;
volatile int moveCount;
volatile bool is_betaCutoff;
volatile bool is_slave[MAX_THREADS];
};
/// Thread struct is used to keep together all the thread related stuff like locks,
/// state and especially split points. We also use per-thread pawn and material hash
/// tables so that once we get a pointer to an entry its life time is unlimited and
/// we don't have to care about someone changing the entry under our feet.
struct Thread {
enum ThreadState
{
INITIALIZING, // Thread is initializing itself
SEARCHING, // Thread is performing work
AVAILABLE, // Thread is waiting for work
BOOKED, // Other thread (master) has booked us as a slave
WORKISWAITING, // Master has ordered us to start
TERMINATED // We are quitting and thread is terminated
};
void wake_up();
bool cutoff_occurred() const;
bool is_available_to(int master) const;
SplitPoint splitPoints[MAX_ACTIVE_SPLIT_POINTS];
MaterialInfoTable materialTable;
PawnInfoTable pawnTable;
int maxPly;
Lock sleepLock;
WaitCondition sleepCond;
volatile ThreadState state;
SplitPoint* volatile splitPoint;
volatile int activeSplitPoints;
};
/// ThreadsManager class is used to handle all the threads related stuff like init,
/// starting, parking and, the most important, launching a slave thread at a split
/// point. All the access to shared thread data is done through this class.
class ThreadsManager {
/* As long as the single ThreadsManager object is defined as a global we don't
need to explicitly initialize to zero its data members because variables with
static storage duration are automatically set to zero before enter main()
*/
public:
Thread& operator[](int threadID) { return threads[threadID]; }
void init();
void exit();
void init_hash_tables();
int min_split_depth() const { return minimumSplitDepth; }
int size() const { return activeThreads; }
void set_size(int cnt) { activeThreads = cnt; }
void read_uci_options();
bool available_slave_exists(int master) const;
void idle_loop(int threadID, SplitPoint* sp);
template <bool Fake>
Value split(Position& pos, SearchStack* ss, Value alpha, Value beta, Value bestValue,
Depth depth, Move threatMove, int moveCount, MovePicker* mp, int nodeType);
private:
Thread threads[MAX_THREADS];
Lock threadsLock;
Depth minimumSplitDepth;
int maxThreadsPerSplitPoint;
int activeThreads;
bool useSleepingThreads;
volatile bool allThreadsShouldExit;
};
extern ThreadsManager Threads;
#endif // !defined(THREAD_H_INCLUDED)