#ifndef THREAD_H_INCLUDED
#define THREAD_H_INCLUDED
+#include <atomic>
#include <bitset>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
#include <vector>
#include "material.h"
struct Thread;
-const int MAX_THREADS = 128;
-const int MAX_SPLITPOINTS_PER_THREAD = 8;
-const int MAX_SLAVES_PER_SPLITPOINT = 4;
+const size_t MAX_THREADS = 128;
+const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
+const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
-/// Mutex and ConditionVariable struct are wrappers of the low level locking
-/// machinery and are modeled after the corresponding C++11 classes.
-struct Mutex {
- Mutex() { lock_init(l); }
- ~Mutex() { lock_destroy(l); }
+/// Spinlock class wraps low level atomic operations to provide a spin lock
- void lock() { lock_grab(l); }
- void unlock() { lock_release(l); }
+class Spinlock {
-private:
- friend struct ConditionVariable;
+ std::atomic_int lock;
- Lock l;
-};
-
-struct ConditionVariable {
- ConditionVariable() { cond_init(c); }
- ~ConditionVariable() { cond_destroy(c); }
-
- void wait(Mutex& m) { cond_wait(c, m.l); }
- void wait_for(Mutex& m, int ms) { timed_wait(c, m.l, ms); }
- void notify_one() { cond_signal(c); }
-
-private:
- WaitCondition c;
+public:
+ Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+ void acquire() {
+ while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+ while (lock.load(std::memory_order_relaxed) <= 0) {}
+ }
+ void release() { lock.store(1, std::memory_order_release); }
};
// Const data after split point has been setup
const Position* pos;
Search::Stack* ss;
- Thread* masterThread;
+ Thread* master;
Depth depth;
Value beta;
int nodeType;
SplitPoint* parentSplitPoint;
// Shared variable data
- Mutex mutex;
+ Spinlock spinlock;
std::bitset<MAX_THREADS> slavesMask;
- int slavesCount;
volatile bool allSlavesSearching;
volatile uint64_t nodes;
volatile Value alpha;
struct ThreadBase {
- ThreadBase() : handle(NativeHandle()), exit(false) {}
- virtual ~ThreadBase() {}
+ virtual ~ThreadBase() = default;
virtual void idle_loop() = 0;
void notify_one();
void wait_for(volatile const bool& b);
- Mutex mutex;
- ConditionVariable sleepCondition;
- NativeHandle handle;
- volatile bool exit;
+ std::thread nativeThread;
+ std::mutex mutex;
+ std::condition_variable sleepCondition;
+ volatile bool exit = false;
};
Thread();
virtual void idle_loop();
bool cutoff_occurred() const;
- bool available_to(const Thread* master) const;
+ bool can_join(const SplitPoint* sp) const;
void split(Position& pos, Search::Stack* ss, Value alpha, Value beta, Value* bestValue, Move* bestMove,
Depth depth, int moveCount, MovePicker* movePicker, int nodeType, bool cutNode);
size_t idx;
int maxPly;
SplitPoint* volatile activeSplitPoint;
- volatile int splitPointsSize;
+ volatile size_t splitPointsSize;
volatile bool searching;
};
/// special threads: the main one and the recurring timer.
struct MainThread : public Thread {
- MainThread() : thinking(true) {} // Avoid a race with start_thinking()
virtual void idle_loop();
- volatile bool thinking;
+ volatile bool thinking = true; // Avoid a race with start_thinking()
};
struct TimerThread : public ThreadBase {
static const int Resolution = 5; // Millisec between two check_time() calls
- TimerThread() : run(false) {}
virtual void idle_loop();
- bool run;
+ bool run = false;
};
MainThread* main() { return static_cast<MainThread*>(at(0)); }
void read_uci_options();
- Thread* available_slave(const Thread* master) const;
+ Thread* available_slave(const SplitPoint* sp) const;
void wait_for_think_finished();
void start_thinking(const Position&, const Search::LimitsType&, Search::StateStackPtr&);
Depth minimumSplitDepth;
- Mutex mutex;
- ConditionVariable sleepCondition;
+ Spinlock spinlock;
+ std::condition_variable sleepCondition;
TimerThread* timer;
};