threads.h

loki库的源代码。loki库是以模板技术和面向对象技术为基础的c++类库。

#ifndef THREADS_H_
#define THREADS_H_
////////////////////////////////////////////////////////////////////////////////
// macro DEFAULT_THREADING
// Selects the default threading model for certain components of Loki
// If you don't define it, it defaults to single-threaded
// All classes in Loki have configurable threading model; DEFAULT_THREADING
// affects only default template arguments
////////////////////////////////////////////////////////////////////////////////

// Last update: Mar 26, 2003
// note: In this VC 6 port all template policies become non-templates with
// either member-template functions or a nested template struct named In

// Changed wrong ctor/dtor names in ObjectLevelLockable.
// Thanks to Adi Shavit for pointing that out

#ifndef DEFAULT_THREADING
#define DEFAULT_THREADING /**/ ::Loki::SingleThreaded
#endif

namespace Loki
{
////////////////////////////////////////////////////////////////////////////////
// class template SingleThreaded
// Implementation of the ThreadingModel policy used by various classes
// Implements a single-threaded model; no synchronization
////////////////////////////////////////////////////////////////////////////////
	class SingleThreaded
    {
    public:
        template <class Host>
		struct In
		{
			struct Lock
			{
				Lock() {}
				explicit Lock(const SingleThreaded&) {}
			};

			typedef Host VolatileType;

			typedef int IntType;

			static IntType AtomicAdd(volatile IntType& lval, IntType val)
			{ return lval += val; }

			static IntType AtomicSubtract(volatile IntType& lval, IntType val)
			{ return lval -= val; }

			static IntType AtomicMultiply(volatile IntType& lval, IntType val)
			{ return lval *= val; }

			static IntType AtomicDivide(volatile IntType& lval, IntType val)
			{ return lval /= val; }

			static IntType AtomicIncrement(volatile IntType& lval)
			{ return ++lval; }

			static IntType AtomicDecrement(volatile IntType& lval)
			{ return --lval; }

			// The following function uses the undefined variable val.
			// Moreover I couldn't find the function in the orginial loki-lib.
			// I therefore commented the function out
			/*
			static IntType AtomicDivide(volatile IntType& lval)
			{ return lval /= val; }
			*/
			static void AtomicAssign(volatile IntType & lval, IntType val)
			{ lval = val; }

			static void AtomicAssign(IntType & lval, volatile IntType & val)
			{ lval = val; }
		};
    };

#ifdef _WINDOWS_

////////////////////////////////////////////////////////////////////////////////
// class template ObjectLevelLockable
// Implementation of the ThreadingModel policy used by various classes
// Implements a object-level locking scheme
////////////////////////////////////////////////////////////////////////////////


    struct ObjectLevelLockable
    {
		template <class Host>
		struct In
		{
		private:
			CRITICAL_SECTION mtx_;

		public:
			In()
			{
				::InitializeCriticalSection(&mtx_);
			}

			~In()
			{
				::DeleteCriticalSection(&mtx_);
			}

			class Lock;
			friend class Lock;

			class Lock
			{
				ObjectLevelLockable::In<Host>& host_;

				Lock(const Lock&);
				Lock& operator=(const Lock&);
				//Lock(); // buggy design
			public:

				explicit Lock(ObjectLevelLockable::In<Host>& host) : host_(host)
				{
					::EnterCriticalSection(&host_.mtx_);
				}
				~Lock()
				{
					::LeaveCriticalSection(&host_.mtx_);
				}
			};

			typedef volatile Host VolatileType;

			typedef LONG IntType;

			static IntType AtomicIncrement(volatile IntType& lval)
			{ return InterlockedIncrement(&const_cast<IntType&>(lval)); }

			static IntType AtomicDecrement(volatile IntType& lval)
			{ return InterlockedDecrement(&const_cast<IntType&>(lval)); }

			static void AtomicAssign(volatile IntType& lval, IntType val)
			{ InterlockedExchange(&const_cast<IntType&>(lval), val); }

			static void AtomicAssign(IntType& lval, volatile IntType& val)
			{ InterlockedExchange(&lval, val); }
		};
    };

    struct ClassLevelLockable
    {
		template <class Host>
		struct In
		{
		public:
			struct Initializer;
			friend struct Initializer;
			struct Initializer
			{

				CRITICAL_SECTION mtx_;

				Initializer()
				{
					::InitializeCriticalSection(&mtx_);
				}
				~Initializer()
				{
					::DeleteCriticalSection(&mtx_);
				}
			};

			static Initializer initializer_;

		public:
			class Lock;
			friend class Lock;

			class Lock
			{
				Lock(const Lock&);
				Lock& operator=(const Lock&);
			public:
				Lock()
				{
					::EnterCriticalSection(&initializer_.mtx_);
				}
				explicit Lock(ClassLevelLockable&)
				{
					::EnterCriticalSection(&initializer_.mtx_);
				}
				~Lock()
				{
					::LeaveCriticalSection(&initializer_.mtx_);
				}
			};

			typedef volatile Host VolatileType;

			typedef LONG IntType;

			static IntType AtomicIncrement(volatile IntType& lval)
			{ return InterlockedIncrement(&const_cast<IntType&>(lval)); }

			static IntType AtomicDecrement(volatile IntType& lval)
			{ return InterlockedDecrement(&const_cast<IntType&>(lval)); }

			static void AtomicAssign(volatile IntType& lval, IntType val)
			{ InterlockedExchange(&const_cast<IntType&>(lval), val); }

			static void AtomicAssign(IntType& lval, volatile IntType& val)
			{ InterlockedExchange(&lval, val); }
		};
    };

    template <class Host>
	typename Loki::ClassLevelLockable::template In<Host>::Initializer
	Loki::ClassLevelLockable::template In<Host>::initializer_;

#endif
}

////////////////////////////////////////////////////////////////////////////////
// Change log:
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// Oct	06,	2002: ported by Benjamin Kaufmann to MSVC 6.0
// Feb	20, 2003: corrected constructor parameter in ObjectLevelLockable::Lock
// Mar	26, 2003: added Loki-Namespace-Qualification to definition of
//					ClassLevelLockable's static member.
////////////////////////////////////////////////////////////////////////////////

#endif