_mutex.h

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#ifndef _RWSTD_RW_MUTEX_H_INCLUDED
#define _RWSTD_RW_MUTEX_H_INCLUDED
 
 
#if __GNUG__ >= 3
#  pragma GCC system_header
#endif   // gcc >= 3
 
 
#ifndef _RWSTD_RW_DEFS_H_INCLUDED
#  include <rw/_defs.h>
#endif   // _RWSTD_RW_DEFS_H_INCLUDED
 
 
#ifndef _RWSTD_RW_ATOMIC_H_INCLUDED
#  include <rw/_atomic.h>
#endif   // _RWSTD_RW_ATOMIC_H_INCLUDED
 
 
#ifdef _RWSTD_REENTRANT
 
#  ifndef _RWSTD_RW_EXCEPTION_H_INCLUDED
#    include <rw/_exception.h>
#  endif   // _RWSTD_RW_EXCEPTION_INCLUDED
 
#  ifndef _RWSTD_RW_ERROR_H_INCLUDED
#    include <rw/_error.h>
#  endif   // _RWSTD_RW_ERROR_H_INCLUDED
 
 
// work around SunOS 5.{8,9}/SunPro bug (see PR #26255)
#  if defined (__SunOS_5_8) || defined (__SunOS_5_9)
#    undef _TIME_T
#  endif   // __SunOS_5_{8,9}
 
#  if defined (_RWSTD_SOLARIS_THREADS)  // assuming Solaris 2.1 or greater
#    include <rw/_mutex-solaris.h>
#  elif defined (_RWSTD_POSIX_THREADS)
#    include <rw/_mutex-pthread.h>
#  elif defined (_RWSTD_DCE_THREADS)
#    include <rw/_mutex-dce.h>
#  elif defined (_WIN32)
#    include <rw/_mutex-win32.h>
#  elif defined (__OS2__)
#    include <rw/_mutex-os2.h>
#  else
#    error unknown thread environment
#  endif
 
 
#  if defined(_RWSTD_NO_STATIC_MUTEX_INIT)
#    include <new>
#  endif  //_RWSTD_NO_STATIC_MUTEX_INIT
 
 
_RWSTD_NAMESPACE (__rw) { 
 
// a using declaration (rather than a directive)
// used to work around yet another MSVC 6.0 bug
_USING (std::exception);
 
class __rw_thread_error : public exception
{
public:
    __rw_thread_error () _THROWS (())
    : exception () { }
 
    virtual const char* what () const _THROWS (()) {
        return "thread synchronization error";
    }
};                            
 
 
// POD type with no user-defined ctor or dtor facilitates static
// initialization of mutex objects with static storage duration
// (important during library initialziation time)
class _RWSTD_EXPORT __rw_mutex_base
{
public:
 
    void _C_acquire () {
#  if !defined (__HP_aCC) || __HP_aCC > 32700
        if (0 != _RWSTD_MUTEX_LOCK (_C_mutex))
            _RW::__rw_throw (_RWSTD_ERROR_RUNTIME_ERROR,
                             "synchronization error");
#  else
        // working around an HP aCC 3.27 bug JAGac88738
        _RWSTD_MUTEX_LOCK (_C_mutex);
#  endif   // !defined (__HP_aCC) || __HP_aCC > 32700
    }
 
    void _C_release ();
 
#  ifdef _RWSTD_NO_STATIC_MUTEX_INIT
 
    // static initialization not an option, define ctor and dtor
    // and make member mutex private
 
    __rw_mutex_base ();
 
    ~__rw_mutex_base ();
 
private:
 
    // not defined
    __rw_mutex_base (const __rw_mutex_base&);
    __rw_mutex_base& operator= (const __rw_mutex_base&);
 
#  endif   // _RWSTD_NO_STATIC_MUTEX_INIT
 
    _RWSTD_MUTEX_T _C_mutex;   // the real thing
};
 
 
inline void __rw_mutex_base::_C_release ()
{
    // we should NOT throw from here as _C_release will typically be called
    // during the destruction of local objects such as __rw_guard (perhaps
    // due to another exception)
    _RWSTD_MUTEX_UNLOCK (_C_mutex);
}
 
 
// non-POD type, always initializes mutex data member via a function call
class _RWSTD_EXPORT __rw_mutex: public __rw_mutex_base
{
public:
 
#  ifndef _RWSTD_NO_STATIC_MUTEX_INIT
 
    __rw_mutex ();
 
    ~__rw_mutex ();
 
private:
 
    // not defined
    __rw_mutex (const __rw_mutex&);
    __rw_mutex& operator= (const __rw_mutex&);
 
#  endif   // _RWSTD_NO_STATIC_MUTEX_INIT
 
};
 
 
#  ifndef _RWSTD_NO_STATIC_MUTEX_INIT
 
// helper factory class - static member is guranteed to be constructed
// during static initialization; objects of this POD class are not
// destroyed during program termination (important to allow them
// to be used in dtors of other objects with static storage duration)
template <class _TypeT>
struct __rw_static_mutex
{
    static __rw_mutex_base _C_mutex;
};
 
 
template <class _TypeT>
__rw_mutex_base __rw_static_mutex<_TypeT>::_C_mutex
 
#    ifdef _RWSTD_MUTEX_INITIALIZER
 
    = { _RWSTD_MUTEX_INITIALIZER }
 
#      undef _RWSTD_MUTEX_INITIALIZER
#    endif   // _RWSTD_MUTEX_INITIALIZER
        ;
 
#    if _RWSTD_INSTANTIATE (_STATIC_MUTEX, _INT)
 
// explicitly instantiated to work around a g++ 2.95.2 bug on COFF systems
// (such as IBM AIX or DEC OSF1) where it "forgets" to do so implicitly for
// explicitly initialized static data members
_RWSTD_INSTANTIATE_1 (class _RWSTD_TI_EXPORT __rw_static_mutex<int>);
_RWSTD_INSTANTIATE_1 (class _RWSTD_TI_EXPORT __rw_static_mutex<size_t>);
 
#    endif   // _RWSTD_INSTANTIATE (_STATIC_MUTEX, _INT)
 
 
inline __rw_mutex::__rw_mutex ()
 
#  else   // if defined (_RWSTD_NO_STATIC_MUTEX_INIT)
 
inline __rw_mutex_base::__rw_mutex_base ()
 
#  endif   // _RWSTD_NO_STATIC_MUTEX_INIT
{ 
    if (0 != _RWSTD_MUTEX_INIT (_C_mutex))
        _RW::__rw_throw (_RWSTD_ERROR_RUNTIME_ERROR, "synchronization error");
}
 
#  ifndef _RWSTD_NO_STATIC_MUTEX_INIT
 
inline __rw_mutex::~__rw_mutex () 
 
#  else   // if defined (_RWSTD_NO_STATIC_MUTEX_INIT)
 
inline __rw_mutex_base::~__rw_mutex_base () 
 
#  endif   // _RWSTD_NO_STATIC_MUTEX_INIT
{
    _RWSTD_MUTEX_DESTROY (_C_mutex);
}
 
// type used in instantiating __rw_get_static_mutex
template<class _TypeT, int _IntI> struct __rw_type { };
 
// mutex factory function avoids problematic initialization dependencies
// introduced by definitions of mutexes with static storage duration
// instead of defining a static mutex member that may not be initialized
// before first use, a non-local class may either declare a unique type
// (enum or class) or use itself as this type, and call this template
// function with a ptr to that type to obtain an initialized mutex object
// that is the same for each unique type passed to the function
 
#  ifndef _RWSTD_NO_STATIC_MUTEX_INIT
 
template <class _TypeT>
inline
__rw_mutex_base& __rw_get_static_mutex (_TypeT*)
{
    // POD mutex already initialized during static initialization
    return __rw_static_mutex<_TypeT>::_C_mutex;
}
 
#  else   // if defined (_RWSTD_NO_STATIC_MUTEX_INIT)
 
#    ifdef _INLINE_WITH_STATICS
 
template <class _TypeT>
_INLINE_WITH_STATICS
__rw_mutex_base& __rw_get_static_mutex (_TypeT*)
 
#    else    // if !defined (_INLINE_WITH_STATICS)
 
template <class _TypeT>
__rw_mutex_base& __rw_get_static_mutex (_TypeT*)
 
#    endif   // _INLINE_WITH_STATICS
 
{
    // allocate properly aligned memory for static mutex (necessary
    // to prevent static local mutex from being destroyed during
    // program termination)
    union __mutex_buf_t {
        long double __pad;   // force alignment (must be first)
        char        __buf [sizeof (__rw_mutex_base)];
    };
 
    // using a named union to work around a bug in HP aCC 3.14.10 (JAGad03246)
    static __mutex_buf_t __mutex_buf;
 
    // initialize mutex reference to refer to the static buffer space
    __rw_mutex_base &__mutex =
        _RWSTD_REINTERPRET_CAST (__rw_mutex_base&, __mutex_buf);
 
    // keep track of number of mutex initialization attempts
    // although `init' may reach a value greater than 1, `mutex'
    // will (should) never be multiply initialized
 
    // implicit initialization used to prevent a g++ 2.95.2 warning on Tru64
    // sorry: semantics of inline function static data are wrong (you'll wind
    // up with multiple copies)
    static volatile int __cntr /* = 0 */;   // initialization counter
 
#    if !defined (_RWSTD_NO_ATOMIC_OPS) && !defined (_RWSTD_NO_INT_ATOMIC_OPS)
    // MT safe
    // cast __cntr to int& (see STDCXX-792)
    // casting should be removed after fixing STDCXX-794
    if (0 == __cntr && 1 == _RWSTD_ATOMIC_PREINCREMENT (
            _RWSTD_CONST_CAST (int&, __cntr), false))
#    else   // _RWSTD_NO_ATOMIC_OPS || _RWSTD_NO_INT_ATOMIC_OPS
    // not so safe (volatile should help)
    if (0 == __cntr && 1 == ++__cntr)
#    endif   // !_RWSTD_NO_ATOMIC_OPS && !_RWSTD_NO_INT_ATOMIC_OPS
 
    {
        // manually initialize `mutex' via a call to placement new
        new (&__mutex) __rw_mutex_base ();
 
        // indicate that `mutex' has been fully initialized
        // (unlikely that we'll have more than 1000 threads)
        __cntr += 1000;
    }
    else
        // busywait until `mutex' has been completely initialized
        while (__cntr < 1000);
 
    return __mutex;
}
 
#  endif   //_RWSTD_NO_STATIC_MUTEX_INIT
 
 
// clean up
#  undef _RWSTD_MUTEX_LOCK
#  undef _RWSTD_MUTEX_UNLOCK
#  undef _RWSTD_MUTEX_T
 
 
// allows safe use of a mutex in the presence of exceptions
class __rw_guard
{
    __rw_mutex_base *_C_mutex;
 
    // undefined
    __rw_guard& operator= (const __rw_guard&);
    
public:
 
    __rw_guard (__rw_guard &__rhs)
        : _C_mutex (__rhs._C_mutex) {
        __rhs._C_mutex = 0;
    }
 
    __rw_guard (__rw_mutex_base &__mutex): _C_mutex (&__mutex) {
        _C_mutex->_C_acquire ();
    }
 
    __rw_guard (__rw_mutex_base *__mutex): _C_mutex (__mutex) {
        if (_C_mutex)
            _C_mutex->_C_acquire ();
    }
 
    ~__rw_guard () {
        if (_C_mutex)
            _C_mutex->_C_release ();
    }
 
    __rw_mutex_base* _C_set (__rw_mutex_base *__mutex) {
        __rw_mutex_base *__tmp = _C_mutex;
        return _C_mutex = __mutex, __tmp;
    }
};
 
 
// base class for obects required to guarantee some degree of MT safety
struct _RWSTD_EXPORT __rw_synchronized
{
    __rw_mutex _C_mutex;
 
    void _C_lock () {
        _C_mutex._C_acquire ();
    }
 
    void _C_unlock () {
        _C_mutex._C_release ();
    }
 
    __rw_guard _C_guard () {
        __rw_guard __guard (_C_mutex);
        return __guard;
    }
};
 
}   // namespace __rw
 
 
// include atomic functions using mutex object
#  ifndef _RWSTD_RW_ATOMIC_MUTEX_H_INCLUDED
#    include <rw/_atomic-mutex.h>
#  endif   // _RWSTD_RW_ATOMIC_MUTEX_H_INCLUDED
 
 
#else   // if !defined (_RWSTD_REENTRANT)
 
_RWSTD_NAMESPACE (__rw) { 
 
// dummy classes used as a base class in single-threaded environments
 
struct __rw_mutex_base
{
    void _C_acquire () { }
 
    void _C_release () { }
};
 
 
struct _RWSTD_EXPORT __rw_mutex: public __rw_mutex_base
{
};
 
 
struct __rw_guard
{
    __rw_guard (__rw_mutex_base&) { }
 
    __rw_guard (__rw_mutex_base*) { }
 
    __rw_mutex_base* _C_set (__rw_mutex_base*) {
        return 0;
    }
};
 
 
struct __rw_synchronized
{
    // static so that it takes up no space
    static _RWSTD_EXPORT __rw_mutex _C_mutex;
 
    void _C_lock () { }
 
    void _C_unlock () { }
 
    __rw_guard _C_guard () {
        return __rw_guard (_C_mutex);
    }
};
 
 
}   // namespace __rw
 
 
#endif   // _RWSTD_REENTRANT
 
// clean up
#ifdef _RWSTD_NO_CHAR_ATOMIC_OPS
#  undef _RWSTD_NO_CHAR_ATOMIC_OPS
#endif
 
#ifdef _RWSTD_NO_SHORT_ATOMIC_OPS
#  undef _RWSTD_NO_SHORT_ATOMIC_OPS
#endif
 
#ifdef _RWSTD_NO_INT_ATOMIC_OPS
#  undef _RWSTD_NO_INT_ATOMIC_OPS
#endif
 
#ifdef _RWSTD_NO_LONG_ATOMIC_OPS
#  undef _RWSTD_NO_LONG_ATOMIC_OPS
#endif
 
#ifdef _RWSTD_NO_LLONG_ATOMIC_OPS
#  undef _RWSTD_NO_LLONG_ATOMIC_OPS
#endif
 
#endif   // _RWSTD_RW_MUTEX_H_INCLUDED