bslmt_muteximpl_win32.h

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/// @file bslmt_muteximpl_win32.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmt_muteximpl_win32.h                                            -*-C++-*-
#ifndef INCLUDED_BSLMT_MUTEXIMPL_WIN32
#define INCLUDED_BSLMT_MUTEXIMPL_WIN32
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmt_muteximpl_win32 bslmt_muteximpl_win32
/// @brief  Provide a win32 implementation of `bslmt::Mutex`.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmt
/// @{
/// @addtogroup bslmt_muteximpl_win32
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmt_muteximpl_win32-purpose"> Purpose</a>
/// * <a href="#bslmt_muteximpl_win32-classes"> Classes </a>
/// * <a href="#bslmt_muteximpl_win32-description"> Description </a>
///   * <a href="#bslmt_muteximpl_win32-usage"> Usage </a>
///
/// # Purpose {#bslmt_muteximpl_win32-purpose}
/// Provide a win32 implementation of `bslmt::Mutex`.
///
/// # Classes {#bslmt_muteximpl_win32-classes}
///
/// -  bslmt::MutexImpl<Platform::Win32Threads>: win32 specialization
///
/// @see  bslmt_mutex
///
/// # Description {#bslmt_muteximpl_win32-description}
/// This component provides an implementation of `bslmt::Mutex` for
/// Windows (win32), `bslmt::MutexImpl<Platform::Win32Threads>`, via the
/// template specialization:
/// @code
/// bslmt::MutexImpl<Platform::Win32Threads>
/// @endcode
/// This template class should not be used (directly) by client code.  Clients
/// should instead use `bslmt::Mutex`.
///
/// ## Usage {#bslmt_muteximpl_win32-usage}
///
///
/// This component is an implementation detail of `bslmt` and is *not* intended
/// for direct client use.  It is subject to change without notice.  As such, a
/// usage example is not provided.
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslmt
 * @{
 */
/** @addtogroup bslmt_muteximpl_win32
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslmt_platform.h>
 
#include <bsls_platform.h>
 
#ifdef BSLMT_PLATFORM_WIN32_THREADS
 
// Platform-specific implementation starts here.
 
// Rather than setting 'WINVER' or 'NTDDI_VERSION', just forward declare the
// Windows 2000 functions that are used.
 
struct _RTL_CRITICAL_SECTION;
 
typedef struct _RTL_CRITICAL_SECTION CRITICAL_SECTION, *LPCRITICAL_SECTION;
typedef int BOOL;
typedef unsigned long DWORD;
 
extern "C" {
    __declspec(dllimport) BOOL __stdcall InitializeCriticalSectionAndSpinCount(
                                    LPCRITICAL_SECTION lpCriticalSection,
                                    DWORD dwSpinCount);
 
    __declspec(dllimport) void __stdcall DeleteCriticalSection(
                                LPCRITICAL_SECTION lpCriticalSection);
 
    __declspec(dllimport) BOOL __stdcall TryEnterCriticalSection(
                                 LPCRITICAL_SECTION lpCriticalSection);
 
    __declspec(dllimport) void __stdcall EnterCriticalSection(
                                LPCRITICAL_SECTION lpCriticalSection);
 
    __declspec(dllimport) void __stdcall LeaveCriticalSection(
                                LPCRITICAL_SECTION lpCriticalSection);
 
}  // extern "C"
 
 
namespace bslmt {
 
template <class THREAD_POLICY>
class MutexImpl;
 
                 // =======================================
                 // class MutexImpl<Platform::Win32Threads>
                 // =======================================
 
/// This class provides a full specialization of `MutexImpl` for Windows.
/// It provides an efficient proxy for Windows critical sections, and related operations.  
/// 
/// \note Note that   the mutex implemented in this class is
/// *not* error checking, and is non-recursive.
/// TYPES
template <>
class MutexImpl<Platform::Win32Threads> {
 
  public:
    enum {
        // Size of the buffer allocated for the critical section, in
        // pointer-sized elements.  We have to make it public so we could
        // access it in a .cpp file to verify the size.
 
#ifdef BSLS_PLATFORM_CPU_64_BIT
        // 5*8 = 40 bytes
        k_CRITICAL_SECTION_BUFFER_SIZE = 5
#else
        // 6*4 = 24 bytes
        k_CRITICAL_SECTION_BUFFER_SIZE = 6
#endif
    };
 
  private:
    enum {
        // A Windows critical section has a configurable spin count.  A lock
        // operation spins this many iterations (on, presumably, some atomic
        // integer) before sleeping on the underlying primitive.
 
        k_SPIN_COUNT = 30
    };
 
    // DATA
    void *d_lock[k_CRITICAL_SECTION_BUFFER_SIZE];
 
  private:
    // NOT IMPLEMENTED
    MutexImpl(const MutexImpl&);
    MutexImpl& operator=(const MutexImpl&);
 
  public:
    // PUBLIC TYPES
 
    /// The underlying OS-level type.  Exposed so that other bslmt components
    /// can operate directly on this mutex.
    typedef _RTL_CRITICAL_SECTION NativeType;
 
    // CREATORS
 
    /// Create a mutex initialized to an unlocked state.
    MutexImpl();
 
    /// Destroy this mutex object.
    ~MutexImpl();
 
    // MANIPULATORS
 
    /// Acquire a lock on this mutex object.  If this object is currently
    /// locked, then suspend execution of the current thread until a lock can be acquired.  
    /// 
    /// \note Note that   the behavior is undefined if the calling
    /// thread already owns the lock on this mutex, and will likely result
    /// in a deadlock.
    void lock();
 
    /// Return a reference to the modifiable OS-level mutex underlying this
    /// object.  This method is intended only to support other bslmt
    /// components that must operate directly on this mutex.
    NativeType& nativeMutex();
 
    /// Attempt to acquire a lock on this mutex object.  Return 0 on
    /// success, and a non-zero value of this object is already locked, or
    /// if an error occurs.
    int tryLock();
 
    /// Release a lock on this mutex that was previously acquired through a
    /// successful call to `lock`, or `tryLock`.  The behavior is undefined,
    /// unless the calling thread currently owns the lock on this mutex.
    void unlock();
};
 
// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================
 
                 // ---------------------------------------
                 // class MutexImpl<Platform::Win32Threads>
                 // ---------------------------------------
 
// CREATORS
inline
MutexImpl<bslmt::Platform::Win32Threads>::MutexImpl()
{
    InitializeCriticalSectionAndSpinCount(
          reinterpret_cast<_RTL_CRITICAL_SECTION *>(d_lock), k_SPIN_COUNT);
}
 
inline
MutexImpl<bslmt::Platform::Win32Threads>::~MutexImpl()
{
    DeleteCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
// MANIPULATORS
inline
void MutexImpl<bslmt::Platform::Win32Threads>::lock()
{
    EnterCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
inline
MutexImpl<bslmt::Platform::Win32Threads>::NativeType&
MutexImpl<bslmt::Platform::Win32Threads>::nativeMutex()
{
    return *reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock);
}
 
inline
int MutexImpl<bslmt::Platform::Win32Threads>::tryLock()
{
    return !TryEnterCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
inline
void MutexImpl<bslmt::Platform::Win32Threads>::unlock()
{
    LeaveCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
}  // close package namespace
 
 
#endif // BSLMT_PLATFORM_WIN32_THREADS
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */