bsls_bsllockimpl_win32.h

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/// @file bsls_bsllockimpl_win32.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bsls_bsllockimpl_win32.h                                           -*-C++-*-
#ifndef INCLUDED_BSLS_BSLLOCKIMPL_WIN32
#define INCLUDED_BSLS_BSLLOCKIMPL_WIN32
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bsls_bsllockimpl_win32 bsls_bsllockimpl_win32
/// @brief  Provide a mutex for use below `bslmt` for windows platform.
/// @addtogroup bsl
/// @{
/// @addtogroup bsls
/// @{
/// @addtogroup bsls_bsllockimpl_win32
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bsls_bsllockimpl_win32-purpose"> Purpose</a>
/// * <a href="#bsls_bsllockimpl_win32-classes"> Classes </a>
/// * <a href="#bsls_bsllockimpl_win32-description"> Description </a>
///   * <a href="#bsls_bsllockimpl_win32-usage"> Usage </a>
///
/// # Purpose {#bsls_bsllockimpl_win32-purpose}
/// Provide a mutex for use below `bslmt` for windows platform.
///
/// # Classes {#bsls_bsllockimpl_win32-classes}
///
/// -  bsls::BslLockImpl_win32: windows mutex
///
/// @see  bslmt_mutex
///
/// # Description {#bsls_bsllockimpl_win32-description}
/// This component provides a mutually exclusive lock primitive
/// ("mutex") by wrapping a suitable platform-specific mechanism.  The
/// `bsls::BslLockImpl_win32` class provides `lock` and `unlock` operations.
/// Note that `bsls::BslLockImpl_win32` is not intended for direct client use;
/// see @ref bslmt_mutex  instead.  Also note that `bsls::BslLockImpl_win32` is not
/// recursive.
///
/// ## Usage {#bsls_bsllockimpl_win32-usage}
///
///
/// This component is an implementation detail of `bsls` 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 bsls
 * @{
 */
/** @addtogroup bsls_bsllockimpl_win32
 * @{
 */
 
#include <bsls_platform.h>
 
#ifdef BSLS_PLATFORM_OS_WINDOWS
 
// This section replaces #include <windows.h> by forward declaring necessary
// structures and API. See {DRQS 147858260}.
 
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) void __stdcall EnterCriticalSection(
                                LPCRITICAL_SECTION lpCriticalSection);
 
    __declspec(dllimport) void __stdcall LeaveCriticalSection(
                                LPCRITICAL_SECTION lpCriticalSection);
 
}  // extern "C"
 
 
namespace bsls {
 
                              // =======================
                              // class BslLockImpl_win32
                              // =======================
 
class BslLockImpl_win32 {
    // This 'class' implements a light-weight wrapper of an OS-level mutex to
    // support intra-process synchronization.  The mutex implemented by this
    // class is *non*-recursive.  Note that 'BslLockImpl_win32' is *not*
    // intended for direct use by client code; it is meant for internal use
    // only.
 
  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
    BslLockImpl_win32(const BslLockImpl_win32&);             // = delete
    BslLockImpl_win32& operator=(const BslLockImpl_win32&);  // = delete
 
  public:
    // CREATORS
    BslLockImpl_win32();
        // Create a lock object initialized to the unlocked state.
 
    ~BslLockImpl_win32();
        // Destroy this lock object.  The behavior is undefined unless this
        // object is in the unlocked state.
 
    // MANIPULATORS
    void lock();
        // Acquire the lock on this object.  If the lock on this object is
        // currently held by another thread, then suspend execution of the
        // calling thread until the lock can be acquired.  The behavior is
        // undefined unless the calling thread does not already hold the lock
        // on this object.  Note that deadlock may result if this method is
        // invoked while the calling thread holds the lock on the object.
 
    void unlock();
        // Release the lock on this object that was previously acquired through
        // a call to 'lock', enabling another thread to acquire the lock.  The
        // behavior is undefined unless the calling thread holds the lock on
        // this object.
};
 
// ============================================================================
//                        INLINE FUNCTION DEFINITIONS
// ============================================================================
 
                              // -----------------------
                              // class BslLockImpl_win32
                              // -----------------------
 
// CREATORS
inline
BslLockImpl_win32::BslLockImpl_win32()
{
    InitializeCriticalSectionAndSpinCount(
          reinterpret_cast<_RTL_CRITICAL_SECTION *>(d_lock), k_SPIN_COUNT);
}
 
inline
BslLockImpl_win32::~BslLockImpl_win32()
{
    DeleteCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
// MANIPULATORS
inline
void BslLockImpl_win32::lock()
{
    EnterCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
inline
void BslLockImpl_win32::unlock()
{
    LeaveCriticalSection(
        reinterpret_cast<_RTL_CRITICAL_SECTION*>(d_lock));
}
 
 
}  // close package namespace
 
 
#endif  // BSLS_PLATFORM_OS_WINDOWS
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2021 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */