bslmt_muteximpl_pthread.h

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/// @file bslmt_muteximpl_pthread.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmt_muteximpl_pthread.h                                          -*-C++-*-
#ifndef INCLUDED_BSLMT_MUTEXIMPL_PTHREAD
#define INCLUDED_BSLMT_MUTEXIMPL_PTHREAD
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmt_muteximpl_pthread bslmt_muteximpl_pthread
/// @brief  Provide a POSIX implementation of `bslmt::Mutex`.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmt
/// @{
/// @addtogroup bslmt_muteximpl_pthread
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmt_muteximpl_pthread-purpose"> Purpose</a>
/// * <a href="#bslmt_muteximpl_pthread-classes"> Classes </a>
/// * <a href="#bslmt_muteximpl_pthread-description"> Description </a>
///   * <a href="#bslmt_muteximpl_pthread-usage"> Usage </a>
///
/// # Purpose {#bslmt_muteximpl_pthread-purpose}
/// Provide a POSIX implementation of `bslmt::Mutex`.
///
/// # Classes {#bslmt_muteximpl_pthread-classes}
///
/// -  bslmt::MutexImpl<Platform::PosixThreads>: POSIX specialization
///
/// @see  bslmt_mutex
///
/// # Description {#bslmt_muteximpl_pthread-description}
/// This component provides an implementation of `bslmt::Mutex` for
/// POSIX threads ("pthreads"), `bslmt::MutexImpl<Platform::PosixThreads>`, via
/// the template specialization:
/// @code
/// bslmt::MutexImpl<Platform::PosixThreads>
/// @endcode
/// This template class should not be used (directly) by client code.  Clients
/// should instead use `bslmt::Mutex`.
///
/// ## Usage {#bslmt_muteximpl_pthread-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_pthread
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslmt_platform.h>
 
#ifdef BSLMT_PLATFORM_POSIX_THREADS
 
// Platform-specific implementation starts here.
 
#include <bsls_assert.h>
 
#include <bsl_cstring.h>
 
#include <pthread.h>
 
 
namespace bslmt {
 
template <class THREAD_POLICY>
class MutexImpl;
 
                 // =======================================
                 // class MutexImpl<Platform::PosixThreads>
                 // =======================================
 
/// This class provides a full specialization of `MutexImpl` for pthreads.
/// It provides a efficient proxy for the @ref pthread_mutex_t  pthreads type, and related operations.  
/// 
/// \note Note that   the mutex implemented in this class
/// is *not* error checking, and is non-recursive.
template <>
class MutexImpl<Platform::PosixThreads> {
 
    // DATA
    pthread_mutex_t d_lock;  // TBD doc
 
  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 pthread_mutex_t NativeType;
 
    // CREATORS
 
    /// Create a mutex initialized to an unlocked state.  This method does
    /// not return normally unless there are sufficient system resources to
    /// construct the object.
    MutexImpl();
 
    /// Destroy this mutex object.  
    /// \pre The behavior is undefined  if the mutex
    /// is in a locked state.
    ~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::PosixThreads>
                 // ---------------------------------------
 
// CREATORS
inline
MutexImpl<bslmt::Platform::PosixThreads>::MutexImpl()
{
    const int status = pthread_mutex_init(&d_lock, 0);
    if (status) {
        BSLS_ASSERT_INVOKE_NORETURN("'pthread_mutex_init' failed");
    }
}
 
// MANIPULATORS
inline
void MutexImpl<bslmt::Platform::PosixThreads>::lock()
{
    BSLS_ASSERT_SAFE(0xdeadbeef !=
                                 *reinterpret_cast<const unsigned *>(&d_lock));
 
    const int status = pthread_mutex_lock(&d_lock);
    (void) status;
    BSLS_ASSERT_SAFE(0 == status);
}
 
inline
int MutexImpl<bslmt::Platform::PosixThreads>::tryLock()
{
    BSLS_ASSERT_SAFE(0xdeadbeef !=
                                 *reinterpret_cast<const unsigned *>(&d_lock));
 
    return pthread_mutex_trylock(&d_lock);
}
 
inline
void MutexImpl<bslmt::Platform::PosixThreads>::unlock()
{
    BSLS_ASSERT_SAFE(0xdeadbeef !=
                                 *reinterpret_cast<const unsigned *>(&d_lock));
 
    const int status = pthread_mutex_unlock(&d_lock);
    (void) status;
    BSLS_ASSERT_SAFE(0 == status);
}
 
inline
MutexImpl<bslmt::Platform::PosixThreads>::NativeType&
MutexImpl<bslmt::Platform::PosixThreads>::nativeMutex()
{
    return d_lock;
}
 
}  // close package namespace
 
 
#endif  // BSLMT_PLATFORM_POSIX_THREADS
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2023 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */