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//===- llvm/System/Mutex.h - Mutex Operating System Concept -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the llvm::sys::Mutex class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SYSTEM_MUTEX_H
#define LLVM_SYSTEM_MUTEX_H
#include "llvm/System/Threading.h"
namespace llvm
{
namespace sys
{
/// @brief Platform agnostic Mutex class.
class MutexImpl
{
/// @name Constructors
/// @{
public:
/// Initializes the lock but doesn't acquire it. if \p recursive is set
/// to false, the lock will not be recursive which makes it cheaper but
/// also more likely to deadlock (same thread can't acquire more than
/// once).
/// @brief Default Constructor.
explicit MutexImpl(bool recursive = true);
/// Releases and removes the lock
/// @brief Destructor
~MutexImpl();
/// @}
/// @name Methods
/// @{
public:
/// Attempts to unconditionally acquire the lock. If the lock is held by
/// another thread, this method will wait until it can acquire the lock.
/// @returns false if any kind of error occurs, true otherwise.
/// @brief Unconditionally acquire the lock.
bool acquire();
/// Attempts to release the lock. If the lock is held by the current
/// thread, the lock is released allowing other threads to acquire the
/// lock.
/// @returns false if any kind of error occurs, true otherwise.
/// @brief Unconditionally release the lock.
bool release();
/// Attempts to acquire the lock without blocking. If the lock is not
/// available, this function returns false quickly (without blocking). If
/// the lock is available, it is acquired.
/// @returns false if any kind of error occurs or the lock is not
/// available, true otherwise.
/// @brief Try to acquire the lock.
bool tryacquire();
//@}
/// @name Platform Dependent Data
/// @{
private:
#ifdef ENABLE_THREADS
void* data_; ///< We don't know what the data will be
#endif
/// @}
/// @name Do Not Implement
/// @{
private:
MutexImpl(const MutexImpl & original);
void operator=(const MutexImpl &);
/// @}
};
/// SmartMutex - A mutex with a compile time constant parameter that
/// indicates whether this mutex should become a no-op when we're not
/// running in multithreaded mode.
template<bool mt_only>
class SmartMutex {
MutexImpl mtx;
public:
explicit SmartMutex(bool recursive = true) : mtx(recursive) { }
bool acquire() {
if (!mt_only || (mt_only && llvm_is_multithreaded()))
return mtx.acquire();
return true;
}
bool release() {
if (!mt_only || (mt_only && llvm_is_multithreaded()))
return mtx.release();
return true;
}
bool tryacquire() {
if (!mt_only || (mt_only && llvm_is_multithreaded()))
return mtx.tryacquire();
return true;
}
private:
SmartMutex<mt_only>(const SmartMutex<mt_only> & original);
void operator=(const SmartMutex<mt_only> &);
};
/// Mutex - A standard, always enforced mutex.
typedef SmartMutex<false> Mutex;
}
}
#endif
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