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//===-- runtime/lock.h ------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Wraps a mutex
#ifndef FORTRAN_RUNTIME_LOCK_H_
#define FORTRAN_RUNTIME_LOCK_H_
#include "terminator.h"
#include "tools.h"
// Avoid <mutex> if possible to avoid introduction of C++ runtime
// library dependence.
#ifndef _WIN32
#define USE_PTHREADS 1
#else
#undef USE_PTHREADS
#endif
#if USE_PTHREADS
#include <pthread.h>
#elif defined(_WIN32)
// Do not define macros for "min" and "max"
#define NOMINMAX
#include <windows.h>
#else
#include <mutex>
#endif
namespace Fortran::runtime {
class Lock {
public:
#if RT_USE_PSEUDO_LOCK
// No lock implementation, e.g. for using together
// with RT_USE_PSEUDO_FILE_UNIT.
// The users of Lock class may use it under
// USE_PTHREADS and otherwise, so it has to provide
// all the interfaces.
RT_API_ATTRS void Take() {}
RT_API_ATTRS bool Try() { return true; }
RT_API_ATTRS void Drop() {}
RT_API_ATTRS bool TakeIfNoDeadlock() { return true; }
#elif USE_PTHREADS
Lock() { pthread_mutex_init(&mutex_, nullptr); }
~Lock() { pthread_mutex_destroy(&mutex_); }
void Take() {
while (pthread_mutex_lock(&mutex_)) {
}
holder_ = pthread_self();
isBusy_ = true;
}
bool TakeIfNoDeadlock() {
if (isBusy_) {
auto thisThread{pthread_self()};
if (pthread_equal(thisThread, holder_)) {
return false;
}
}
Take();
return true;
}
bool Try() { return pthread_mutex_trylock(&mutex_) == 0; }
void Drop() {
isBusy_ = false;
pthread_mutex_unlock(&mutex_);
}
#elif defined(_WIN32)
Lock() { InitializeCriticalSection(&cs_); }
~Lock() { DeleteCriticalSection(&cs_); }
void Take() { EnterCriticalSection(&cs_); }
bool Try() { return TryEnterCriticalSection(&cs_); }
void Drop() { LeaveCriticalSection(&cs_); }
#else
void Take() { mutex_.lock(); }
bool Try() { return mutex_.try_lock(); }
void Drop() { mutex_.unlock(); }
#endif
void CheckLocked(const Terminator &terminator) {
if (Try()) {
Drop();
terminator.Crash("Lock::CheckLocked() failed");
}
}
private:
#if RT_USE_PSEUDO_FILE_UNIT
// No state.
#elif USE_PTHREADS
pthread_mutex_t mutex_{};
volatile bool isBusy_{false};
volatile pthread_t holder_;
#elif defined(_WIN32)
CRITICAL_SECTION cs_;
#else
std::mutex mutex_;
#endif
};
class CriticalSection {
public:
explicit RT_API_ATTRS CriticalSection(Lock &lock) : lock_{lock} {
lock_.Take();
}
RT_API_ATTRS ~CriticalSection() { lock_.Drop(); }
private:
Lock &lock_;
};
} // namespace Fortran::runtime
#endif // FORTRAN_RUNTIME_LOCK_H_
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