#include <mutex>
#include <shared_mutex>
+// std::shared_timed_mutex is only availble on macOS 10.12 and later.
+#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \
+ defined(__MAC_10_12) && \
+ __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < __MAC_10_12
+#define USE_RW_MUTEX_IMPL
+#endif
+
namespace llvm {
namespace sys {
- /// SmartMutex - An R/W 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 SmartRWMutex {
- // shared_mutex (C++17) is more efficient than shared_timed_mutex (C++14)
- // on Windows and always available on MSVC.
+#if defined(USE_RW_MUTEX_IMPL)
+/// Platform agnostic RWMutex class.
+class RWMutexImpl {
+ /// @name Constructors
+ /// @{
+public:
+ /// Initializes the lock but doesn't acquire it.
+ /// Default Constructor.
+ explicit RWMutexImpl();
+
+ /// @}
+ /// @name Do Not Implement
+ /// @{
+ RWMutexImpl(const RWMutexImpl &original) = delete;
+ RWMutexImpl &operator=(const RWMutexImpl &) = delete;
+ /// @}
+
+ /// Releases and removes the lock
+ /// Destructor
+ ~RWMutexImpl();
+
+ /// @}
+ /// @name Methods
+ /// @{
+public:
+ /// Attempts to unconditionally acquire the lock in reader mode. If the
+ /// lock is held by a writer, this method will wait until it can acquire
+ /// the lock.
+ /// @returns false if any kind of error occurs, true otherwise.
+ /// Unconditionally acquire the lock in reader mode.
+ bool lock_shared();
+
+ /// Attempts to release the lock in reader mode.
+ /// @returns false if any kind of error occurs, true otherwise.
+ /// Unconditionally release the lock in reader mode.
+ bool unlock_shared();
+
+ /// Attempts to unconditionally acquire the lock in reader mode. If the
+ /// lock is held by any readers, this method will wait until it can
+ /// acquire the lock.
+ /// @returns false if any kind of error occurs, true otherwise.
+ /// Unconditionally acquire the lock in writer mode.
+ bool lock();
+
+ /// Attempts to release the lock in writer mode.
+ /// @returns false if any kind of error occurs, true otherwise.
+ /// Unconditionally release the lock in write mode.
+ bool unlock();
+
+ //@}
+ /// @name Platform Dependent Data
+ /// @{
+private:
+#if defined(LLVM_ENABLE_THREADS) && LLVM_ENABLE_THREADS != 0
+ void *data_ = nullptr; ///< We don't know what the data will be
+#endif
+};
+#endif
+
+/// SmartMutex - An R/W 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 SmartRWMutex {
+ // shared_mutex (C++17) is more efficient than shared_timed_mutex (C++14)
+ // on Windows and always available on MSVC.
#if defined(_MSC_VER) || __cplusplus > 201402L
- std::shared_mutex impl;
+ std::shared_mutex impl;
+#else
+#if !defined(USE_RW_MUTEX_IMPL)
+ std::shared_timed_mutex impl;
+#else
+ RWMutexImpl impl;
+#endif
+#endif
+ unsigned readers = 0;
+ unsigned writers = 0;
+
+public:
+ bool lock_shared() {
+ if (!mt_only || llvm_is_multithreaded()) {
+ impl.lock_shared();
+ return true;
+ }
+
+ // Single-threaded debugging code. This would be racy in multithreaded
+ // mode, but provides not sanity checks in single threaded mode.
+ ++readers;
+ return true;
+ }
+
+ bool unlock_shared() {
+ if (!mt_only || llvm_is_multithreaded()) {
+ impl.unlock_shared();
+ return true;
+ }
+
+ // Single-threaded debugging code. This would be racy in multithreaded
+ // mode, but provides not sanity checks in single threaded mode.
+ assert(readers > 0 && "Reader lock not acquired before release!");
+ --readers;
+ return true;
+ }
+
+ bool lock() {
+ if (!mt_only || llvm_is_multithreaded()) {
+ impl.lock();
+ return true;
+ }
+
+ // Single-threaded debugging code. This would be racy in multithreaded
+ // mode, but provides not sanity checks in single threaded mode.
+ assert(writers == 0 && "Writer lock already acquired!");
+ ++writers;
+ return true;
+ }
+
+ bool unlock() {
+ if (!mt_only || llvm_is_multithreaded()) {
+ impl.unlock();
+ return true;
+ }
+
+ // Single-threaded debugging code. This would be racy in multithreaded
+ // mode, but provides not sanity checks in single threaded mode.
+ assert(writers == 1 && "Writer lock not acquired before release!");
+ --writers;
+ return true;
+ }
+};
+
+typedef SmartRWMutex<false> RWMutex;
+
+/// ScopedReader - RAII acquisition of a reader lock
+#if !defined(USE_RW_MUTEX_IMPL)
+template <bool mt_only>
+using SmartScopedReader = const std::shared_lock<SmartRWMutex<mt_only>>;
+#else
+template <bool mt_only> struct SmartScopedReader {
+ SmartRWMutex<mt_only> &mutex;
+
+ explicit SmartScopedReader(SmartRWMutex<mt_only> &m) : mutex(m) {
+ mutex.lock_shared();
+ }
+
+ ~SmartScopedReader() { mutex.unlock_shared(); }
+};
+#endif
+typedef SmartScopedReader<false> ScopedReader;
+
+/// ScopedWriter - RAII acquisition of a writer lock
+#if !defined(USE_RW_MUTEX_IMPL)
+template <bool mt_only>
+using SmartScopedWriter = std::lock_guard<SmartRWMutex<mt_only>>;
#else
- std::shared_timed_mutex impl;
+template <bool mt_only> struct SmartScopedWriter {
+ SmartRWMutex<mt_only> &mutex;
+
+ explicit SmartScopedWriter(SmartRWMutex<mt_only> &m) : mutex(m) {
+ mutex.lock();
+ }
+
+ ~SmartScopedWriter() { mutex.unlock(); }
+};
#endif
- unsigned readers = 0;
- unsigned writers = 0;
-
- public:
- bool lock_shared() {
- if (!mt_only || llvm_is_multithreaded()) {
- impl.lock_shared();
- return true;
- }
-
- // Single-threaded debugging code. This would be racy in multithreaded
- // mode, but provides not sanity checks in single threaded mode.
- ++readers;
- return true;
- }
-
- bool unlock_shared() {
- if (!mt_only || llvm_is_multithreaded()) {
- impl.unlock_shared();
- return true;
- }
-
- // Single-threaded debugging code. This would be racy in multithreaded
- // mode, but provides not sanity checks in single threaded mode.
- assert(readers > 0 && "Reader lock not acquired before release!");
- --readers;
- return true;
- }
-
- bool lock() {
- if (!mt_only || llvm_is_multithreaded()) {
- impl.lock();
- return true;
- }
-
- // Single-threaded debugging code. This would be racy in multithreaded
- // mode, but provides not sanity checks in single threaded mode.
- assert(writers == 0 && "Writer lock already acquired!");
- ++writers;
- return true;
- }
-
- bool unlock() {
- if (!mt_only || llvm_is_multithreaded()) {
- impl.unlock();
- return true;
- }
-
- // Single-threaded debugging code. This would be racy in multithreaded
- // mode, but provides not sanity checks in single threaded mode.
- assert(writers == 1 && "Writer lock not acquired before release!");
- --writers;
- return true;
- }
- };
-
- typedef SmartRWMutex<false> RWMutex;
-
- /// ScopedReader - RAII acquisition of a reader lock
- template<bool mt_only>
- using SmartScopedReader = const std::shared_lock<SmartRWMutex<mt_only>>;
-
- typedef SmartScopedReader<false> ScopedReader;
-
- /// ScopedWriter - RAII acquisition of a writer lock
- template<bool mt_only>
- using SmartScopedWriter = std::lock_guard<SmartRWMutex<mt_only>>;
-
- typedef SmartScopedWriter<false> ScopedWriter;
+typedef SmartScopedWriter<false> ScopedWriter;
} // end namespace sys
} // end namespace llvm
--- /dev/null
+//===- RWMutex.cpp - Reader/Writer Mutual Exclusion Lock --------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the llvm::sys::RWMutex class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/RWMutex.h"
+#include "llvm/Config/config.h"
+
+#if defined(USE_RW_MUTEX_IMPL)
+using namespace llvm;
+using namespace sys;
+
+#if !defined(LLVM_ENABLE_THREADS) || LLVM_ENABLE_THREADS == 0
+// Define all methods as no-ops if threading is explicitly disabled
+
+RWMutexImpl::RWMutexImpl() = default;
+RWMutexImpl::~RWMutexImpl() = default;
+
+bool RWMutexImpl::lock_shared() { return true; }
+bool RWMutexImpl::unlock_shared() { return true; }
+bool RWMutexImpl::lock() { return true; }
+bool RWMutexImpl::unlock() { return true; }
+
+#else
+
+#if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_RWLOCK_INIT)
+
+#include <cassert>
+#include <cstdlib>
+#include <pthread.h>
+
+// Construct a RWMutex using pthread calls
+RWMutexImpl::RWMutexImpl()
+{
+ // Declare the pthread_rwlock data structures
+ pthread_rwlock_t* rwlock =
+ static_cast<pthread_rwlock_t*>(safe_malloc(sizeof(pthread_rwlock_t)));
+
+#ifdef __APPLE__
+ // Workaround a bug/mis-feature in Darwin's pthread_rwlock_init.
+ bzero(rwlock, sizeof(pthread_rwlock_t));
+#endif
+
+ // Initialize the rwlock
+ int errorcode = pthread_rwlock_init(rwlock, nullptr);
+ (void)errorcode;
+ assert(errorcode == 0);
+
+ // Assign the data member
+ data_ = rwlock;
+}
+
+// Destruct a RWMutex
+RWMutexImpl::~RWMutexImpl()
+{
+ pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+ assert(rwlock != nullptr);
+ pthread_rwlock_destroy(rwlock);
+ free(rwlock);
+}
+
+bool
+RWMutexImpl::lock_shared()
+{
+ pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+ assert(rwlock != nullptr);
+
+ int errorcode = pthread_rwlock_rdlock(rwlock);
+ return errorcode == 0;
+}
+
+bool
+RWMutexImpl::unlock_shared()
+{
+ pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+ assert(rwlock != nullptr);
+
+ int errorcode = pthread_rwlock_unlock(rwlock);
+ return errorcode == 0;
+}
+
+bool
+RWMutexImpl::lock()
+{
+ pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+ assert(rwlock != nullptr);
+
+ int errorcode = pthread_rwlock_wrlock(rwlock);
+ return errorcode == 0;
+}
+
+bool
+RWMutexImpl::unlock()
+{
+ pthread_rwlock_t* rwlock = static_cast<pthread_rwlock_t*>(data_);
+ assert(rwlock != nullptr);
+
+ int errorcode = pthread_rwlock_unlock(rwlock);
+ return errorcode == 0;
+}
+
+#else
+
+RWMutexImpl::RWMutexImpl() : data_(new MutexImpl(false)) { }
+
+RWMutexImpl::~RWMutexImpl() {
+ delete static_cast<MutexImpl *>(data_);
+}
+
+bool RWMutexImpl::lock_shared() {
+ return static_cast<MutexImpl *>(data_)->acquire();
+}
+
+bool RWMutexImpl::unlock_shared() {
+ return static_cast<MutexImpl *>(data_)->release();
+}
+
+bool RWMutexImpl::lock() {
+ return static_cast<MutexImpl *>(data_)->acquire();
+}
+
+bool RWMutexImpl::unlock() {
+ return static_cast<MutexImpl *>(data_)->release();
+}
+
+#endif
+#endif
+#endif
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