278 lines
9 KiB
C++
278 lines
9 KiB
C++
|
// © 2016 and later: Unicode, Inc. and others.
|
||
|
|
// License & terms of use: http://www.unicode.org/copyright.html
|
||
|
|
/*
|
||
|
|
**********************************************************************
|
||
|
|
* Copyright (C) 1997-2015, International Business Machines
|
||
|
|
* Corporation and others. All Rights Reserved.
|
||
|
|
**********************************************************************
|
||
|
|
*
|
||
|
|
* File UMUTEX.H
|
||
|
|
*
|
||
|
|
* Modification History:
|
||
|
|
*
|
||
|
|
* Date Name Description
|
||
|
|
* 04/02/97 aliu Creation.
|
||
|
|
* 04/07/99 srl rewrite - C interface, multiple mutices
|
||
|
|
* 05/13/99 stephen Changed to umutex (from cmutex)
|
||
|
|
******************************************************************************
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef UMUTEX_H
|
||
|
|
#define UMUTEX_H
|
||
|
|
|
||
|
|
#include <atomic>
|
||
|
|
#include <condition_variable>
|
||
|
|
#include <mutex>
|
||
|
|
#include <type_traits>
|
||
|
|
|
||
|
|
#include "unicode/utypes.h"
|
||
|
|
#include "unicode/uclean.h"
|
||
|
|
#include "unicode/uobject.h"
|
||
|
|
|
||
|
|
#include "putilimp.h"
|
||
|
|
|
||
|
|
#if defined(U_USER_ATOMICS_H) || defined(U_USER_MUTEX_H)
|
||
|
|
// Support for including an alternate implementation of atomic & mutex operations has been withdrawn.
|
||
|
|
// See issue ICU-20185.
|
||
|
|
#error U_USER_ATOMICS and U_USER_MUTEX_H are not supported
|
||
|
|
#endif
|
||
|
|
|
||
|
|
// Export an explicit template instantiation of std::atomic<int32_t>.
|
||
|
|
// When building DLLs for Windows this is required as it is used as a data member of the exported SharedObject class.
|
||
|
|
// See digitlst.h, pluralaffix.h, datefmt.h, and others for similar examples.
|
||
|
|
//
|
||
|
|
// Similar story for std::atomic<std::mutex *>, and the exported UMutex class.
|
||
|
|
#if U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN && !defined(U_IN_DOXYGEN)
|
||
|
|
#if defined(__clang__) || defined(_MSC_VER)
|
||
|
|
#if defined(__clang__)
|
||
|
|
// Suppress the warning that the explicit instantiation after explicit specialization has no effect.
|
||
|
|
#pragma clang diagnostic push
|
||
|
|
#pragma clang diagnostic ignored "-Winstantiation-after-specialization"
|
||
|
|
#endif
|
||
|
|
template struct U_COMMON_API std::atomic<int32_t>;
|
||
|
|
template struct U_COMMON_API std::atomic<std::mutex *>;
|
||
|
|
#if defined(__clang__)
|
||
|
|
#pragma clang diagnostic pop
|
||
|
|
#endif
|
||
|
|
#elif defined(__GNUC__)
|
||
|
|
// For GCC this class is already exported/visible, so no need for U_COMMON_API.
|
||
|
|
template struct std::atomic<int32_t>;
|
||
|
|
template struct std::atomic<std::mutex *>;
|
||
|
|
#endif
|
||
|
|
#endif
|
||
|
|
|
||
|
|
|
||
|
|
U_NAMESPACE_BEGIN
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
*
|
||
|
|
* Low Level Atomic Operations, ICU wrappers for.
|
||
|
|
*
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
typedef std::atomic<int32_t> u_atomic_int32_t;
|
||
|
|
#define ATOMIC_INT32_T_INITIALIZER(val) ATOMIC_VAR_INIT(val)
|
||
|
|
|
||
|
|
inline int32_t umtx_loadAcquire(u_atomic_int32_t &var) {
|
||
|
|
return var.load(std::memory_order_acquire);
|
||
|
|
}
|
||
|
|
|
||
|
|
inline void umtx_storeRelease(u_atomic_int32_t &var, int32_t val) {
|
||
|
|
var.store(val, std::memory_order_release);
|
||
|
|
}
|
||
|
|
|
||
|
|
inline int32_t umtx_atomic_inc(u_atomic_int32_t *var) {
|
||
|
|
return var->fetch_add(1) + 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
inline int32_t umtx_atomic_dec(u_atomic_int32_t *var) {
|
||
|
|
return var->fetch_sub(1) - 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*************************************************************************************************
|
||
|
|
*
|
||
|
|
* UInitOnce Definitions.
|
||
|
|
*
|
||
|
|
*************************************************************************************************/
|
||
|
|
|
||
|
|
struct UInitOnce {
|
||
|
|
u_atomic_int32_t fState;
|
||
|
|
UErrorCode fErrCode;
|
||
|
|
void reset() {fState = 0;}
|
||
|
|
UBool isReset() {return umtx_loadAcquire(fState) == 0;}
|
||
|
|
// Note: isReset() is used by service registration code.
|
||
|
|
// Thread safety of this usage needs review.
|
||
|
|
};
|
||
|
|
|
||
|
|
#define U_INITONCE_INITIALIZER {ATOMIC_INT32_T_INITIALIZER(0), U_ZERO_ERROR}
|
||
|
|
|
||
|
|
|
||
|
|
U_COMMON_API UBool U_EXPORT2 umtx_initImplPreInit(UInitOnce &);
|
||
|
|
U_COMMON_API void U_EXPORT2 umtx_initImplPostInit(UInitOnce &);
|
||
|
|
|
||
|
|
template<class T> void umtx_initOnce(UInitOnce &uio, T *obj, void (U_CALLCONV T::*fp)()) {
|
||
|
|
if (umtx_loadAcquire(uio.fState) == 2) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (umtx_initImplPreInit(uio)) {
|
||
|
|
(obj->*fp)();
|
||
|
|
umtx_initImplPostInit(uio);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// umtx_initOnce variant for plain functions, or static class functions.
|
||
|
|
// No context parameter.
|
||
|
|
inline void umtx_initOnce(UInitOnce &uio, void (U_CALLCONV *fp)()) {
|
||
|
|
if (umtx_loadAcquire(uio.fState) == 2) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (umtx_initImplPreInit(uio)) {
|
||
|
|
(*fp)();
|
||
|
|
umtx_initImplPostInit(uio);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// umtx_initOnce variant for plain functions, or static class functions.
|
||
|
|
// With ErrorCode, No context parameter.
|
||
|
|
inline void umtx_initOnce(UInitOnce &uio, void (U_CALLCONV *fp)(UErrorCode &), UErrorCode &errCode) {
|
||
|
|
if (U_FAILURE(errCode)) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (umtx_loadAcquire(uio.fState) != 2 && umtx_initImplPreInit(uio)) {
|
||
|
|
// We run the initialization.
|
||
|
|
(*fp)(errCode);
|
||
|
|
uio.fErrCode = errCode;
|
||
|
|
umtx_initImplPostInit(uio);
|
||
|
|
} else {
|
||
|
|
// Someone else already ran the initialization.
|
||
|
|
if (U_FAILURE(uio.fErrCode)) {
|
||
|
|
errCode = uio.fErrCode;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// umtx_initOnce variant for plain functions, or static class functions,
|
||
|
|
// with a context parameter.
|
||
|
|
template<class T> void umtx_initOnce(UInitOnce &uio, void (U_CALLCONV *fp)(T), T context) {
|
||
|
|
if (umtx_loadAcquire(uio.fState) == 2) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (umtx_initImplPreInit(uio)) {
|
||
|
|
(*fp)(context);
|
||
|
|
umtx_initImplPostInit(uio);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// umtx_initOnce variant for plain functions, or static class functions,
|
||
|
|
// with a context parameter and an error code.
|
||
|
|
template<class T> void umtx_initOnce(UInitOnce &uio, void (U_CALLCONV *fp)(T, UErrorCode &), T context, UErrorCode &errCode) {
|
||
|
|
if (U_FAILURE(errCode)) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
if (umtx_loadAcquire(uio.fState) != 2 && umtx_initImplPreInit(uio)) {
|
||
|
|
// We run the initialization.
|
||
|
|
(*fp)(context, errCode);
|
||
|
|
uio.fErrCode = errCode;
|
||
|
|
umtx_initImplPostInit(uio);
|
||
|
|
} else {
|
||
|
|
// Someone else already ran the initialization.
|
||
|
|
if (U_FAILURE(uio.fErrCode)) {
|
||
|
|
errCode = uio.fErrCode;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// UMutex should be constexpr-constructible, so that no initialization code
|
||
|
|
// is run during startup.
|
||
|
|
// This works on all C++ libraries except MS VS before VS2019.
|
||
|
|
#if (defined(_CPPLIB_VER) && !defined(_MSVC_STL_VERSION)) || \
|
||
|
|
(defined(_MSVC_STL_VERSION) && _MSVC_STL_VERSION < 142)
|
||
|
|
// (VS std lib older than VS2017) || (VS std lib version < VS2019)
|
||
|
|
# define UMUTEX_CONSTEXPR
|
||
|
|
#else
|
||
|
|
# define UMUTEX_CONSTEXPR constexpr
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/**
|
||
|
|
* UMutex - ICU Mutex class.
|
||
|
|
*
|
||
|
|
* This is the preferred Mutex class for use within ICU implementation code.
|
||
|
|
* It is a thin wrapper over C++ std::mutex, with these additions:
|
||
|
|
* - Static instances are safe, not triggering static construction or destruction,
|
||
|
|
* and the associated order of construction or destruction issues.
|
||
|
|
* - Plumbed into u_cleanup() for destructing the underlying std::mutex,
|
||
|
|
* which frees any OS level resources they may be holding.
|
||
|
|
*
|
||
|
|
* Limitations:
|
||
|
|
* - Static or global instances only. Cannot be heap allocated. Cannot appear as a
|
||
|
|
* member of another class.
|
||
|
|
* - No condition variables or other advanced features. If needed, you will need to use
|
||
|
|
* std::mutex and std::condition_variable directly. For an example, see unifiedcache.cpp
|
||
|
|
*
|
||
|
|
* Typical Usage:
|
||
|
|
* static UMutex myMutex;
|
||
|
|
*
|
||
|
|
* {
|
||
|
|
* Mutex lock(myMutex);
|
||
|
|
* ... // Do stuff that is protected by myMutex;
|
||
|
|
* } // myMutex is released when lock goes out of scope.
|
||
|
|
*/
|
||
|
|
|
||
|
|
class U_COMMON_API UMutex {
|
||
|
|
public:
|
||
|
|
UMUTEX_CONSTEXPR UMutex() {}
|
||
|
|
~UMutex() = default;
|
||
|
|
|
||
|
|
UMutex(const UMutex &other) = delete;
|
||
|
|
UMutex &operator =(const UMutex &other) = delete;
|
||
|
|
void *operator new(size_t) = delete;
|
||
|
|
|
||
|
|
// requirements for C++ BasicLockable, allows UMutex to work with std::lock_guard
|
||
|
|
void lock() {
|
||
|
|
std::mutex *m = fMutex.load(std::memory_order_acquire);
|
||
|
|
if (m == nullptr) { m = getMutex(); }
|
||
|
|
m->lock();
|
||
|
|
}
|
||
|
|
void unlock() { fMutex.load(std::memory_order_relaxed)->unlock(); }
|
||
|
|
|
||
|
|
static void cleanup();
|
||
|
|
|
||
|
|
private:
|
||
|
|
alignas(std::mutex) char fStorage[sizeof(std::mutex)] {};
|
||
|
|
std::atomic<std::mutex *> fMutex { nullptr };
|
||
|
|
|
||
|
|
/** All initialized UMutexes are kept in a linked list, so that they can be found,
|
||
|
|
* and the underlying std::mutex destructed, by u_cleanup().
|
||
|
|
*/
|
||
|
|
UMutex *fListLink { nullptr };
|
||
|
|
static UMutex *gListHead;
|
||
|
|
|
||
|
|
/** Out-of-line function to lazily initialize a UMutex on first use.
|
||
|
|
* Initial fast check is inline, in lock(). The returned value may never
|
||
|
|
* be nullptr.
|
||
|
|
*/
|
||
|
|
std::mutex *getMutex();
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
/* Lock a mutex.
|
||
|
|
* @param mutex The given mutex to be locked. Pass NULL to specify
|
||
|
|
* the global ICU mutex. Recursive locks are an error
|
||
|
|
* and may cause a deadlock on some platforms.
|
||
|
|
*/
|
||
|
|
U_CAPI void U_EXPORT2 umtx_lock(UMutex* mutex);
|
||
|
|
|
||
|
|
/* Unlock a mutex.
|
||
|
|
* @param mutex The given mutex to be unlocked. Pass NULL to specify
|
||
|
|
* the global ICU mutex.
|
||
|
|
*/
|
||
|
|
U_CAPI void U_EXPORT2 umtx_unlock (UMutex* mutex);
|
||
|
|
|
||
|
|
|
||
|
|
U_NAMESPACE_END
|
||
|
|
|
||
|
|
#endif /* UMUTEX_H */
|
||
|
|
/*eof*/
|