chromium/third_party/icu/source/common/umutex.cpp

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
*   Copyright (C) 1997-2016, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*
* File umutex.cpp
*
* Modification History:
*
*   Date        Name        Description
*   04/02/97    aliu        Creation.
*   04/07/99    srl         updated
*   05/13/99    stephen     Changed to umutex (from cmutex).
*   11/22/99    aliu        Make non-global mutex autoinitialize [j151]
******************************************************************************
*/

#include "umutex.h"

#include "unicode/utypes.h"
#include "uassert.h"
#include "ucln_cmn.h"
#include "cmemory.h"

U_NAMESPACE_BEGIN


#if defined(U_USER_MUTEX_CPP)
// Support for including an alternate implementation of mutexes has been withdrawn.
// See issue ICU-20185.
#error U_USER_MUTEX_CPP not supported
#endif


/*************************************************************************************************
 *
 *  ICU Mutex wrappers.
 *
 *************************************************************************************************/

namespace {
std::mutex *initMutex;
std::condition_variable *initCondition;

// The ICU global mutex.
// Used when ICU implementation code passes nullptr for the mutex pointer.
UMutex globalMutex;

std::once_flag initFlag;
std::once_flag *pInitFlag = …;

}  // Anonymous namespace

U_CDECL_BEGIN
static UBool U_CALLCONV umtx_cleanup() { … }

static void U_CALLCONV umtx_init() { … }
U_CDECL_END


std::mutex *UMutex::getMutex() { … }

UMutex *UMutex::gListHead = …;

void UMutex::cleanup() { … }


U_CAPI void  U_EXPORT2
umtx_lock(UMutex *mutex) { … }


U_CAPI void  U_EXPORT2
umtx_unlock(UMutex* mutex)
{ … }


/*************************************************************************************************
 *
 *  UInitOnce Implementation
 *
 *************************************************************************************************/

// This function is called when a test of a UInitOnce::fState reveals that
//   initialization has not completed, that we either need to call the init
//   function on this thread, or wait for some other thread to complete.
//
// The actual call to the init function is made inline by template code
//   that knows the C++ types involved. This function returns true if
//   the caller needs to call the Init function.
//
U_COMMON_API UBool U_EXPORT2
umtx_initImplPreInit(UInitOnce &uio) { … }


// This function is called by the thread that ran an initialization function,
// just after completing the function.
//   Some threads may be waiting on the condition, requiring the broadcast wakeup.
//   Some threads may be racing to test the fState variable outside of the mutex,
//   requiring the use of store/release when changing its value.

U_COMMON_API void U_EXPORT2
umtx_initImplPostInit(UInitOnce &uio) { … }

U_NAMESPACE_END

/*************************************************************************************************
 *
 *  Deprecated functions for setting user mutexes.
 *
 *************************************************************************************************/

U_DEPRECATED void U_EXPORT2
u_setMutexFunctions(const void * /*context */, UMtxInitFn *, UMtxFn *,
                    UMtxFn *,  UMtxFn *, UErrorCode *status) { … }



U_DEPRECATED void U_EXPORT2
u_setAtomicIncDecFunctions(const void * /*context */, UMtxAtomicFn *, UMtxAtomicFn *,
                           UErrorCode *status) { … }