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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#include <aws/common/mutex.h>
#include <aws/common/thread.h>
#include <windows.h>
/* Convert a string from a macro to a wide string */
#define WIDEN2(s) L## #s
#define WIDEN(s) WIDEN2(s)
int aws_mutex_init(struct aws_mutex *mutex) {
/* Ensure our mutex and Windows' mutex are the same size */
AWS_STATIC_ASSERT(sizeof(SRWLOCK) == sizeof(mutex->mutex_handle));
InitializeSRWLock(AWSMUTEX_TO_WINDOWS(mutex));
mutex->initialized = true;
return AWS_OP_SUCCESS;
}
/* turn off unused named parameter warning on msvc.*/
#ifdef _MSC_VER
# pragma warning(push)
# pragma warning(disable : 4100)
#endif
void aws_mutex_clean_up(struct aws_mutex *mutex) {
AWS_PRECONDITION(mutex);
AWS_ZERO_STRUCT(*mutex);
}
int aws_mutex_lock(struct aws_mutex *mutex) {
AWS_PRECONDITION(mutex && mutex->initialized);
AcquireSRWLockExclusive(AWSMUTEX_TO_WINDOWS(mutex));
return AWS_OP_SUCCESS;
}
/* Check for functions that don't exist on ancient windows */
static aws_thread_once s_check_functions_once = INIT_ONCE_STATIC_INIT;
typedef BOOLEAN WINAPI TryAcquireSRWLockExclusive_fn(PSRWLOCK SRWLock);
static TryAcquireSRWLockExclusive_fn *s_TryAcquireSRWLockExclusive;
static void s_check_try_lock_function(void *user_data) {
(void)user_data;
s_TryAcquireSRWLockExclusive = (TryAcquireSRWLockExclusive_fn *)GetProcAddress(
GetModuleHandleW(WIDEN(WINDOWS_KERNEL_LIB) L".dll"), "TryAcquireSRWLockExclusive");
}
int aws_mutex_try_lock(struct aws_mutex *mutex) {
AWS_PRECONDITION(mutex && mutex->initialized);
/* Check for functions that don't exist on ancient Windows */
aws_thread_call_once(&s_check_functions_once, s_check_try_lock_function, NULL);
if (!s_TryAcquireSRWLockExclusive) {
return aws_raise_error(AWS_ERROR_UNSUPPORTED_OPERATION);
}
BOOL res = s_TryAcquireSRWLockExclusive(AWSMUTEX_TO_WINDOWS(mutex));
/*
* Per Windows documentation, a return value of zero indicates a failure to acquire the lock.
*/
if (!res) {
return aws_raise_error(AWS_ERROR_MUTEX_TIMEOUT);
}
return AWS_OP_SUCCESS;
}
int aws_mutex_unlock(struct aws_mutex *mutex) {
AWS_PRECONDITION(mutex && mutex->initialized);
ReleaseSRWLockExclusive(AWSMUTEX_TO_WINDOWS(mutex));
return AWS_OP_SUCCESS;
}
#ifdef _MSC_VER
# pragma warning(pop)
#endif
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