#include <nitro/os.h>BOOL OS_TryLockMutexFromRToW( OSMutex* mutex );BOOL OS_TryLockMutexFromWToR( OSMutex* mutex );mutex |
Pointer to the OSMutex structure |
Returns TRUE if the mutex lock can be changed from read lock to write lock, or conversely from write lock to read lock. If not, the function returns FALSE.
Changes the type of the mutex that is locked.
mutex is the pointer to the OSMutex structure to be changed.
The OS_TryLockMutexFromWToR function takes a mutex that is set to write lock and changes the setting to read lock. When the function succeeds, the mutex type is read lock. To unlock it you need to execute either the OS_UnlockMutexR or OS_UnlockMutexRW function.
The OS_TryLockMutexFromRToW takes a mutex that is set to read lock and changes the setting to write lock. When the function succeeds, the mutex type is write lock. To unlock it you need to execute either the OS_UnlockMutexW or OS_UnlockMutexRW function.
If mutex is locked at multiple levels or if the type is wrong, the function fails and returns FALSE. A multi-level locked mutex is one that is either locked by multiple threads, or by one thread in which more than one lock function calls the same OSMutex structure. A wrong type, for example, is when the function attempts to change a read lock mutex into a write lock mutex, but the target is not a read lock mutex.
Example 1
OSMutex mutex;
OS_LockMutexR( &mutex );
OS_LockMutexR( &mutex );
if ( OS_TryLockMutexFromRToW( &mutex ) == FALSE ) Returns FALSE because mutex is locked at multiple levels.
{
:
}Example 2
OSMutex mutex;
OS_LockMutexR( &mutex );
if ( OS_TryLockMutexFromWToR( &mutex ) == FALSE ) Returns FALSE because mutex is read lock, thus the wrong type for FromWToR.
{
:
}This function returns immediately, regardless of whether it succeeds or fails. Threads are not switched.
OS_InitMutex
OS_LockMutex
OS_UnlockMutex
OS_LockMutexR
OS_LockMutexW
OS_UnlocMutexR
OS_UnlocMutexW
OS_TryLockMutexR
OS_TryLockMutexW
OS_LockMutexFromRToW
OS_LockMutexFromWToR
2008/12/16 Initial version.
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