RWNullMutexLock

Module:  Threads   Package:  Synchronization

RWNullMutexLock   RWSynchObject

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Members

acquire() acquireRead() acquireWrite() isAcquired() LockGuard operator

ReadLockGuard ReadUnlockGuard release() RWMutexLock() RWNullMutexLock() tryAcquire()

tryAcquireRead() tryAcquireWrite() TryLockGuard TryReadLockGuard TryWriteLockGuard UnlockGuard

WriteLockGuard WriteUnlockGuard ~RWMutexLock()

#include <rw/sync/RWNullMutexLock.h> 

An RWNullMutexLock is an efficient stand-in for a mutual exclusion lock, particularly when you know that critical sections of code do not need synchronization. For example, you may know that it is not possible for more than one thread to simultaneously enter a section of code that would otherwise require locking. In such cases you can use an RWNullMutexLock to eliminate the unnecessary overhead of acquiring and releasing a mutex. This class can also be used to instantiate a single-threaded or non-thread-safe version of a template classes that accept a mutex parameter, such as RWTMonitor<Mutex>.

#include <rw/sync/RWMutexLock.h>
#include <rw/sync/RWNullMutexLock.h>

#if SYNCHRONIZATION_REQUIRED
typedef RWMutexLock MUTEX;
#else
typedef RWNullMutexLock MUTEX;
#endif

MUTEX mutex;

mutex.acquire();  // No cost if synchronization not required
// critical section
mutex.release();

// Same thing, this time using a guard:
{  
   MUTEX::Lockguard lock(mutex); // does nothing if
                                 // synchronization not required
   // critical section
   
   // If synchronization required, lock will be released
   // automatically
}

typedef RWTLockGuard<RWNullMutexLock>          LockGuard;
typedef RWTReadLockGuard<RWNullMutexLock>      ReadLockGuard;
typedef RWTWriteLockGuard<RWNullMutexLock>     WriteLockGuard;
typedef RWTTryLockGuard<RWNullMutexLock>       TryLockGuard;
typedef RWTTryReadLockGuard<RWNullMutexLock> TryReadLockGuard;
typedef RWTTryWriteLockGuard<RWNullMutexLock>
        TryWriteLockGuard;
typedef RWTUnlockGuard<RWNullMutexLock>        UnlockGuard;
typedef RWTReadUnlockGuard<RWNullMutexLock>   ReadUnlockGuard;
typedef RWTWriteUnlockGuard<RWNullMutexLock> WriteUnlockGuard;

Predefined types for compatible guards.

RWNullMutexLock(RWStaticCtor);

Creates an RWNullMutexLock.

RWMutexLock(RWCancellationState 
            state=RW_CANCELLATION_DISABLED);

Creates an RWNullMutexLock. state is ignored.

~RWMutexLock();

Destructor.

void
acquire();

Does nothing

RWWaitStatus
acquire(unsigned long milliseconds);

Returns RW_THR_ACQUIRED.

void
acquireRead();

Does nothing.

RWWaitStatus
acquireRead(unsigned long milliseconds);

Returns RW_THR_ACQUIRED.

void
acquireWrite();

Does nothing.

RWWaitStatus
acquireWrite(unsigned long milliseconds);

Returns RW_THR_ACQUIRED.

bool
isAcquired() const;

Returns true.

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NOTE -- Only available from the debug version of the Threads Module.

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void
release();

Does nothing.

bool
tryAcquire();

Returns true.

bool
tryAcquireRead();

Returns true.

bool
tryAcquireWrite();

Returns true.

RWNullMutexLock(const RWNullMutexLock& second);

Copy construction prohibited.

RWNullMutexLock&
operator=(const RWNullMutexLock& second);

Assignment prohibited.

RWMutexLock, RWTLockGuard<Resource>, RWTUnlockGuard<Resource>, RWTTryLockGuard<Resource>

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