RWTTryWriteLockGuard<Resource>

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RWTTryWriteLockGuard<Resource>

Module: Threads Package: Synchronization


RWTTryWriteLockGuard<Resource>   RWTLockGuardBase<Resource>

Local Index
Header File
Description
Example
Public Typedef
Public Constructor
Public Destructor
Public Member Function
Private Constructor
Private Member Operator
See Also

Local Index

Members

operator=()
Resource

RWTTryWriteLockGuard()
tryAcquire()

~RWTTryWriteLockGuard()

Header File

#include <rw/sync/RWTTryWriteLockGuard.h>

Description

RWTTryWriteLockGuard<Resource> is a guard class that tries to acquire write access on its resource upon creation and, if successful, releases it upon destruction. Guard objects work in conjunction with block statements in such a way as to establish an appropriate state upon creation, maintain that state for the duration of the block, and restore the original state upon destruction. For example, a guard may acquire write access on a mutex upon creation and release it when destructed. The class used as the actual template parameter for Resource must be one that provides tryAcquireWrite and release methods (such as some synchronization classes provided in this module).

Example

#include <rw/sync/RWReadersWriterLock.h>
#include <rw/sync/RWTTryWriteLockGuard.h>

RWReadersWriterLock rwlock;

bool foo()
{
  // ...
  {  
     // try to acquire write access on a readers-writer lock:
     RWTTryWriteLockGuard<RWReadersWriterLock> lock(rwlock);
     
     // See if the lock was acquired:
     if (!lock.isAcquired()) {
       return false;  // Can't get lock, give up and 
                      // return error
     }

     // ... critical section

     // lock will be released in RWTTryWriteLockGuard destructor
     // before leaving scope, especially important if 
     // an exception might be thrown!
  }

  // ...
  return true;
}

Public Typedef

typedef Resource     ResourceType;

Public Constructor

RWTTryWriteLockGuard(Resource& resource);

Constructs an instance with the given resource and attempts to acquire write access on that resource. Uses the inherited isAcquired() member function to see if the acquisition was successful.

Public Destructor

~RWTTryWriteLockGuard();

Destructor.

Public Member Function

bool
tryAcquire();

Tries again to acquire write access on the resource. Uses this function instead of manipulating the resource directly so that the guard will automatically release it.

Private Constructor

RWTTryWriteLockGuard(const 
                    RWTTryWriteLockGuard<Resource>& second);

Copy construction prohibited.

Private Member Operator

RWTTryWriteLockGuard<Resource>&
operator=(const RWTTryWriteLockGuard<Resource>& second);

Assignment prohibited.