RWTTryLockGuard<Resource>

Threads Module Reference Guide
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RWTTryLockGuard<Resource>

Module: Threads Package: Synchronization


RWTTryLockGuard<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=()
ResourceType

RWTTryLockGuard()
tryAcquire()

~RWTTryLockGuard()

Header File

#include <rw/sync/RWTTryLockGuard.h>

Description

RWTTryLockGuard<Resource> is a guard class that tries to acquire its resource upon creation and, if successful, release 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 a mutex upon creation and release it when destructed. The class used as the actual template parameter for Resource must be one that provides tryAcquire and release methods (such as some synchronization classes provided in this module).

Example

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

RWMutexLock mutex;

bool foo()
{
  // ...
  {  
     // try to acquire mutex:
     RWTTryLockGuard<RWMutexLock> lock(mutex);
     
     // See if the mutex was acquired:
     if (!lock.isAcquired()) {
       return false;     // Can't get lock, 
                         // give up and return error
     }
     // ... critical section

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

  // ...
  return true;
}

Public Typedef

typedef Resource     ResourceType;

Public Constructor

RWTTryLockGuard(Resource& resource);

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

Public Destructor

~RWTTryLockGuard();

Destructor.

Public Member Function

bool
tryAcquire();

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

Private Constructor

RWTTryLockGuard(const RWTTryLockGuard<Resource>& second);

Copy construction prohibited.

Private Member Operator

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

Assignment prohibited.