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Full Discussion: multithreading on OSX
Top Forums Programming multithreading on OSX Post 302209383 by eBay on Thursday 26th of June 2008 07:25:05 PM
Old 06-26-2008
OT: A Helpful Class
I've been out of the game for a while with C++ but as I read your post, I was reminded of some classes I wrote to manage multiple threads. Also, Bartosz Milewski of Reliable Software - Creators of the distributed version control system, Code Co-op wrote a really cool critical section class wrapper that totally protects against accidentally leaving a lock in place. His discussion of how resource management is the key to reliable message driven software was well done and he had numerous ways to protect against leaving resources open or laying around that would cause memory leaks or hangs. Here it is:
Code:
// CriticalSection.h
// 
// A class using Resource Management technique(RM: see 
// http://www.relisoft.com/resource/resource.html for
// discussion) to handle critical section code that 
// guarantees no memory leaks or open locks.
//
// Revision Log
//
// Date       Who SAR     Notes
// ========== === ======= =====================================
//                        (c) Reliable Software, 1997, 98
//                        Bartosz Milewski, www.relisoft.com
// 

#ifdef SAMPLE_CODE

   // somewhere with the resource to protect
   CCriticalSection _critSect;

   // later in the code...
   {
      CLock lock(_critSect);
      // perform action which may throw
      myVar += 10;
      // guaranteed automatic destructor of lock
      // when it goes out of scope
   }
}
#endif


#ifndef RFC_CRITICAL_SECTION_H
#define RFC_CRITICAL_SECTION_H

#include <windows.h>

class CCriticalSection
{
   friend class CLock;
public:
   CCriticalSection() { InitializeCriticalSection(&_critSectStruct); }
   ~CCriticalSection() { DeleteCriticalSection(&_critSectStruct); }
private: 
   // these must only be used by CLock object, never directly
   void Enter() { EnterCriticalSection(&_critSectStruct); }
   void Leave() { LeaveCriticalSection(&_critSectStruct); }

   CCriticalSection(CCriticalSection& o); // not allowed
   CCriticalSection& operator=(CCriticalSection& o); // not allowed

   CRITICAL_SECTION _critSectStruct;
};

class CLock 
{
public:
    CLock(CCriticalSection& critSect) 
        : _critSectObj(critSect) 
    {
        _critSectObj.Enter();
    }
    ~CLock()
    {
        _critSectObj.Leave();
    }
private:
    CCriticalSection & _critSectObj;
};

#endif

 

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LEARN ABOUT HPUX

xtgetconstraintresourcelist

XtGetConstraintResourceList()											     XtGetConstraintResourceList()

Name
  XtGetConstraintResourceList - get the constraint resource list structure for a particular widget class.

Synopsis
  void XtGetConstraintResourceList(object_class, resources_return, num_resources_return)
	   WidgetClass object_class;
	   XtResourceList *resources_return;
	   Cardinal *num_resources_return;

Inputs
  object_class	 Specifies the object class to be queried; may be of class objectClass or any subclass thereof.

Outputs
  resources_return
		 Returns the constraint resource list.

  num_resources_return
		 Returns the number of entries in the constraint resource list.

Availability
  Release 4 and later.

Description
  XtGetConstraintResources()  returns  the resource list of the constraintClassPart of the widget class object_class.  If it is called before
  the widget class is initialized, the resource list as specified in the widget class record will be returned.	If it  is  called  after  the
  widget  class  has  been initialized, the merged resource list for the class and all constraint superclasses is returned.  If the specified
  object_class is not a subclass of constraintWidgetClass, *resources_return is set to NULL and *num_resources_return is set  to  zero.   The
  list returned by XtGetConstraintResourceList() should be freed using XtFree() when it is no longer needed.

Usage
  Most	applications  will  never need to query a widget class for the resources it supports.  This function is intended to support interface
  builders and applications like editres which allow the use to view the available resources and set them interactively.

  To get the normal resources of a widget rather than the constraint resources, use XtGetResourceList().

See Also
  XtGetResourceList(1).

Xt - Resource Management											     XtGetConstraintResourceList()
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