Question

Use of conditional locking mechanism

Asked by: harish_dixit1

Hi,

I am having a C++ function and i want to use mutex lock for the entire function only if certain condition is true. If that condition is false then i dont want to use mutex lock. Please suggest me simple wayu to do it.

Here problem i m facing is, that i am using my own mutext class which constructor and destructor is hadnlong locking and unlocking. So using this class will be more convenient for me other my code is having multiple return path and exception handlers. So using this class will avoid code redundancy and will increase correctness.

When i create object of this class then automatically it will lock the whole method. and whenever object will destroy it will unlock the mutex.

For example say my mutex class is: CMyMutexLock

But if i write such if condition in code then its scope will be limited to the if block only.

Is there any easy way so that by using #define i can achieve it?

#define LOCK CMyMutexLock obj;

void f(bool bNeedToLock)
{
  if(bNeedToLock)
  //need to lock the mutex object
  CMyMutexLock obj;
 
 //remaining function code
}

                                  
1:
2:
3:
4:
5:
6:
7:
8:

Select allOpen in new window

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-10-09 at 07:01:31ID24799243
Topics

Windows Vista

,

C++ Programming Language

Participating Experts
3
Points
500
Comments
4

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. private destructor
    what is the significance of private destructor? In which cases we can use them and in which we cannt.
  2. Constructor and destructor with TThread
    Hi, I am creating my own thread class, by deriving a class from TThread. Now I need to be able to add my own constructor (with my own parameters, used to initialise some data before the thread starts) and destructor (to clean up after it) to the class. How can I add my own...
  3. constructor and destructor
    I am told to write a constructor which accepts data from a file and writes it to a node and a destructor which reads data from the node to a file. I am not knowing what to pass as parameter for the destructors. Could you please give me a sample code. For example reading dates...
  4. Deadlocking on the same mutex
    Hello... I am using a mutex synch mechanism in an multi-threaded environmnet (apache). When I got several of the threads working - note that Apache choses the threads to be runned from a thread pool - the system gets into a deadlock and all the threads are waiting on the sa...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: ZoppoPosted on 2009-10-09 at 07:12:55ID: 25535145

Hi harish_dixit1,

the code you posted won't wokr as you need since the 'obj' will be destroyed immediately after the 'if' ends, not when the function terminates.

My suggestion is that you extend the 'CMyMutexLock' class in a way you can instantiate it optionally in a none locked state and than later lock it 'manually', i.e.:

class CMyMutexLock
{
 bool m_bLocked;
 ...
public:
 CMyMutexLock( bool bIntiallyLocked = true ) : m_bLocked( false )
 {
  if ( false != bInitiallyLocked )
  {
   Lock();
  }
 }

 ~CMyMutexLock()
 {
  if ( false != m_bLocked )
  {
   Unlock();
  }

  void Lock()
  {
   m_bLocked = true;
   ... // do the locking here
  }

  void Unlock()
  {
   m_bLocked =false;
   // do the unlocking here
  }
 }
};


Then you can do something like this:

void f(bool bNeedToLock)
{
  CMyMutexLock obj( false );

  if(bNeedToLock)
  //need to lock the mutex object
    obj.Lock();
 //remaining function code
}

Hope that helps,

ZOPPO

 

by: ZoppoPosted on 2009-10-09 at 07:13:31ID: 25535152

Sorry, there's at least one '}' missing at ~CMyMutexLock ...

 

by: evilrixPosted on 2009-10-09 at 07:13:52ID: 25535153

You could use an auto_ptr and create the mutex object on the heap.
http://www.cplusplus.com/reference/std/memory/auto_ptr/

void f(bool bNeedToLock)
{
  auto_ptr< CMyMutexLock > pMutex; // Scoped to function f but only created if needed

  if(bNeedToLock)
    pMutex.reset(new CMyMutexLoc);
 
 //remaining function code
}

 

by: itsmeandnobodyelsePosted on 2009-10-09 at 07:49:40ID: 25535585

If you need a conditional lock you could use a class like the below

class MyMutex
{
     bool locked;
     CRITICAL_SECTION mycs;
public:
      MyMutex() : locked(true) { InitializeCriticalSection(&mycs);  lock(); }
      MyMutex(bool initlock) : locked(initlock) {InitializeCriticalSection(&mycs); if (locked) lock(); }
     ~MyMutex() { if (locked) unlock(); DeleteCriticalSection(&mycs);
      lock() { if (!locked) EnterCriticalSection(&mycs); locked = true; } 
      unlock() { if (locked) LeaveCriticalSection(&mycs); locked = false; } 
};

                                              
1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:

Select allOpen in new window

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...