Re: [Boost-users] [Locks/Mutex] choices between types

Subject: Re: [Boost-users] [Locks/Mutex] choices between types
From: Markus Bernhardt (markus.bernhardt_at_[hidden])
Date: 2009-07-01 13:45:10

Hi Alex,

A mutex object contains all the data structures for locking.

A lock object locks the given mutex object in the constructor and
unlocks it in its destructor.

Example:

class ThreadSafeSomething
{
 private: 
  boost::mutex mutex;  
 public:
  void doSomething()
  {
    boost::mutex::scoped_lock(mutex);
    something();
  } // mutex is unlocked here
};

If there would be no lock object you would have to write something like (welcome to java world):

class ThreadSafeSomething 
{
 private: 
  my::special::mutex mutex;  
 public:
  void doSomething()
  {
    mutex.lock();
    something();
    mutex.unlock();
  } 
};

Final question: What happens when an exception is thrown in something()?

Kind regards,
Markus

Am Mittwoch, den 01.07.2009, 17:08 +0200 schrieb Axel:
> Hello
> 
> This post may not be well suited to this mailing list.
> I have some questions about the lockable concept provided in boost. 
> There are many "lock" types, and many "mutex" types.
> My main question is then : when should I chose a given lock type rather 
> a given mutex type ?
> Given the fact that some of lock types are not thread-safe, if only one 
> thread needs locks, why should I use one of these lock types and why 
> shouldnt I use some mutex type ?
> 
> Finally, what were the goals of providing so much different ways to 
> lock/unlock resources ? (I may not be aware of all the concepts related 
> to secure resource access)
> 
> Since the "lock" et "mutex" types provide ways to lock/unlock access to 
> resources, why are not these types defined under the same name ? Are the 
> concepts they implements much more different than I think ?
> 
> 
> Thanks
> Axel
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