[ECOS] Nested calls to Mutexes

["Rosimildo daSilva" <rosimildo at hotmail dot com>]

Hi, the project I am working on, we have faced a small problem
with mutexes.

>From ecos documentation:

"When a thread locks a mutex it becomes the owner. Only the mutex's
owner
may unlock it. While a mutex remains locked, the owner should not lock
it
again, as the behavior is undefined and probably dangerous. "


I disagree with this statement. It is a *common idiom* to
have routines that needs to "lock" some access to start
calling other routines that "locks" the mutex again.
In any sizeable project, this happens eventually.
As long as the acquire()/release() calls are balanced,
it should be no problem.

  class A
  {
    public:

     void setData()
     {
        m.lock();
        // set some important data
        m.unlock();
     }


     void anotherMehod()
     {
        m.lock();

        // do some atomic operations here.

        if( ok )
        {
          setData();
        }

        // continue atomic operation

        m.unlock();
     }


   private:

    Mutex m;
  }


Many implementations out there support the concept of
nested/balanced mutex calls. That is the programmer's
expectation. Sorry, to put this way, but I consider
this a *bug*.

Rosimildo.


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