Re: [Threads-devel] Request Help On boost::lock_error

Subject: Re: [Threads-devel] Request Help On boost::lock_error
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2010-09-14 12:05:57

  ----- Original Message ----- 
  From: Ashutosh Warikoo 
  To: threads-devel_at_[hidden] 
  Sent: Tuesday, September 14, 2010 11:21 AM
  Subject: [Threads-devel] Request Help On boost::lock_error

  Hello 
  I am trying to model a usecase where a member function reads in a value & now has to modify the value by calling another function. The code which I have written using upgrade_locks fails at run time. I have gone through the documentation & have cleared the code as best as I could to arrive at a condensed usecase. I have also attached some sample erroneous outputs & a backtrace of the thread in question. Can someone please have a look? 
   
  [...]

  int boostThreadLocksTest::firstFunction(boostThreadLocksTest *pBoostThreadLocksTest) 
  { 
          pBoostThreadLocksTest->myLock.lock(); 
          pBoostThreadLocksTest->secondFunction(pBoostThreadLocksTest); 
          pBoostThreadLocksTest->myLock.unlock(); 
          return(0); 
  } 
  int boostThreadLocksTest::secondFunction(boostThreadLocksTest *pBoostThreadLocksTest) 
  { 
          boost::upgrade_to_unique_lock<boost::shared_mutex> localUniqueLock(pBoostThreadLocksTest->myLock); 
          return(0); 
  } 
  ***********************************************

  Hi,

  Unfortunately boost::shared_mutex is not recursive :(. 

  Why do you use a shared mutex if you lock it exclusively in firstFunction and secondFunction? upgrade_to_unique_lock has a sens only if the mutext has been lock_shared. Shouldn't you user lock_shared()/unlock_shared() in firstFunction?

  Best,
  Vicente