Re: [Boost-users] thread mutex problem

Subject: Re: [Boost-users] thread mutex problem
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2010-09-06 17:49:45

Kraus Philipp <philipp.kraus_at_[hidden]> writes:

> I'm new with boost thread, I have some problems.
> I have got two methods, one for writing and one for reading my data and I would
> do this thread-safe.
> I have tried to do this with boost::unique_lock<boost::shared_mutex> lock(...),
> but I have created a deadlock.
>
> For example my methods are called within the threads and set / get data to /
> from a ublas matrix.

> How can I do both methods in the correct way thread-safe? 

boost::mutex m;

void setData( const size_t row, const size_t col, const size_t data) {
    boost::unique_lock<boost::mutex> lk(m);
    _matrix(row, col) = data 
}

void getData( const size_t row, const size_t col, size_t& a, size_t& b) {
    boost::unique_lock<boost::mutex> lk(m);
    a = _matrix(row, col);
    b = _matrix(col, row);
}

Once you've got the basics working, you can change the mutex to a
boost::shared_mutex and the lock in getData to a shared_lock rather than
a unique_lock if profiling determines that this is the bottle neck, *and*
the shared_mutex helps.

Anthony
-- 
Author of C++ Concurrency in Action     http://www.stdthread.co.uk/book/
just::thread C++0x thread library             http://www.stdthread.co.uk
Just Software Solutions Ltd       http://www.justsoftwaresolutions.co.uk
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