Ah thanks. I had to change the check to if (! tls_buffer.get()) or

In file included from ./EventWorker.h:13:
./Util.h:85:13: error: invalid argument type
      'boost::thread_specific_ptr<std::stringstream>' to unary expression
        if (! tls_buffer) {
            ^ ~~~~~~~~~~
1 error generated.
make: *** [EventWorker.o] Error 1

but it seems to work now.

Mike

> On Dec 21, 2015, at 10:04 AM, Juan Ramírez <jramirez.uy@gmail.com> wrote:
>
> tls_buffer is not initialized, thread_specific_ptr will not allocate memory for you (it will call delete on thread exit tough)
>
> if (!tls_buffer) {
>    tls_buffer.reset(new std::stringstream());
> }
>
> The previous must be done before any attempt to use that variable
>
> On Mon, Dec 21, 2015 at 11:34 AM, Michael P. Soulier <msoulier@digitaltorque.ca> wrote:
> Hello,
>
> I’m trying to implement a thread-safe logger that uses a boost::thread_specific_ptr to a std::stringstream as a logging buffer.
>
> static boost::thread_specific_ptr<std::stringstream> tls_buffer;
>
> class MLoggerHandler
> {
> public:
>     MLoggerHandler(boost::mutex& mutex, std::ostream& ostream);
>     ~MLoggerHandler();
>     void setLevel(int level);
>
>     template <class T>
>     // For handling << from any object.
>     MLoggerHandler& operator <<(T input) {
>         std::cerr << "Adding to buffer" << std::endl;
>         if (m_start) {
>             *tls_buffer << localDateTime() << " " << input; <================= SEGFAULT
>             m_start = false;
>         }
>         else {
>             *tls_buffer << input;
>         }
>         std::cerr << "On buffer: " << tls_buffer->str() << std::endl;
>         return *this;
>     }
>     // For handling std::endl
>     std::ostream& operator <<(std::ostream& (*f)(std::ostream&)) {
>         std::cerr << "Flushing buffer" << std::endl;
>         m_start = true;
>         std::ostream& rv = f(m_ostream);
>         m_mutex.lock();
>         m_ostream << tls_buffer->str();
>         m_mutex.unlock();
>         tls_buffer->str("");
>         return rv;
>     }
> private:
>     // A flag to indicate the beginning of a new line.
>     bool m_start = true;
>     // A mutex passed in from the main logger for synchronization.
>     boost::mutex& m_mutex;
>     // The logging level.
>     int m_level;
>     // The output stream.
>     std::ostream& m_ostream;
>     // Return the current date and time as a localized string.
>     const std::string localDateTime();
> };
>
> The initial idea, was to flush the buffer and write when a terminating std::endl was encountered. But, just trying to dereference the pointer and write to the std::stringstream is crashing. Do I need to initialize the std::stringstream, or is it initialized in constructor?
>
> Thanks,
> Mike
> _______________________________________________
> Boost-users mailing list
> Boost-users@lists.boost.org
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>
>
>
> --
> Juan
> :wq
>
> _______________________________________________
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