c++ work queues with blocking

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This question should be a little simpler than my last few. I've implemented the following work queue in my program:

Pool.h:

// tpool class
// It's always closed. :glasses:
#ifndef __POOL_H
#define __POOL_H
class tpool {
    public:
        tpool( std::size_t tpool_size );
        ~tpool();
        template< typename Task >
        void run_task( Task task ){
        boost::unique_lock< boost::mutex > lock( mutex_ );
            if( 0 < available_ ) {
                --available_;
                io_service_.post( boost::bind( &tpool::wrap_task, this, boost::function< void() > ( task ) ) );
            }
        }
    private:
        boost::asio::io_service io_service_;
        boost::asio::io_service::work work_;
        boost::thread_group threads_;
        std::size_t available_;
        boost::mutex mutex_;
        void wrap_task( boost::function< void() > task );
};
extern tpool dbpool;
#endif

pool.cpp:

#include <boost/asio/io_service.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/bind.hpp>
#include <boost/thread.hpp>
#include "pool.h"
tpool::tpool( std::size_t tpool_size ) : work_( io_service_ ), available_( tpool_size ) {
    for ( std::size_t i = 0; i < tpool_size; ++i ){
        threads_.create_thread( boost::bind( &boost::asio::io_service::run, &io_service_ ) );
    }
}
tpool::~tpool() {
    io_service_.stop();
    try {
        threads_.join_all();
    }
    catch( ... ) {}
}
void tpool::wrap_task( boost::function< void() > task ) {
    // run the supplied task
    try {
        task();
    } // suppress exceptions
    catch( ... ) {
    }
    boost::unique_lock< boost::mutex > lock( mutex_ );
    ++available_;
}
tpool dbpool( 50 );

The problem is, though, is that not all my calls to run_task() are being completed by worker threads. I'm not sure if it's because it's not entering into the queue or because the task vanishes when the thread that created it exits.

So my question is, is there anything special I have to give to boost::thread to make it wait until the queue is unlocked? and what is the expected lifetime of a task entered into a queue? Do the tasks go out of scope when the thread that created them exits? If so, how can I prevent that from happening?

asked 8 secs ago

Oblivious12

16

c++ work queues with blocking