...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Copy constructor notifies the io_service that work is starting.
work( const work & other);
The constructor is used to inform the io_service that some work has begun. This ensures that the io_service's run() function will not exit while the work is underway.