Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Query the current value of the context property.

static system_context & query(
    execution::context_t );

Do not call this function directly. It is intended for use with the query customisation point.

For example:

boost::asio::system_executor ex;
boost::asio::system_context& pool = boost::asio::query(
    ex, boost::asio::execution::context);