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
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
Retrieves a connection from the pool.
template< class CompletionToken> auto async_get_connection( std::chrono::steady_clock::duration timeout, diagnostics& diag, CompletionToken&& token);
Retrieves an idle connection from the pool to be used.
If this function completes successfully (empty error code), the return
pooled_connection will have
valid()
== true
and will be usable. If it completes with a non-empty error code, it will
have valid()
== false.
If a connection is idle when the operation is started, it will complete
immediately with that connection. Otherwise, it will wait for a connection
to become idle (possibly creating one in the process, if pool configuration
allows it), up to a duration of timeout.
A zero timeout disables it.
If a timeout happens because connection establishment has failed, appropriate diagnostics will be returned.
this->valid() == true
Timeout values must be positive: timeout.count() >= 0.
While the operation is outstanding, the pool's internal data will be
kept alive. It is safe to destroy *this while the operation is outstanding.
The handler signature for this operation is void(boost::mysql::error_code, boost::mysql::pooled_connection)
any_connection::async_connect, if a timeout
happens because connection establishment is failing.
client_errc::timeout, if a timeout happens
for any other reason (e.g. all connections are in use and limits
forbid creating more).
client_errc::cancelled if cancel was called before
the operation is started or while it is outstanding, or if the pool
is not running.
This function will run entirely in the pool's executor (as given by
this->get_executor()).
No internal data will be accessed or modified as part of the initiating
function. This simplifies thread-safety.
When the pool is constructed with adequate executor configuration, this
function is safe to be called concurrently with async_run, cancel, ~pooled_connection and pooled_connection::return_without_reset.