Disown causes a connection to no longer be tracked by the listener.

MarkIdle marks the given connection as being idle, and therefore eligible for closing at any time.

MarkInUse marks this connection as being in use, removing it from the set of connections which are eligible for closing.

Wrap a net.Listener, returning a net.Listener which supports idle connection tracking and shutdown.

Automatic mode is what most users probably want: calling Read on a connection will mark it as in use, but users must manually call MarkIdle to indicate when connections may be safely closed.

Deadline mode is like automatic mode, except that calling SetReadDeadline on a connection will also mark it as being idle.

Manual mode is completely manual: users must use use MarkIdle and MarkInUse to indicate when connections are busy servicing requests or are eligible for termination.

T is the type of this package's graceful listeners.