at https://github.com/c-ares/c-ares/pull/601#issuecomment-1801935063 you
chose not to scatter `const` on the public interface because of the plan
- now realised - to add threading to c-ares, and in the expectation that
even read operations would need to lock the mutex.
But the threading implementation has a _pointer_ to a mutex inside the
ares channel and as I understand it, that means that it is just fine to
mark `ares__channel_lock` (and `ares__channel_unlock`) as taking a
`const` channel. It is the pointed-to mutex that is not constant, but C
does not propagate `const`-ness through pointers.
This PR sprinkles const where appropriate on public interfaces.
Fix By: David Hotham (@dimbleby)
Add a function to request the number of active queries from an ares
channel. This will return the number of inflight requests to dns
servers. Some functions like `ares_getaddrinfo()` when using `AF_UNSPEC`
may enqueue multiple queries which will be reflected in this count.
In the future, if we implement support for queuing (e.g. for throttling
purposes), and/or implement support for tracking user-requested queries
(e.g. for cancelation), we can provide additional functions for
inspecting those queues.
Fix By: Brad House (@bradh352)
It may be useful to wait for the queue to be empty under certain conditions (mainly test cases), expose a function to efficiently do this and rework test cases to use it.
Fix By: Brad House (@bradh352)
David Hotham
Brad House