Add native-mt support for CIO client

[e5l]

No description provided.

[Ololoshechkin]

Please, check all .api files: there seem to be remove and change operations in diff signalling that there might be breaking changes.

[vlsi]

This is wonderful, however, the following line in the release notes is hard to understand for those who have no idea what CIO is:

https://blog.jetbrains.com/ktor/2020/08/18/ktor-1-4-0-now-available/
Partial support for CIO (native-mt) which includes Sockets and HTTP*.

Please un-abbreviate the used acronyms at least once. Than you.

[dalewking]

Just upgraded to latest Ktor and the change in MockEngine to using ConcurrentList for storing request and response history is annoying. I have tests where I want to see how many times a particular call was made (I am testing some caching logic) using a method like this:

protected fun numberOfCallsMade(url: String)
        = mockEngine.requestHistory
            .map(HttpRequestData::url)
            .map(Url::toString)
            .filter { it == url }
            .count()

That now fails because ConcurrentList does not support an iterator.

[Stexxe]

@dalewking could you please file an issue in Youtrack with the full sample code attached?

[dalewking]

Don't see the point of sample code. The issue is simple. The object backing requestHistory and responseHistory were changed by this PR from MutableList to ConcurrentList and you can see right here that ConcurrentList does not support an iterator. So this is a regression in the features of requestHistory and responseHistory. That may be acceptable, but it isn't even documented.

[Stexxe]

@dalewking I've created a Youtrack issue about this problem.