Add the ability for manual invalidation of requests, preventi…

[arb000r]

Hello,

I would like to propose a feature to allow manual invalidation of requests.
Currently the pool (and any custom implementations) can only rely on disconnected as the primary flag for overseeing that a Connection is not pushed back into the pool. Updating it so that the disconnected flag could be updated did not seem to be the correct path, as it the flag would be responsible for two meanings.

I introduced a new flag called invalidated which can be marked by the request, which results in the underlying Connection not making it back to the pool.

[HaveFunTrading]

hi @arb000r - could you provide some use cases for the above? if we want more control over when a connection is dropped when returned to the pool I would try to make the contract stronger/better defined rather than relying on certain field(s).

[arb000r]

Heya,

The example I was trying to make it fit was for expiring requests.

1. Create request with a defined deadline
2. Request is polled through a wrapper fn which checks above deadline. If deadline has passed. Return Err.
3. Even though from a client implementation the deadline is passed, that connection may eventually have the response arrive. If the connection is returned to the pool and used for another request, the previous response will still be there.

The ability to invalidate a certain connection arbitrarily would be useful for custom pool implementations.

[HaveFunTrading]

sorry for the late reply @arb000r

I have reviewed this and added a way to invalidate the HttpRequest

    /// Immediately terminate and consume this request.
    ///
    /// The request's connection is dropped instead of returned to the pool. Use this when the request
    /// can no longer complete or its connection may not be safe to reuse, such as after a timeout.
    pub fn invalidate(mut self) {
        self.conn.take();
    }

it will be released in 0.0.79

in the meantime I will close your PR