Motivation Right now, we insert HTTP/2 handlers in a callback on a future that is done very late. The result of this is that an entire ALPN negotiaton _can_ complete before this callback is attached. That can in rare cases cause the HTTP/2 handler to miss the server preamble, because it gets added too late. Modifications This patch refactors the existing code to close that window. It does so by passing a promise into the connection path and completing that promise _on_ the event loop where we add the ALPN handlers, which should ensure this will execute immediately when the ALPN negotiation completes. Immportantly, we attach our promise callbacks to that promise _before_ we hand it off, making sure the timing windows go away. Results Timing window is closed

This resolves warnings around SendableMetatype in the AHC codebase, and gets our 6.2 builds working again.

Motivation: * More secure GitHub Actions workflows Modifications: Add explicit 'contents: read' permissions to workflows that did not have explicit permissions defined. This follows GitHub Actions security best practices by limiting the default GITHUB_TOKEN permissions. Result: An extra layer of security.

Motivation: The various 'withMumbleContinuation' APIs are supposed to be invoked synchronously with the caller. This assumption allows a lock to be acquired before the call and released from the body of the 'withMumbleContinuation' after e.g. storing the continuation. However this isn't the case and the job may be re-enqueued on the executor meaning that this is pattern is vulnerable to deadlocks. Modifications: - Drop and reacquire the lock in Transaction Result: Lower chance of deadlock

### Motivation When creating a connection, we wrongfully assumed that `failedToCreateNewConnection` will always be called before `http*ConnectionClosed` in the `HTTPConnectionPoolStateMachine`. However this is far from correct. In NIO Futures are fulfilled before `ChannelHandler` callbacks. Ordering in futures should not be assumed in such a complex project. ### Change We change the `http*ConnectionClosed` methods to be noops, if the connection is in the starting state. We instead wait for the `failedToCreateNewConnection` to create backoff timers and friends. rdar://164674912 --------- Co-authored-by: George Barnett <[email protected]>

Motivation: The various 'withMumbleContinuation' APIs are supposed to be invoked synchronously with the caller. This assumption allows a lock to be acquired before the call and released from the body of the 'withMumbleContinuation' after e.g. storing the continuation. However this isn't the case and the job may be re-enqueued on the executor meaning that this is pattern is vulnerable to deadlocks. Modifications: - Rework the test helpers to avoid holding a lock when a continuation is created. - Switch to using NIOLockedValue box Result: Lower chance of deadlock

…ryLogHandler from swift-log (#874) Swift log now has an InMemoryLogHandler. Lets depend on that instead of having our own `CollectEverythingLogHandler`. I've added an extension on top, to make it easier to create the logger too Result: less code