* Make EventLoopFuture.cascade and cascadeFailure accept an optional promise
Motivation:
fixes#756
Modifications:
Change EventLoopFuture.cascade to func cascade(promise: EventLoopPromise<T>?)
Result:
EventLoopFuture.cascade can be called without needing to check if the promise is nil
Motivation:
Swift naming guidelines mandate that factory methods start with `make`,
like `makeSomething`. We had a few that were `newSomething`.
Modifications:
make all factories start with make
Result:
more compliant to Swift naming rules
Motivation:
_ = expression() is ugly and in many cases unimportant. In fact we train
ourselves to overread it which makes special cases where you'd actually
expect a result to be used just look normal.
Modifications:
remove _ = from a lot of places. In many cases we already had a better
(and sometimes cheaper way) to not return a value but in some cases
(mostly `remove` functions) I added `@discardableResult`
Result:
NIO source code looks nicer
Motivation:
@pushkarnk hit an interesting edge case that we previously mishandled
and crashed. All these conditions need to be true
1. Whilst have an ongoing request (ie. outstanding response), ...
2. ... a `HTTPParserError` arrives (which we correctly queue)
3. Later the outstanding response is completed and then ...
4. ... the `HTTPServerProtocolErrorHandler` sends a .badRequest response
We previously crashed. The reason we crashed is that the
`HTTPServerPipelineHandler` obviously tracks state and then asserts that
no response is sent for a wrong request. It does have an affordance to
allow a .badRequest response for a request it couldn't parse. However
this state tracking wasn't done if the error itself was enqueued for
later delivery.
Thanks very much @pushkarnk for the report!
Modifications:
instead of delivering the error directly use the `deliverOneError`
function which transitions the state correctly.
Result:
fewer crashes & hopefully happy Pushkar
Motivation:
In certain cases it's useful to quiesce a channel instead of just
closing them immediately for example when receiving a signal.
This lays the groundwork by introducing the
`ChannelShouldQuiesceUserEvent` user event that when received can be
interpreted by a ChannelHandler in a protocol & application specific
way. Some protocols support tear down and that would be a good place to
initiate the tear down.
Modifications:
- introduce `ChannelShouldQuiesceUserEvent`
- handle `ChannelShouldQuiesceUserEvent` in the `AcceptHandler` with
closing the server socket
- handle `ChannelShouldQuiesceUserEvent` in the
`HTTPServerPipelineHandler` by only handling a already in-flight
request and then no longer accepting input
- added `CircularBuffer.removeAll` (& tests)
- added tests for `nextPowerOf2()`
Result:
- handlers can now support quiescing
Motivation:
The pipelining handler made the assumption that `channelRead` is never
called recursively. That's mostly true but there is at least one
situation where that's not true:
- pipelining handler seen a response .end and delivers a .head (which is
done in `channelRead`)
- a handler further down stream writes and flushes some response data
- the flushes fail which leads to us draining the receive buffer
- if the receive buffer contained more requests, the pipelining
handler's `channelRead` is called again (recursively)
The net result of that was that the new request parts from the receive
buffer would now jump the queue and go through the channel pipeline
next, before other already buffered messages.
Modifications:
made the pipelining handler buffer if a `channelRead` comes in from the
pipeline and there is already at least one message buffered.
Result:
the ordering of the incoming messages should now be respected which is
very important...
Motivation:
We had a bug which is happens in the combination of these states:
- we held a request in the pipelining handler (because we're procesing a
previous one)
- a http handler error happened whilst a response's `.head` had already
been sent (but not yet the `.end`)
- the HTTPServerProtocolErrors handler is in use
That would lead to this situation:
- the error isn't held by the pipelining handler
- the error handler then just sends a full response (`.head` and `.end`)
but the actual http server already send a `.head`. So all in all, we
sent `.head`, `.head`, `.end` which is illegal
- the pipelining handler didn't notice this and beause it saw an `.end`
it would send through the next requst
- now the http server handler is in the situation that it gets `.head`,
`.head` too (which is illegal)
Modifications:
- hold HTTP errors in the pipelining handler too
Result:
- more correctness
Motivation:
HTTP pipelining can be tricky to handle properly on the server side.
In particular, it's very easy to write out of order or inconsistently
mutate state. Users often need help to handle this appropriately.
Modifications:
Added a HTTPServerPipelineHandler that only lets one request through
at a time.
Result:
Better servers that are more able to handle HTTP pipelining
David Skrundz