- `_idleTimer` and `_backoffTimer` are protected by `stateLock`
- Added a new `struct Actions` that splits up actions from the state machine into actions that need to be executed inside the `stateLock` and outside in `stateLock`
- Add HTTP/1.1 connection pool stress test
- a new `RequestOptions` struct was created, that can be used to set request specific options. It is required by the `HTTPExecutableRequest`
- Added support for `ignoreUncleanSSLShutdown` in the `HTTPRequestStateMachine` and the `HTTP1ConnectionStateMachine`. In http/2 `ignoreUncleanSSLShutdown` is always off.
### Motivation
NIO may send `channelRead` events without a handlers requesting more data with a `context.read()` invocation. This happens if the remote has closed the connection and NIO wants to inform the handlers as soon as possible.
### Changes
- Don't `precondition` on `channelRead` events anymore.
- Close channel if we received an http end without a `context.read()` invocation
### Motivation
In the `HTTP1ConnectionStateMachine` we set the connection state to `.closed` after having forwarded an error to the inner RequestStateMachine. Since we set the state to close, the `state.modify` function did not create an action that would close the connection.
### Changes
- Modify the ConnectionState based on the RequestStateMachine's action only in the `state.modify` function.
- Add a test to verify the fixed behavior.
- Use ExpressibleByDictionaryLiteral syntax for some HTTPHeaders to increase readability.
### Result
Connections are closed, if an error happens, while we are in a request.
If a request times out because no connection could be attained, we should fail the request with the last connection creation error. If no connection creation error is present and there is no active connection, we fail the request with a connectTimeout error.
Add a `HTTPConnectionPool.Connection` type that is a box around an actual connection. The purpose of the box is to ensure no actions are invoked on the connection within the state machine. Further the box can be used for testing the state machine without creating actual connections.
- Refactored code from `TaskHandler` into new method `HTTPClient.Request.createRequestHead` that creates an `HTTPRequestHead` and matching `RequestFramingMetadata`
- Added required property `requestFramingMetadata` to `HTTPExecutingRequest`
- Added property `requestFramingMetadata` to `RequestBag`
Co-authored-by: Cory Benfield <lukasa@apple.com>
- Adding four new protocols:
- `HTTPExecutingRequest` a protocol representing an HTTP task that is executed on a ChannelHandler.
- `HTTPScheduledRequest` a protocol representing an HTTP task that is scheduled for execution, but in a waiting state (example: Waiting for an idle connection in the connection pool).
- `HTTPRequestExecutor` a protocol that can be used from the `HTTPExecutingRequest` abstracting away functionality that will normally be implemented by a `ChannelHandler`
- `HTTPRequestScheduler` a protocol that can be used from the `HTTPScheduledRequest` abstracting away functionality that will normally be implemented by a `ConnectionPool`
- An implementation of the `HTTPExecutingTask` and `HTTPScheduledRequest` called `RequestBag`. It implements our current API using the new protocols
Co-authored-by: George Barnett <gbarnett@apple.com>
Co-authored-by: Cory Benfield <lukasa@apple.com>
- `ConsumerControlState` was replaced with `ResponseStreamState` in `HTTPRequestStateMachine`
- `channelRead`s are buffered up to a `channelReadComplete`.
- on `channelReadComplete` all buffered body parts are forwarded to the consumer
This commit adds an explicit `HTTPRequestStateMachine`. It is intended to be used in two instances in the future:
1. As a substate machine for a `HTTP1ConnectionStateMachine`, when the connection is in a request.
2. As a state machine for a `HTTP2RequestHandler` that operates on a single http2 stream created by the multiplexer.
The new code paths are not triggered today, but will be enabled in the future.
- The connection creation logic has been refactored into a number of smaller methods that can be combined
- Connection creation now has a logical home. It is moved from `Utils.swift` into a `ConnectionFactory`
- There are explicit `ChannelHandlers` that are used for connection creation:
- `TLSEventsHandler` got its own file and unit tests
- `HTTP1ProxyConnectHandler` got its own file and unit tests
- `SOCKSEventsHandler` got its own file and unit tests
- Some small things are already part of this pr that will get their context later. For example:
- `HTTPConnectionPool` is added as a namespace to not cause major renames in follow up PRs
- `HTTPConnectionPool.Connection.ID` and its generator were added now. (This will be used later to identify a connection during its lifetime)
- the file `HTTPConnectionPool+Manager` was added to give `HTTPConnectionPool.Connection.ID.Generator` already its final destination.
Updated:
NIO
NIOSSL
NIO Extras
NIOTS
Also fix TLSConfiguration.forClient() warnings by converting to TLSConfiguration.makeClientConfiguration(). Also the same for forServer().
Motivation:
In the vast majority of cases, we'll only ever create one and only one
`NIOSSLContext`. It's therefore wasteful to keep around a whole thread
doing nothing just for that. A `DispatchQueue` is absolutely fine here.
Modification:
Run the `NIOSSLContext` creation on a `DispatchQueue` instead.
Result:
Fewer threads hanging around.
This PR is a result of another #321.
In that PR I provided an alternative structure to TLSConfiguration for when connecting with Transport Services.
In this one I construct the NWProtocolTLS.Options from TLSConfiguration. It does mean a little more work for whenever we make a connection, but having spoken to @weissi he doesn't seem to think that is an issue.
Also there is no method to create a SecIdentity at the moment. We need to generate a pkcs#12 from the certificate chain and private key, which can then be used to create the SecIdentity.
This should resolve#292
Motivation:
At the moment, AHC assumes that creating a `NIOSSLContext` is both cheap
and doesn't block.
Neither of these two assumptions are true.
To create a `NIOSSLContext`, BoringSSL will have to read a lot of
certificates in the trust store (on disk) which require a lot of ASN1
parsing and much much more.
On my Ubuntu test machine, creating one `NIOSSLContext` is about 27,000
allocations!!! To make it worse, AHC allocates a fresh `NIOSSLContext`
for _every single connection_, whether HTTP or HTTPS. Yes, correct.
Modification:
- Cache NIOSSLContexts per TLSConfiguration in a LRU cache
- Don't get an NIOSSLContext for HTTP (plain text) connections
Result:
New connections should be _much_ faster in general assuming that you're
not using a different TLSConfiguration for every connection.
Motivation:
Users of the HTTPClientResponseDelegate expect that the event loop
futures returned from didReceiveHead and didReceiveBodyPart can be used
to exert backpressure. To be fair to them, they somewhat can. However,
the TaskHandler has a bit of a misunderstanding about how NIO
backpressure works, and does not correctly manage the buffer of inbound
data.
The result of this misunderstanding is that multiple calls to
didReceiveBodyPart and didReceiveHead can be outstanding at once. This
would likely lead to severe bugs in most delegates, as they do not
expect it.
We should make things work the way delegate implementers believe it
works.
Modifications:
- Added a buffer to the TaskHandler to avoid delivering data that the
delegate is not ready for.
- Added a new "pending close" state that keeps track of a state where
the TaskHandler has received .end but not yet delivered it to the
delegate. This allows better error management.
- Added some more tests.
- Documented our backpressure commitments.
Result:
Better respect for backpressure.
Resolves#348
Motivation:
AsyncHTTPClient attempts to avoid the problem of Happy Eyeballs making
it hard to know which Channel will be returned by only inserting the
TLSEventsHandler upon completion of the connect promise. Unfortunately,
as this may involve event loop hops, there are some awkward timing
windows in play where the connect may complete before this handler gets
added.
We should remove that timing window by ensuring that all channels always
have this handler in place, and instead of trying to wait until we know
which Channel will win, we can find the TLSEventsHandler that belongs to
the winning channel after the fact.
Modifications:
- TLSEventsHandler no longer removes itself from the pipeline or throws
away its promise.
- makeHTTP1Channel now searches for the TLSEventsHandler from the
pipeline that was created and is also responsible for removing it.
- Better sanity checking that the proxy TLS case does not overlap with
the connection-level TLS case.
Results:
Further shrinking windows for pipeline management issues.
Motivation:
There is an awkward timing window in the TLSEventsHandler flow where it
is possible for the NIOSSLClientHandler to fail the handshake on
handlerAdded. If this happens, the TLSEventsHandler will not be in the
pipeline, and so the handshake failure error will be lost and we'll get
a generic one instead.
This window can be resolved without performance penalty if we use the
new synchronous pipeline operations view to add the two handlers
backwards. If this is done then we can ensure that the TLSEventsHandler
is always in the pipeline before the NIOSSLClientHandler, and so there
is no risk of event loss.
While I'm here, AHC does a lot of pipeline modification. This has led to
lengthy future chains with lots of event loop hops for no particularly
good reason. I've therefore replaced all pipeline operations with their
synchronous counterparts. All but one sequence was happening on the
correct event loop, and for the one that may not I've added a fast-path
dispatch that should tolerate being on the wrong one. The result is
cleaner, more linear code that also reduces the allocations and event
loop hops.
Modifications:
- Use synchronous pipeline operations everywhere
- Change the order of adding TLSEventsHandler and NIOSSLClientHandler
Result:
Faster, safer, fewer timing windows.
Fabian FettandGitHub
David NadobaandGitHub
David NadobaandGitHub
Jake PetroulesandGitHub
David EvansandGitHub
Johannes WeissandGitHub
Adam FowlerandGitHub
Mads OdgaardandGitHub