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Fix Connection Creation Crash (#873)

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### 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 <gbarnett@apple.com>
This commit is contained in:
Fabian Fett
2025-12-01 09:31:32 +01:00
committed by GitHub
co-authored by George Barnett
parent ce04df0613
commit 3c45dbde2d
8 changed files with 165 additions and 38 deletions
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Sources/AsyncHTTPClient/ConnectionPool/State Machine/HTTPConnectionPool+HTTP1Connections.swift
+35 -18
View File
@@ -166,10 +166,22 @@ extension HTTPConnectionPool {
}
}
mutating func fail() {
enum FailAction {
case removeConnection
case none
}
mutating func fail() -> FailAction {
switch self.state {
case .starting, .backingOff, .idle, .leased:
case .starting:
// If the connection fails while we are starting it, the fail call raced with
// `failedToConnect` (promises are succeeded or failed before channel handler
// callbacks). let's keep the state in `starting`, so that `failedToConnect` can
// create a backoff timer.
return .none
case .backingOff, .idle, .leased:
self.state = .closed
return .removeConnection
case .closed:
preconditionFailure("Invalid state: \(self.state)")
}
@@ -559,23 +571,28 @@ extension HTTPConnectionPool {
}
let use: ConnectionUse
self.connections[index].fail()
let eventLoop = self.connections[index].eventLoop
let starting: Int
if index < self.overflowIndex {
use = .generalPurpose
starting = self.startingGeneralPurposeConnections
} else {
use = .eventLoop(eventLoop)
starting = self.startingEventLoopConnections(on: eventLoop)
}
switch self.connections[index].fail() {
case .removeConnection:
let eventLoop = self.connections[index].eventLoop
let starting: Int
if index < self.overflowIndex {
use = .generalPurpose
starting = self.startingGeneralPurposeConnections
} else {
use = .eventLoop(eventLoop)
starting = self.startingEventLoopConnections(on: eventLoop)
}
let context = FailedConnectionContext(
eventLoop: eventLoop,
use: use,
connectionsStartingForUseCase: starting
)
return (index, context)
let context = FailedConnectionContext(
eventLoop: eventLoop,
use: use,
connectionsStartingForUseCase: starting
)
return (index, context)
case .none:
return nil
}
}
// MARK: Migration