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Fix HTTP1 to HTTP2 migration while shutdown is in progress (#530)

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* Fix HTTP1 to HTTP2 migration while shutdown is in progress

### Motivation
Calling `HTTPClient.shutdown()` may never return if connections are still starting and one new established connection results in a state migration (i.e. from HTTP1 to HTTP2 or vice versa). We forgot to migrate the shutdown state. This could result in a large dealy until `.shutdown()` returns because we wait until connections are closed because of idle timeout. Worse, it could also never return if more requests are queued because the connections would not be idle and therefore not close itself.
###Changes
- Mirgrate shutdown state too
- add tests for this specific case

* simplify testMigrationFromHTTP1ToHTTP2WhileShuttingDown
* add http2 to http1 migration test
This commit is contained in:
David Nadoba
2021-12-17 14:44:11 +01:00
committed by GitHub
parent d95277640f
commit e4b11eb547
6 changed files with 199 additions and 59 deletions
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Sources/AsyncHTTPClient/ConnectionPool/State Machine/HTTPConnectionPool+HTTP1StateMachine.swift
+18 -19
View File
@@ -16,12 +16,6 @@ import NIOCore
extension HTTPConnectionPool {
struct HTTP1StateMachine {
enum State: Equatable {
case running
case shuttingDown(unclean: Bool)
case shutDown
}
typealias Action = HTTPConnectionPool.StateMachine.Action
typealias ConnectionMigrationAction = HTTPConnectionPool.StateMachine.ConnectionMigrationAction
typealias EstablishedAction = HTTPConnectionPool.StateMachine.EstablishedAction
@@ -34,15 +28,20 @@ extension HTTPConnectionPool {
private var lastConnectFailure: Error?
private(set) var requests: RequestQueue
private var state: State = .running
private(set) var lifecycleState: StateMachine.LifecycleState
init(idGenerator: Connection.ID.Generator, maximumConcurrentConnections: Int) {
init(
idGenerator: Connection.ID.Generator,
maximumConcurrentConnections: Int,
lifecycleState: StateMachine.LifecycleState
) {
self.connections = HTTP1Connections(
maximumConcurrentConnections: maximumConcurrentConnections,
generator: idGenerator
)
self.requests = RequestQueue()
self.lifecycleState = lifecycleState
}
mutating func migrateFromHTTP2(
@@ -111,7 +110,7 @@ extension HTTPConnectionPool {
// MARK: - Events -
mutating func executeRequest(_ request: Request) -> Action {
switch self.state {
switch self.lifecycleState {
case .running:
if let eventLoop = request.requiredEventLoop {
return self.executeRequestOnRequiredEventLoop(request, eventLoop: eventLoop)
@@ -218,7 +217,7 @@ extension HTTPConnectionPool {
self.failedConsecutiveConnectionAttempts += 1
self.lastConnectFailure = error
switch self.state {
switch self.lifecycleState {
case .running:
// We don't care how many waiting requests we have at this point, we will schedule a
// retry. More tasks, may appear until the backoff has completed. The final
@@ -243,7 +242,7 @@ extension HTTPConnectionPool {
}
mutating func connectionCreationBackoffDone(_ connectionID: Connection.ID) -> Action {
switch self.state {
switch self.lifecycleState {
case .running:
// The naming of `failConnection` is a little confusing here. All it does is moving the
// connection state from `.backingOff` to `.closed` here. It also returns the
@@ -271,7 +270,7 @@ extension HTTPConnectionPool {
return .none
}
precondition(self.state == .running, "If we are shutting down, we must not have any idle connections")
precondition(self.lifecycleState == .running, "If we are shutting down, we must not have any idle connections")
return .init(
request: .none,
@@ -332,7 +331,7 @@ extension HTTPConnectionPool {
}
mutating func shutdown() -> Action {
precondition(self.state == .running, "Shutdown must only be called once")
precondition(self.lifecycleState == .running, "Shutdown must only be called once")
// If we have remaining request queued, we should fail all of them with a cancelled
// error.
@@ -350,10 +349,10 @@ extension HTTPConnectionPool {
let isShutdown: StateMachine.ConnectionAction.IsShutdown
let unclean = !(cleanupContext.cancel.isEmpty && waitingRequests.isEmpty)
if self.connections.isEmpty && self.http2Connections == nil {
self.state = .shutDown
self.lifecycleState = .shutDown
isShutdown = .yes(unclean: unclean)
} else {
self.state = .shuttingDown(unclean: unclean)
self.lifecycleState = .shuttingDown(unclean: unclean)
isShutdown = .no
}
@@ -371,7 +370,7 @@ extension HTTPConnectionPool {
at index: Int,
context: HTTP1Connections.IdleConnectionContext
) -> EstablishedAction {
switch self.state {
switch self.lifecycleState {
case .running:
switch context.use {
case .generalPurpose:
@@ -457,7 +456,7 @@ extension HTTPConnectionPool {
at index: Int,
context: HTTP1Connections.FailedConnectionContext
) -> Action {
switch self.state {
switch self.lifecycleState {
case .running:
switch context.use {
case .generalPurpose:
@@ -537,7 +536,7 @@ extension HTTPConnectionPool {
}
mutating func http2ConnectionClosed(_ connectionID: Connection.ID) -> Action {
switch self.state {
switch self.lifecycleState {
case .running:
_ = self.http2Connections?.failConnection(connectionID)
if self.http2Connections?.isEmpty == true {
@@ -570,7 +569,7 @@ extension HTTPConnectionPool {
mutating func http2ConnectionStreamClosed(_ connectionID: Connection.ID) -> Action {
// It is save to bang the http2Connections here. If we get this callback but we don't have
// http2 connections something has gone terribly wrong.
switch self.state {
switch self.lifecycleState {
case .running:
let (index, context) = self.http2Connections!.releaseStream(connectionID)
guard context.isIdle else {