EventLoop preferences (#415)

Author: fabianfett

Sources/AsyncHTTPClient/ConnectionPool/HTTPConnectionPool.swift

@@ -149,12 +149,15 @@ extension HTTPConnectionPool {
         }
 
         var requiredEventLoop: EventLoop? {
-            switch self.req.eventLoopPreference.preference {
-            case .indifferent, .delegate:
-                return nil
-            case .delegateAndChannel(on: let eventLoop), .testOnly_exact(channelOn: let eventLoop, delegateOn: _):
-                return eventLoop
-            }
+            self.req.requiredEventLoop
+        }
+
+        var preferredEventLoop: EventLoop {
+            self.req.preferredEventLoop
+        }
+
+        var connectionDeadline: NIODeadline? {
+            self.req.connectionDeadline
         }
 
         func __testOnly_wrapped_request() -> HTTPSchedulableRequest {

Sources/AsyncHTTPClient/ConnectionPool/HTTPExecutableRequest.swift

@@ -146,8 +146,12 @@ protocol HTTPSchedulableRequest: HTTPExecutableRequest {
     /// A connection to run this task on needs to be found before this deadline!
     var connectionDeadline: NIODeadline { get }
 
-    /// The task's `EventLoop` preference
-    var eventLoopPreference: HTTPClient.EventLoopPreference { get }
+    /// The user has expressed an intent for this request to be executed on this EventLoop. If a
+    /// connection is available on another one, just use the one handy.
+    var preferredEventLoop: EventLoop { get }
+
+    /// The user required the request to be executed on a connection that is handled by this EventLoop.
+    var requiredEventLoop: EventLoop? { get }
 
     /// Informs the task, that it was queued for execution
     ///

Sources/AsyncHTTPClient/RequestBag.swift

@@ -335,6 +335,26 @@ extension RequestBag: HTTPSchedulableRequest {
 }
 
 extension RequestBag: HTTPExecutableRequest {
+    var requiredEventLoop: EventLoop? {
+        switch self.eventLoopPreference.preference {
+        case .indifferent, .delegate:
+            return nil
+        case .delegateAndChannel(on: let eventLoop), .testOnly_exact(channelOn: let eventLoop, delegateOn: _):
+            return eventLoop
+        }
+    }
+
+    var preferredEventLoop: EventLoop {
+        switch self.eventLoopPreference.preference {
+        case .indifferent:
+            return self.task.eventLoop
+        case .delegate(let eventLoop),
+             .delegateAndChannel(on: let eventLoop),
+             .testOnly_exact(channelOn: let eventLoop, delegateOn: _):
+            return eventLoop
+        }
+    }
+
     func willExecuteRequest(_ executor: HTTPRequestExecutor) {
         if self.task.eventLoop.inEventLoop {
             self.willExecuteRequest0(executor)

Tests/AsyncHTTPClientTests/HTTPConnectionPool+RequestQueueTests.swift

@@ -24,14 +24,14 @@ class HTTPConnectionPool_RequestQueueTests: XCTestCase {
         var queue = HTTPConnectionPool.RequestQueue()
         XCTAssertTrue(queue.isEmpty)
         XCTAssertEqual(queue.count, 0)
-        let req1 = MockScheduledRequest(eventLoopPreference: .indifferent)
+        let req1 = MockScheduledRequest(requiredEventLoop: nil)
         let req1ID = queue.push(.init(req1))
         XCTAssertFalse(queue.isEmpty)
         XCTAssertFalse(queue.isEmpty(for: nil))
         XCTAssertEqual(queue.count, 1)
         XCTAssertEqual(queue.count(for: nil), 1)
 
-        let req2 = MockScheduledRequest(eventLoopPreference: .indifferent)
+        let req2 = MockScheduledRequest(requiredEventLoop: nil)
         let req2ID = queue.push(.init(req2))
         XCTAssertEqual(queue.count, 2)
 
@@ -47,7 +47,7 @@ class HTTPConnectionPool_RequestQueueTests: XCTestCase {
 
         XCTAssertTrue(queue.isEmpty(for: eventLoop))
         XCTAssertEqual(queue.count(for: eventLoop), 0)
-        let req3 = MockScheduledRequest(eventLoopPreference: .delegateAndChannel(on: eventLoop))
+        let req3 = MockScheduledRequest(requiredEventLoop: eventLoop)
         let req3ID = queue.push(.init(req3))
         XCTAssertFalse(queue.isEmpty(for: eventLoop))
         XCTAssertEqual(queue.count(for: eventLoop), 1)
@@ -60,13 +60,13 @@ class HTTPConnectionPool_RequestQueueTests: XCTestCase {
         XCTAssertTrue(queue.isEmpty)
         XCTAssertEqual(queue.count, 0)
 
-        let req4 = MockScheduledRequest(eventLoopPreference: .delegateAndChannel(on: eventLoop))
+        let req4 = MockScheduledRequest(requiredEventLoop: eventLoop)
         let req4ID = queue.push(.init(req4))
         XCTAssert(queue.remove(req4ID)?.__testOnly_wrapped_request() === req4)
 
-        let req5 = MockScheduledRequest(eventLoopPreference: .indifferent)
+        let req5 = MockScheduledRequest(requiredEventLoop: nil)
         queue.push(.init(req5))
-        let req6 = MockScheduledRequest(eventLoopPreference: .delegateAndChannel(on: eventLoop))
+        let req6 = MockScheduledRequest(requiredEventLoop: eventLoop)
         queue.push(.init(req6))
         let all = queue.removeAll()
         let testSet = all.map { $0.__testOnly_wrapped_request() }
@@ -82,13 +82,15 @@ class HTTPConnectionPool_RequestQueueTests: XCTestCase {
 }
 
 private class MockScheduledRequest: HTTPSchedulableRequest {
-    init(eventLoopPreference: HTTPClient.EventLoopPreference) {
-        self.eventLoopPreference = eventLoopPreference
+    let requiredEventLoop: EventLoop?
+
+    init(requiredEventLoop: EventLoop?) {
+        self.requiredEventLoop = requiredEventLoop
     }
 
     var logger: Logger { preconditionFailure("Unimplemented") }
     var connectionDeadline: NIODeadline { preconditionFailure("Unimplemented") }
-    let eventLoopPreference: HTTPClient.EventLoopPreference
+    var preferredEventLoop: EventLoop { preconditionFailure("Unimplemented") }
 
     func requestWasQueued(_: HTTPRequestScheduler) {
         preconditionFailure("Unimplemented")