Revert "Final removal of actors (#57)"

This reverts commit 2f8d44c.

Sources/FreeCombine/State/StateTask.swift

@@ -21,12 +21,12 @@
 /*:
  #actor problems
 
- 1. no oneway funcs (i.e. they can’t be called from synchronous code)
- 2. can’t selectively block callers in order (i.e. passing a continuation to an actor requires spawning a task which gives up ordering guarantees)
- 3. can’t block calling tasks on internal state (can only block with async call to another task)
- 4. have no concept of cancellation (cannot perform orderly shutdown with outstanding requests in flight)
- 5. they execute on global actor queues (generally not needed or desirable to go off-Task for these things)
- 6. No way to allow possible failure to enqueue on an overburdened actor, all requests enter an unbounded queue
+ 1. no oneway funcs (can't call from synchronous code)
+ 2. can't selectively block callers (to pass a continuation to an actor requires spawning a task which gives up ordering guarantees)
+ 3. can't block calling tasks on internal state (can only block with async call to another task)
+ 4. no concept of cancellation (cannot perform orderly shutdown with outstanding requests in flight)
+ 5. execute on global actor queues (generally not needed or desirable)
+ 6. No way of possible failure to enqueue on an overburdened actor, all requests enter an unbounded queue
 
  #actor solutions: StateTask - a swift implementation of the Haskell ST monad
 

Sources/FreeCombine/Synchronization/SingleConsumerStack.swift

@@ -1,28 +1,17 @@
+//===----------------------------------------------------------------------===//
 //
-//  Semaphore.swift
+// This source file is part of the Swift Atomics open source project
 //
+// Copyright (c) 2020-2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
 //
-//  Created by Van Simmons on 4/24/22.
-//  Derived from: https://github.com/apple/swift-atomics/blob/main/Tests/AtomicsTests/LockFreeSingleConsumerStack.swift
-//  As per, the Apache license this is a derivative work.
-//
-//  Copyright 2022, ComputeCycles, LLC
-//
-//  Licensed under the Apache License, Version 2.0 (the "License");
-//  you may not use this file except in compliance with the License.
-//  You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-//  Unless required by applicable law or agreed to in writing, software
-//  distributed under the License is distributed on an "AS IS" BASIS,
-//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-//  See the License for the specific language governing permissions and
-//  limitations under the License.
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
+//===----------------------------------------------------------------------===//
 import Atomics
 
-class SingleConsumerStack<Element> {
+class LockFreeSingleConsumerStack<Element> {
     struct Node {
         let value: Element
         var next: UnsafeMutablePointer<Node>?
@@ -35,7 +24,7 @@ class SingleConsumerStack<Element> {
 
     deinit {
         // Discard remaining nodes
-        while let _ = pop() { }
+        while let _ = pop() {}
         _last.destroy()
         _consumerCount.destroy()
     }
@@ -53,17 +42,17 @@ class SingleConsumerStack<Element> {
             (done, current) = _last.compareExchange(
                 expected: current,
                 desired: new,
-                ordering: .releasing
-            )
+                ordering: .releasing)
         }
     }
 
     // Pop and return the topmost element from the stack.
     // This method does not support multiple overlapping concurrent calls.
     func pop() -> Element? {
-        guard _consumerCount.loadThenWrappingIncrement(ordering: .acquiring) == 0 else {
-            return .none
-        }
+        precondition(
+            _consumerCount.loadThenWrappingIncrement(ordering: .acquiring) == 0,
+            "Multiple consumers detected"
+        )
         defer { _consumerCount.wrappingDecrement(ordering: .releasing) }
         var done = false
         var current = _last.load(ordering: .acquiring)

Sources/FreeCombine/Utils/Counter.swift

@@ -45,7 +45,7 @@ public struct Counter {
     }
 
     @discardableResult
-    public func decrement(by: Int = 1) -> Int {
+    public func decrement(by: Int = -1) -> Int {
         var c = atomicValue.load(ordering: .sequentiallyConsistent)
         while !atomicValue.compareExchange(
             expected: c,

Sources/Time/TimeNever.swift

@@ -4,20 +4,7 @@
 //
 //  Created by Van Simmons on 7/4/22.
 //
-//  Copyright 2022, ComputeCycles, LLC
-//
-//  Licensed under the Apache License, Version 2.0 (the "License");
-//  you may not use this file except in compliance with the License.
-//  You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-//  Unless required by applicable law or agreed to in writing, software
-//  distributed under the License is distributed on an "AS IS" BASIS,
-//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-//  See the License for the specific language governing permissions and
-//  limitations under the License.
-//
+
 enum TimeNever {
-    // Provide a type for this package which is only used for testing
+
 }