[Observation] Refactor for state machine (and behavior robustness) and adjust protocol requirement names (#64414)

* [Observation] Change visibility of observation runtime functions to be hidden

* [Observation] Update API requirements for Observable AsyncSequence names and alter the behavior of value emissions to be based upon transactionality

* [Observation] Slight naming alteration of isolation -> isolatedTo

Note: This re-enables the previously disabled tests since the implementation should be considerably more robust to hangs.

Author: phausler

lib/Macros/Sources/ObservationMacros/ObservableMacro.swift

@@ -51,17 +51,22 @@ public struct ObservableMacro: MemberMacro, MemberAttributeMacro, ConformanceMac
       let _registrar = ObservationRegistrar<\(parentName)>()
       """
 
-    let transactions: DeclSyntax =
+    let changes: DeclSyntax =
       """
-      public nonisolated func transactions<Delivery>(for properties: TrackedProperties<\(parentName)>, isolation: Delivery) -> ObservedTransactions<\(parentName), Delivery> where Delivery: Actor {
-        _registrar.transactions(for: properties, isolation: isolation)
+      public nonisolated func changes<Isolation: Actor>(
+        for properties: TrackedProperties<\(parentName)>,
+        isolatedTo isolation: Isolation
+      ) -> ObservedChanges<\(parentName), Isolation> {
+        _registrar.changes(for: properties, isolatedTo: isolation)
       }
       """
 
-    let changes: DeclSyntax =
+    let values: DeclSyntax =
       """
-      public nonisolated func changes<Member>(for keyPath: KeyPath<\(parentName), Member>) -> ObservedChanges<\(parentName), Member> where Member: Sendable {
-        _registrar.changes(for: keyPath)
+      public nonisolated func values<Member: Sendable>(
+        for keyPath: KeyPath<\(parentName), Member>
+      ) -> ObservedValues<\(parentName), Member> {
+        _registrar.values(for: keyPath)
       }
       """
 
@@ -85,8 +90,8 @@ public struct ObservableMacro: MemberMacro, MemberAttributeMacro, ConformanceMac
 
     return [
       registrar,
-      transactions,
       changes,
+      values,
       storageStruct,
       storage,
     ]

stdlib/public/Observation/Sources/Observation/CMakeLists.txt

@@ -12,15 +12,16 @@
 
 list(APPEND swift_runtime_library_compile_flags -I${SWIFT_SOURCE_DIR}/stdlib/include -I${SWIFT_SOURCE_DIR}/include)
 
-add_swift_target_library(swiftObservation ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
+add_swift_target_library(swift_Observation ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
   Locking.cpp
   Locking.swift
   Macros.swift
   Observable.swift
   ObservationRegistrar.swift
+  ObservationRegistrarStateMachine.swift
   ObservationTracking.swift
   ObservedChanges.swift
-  ObservedTransactions.swift
+  ObservedValues.swift
   ThreadLocal.cpp
   ThreadLocal.swift
   TrackedProperties.swift

stdlib/public/Observation/Sources/Observation/Locking.cpp

@@ -15,7 +15,7 @@
 
 using namespace swift;
 
-extern "C" SWIFT_CC(swift)
+extern "C" SWIFT_CC(swift) __attribute__((visibility("hidden")))
 size_t _swift_observation_lock_size() {
   size_t bytes = sizeof(Mutex);
 
@@ -26,17 +26,17 @@ size_t _swift_observation_lock_size() {
   return bytes;
 }
 
-extern "C" SWIFT_CC(swift)
+extern "C" SWIFT_CC(swift) __attribute__((visibility("hidden")))
 void _swift_observation_lock_init(Mutex &lock) {
   new (&lock) Mutex();
 }
 
-extern "C" SWIFT_CC(swift)
+extern "C" SWIFT_CC(swift) __attribute__((visibility("hidden")))
 void _swift_observation_lock_lock(Mutex &lock) {
   lock.lock();
 }
 
-extern "C" SWIFT_CC(swift)
+extern "C" SWIFT_CC(swift) __attribute__((visibility("hidden")))
 void _swift_observation_lock_unlock(Mutex &lock) {
   lock.unlock();
 }

stdlib/public/Observation/Sources/Observation/Locking.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2022 Apple Inc. and the Swift project authors
+// Copyright (c) 2023 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information

stdlib/public/Observation/Sources/Observation/Macros.swift

@@ -12,7 +12,7 @@
 #if $Macros && hasAttribute(attached)
 
 @available(SwiftStdlib 5.9, *)
-@attached(member, names: named(_registrar), named(transactions), named(changes), named(_Storage), named(_storage))
+@attached(member, names: named(_registrar), named(changes), named(values), named(_Storage), named(_storage))
 @attached(memberAttribute)
 @attached(conformance)
 public macro Observable() = 

stdlib/public/Observation/Sources/Observation/Observable.swift

@@ -13,14 +13,14 @@ import _Concurrency
 
 @available(SwiftStdlib 5.9, *)
 public protocol Observable {
-  nonisolated func transactions<Delivery: Actor>(
+  nonisolated func changes<Isolation: Actor>(
     for properties: TrackedProperties<Self>,
-    isolation: Delivery
-  ) -> ObservedTransactions<Self, Delivery>
+    isolatedTo isolation: Isolation
+  ) -> ObservedChanges<Self, Isolation>
 
-  nonisolated func changes<Member: Sendable>(
+  nonisolated func values<Member: Sendable>(
     for keyPath: KeyPath<Self, Member>
-  ) -> ObservedChanges<Self, Member>
+  ) -> ObservedValues<Self, Member>
 
   nonisolated static func dependencies(
     of keyPath: PartialKeyPath<Self>
@@ -30,23 +30,23 @@ public protocol Observable {
 
 @available(SwiftStdlib 5.9, *)
 extension Observable {
-  public nonisolated func transactions<Member, Delivery: Actor>(
+  public nonisolated func changes<Member, Isolation: Actor>(
     for keyPath: KeyPath<Self, Member>,
-    isolation: Delivery
-  ) -> ObservedTransactions<Self, Delivery> {
-    transactions(for: [keyPath], isolation: isolation)
+    isolatedTo isolation: Isolation
+  ) -> ObservedChanges<Self, Isolation> {
+    changes(for: [keyPath], isolatedTo: isolation)
   }
 
-  public nonisolated func transactions(
+  public nonisolated func changes(
     for properties: TrackedProperties<Self>
-  ) -> ObservedTransactions<Self, MainActor.ActorType> {
-    transactions(for: properties, isolation: MainActor.shared)
+  ) -> ObservedChanges<Self, MainActor.ActorType> {
+    changes(for: properties, isolatedTo: MainActor.shared)
   }
 
-  public nonisolated func transactions<Member>(
+  public nonisolated func changes<Member>(
     for keyPath: KeyPath<Self, Member>
-  ) -> ObservedTransactions<Self, MainActor.ActorType> {
-    transactions(for: [keyPath], isolation: MainActor.shared)
+  ) -> ObservedChanges<Self, MainActor.ActorType> {
+    changes(for: [keyPath], isolatedTo: MainActor.shared)
   }
 
   public nonisolated static func dependencies(