Fix AtomicInt usages of deprecated atomic APIs (#26)

neakor · rudro · commit 9c2d8fbdb789 · 2018-12-13T13:22:43.000-08:00
* Fix AtomicInt usages of deprecated atomic APIs

As of iOS 10.0 and MacOS 10.12 the old `OSMemoryBarrier`, `OSAtomicCompareAndSwap64Barrier`, `OSAtomicIncrement64Barrier`, and `OSAtomicDecrement64Barrier, APIs are deprecated. The warnings suggested new APIs are C++ and are not accessible from Swift.

`OSMemoryBarrier` can be directly replaced with `atomic_thread_fence(memory_order_seq_cst)` which is accessible from Swift.

The rest of the suggested C++ APIs `atomic_fetch_add`, `atomic_fetch_sub`, and `atomic_compare_exchange_strong` are not accessible from Swift. This change creates a Objective-C wrapper for these C++ APIs, so Swift code can access them.

* Update TravisCI to use Xcode 10.1
diff --git a/.gitignore b/.gitignore
@@ -35,3 +35,4 @@ Packages/
 Package.pins
 Package.resolved
 .build/
+.DS_Store
diff --git a/.travis.yml b/.travis.yml
@@ -1,10 +1,10 @@
 language: objective-c
-osx_image: xcode9
+osx_image: xcode10.1
 
 env:
   - ACTION=test  PLATFORM=Mac     DESTINATION='platform=OS X'
-  - ACTION=test  PLATFORM=iOS     DESTINATION='platform=iOS Simulator,name=iPhone 7'
-  - ACTION=test  PLATFORM=tvOS    DESTINATION='platform=tvOS Simulator,name=Apple TV 1080p'
+  - ACTION=test  PLATFORM=iOS     DESTINATION='platform=iOS Simulator,name=iPhone XS'
+  - ACTION=test  PLATFORM=tvOS    DESTINATION='platform=tvOS Simulator,name=Apple TV 4K'
 
 script:
   - swift test
diff --git a/Concurrency.xcodeproj/Concurrency_Info.plist b/Concurrency.xcodeproj/Concurrency_Info.plist
@@ -1,26 +1,25 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
-	<key>CFBundleDevelopmentRegion</key>
-	<string>en</string>
-	<key>CFBundleExecutable</key>
-	<string>$(EXECUTABLE_NAME)</string>
-	<key>CFBundleIdentifier</key>
-	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
-	<key>CFBundleInfoDictionaryVersion</key>
-	<string>6.0</string>
-	<key>CFBundleName</key>
-	<string>$(PRODUCT_NAME)</string>
-	<key>CFBundlePackageType</key>
-	<string>FMWK</string>
-	<key>CFBundleShortVersionString</key>
-	<string>0.6.1</string>
-	<key>CFBundleSignature</key>
-	<string>????</string>
-	<key>CFBundleVersion</key>
-	<string>0.6.1</string>
-	<key>NSPrincipalClass</key>
-	<string></string>
+  <key>CFBundleDevelopmentRegion</key>
+  <string>en</string>
+  <key>CFBundleExecutable</key>
+  <string>$(EXECUTABLE_NAME)</string>
+  <key>CFBundleIdentifier</key>
+  <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+  <key>CFBundleInfoDictionaryVersion</key>
+  <string>6.0</string>
+  <key>CFBundleName</key>
+  <string>$(PRODUCT_NAME)</string>
+  <key>CFBundlePackageType</key>
+  <string>FMWK</string>
+  <key>CFBundleShortVersionString</key>
+  <string>1.0</string>
+  <key>CFBundleSignature</key>
+  <string>????</string>
+  <key>CFBundleVersion</key>
+  <string>$(CURRENT_PROJECT_VERSION)</string>
+  <key>NSPrincipalClass</key>
+  <string></string>
 </dict>
 </plist>
diff --git a/Concurrency.xcodeproj/GeneratedModuleMap/ObjCBridges/module.modulemap b/Concurrency.xcodeproj/GeneratedModuleMap/ObjCBridges/module.modulemap
@@ -0,0 +1,4 @@
+module ObjCBridges {
+    umbrella "/Users/yiw/Uber/GitHub/swift-concurrency/Sources/ObjCBridges/include"
+    export *
+}
diff --git a/Concurrency.xcodeproj/ObjCBridges_Info.plist b/Concurrency.xcodeproj/ObjCBridges_Info.plist
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<plist version="1.0">
+<dict>
+  <key>CFBundleDevelopmentRegion</key>
+  <string>en</string>
+  <key>CFBundleExecutable</key>
+  <string>$(EXECUTABLE_NAME)</string>
+  <key>CFBundleIdentifier</key>
+  <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+  <key>CFBundleInfoDictionaryVersion</key>
+  <string>6.0</string>
+  <key>CFBundleName</key>
+  <string>$(PRODUCT_NAME)</string>
+  <key>CFBundlePackageType</key>
+  <string>FMWK</string>
+  <key>CFBundleShortVersionString</key>
+  <string>1.0</string>
+  <key>CFBundleSignature</key>
+  <string>????</string>
+  <key>CFBundleVersion</key>
+  <string>$(CURRENT_PROJECT_VERSION)</string>
+  <key>NSPrincipalClass</key>
+  <string></string>
+</dict>
+</plist>
diff --git a/Concurrency.xcodeproj/project.pbxproj b/Concurrency.xcodeproj/project.pbxproj
diff --git a/Concurrency.xcodeproj/project.xcworkspace/contents.xcworkspacedata b/Concurrency.xcodeproj/project.xcworkspace/contents.xcworkspacedata
diff --git a/Concurrency.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings b/Concurrency.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>IDEWorkspaceSharedSettings_AutocreateContextsIfNeeded</key>
+    <false/>
+</dict>
+</plist>
diff --git a/Concurrency.xcodeproj/xcshareddata/xcschemes/Concurrency.xcscheme b/Concurrency.xcodeproj/xcshareddata/xcschemes/Concurrency.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1000"
+   LastUpgradeVersion = "1010"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/Concurrency.xcodeproj/xcshareddata/xcschemes/ConcurrencyTests.xcscheme b/Concurrency.xcodeproj/xcshareddata/xcschemes/ConcurrencyTests.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1000"
+   LastUpgradeVersion = "1010"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/Package.swift b/Package.swift
@@ -12,9 +12,12 @@ let package = Package(
     ],
     dependencies: [],
     targets: [
+        .target(
+            name: "ObjCBridges",
+            dependencies:[]),
         .target(
             name: "Concurrency",
-            dependencies: []),
+            dependencies: ["ObjCBridges"]),
         .testTarget(
             name: "ConcurrencyTests",
             dependencies: ["Concurrency"]),
diff --git a/Sources/Concurrency/AtomicInt.swift b/Sources/Concurrency/AtomicInt.swift
@@ -16,6 +16,7 @@
 
 import Foundation
 import libkern
+import ObjCBridges
 
 /// A concurrency utility class that supports locking-free synchronization on mutating an integer
 /// value. Unlike using a lock, concurrent read and write accesses to this class is allowed. At
@@ -28,8 +29,8 @@ public class AtomicInt {
         get {
             // Create a memory barrier to ensure the entire memory stack is in sync so we
             // can safely retrieve the value. This guarantees the initial value is in sync.
-            OSMemoryBarrier()
-            return Int(wrappedValue)
+            atomic_thread_fence(memory_order_seq_cst)
+            return wrappedValue
         }
         set {
             while true {
@@ -45,7 +46,7 @@ public class AtomicInt {
     ///
     /// - parameter initialValue: The initial value.
     public init(initialValue: Int) {
-        wrappedValue = Int64(initialValue)
+        wrappedValue = initialValue
     }
 
     /// Atomically sets the new value, if the current value equals the expected value.
@@ -55,53 +56,52 @@ public class AtomicInt {
     /// - returns: true if the comparison succeeded and the value is set. false otherwise.
     @discardableResult
     public func compareAndSet(expect: Int, newValue: Int) -> Bool {
-        return OSAtomicCompareAndSwap64Barrier(Int64(expect), Int64(newValue), &wrappedValue)
+        var mutableExpected = expect
+        return AtomicBridges.compare(wrappedValueOpaquePointer, withExpected: UnsafeMutablePointer<Int>(&mutableExpected), andSwap: newValue)
     }
 
     /// Atomically increment the value and retrieve the new value.
     ///
     /// - returns: The new value after incrementing.
     @discardableResult
     public func incrementAndGet() -> Int {
-        let result = OSAtomicIncrement64Barrier(&wrappedValue)
-        return Int(result)
+        while true {
+            let oldValue = self.value
+            let newValue = oldValue + 1
+            if self.compareAndSet(expect: oldValue, newValue: newValue) {
+                return newValue
+            }
+        }
     }
 
     /// Atomically decrement the value and retrieve the new value.
     ///
     /// - returns: The new value after decrementing.
     @discardableResult
     public func decrementAndGet() -> Int {
-        let result = OSAtomicDecrement64Barrier(&wrappedValue)
-        return Int(result)
+        while true {
+            let oldValue = self.value
+            let newValue = oldValue - 1
+            if self.compareAndSet(expect: oldValue, newValue: newValue) {
+                return newValue
+            }
+        }
     }
 
     /// Atomically increment the value and retrieve the old value.
     ///
     /// - returns: The old value before incrementing.
     @discardableResult
     public func getAndIncrement() -> Int {
-        while true {
-            let oldValue = self.value
-            let newValue = oldValue + 1
-            if self.compareAndSet(expect: oldValue, newValue: newValue) {
-                return oldValue
-            }
-        }
+        return AtomicBridges.fetchAndIncrementBarrier(wrappedValueOpaquePointer)
     }
 
     /// Atomically decrement the value and retrieve the old value.
     ///
     /// - returns: The old value before decrementing.
     @discardableResult
     public func getAndDecrement() -> Int {
-        while true {
-            let oldValue = self.value
-            let newValue = oldValue - 1
-            if self.compareAndSet(expect: oldValue, newValue: newValue) {
-                return oldValue
-            }
-        }
+        return AtomicBridges.fetchAndDecrementBarrier(wrappedValueOpaquePointer)
     }
 
     /// Atomically sets to the given new value and returns the old value.
@@ -120,5 +120,9 @@ public class AtomicInt {
 
     // MARK: - Private
 
-    private var wrappedValue: Int64
+    private var wrappedValue: Int
+
+    private var wrappedValueOpaquePointer: OpaquePointer {
+        return OpaquePointer(UnsafeMutablePointer<Int>(&wrappedValue))
+    }
 }
diff --git a/Sources/ObjCBridges/AtomicBridges.m b/Sources/ObjCBridges/AtomicBridges.m
@@ -0,0 +1,33 @@
+//
+//  Copyright (c) 2018. Uber Technologies
+//
+//  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.
+//
+
+#import "AtomicBridges.h"
+
+@implementation AtomicBridges
+
++ (long)fetchAndIncrementBarrier:(_Atomic(long) *)value {
+    return atomic_fetch_add(value, 1);
+}
+
++ (long)fetchAndDecrementBarrier:(_Atomic(long) *)value {
+    return atomic_fetch_sub(value, 1);
+}
+
++ (bool)compare:(_Atomic(long) *)value withExpected:(long *)expected andSwap:(long)desired {
+    return atomic_compare_exchange_strong(value, expected, desired);
+}
+
+@end
diff --git a/Sources/ObjCBridges/include/AtomicBridges.h b/Sources/ObjCBridges/include/AtomicBridges.h
@@ -14,13 +14,19 @@
 //  limitations under the License.
 //
 
-import XCTest
-@testable import ConcurrencyTests
-
-XCTMain([
-    testCase(AtomicBoolTests.allTests),
-    testCase(AtomicIntTests.allTests),
-    testCase(AtomicReferenceTests.allTests),
-    testCase(CountDownLatchTests.allTests),
-    testCase(ConcurrentSequenceExecutorTests.allTests),
-])
+#import <Foundation/Foundation.h>
+#import <stdatomic.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface AtomicBridges: NSObject
+
++ (long)fetchAndIncrementBarrier:(_Atomic(long) *)value;
+
++ (long)fetchAndDecrementBarrier:(_Atomic(long) *)value;
+
++ (bool)compare:(_Atomic(long) *)value withExpected:(long *)expected andSwap:(long)desired;
+
+@end
+
+NS_ASSUME_NONNULL_END
