ReactiveObjc: Replace OSAtomic with stdatomic.

OSAtomic is deprecated as of iOS10. This change is mainly a cherry pick
of upstream PR: ReactiveCocoa#178.

Author: arangato

ReactiveObjC/NSObject+RACPropertySubscribing.m

@@ -17,7 +17,6 @@
 #import "RACSubscriber.h"
 #import "RACSignal+Operations.h"
 #import "RACTuple.h"
-#import <libkern/OSAtomic.h>
 
 @implementation NSObject (RACPropertySubscribing)
 

ReactiveObjC/RACCommand.m

@@ -17,7 +17,7 @@
 #import "RACScheduler.h"
 #import "RACSequence.h"
 #import "RACSignal+Operations.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 NSString * const RACCommandErrorDomain = @"RACCommandErrorDomain";
 NSString * const RACUnderlyingCommandErrorKey = @"RACUnderlyingCommandErrorKey";
@@ -26,7 +26,7 @@
 
 @interface RACCommand () {
   // Atomic backing variable for `allowsConcurrentExecution`.
-  volatile uint32_t _allowsConcurrentExecution;
+  atomic_uint _allowsConcurrentExecution;
 }
 
 /// A subject that sends added execution signals.
@@ -55,9 +55,9 @@ - (BOOL)allowsConcurrentExecution {
 
 - (void)setAllowsConcurrentExecution:(BOOL)allowed {
   if (allowed) {
-    OSAtomicOr32Barrier(1, &_allowsConcurrentExecution);
+    atomic_fetch_or(&_allowsConcurrentExecution, 1);
   } else {
-    OSAtomicAnd32Barrier(0, &_allowsConcurrentExecution);
+    atomic_fetch_and(&_allowsConcurrentExecution, 0);
   }
 
   [self.allowsConcurrentExecutionSubject sendNext:@(_allowsConcurrentExecution)];

ReactiveObjC/RACDisposable.m

@@ -8,15 +8,15 @@
 
 #import "RACDisposable.h"
 #import "RACScopedDisposable.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 @interface RACDisposable () {
   // A copied block of type void (^)(void) containing the logic for disposal,
   // a pointer to `self` if no logic should be performed upon disposal, or
   // NULL if the receiver is already disposed.
   //
   // This should only be used atomically.
-  void * volatile _disposeBlock;
+  _Atomic(void *) _disposeBlock;
 }
 
 @end
@@ -35,7 +35,7 @@ - (instancetype)init {
   self = [super init];
 
   _disposeBlock = (__bridge void *)self;
-  OSMemoryBarrier();
+  atomic_thread_fence(memory_order_seq_cst);
 
   return self;
 }
@@ -45,8 +45,8 @@ - (instancetype)initWithBlock:(void (^)(void))block {
 
   self = [super init];
 
-  _disposeBlock = (void *)CFBridgingRetain([block copy]); 
-  OSMemoryBarrier();
+  _disposeBlock = (void *)CFBridgingRetain([block copy]);
+  atomic_thread_fence(memory_order_seq_cst);
 
   return self;
 }
@@ -69,7 +69,7 @@ - (void)dispose {
 
   while (YES) {
     void *blockPtr = _disposeBlock;
-    if (OSAtomicCompareAndSwapPtrBarrier(blockPtr, NULL, &_disposeBlock)) {
+    if (atomic_compare_exchange_strong(&_disposeBlock, &blockPtr, NULL)) {
       if (blockPtr != (__bridge void *)self) {
         disposeBlock = CFBridgingRelease(blockPtr);
       }

ReactiveObjC/RACDynamicSequence.m

@@ -7,7 +7,7 @@
 //
 
 #import "RACDynamicSequence.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 // Determines how RACDynamicSequences will be deallocated before the next one is
 // shifted onto the autorelease pool.
@@ -114,10 +114,10 @@ + (RACSequence *)sequenceWithLazyDependency:(id (^)(void))dependencyBlock headBl
 }
 
 - (void)dealloc {
-  static volatile int32_t directDeallocCount = 0;
+  static atomic_int directDeallocCount = 0;
 
-  if (OSAtomicIncrement32(&directDeallocCount) >= DEALLOC_OVERFLOW_GUARD) {
-    OSAtomicAdd32(-DEALLOC_OVERFLOW_GUARD, &directDeallocCount);
+  if (atomic_fetch_add(&directDeallocCount, 1) + 1 >= DEALLOC_OVERFLOW_GUARD) {
+    atomic_fetch_add(&directDeallocCount, -DEALLOC_OVERFLOW_GUARD);
 
     // Put this sequence's tail onto the autorelease pool so we stop
     // recursing.

ReactiveObjC/RACDynamicSignal.m

@@ -12,7 +12,6 @@
 #import "RACPassthroughSubscriber.h"
 #import "RACScheduler+Private.h"
 #import "RACSubscriber.h"
-#import <libkern/OSAtomic.h>
 
 @interface RACDynamicSignal ()
 

ReactiveObjC/RACMulticastConnection.m

@@ -11,7 +11,7 @@
 #import "RACDisposable.h"
 #import "RACSerialDisposable.h"
 #import "RACSubject.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 @interface RACMulticastConnection () {
   RACSubject *_signal;
@@ -24,7 +24,7 @@ @interface RACMulticastConnection () {
   //
   // If the swap is unsuccessful it means that `_sourceSignal` has already been
   // connected and the caller has no action to take.
-  int32_t volatile _hasConnected;
+  _Atomic(BOOL) _hasConnected;
 }
 
 @property (nonatomic, readonly, strong) RACSignal *sourceSignal;
@@ -51,7 +51,8 @@ - (instancetype)initWithSourceSignal:(RACSignal *)source subject:(RACSubject *)s
 #pragma mark Connecting
 
 - (RACDisposable *)connect {
-  BOOL shouldConnect = OSAtomicCompareAndSwap32Barrier(0, 1, &_hasConnected);
+  BOOL expected = NO;
+  BOOL shouldConnect = atomic_compare_exchange_strong(&_hasConnected, &expected, YES);
 
   if (shouldConnect) {
     self.serialDisposable.disposable = [self.sourceSignal subscribe:_signal];
@@ -61,19 +62,19 @@ - (RACDisposable *)connect {
 }
 
 - (RACSignal *)autoconnect {
-  __block volatile int32_t subscriberCount = 0;
+  __block atomic_int subscriberCount = 0;
 
   return [[RACSignal
     createSignal:^(id<RACSubscriber> subscriber) {
-      OSAtomicIncrement32Barrier(&subscriberCount);
+      atomic_fetch_add(&subscriberCount, 1);
 
       RACDisposable *subscriptionDisposable = [self.signal subscribe:subscriber];
       RACDisposable *connectionDisposable = [self connect];
 
       return [RACDisposable disposableWithBlock:^{
         [subscriptionDisposable dispose];
 
-        if (OSAtomicDecrement32Barrier(&subscriberCount) == 0) {
+        if (atomic_fetch_sub(&subscriberCount, 1) - 1 == 0) {
           [connectionDisposable dispose];
         }
       }];

ReactiveObjC/RACSignal+Operations.m

@@ -26,7 +26,7 @@
 #import "RACSubscriber.h"
 #import "RACTuple.h"
 #import "RACUnit.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 #import <objc/runtime.h>
 #import <os/lock.h>
 
@@ -700,7 +700,7 @@ - (RACDisposable *)setKeyPath:(NSString *)keyPath onObject:(NSObject *)object ni
 
   // Purposely not retaining 'object', since we want to tear down the binding
   // when it deallocates normally.
-  __block void * volatile objectPtr = (__bridge void *)object;
+  __block _Atomic(void *) objectPtr = (__bridge void *)object;
 
   RACDisposable *subscriptionDisposable = [self subscribeNext:^(id x) {
     // Possibly spec, possibly compiler bug, but this __bridge cast does not
@@ -752,7 +752,7 @@ - (RACDisposable *)setKeyPath:(NSString *)keyPath onObject:(NSObject *)object ni
 
     while (YES) {
       void *ptr = objectPtr;
-      if (OSAtomicCompareAndSwapPtrBarrier(ptr, NULL, &objectPtr)) {
+      if (atomic_compare_exchange_strong(&objectPtr, &ptr, NULL)) {
         break;
       }
     }
@@ -1151,17 +1151,17 @@ - (RACSignal *)subscribeOn:(RACScheduler *)scheduler {
 
 - (RACSignal *)deliverOnMainThread {
   return [[RACSignal createSignal:^(id<RACSubscriber> subscriber) {
-    __block volatile int32_t queueLength = 0;
-    
+    __block atomic_int queueLength = 0;
+
     void (^performOnMainThread)(dispatch_block_t) = ^(dispatch_block_t block) {
-      int32_t queued = OSAtomicIncrement32(&queueLength);
+      int32_t queued = atomic_fetch_add(&queueLength, 1) + 1;
       if (NSThread.isMainThread && queued == 1) {
         block();
-        OSAtomicDecrement32(&queueLength);
+        atomic_fetch_sub(&queueLength, 1);
       } else {
         dispatch_async(dispatch_get_main_queue(), ^{
           block();
-          OSAtomicDecrement32(&queueLength);
+          atomic_fetch_sub(&queueLength, 1);
         });
       }
     };

ReactiveObjC/RACSignal.m

@@ -23,7 +23,7 @@
 #import "RACSubject.h"
 #import "RACSubscriber+Private.h"
 #import "RACTuple.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 @implementation RACSignal
 
@@ -108,12 +108,12 @@ - (RACSignal *)bind:(RACSignalBindBlock (^)(void))block {
   return [[RACSignal createSignal:^(id<RACSubscriber> subscriber) {
     RACSignalBindBlock bindingBlock = block();
 
-    __block volatile int32_t signalCount = 1;   // indicates self
+    __block atomic_int signalCount = 1;   // indicates self
 
     RACCompoundDisposable *compoundDisposable = [RACCompoundDisposable compoundDisposable];
 
     void (^completeSignal)(RACDisposable *) = ^(RACDisposable *finishedDisposable) {
-      if (OSAtomicDecrement32Barrier(&signalCount) == 0) {
+      if (atomic_fetch_sub(&signalCount, 1) - 1 == 0) {
         [subscriber sendCompleted];
         [compoundDisposable dispose];
       } else {
@@ -122,7 +122,7 @@ - (RACSignal *)bind:(RACSignalBindBlock (^)(void))block {
     };
 
     void (^addSignal)(RACSignal *) = ^(RACSignal *signal) {
-      OSAtomicIncrement32Barrier(&signalCount);
+      atomic_fetch_add(&signalCount, 1);
 
       RACSerialDisposable *selfDisposable = [[RACSerialDisposable alloc] init];
       [compoundDisposable addDisposable:selfDisposable];
@@ -363,7 +363,7 @@ - (instancetype)filter:(BOOL (^)(id))block {
 
 - (instancetype)flattenMap:(RACSignal *(^)(id))block {
   return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
-    __block volatile int32_t subscriptionCount = 1;
+    __block atomic_int subscriptionCount = 1;
 
     RACCompoundDisposable *disposable = [RACCompoundDisposable compoundDisposable];
 
@@ -378,15 +378,15 @@ - (instancetype)flattenMap:(RACSignal *(^)(id))block {
       }
       NSCAssert([signal isKindOfClass:RACSignal.class], @"Expected a RACSignal, got %@", signal);
 
-      OSAtomicIncrement32(&subscriptionCount);
+      atomic_fetch_add(&subscriptionCount, 1);
 
       RACDisposable *innerDisposable = [signal subscribeNext:^(id x) {
         [subscriber sendNext:x];
       } error:^(NSError *error) {
         [subscriber sendError:error];
         [disposable dispose];
       } completed:^{
-        if (!OSAtomicDecrement32(&subscriptionCount)) {
+        if (atomic_fetch_sub(&subscriptionCount, 1) - 1 == 0) {
           [subscriber sendCompleted];
         }
       }];
@@ -395,7 +395,7 @@ - (instancetype)flattenMap:(RACSignal *(^)(id))block {
     } error:^(NSError *error) {
       [subscriber sendError:error];
     } completed:^{
-      if (!OSAtomicDecrement32(&subscriptionCount)) {
+      if (atomic_fetch_sub(&subscriptionCount, 1) - 1 == 0) {
         [subscriber sendCompleted];
       }
     }];

ReactiveObjC/extobjc/EXTRuntimeExtensions.m

@@ -11,7 +11,6 @@
 
 #import <ctype.h>
 #import <Foundation/Foundation.h>
-#import <libkern/OSAtomic.h>
 #import <objc/message.h>
 #import <pthread.h>
 #import <stdio.h>

ReactiveObjCTests/RACMulticastConnectionSpec.m

@@ -15,7 +15,6 @@
 #import "RACSubscriber.h"
 #import "RACReplaySubject.h"
 #import "RACScheduler.h"
-#import <libkern/OSAtomic.h>
 
 QuickSpecBegin(RACMulticastConnectionSpec)
 

ReactiveObjCTests/RACSignalSpec.m

@@ -121,7 +121,7 @@ + (void)configure:(Configuration *)configuration {
     }];
 
     return [RACDisposable disposableWithBlock:^{
-      ++done;
+      atomic_fetch_add(&done, 1);
     }];
   }];
 

ReactiveObjCTests/RACSubscriberSpec.m

@@ -13,15 +13,15 @@
 
 #import "RACSubscriber.h"
 #import "RACSubscriber+Private.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 QuickSpecBegin(RACSubscriberSpec)
 
 __block RACSubscriber *subscriber;
 __block NSMutableArray *values;
 
-__block volatile BOOL finished;
-__block volatile int32_t nextsAfterFinished;
+__block _Atomic(BOOL) finished;
+__block atomic_int nextsAfterFinished;
 
 __block BOOL success;
 __block NSError *error;
@@ -36,7 +36,7 @@
   error = nil;
 
   subscriber = [RACSubscriber subscriberWithNext:^(id value) {
-    if (finished) OSAtomicIncrement32Barrier(&nextsAfterFinished);
+    if (finished) atomic_fetch_add(&nextsAfterFinished, 1);
 
     [values addObject:value];
   } error:^(NSError *e) {
@@ -111,7 +111,7 @@
       [subscriber sendCompleted];
 
       finished = YES;
-      OSMemoryBarrier();
+      atomic_thread_fence(memory_order_seq_cst);
     });
   });
 
@@ -122,7 +122,7 @@
       [subscriber sendError:nil];
 
       finished = YES;
-      OSMemoryBarrier();
+      atomic_thread_fence(memory_order_seq_cst);
     });
   });
 });

ReactiveObjCTests/RACTargetQueueSchedulerSpec.m

@@ -10,7 +10,7 @@
 @import Nimble;
 
 #import "RACTargetQueueScheduler.h"
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 QuickSpecBegin(RACTargetQueueSchedulerSpec)
 
@@ -28,20 +28,20 @@
 qck_it(@"should schedule blocks FIFO even when given a concurrent queue", ^{
   dispatch_queue_t queue = dispatch_queue_create("test-queue", DISPATCH_QUEUE_CONCURRENT);
   RACScheduler *scheduler = [[RACTargetQueueScheduler alloc] initWithName:@"test-scheduler" targetQueue:queue];
-  __block volatile int32_t startedCount = 0;
-  __block volatile uint32_t waitInFirst = 1;
+  __block atomic_int startedCount = 0;
+  __block atomic_uint waitInFirst = 1;
   [scheduler schedule:^{
-    OSAtomicIncrement32Barrier(&startedCount);
+    atomic_fetch_add(&startedCount, 1);
     while (waitInFirst == 1) ;
   }];
 
   [scheduler schedule:^{
-    OSAtomicIncrement32Barrier(&startedCount);
+    atomic_fetch_add(&startedCount, 1);
   }];
 
   expect(@(startedCount)).toEventually(equal(@1));
 
-  OSAtomicAnd32Barrier(0, &waitInFirst);
+  atomic_fetch_and(&waitInFirst, 0);
 
   expect(@(startedCount)).toEventually(equal(@2));
 });