Fix i386 build by providing fallbacks to thread_local variables (Text…

…ureGroup#1025)

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## master
 * Add your own contributions to the next release on the line below this with your name.
+- Fix build on 32-bit simulator in Xcode 9.3 and later, caused by `Thread-local storage is not supported on this architecture.` [Adlai Holler](https://github.com/Adlai-Holler)
 
 ## 2.7
 - Fix pager node for interface coalescing. [Max Wang](https://github.com/wsdwsd0829) [#877](https://github.com/TextureGroup/Texture/pull/877)

Source/ASDisplayNode.mm

@@ -1169,22 +1169,29 @@ - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
                      restrictedToSize:(ASLayoutElementSize)size
                  relativeToParentSize:(CGSize)parentSize
 {
-  // We only want one calculateLayout signpost interval per thread.
-  static _Thread_local NSInteger tls_callDepth;
   as_activity_scope_verbose(as_activity_create("Calculate node layout", AS_ACTIVITY_CURRENT, OS_ACTIVITY_FLAG_DEFAULT));
   as_log_verbose(ASLayoutLog(), "Calculating layout for %@ sizeRange %@", self, NSStringFromASSizeRange(constrainedSize));
+
+#if AS_KDEBUG_ENABLE
+  // We only want one calculateLayout signpost interval per thread.
+  // Currently there is no fallback for profiling i386, since it's not useful.
+  static _Thread_local NSInteger tls_callDepth;
   if (tls_callDepth++ == 0) {
     ASSignpostStart(ASSignpostCalculateLayout);
   }
+#endif
 
   ASSizeRange styleAndParentSize = ASLayoutElementSizeResolve(self.style.size, parentSize);
   const ASSizeRange resolvedRange = ASSizeRangeIntersect(constrainedSize, styleAndParentSize);
   ASLayout *result = [self calculateLayoutThatFits:resolvedRange];
   as_log_verbose(ASLayoutLog(), "Calculated layout %@", result);
 
+#if AS_KDEBUG_ENABLE
   if (--tls_callDepth == 0) {
     ASSignpostEnd(ASSignpostCalculateLayout);
   }
+#endif
+
   return result;
 }
 

Source/Base/ASAssert.m

@@ -11,9 +11,11 @@
 //
 
 #import <AsyncDisplayKit/ASAssert.h>
+#import <AsyncDisplayKit/ASAvailability.h>
 
-static _Thread_local int tls_mainThreadAssertionsDisabledCount;
+#if AS_TLS_AVAILABLE
 
+static _Thread_local int tls_mainThreadAssertionsDisabledCount;
 BOOL ASMainThreadAssertionsAreDisabled() {
   return tls_mainThreadAssertionsDisabledCount > 0;
 }
@@ -26,3 +28,35 @@ void ASPopMainThreadAssertionsDisabled() {
   tls_mainThreadAssertionsDisabledCount -= 1;
   ASDisplayNodeCAssert(tls_mainThreadAssertionsDisabledCount >= 0, @"Attempt to pop thread assertion-disabling without corresponding push.");
 }
+
+#else
+
+#import <dispatch/once.h>
+
+static pthread_key_t ASMainThreadAssertionsDisabledKey() {
+  static pthread_key_t k;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    pthread_key_create(&k, NULL);
+  });
+  return k;
+}
+
+BOOL ASMainThreadAssertionsAreDisabled() {
+  return (pthread_getspecific(ASMainThreadAssertionsDisabledKey()) > 0);
+}
+
+void ASPushMainThreadAssertionsDisabled() {
+  let key = ASMainThreadAssertionsDisabledKey();
+  let oldVal = pthread_getspecific(key);
+  pthread_setspecific(key, oldVal + 1);
+}
+
+void ASPopMainThreadAssertionsDisabled() {
+  let key = ASMainThreadAssertionsDisabledKey();
+  let oldVal = pthread_getspecific(key);
+  pthread_setspecific(key, oldVal - 1);
+  ASDisplayNodeCAssert(oldVal > 0, @"Attempt to pop thread assertion-disabling without corresponding push.");
+}
+
+#endif // AS_TLS_AVAILABLE

Source/Base/ASAvailability.h

@@ -19,6 +19,12 @@
 
 #pragma once
 
+#ifdef __i386__
+  #define AS_TLS_AVAILABLE 0
+#else
+  #define AS_TLS_AVAILABLE 1
+#endif
+
 #ifndef kCFCoreFoundationVersionNumber_iOS_10_0
   #define kCFCoreFoundationVersionNumber_iOS_10_0 1348.00
 #endif

Source/Layout/ASLayoutElement.mm

@@ -50,6 +50,8 @@ - (instancetype)init
 int32_t const ASLayoutElementContextInvalidTransitionID = 0;
 int32_t const ASLayoutElementContextDefaultTransitionID = ASLayoutElementContextInvalidTransitionID + 1;
 
+#if AS_TLS_AVAILABLE
+
 static _Thread_local __unsafe_unretained ASLayoutElementContext *tls_context;
 
 void ASLayoutElementPushContext(ASLayoutElementContext *context)
@@ -73,6 +75,42 @@ void ASLayoutElementPopContext()
   tls_context = nil;
 }
 
+#else
+
+static pthread_key_t ASLayoutElementContextKey() {
+  static pthread_key_t k;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    pthread_key_create(&k, NULL);
+  });
+  return k;
+}
+void ASLayoutElementPushContext(ASLayoutElementContext *context)
+{
+  // NOTE: It would be easy to support nested contexts – just use an NSMutableArray here.
+  ASDisplayNodeCAssertNil(pthread_getspecific(ASLayoutElementContextKey()), @"Nested ASLayoutElementContexts aren't supported.");
+
+  let cfCtx = (__bridge_retained CFTypeRef)context;
+  pthread_setspecific(ASLayoutElementContextKey(), cfCtx);
+}
+
+ASLayoutElementContext *ASLayoutElementGetCurrentContext()
+{
+  // Don't retain here. Caller will retain if it wants to!
+  let ctxPtr = pthread_getspecific(ASLayoutElementContextKey());
+  return (__bridge ASLayoutElementContext *)ctxPtr;
+}
+
+void ASLayoutElementPopContext()
+{
+  let ctx = (CFTypeRef)pthread_getspecific(ASLayoutElementContextKey());
+  ASDisplayNodeCAssertNotNil(ctx, @"Attempt to pop context when there wasn't a context!");
+  CFRelease(ctx);
+  pthread_setspecific(ASLayoutElementContextKey(), NULL);
+}
+
+#endif // AS_TLS_AVAILABLE
+
 #pragma mark - ASLayoutElementStyle
 
 NSString * const ASLayoutElementStyleWidthProperty = @"ASLayoutElementStyleWidthProperty";