Avoid using global Mutex variables

Source/ASImageNode.mm

@@ -433,11 +433,15 @@ + (UIImage *)displayWithParameters:(id<NSObject>)parameter isCancelled:(NS_NOESC
 }
 
 static ASWeakMap<ASImageNodeContentsKey *, UIImage *> *cache = nil;
-// Allocate cacheLock on the heap to prevent destruction at app exit (https://github.com/TextureGroup/Texture/issues/136)
-static auto *cacheLock = new ASDN::Mutex;
 
 + (ASWeakMapEntry *)contentsForkey:(ASImageNodeContentsKey *)key drawParameters:(id)drawParameters isCancelled:(asdisplaynode_iscancelled_block_t)isCancelled
 {
+  static dispatch_once_t onceToken;
+  static ASDN::Mutex *cacheLock = nil;
+  dispatch_once(&onceToken, ^{
+    cacheLock = new ASDN::Mutex();
+  });
+
   {
     ASDN::MutexLocker l(*cacheLock);
     if (!cache) {

Source/ASTextNode2.mm

@@ -54,11 +54,11 @@ @implementation ASTextCacheValue
  * NOTE: Be careful to copy `text` if needed.
  */
 static NS_RETURNS_RETAINED ASTextLayout *ASTextNodeCompatibleLayoutWithContainerAndText(ASTextContainer *container, NSAttributedString *text)  {
-  // Allocate layoutCacheLock on the heap to prevent destruction at app exit (https://github.com/TextureGroup/Texture/issues/136)
-  static auto *layoutCacheLock = new ASDN::Mutex;
-  static NSCache<NSAttributedString *, ASTextCacheValue *> *textLayoutCache;
   static dispatch_once_t onceToken;
+  static ASDN::Mutex *layoutCacheLock;
+  static NSCache<NSAttributedString *, ASTextCacheValue *> *textLayoutCache;
   dispatch_once(&onceToken, ^{
+    layoutCacheLock = new ASDN::Mutex();
     textLayoutCache = [[NSCache alloc] init];
   });
 

Source/Details/ASBasicImageDownloader.mm

@@ -38,12 +38,20 @@ @interface ASBasicImageDownloaderContext ()
 @implementation ASBasicImageDownloaderContext
 
 static NSMutableDictionary *currentRequests = nil;
-// Allocate currentRequestsLock on the heap to prevent destruction at app exit (https://github.com/TextureGroup/Texture/issues/136)
-static auto *currentRequestsLock = new ASDN::Mutex;
+
++ (ASDN::Mutex *)currentRequestLock
+{
+  static dispatch_once_t onceToken;
+  static ASDN::Mutex *currentRequestsLock;
+  dispatch_once(&onceToken, ^{
+    currentRequestsLock = new ASDN::Mutex();
+  });
+  return currentRequestsLock;
+}
 
 + (ASBasicImageDownloaderContext *)contextForURL:(NSURL *)URL
 {
-  ASDN::MutexLocker l(*currentRequestsLock);
+  ASDN::MutexLocker l(*self.currentRequestLock);
   if (!currentRequests) {
     currentRequests = [[NSMutableDictionary alloc] init];
   }
@@ -57,7 +65,7 @@ + (ASBasicImageDownloaderContext *)contextForURL:(NSURL *)URL
 
 + (void)cancelContextWithURL:(NSURL *)URL
 {
-  ASDN::MutexLocker l(*currentRequestsLock);
+  ASDN::MutexLocker l(*self.currentRequestLock);
   if (currentRequests) {
     [currentRequests removeObjectForKey:URL];
   }

Source/TextKit/ASTextKitContext.mm

@@ -34,9 +34,13 @@ - (instancetype)initWithAttributedString:(NSAttributedString *)attributedString
 
 {
   if (self = [super init]) {
+    static dispatch_once_t onceToken;
+    static ASDN::Mutex *mutex;
+    dispatch_once(&onceToken, ^{
+      mutex = new ASDN::Mutex();
+    });
+
     // Concurrently initialising TextKit components crashes (rdar://18448377) so we use a global lock.
-    // Allocate mutex on the heap to prevent destruction at app exit (https://github.com/TextureGroup/Texture/issues/136)
-    static auto *mutex = new ASDN::Mutex;
     ASDN::MutexLocker l(*mutex);
 
     __instanceLock__ = std::make_shared<ASDN::Mutex>();