Fix a potential deadlock that could occur when encoding for REST.

We didn't actually need to hold the lock here, and if we did, another thread could have acquired these locks in another order, causing a deadlock.

Should help to fix #398, #11, and a few others.

Author: richardjrossiii

Parse/PFObject.m

@@ -958,25 +958,33 @@ + (BFTask *)_migrateObjectInBackgroundFromFile:(NSString *)fileName
  */
 - (NSDictionary *)RESTDictionaryWithObjectEncoder:(PFEncoder *)objectEncoder
                                 operationSetUUIDs:(NSArray **)operationSetUUIDs {
+    NSArray *operationQueue = nil;
+    PFObjectState *state = nil;
+    BOOL deleting = NO;
     @synchronized (lock) {
         [self checkForChangesToMutableContainers];
-        PFObjectState *state = self._state;
-        return [self RESTDictionaryWithObjectEncoder:objectEncoder
-                                   operationSetUUIDs:operationSetUUIDs
-                                               state:state
-                                   operationSetQueue:operationSetQueue];
+        state = self._state;
+        operationQueue = [[NSArray alloc] initWithArray:operationSetQueue copyItems:YES];
+        deleting = _deletingEventually;
     }
+
+    return [self RESTDictionaryWithObjectEncoder:objectEncoder
+                               operationSetUUIDs:operationSetUUIDs
+                                            state:state
+                               operationSetQueue:operationQueue
+                              deletingEventually:deleting];
 }
 
 - (NSDictionary *)RESTDictionaryWithObjectEncoder:(PFEncoder *)objectEncoder
                                 operationSetUUIDs:(NSArray **)operationSetUUIDs
                                             state:(PFObjectState *)state
-                                operationSetQueue:(NSArray *)queue {
+                                operationSetQueue:(NSArray *)queue
+                               deletingEventually:(BOOL)isDeletingEventually {
     NSMutableDictionary *result = [[state dictionaryRepresentationWithObjectEncoder:objectEncoder] mutableCopy];
     result[PFObjectClassNameRESTKey] = state.parseClassName;
     result[PFObjectCompleteRESTKey] = @(state.complete);
 
-    result[PFObjectIsDeletingEventuallyRESTKey] = @(_deletingEventually);
+    result[PFObjectIsDeletingEventuallyRESTKey] = @(isDeletingEventually);
 
     // TODO (hallucinogen): based on some note from Android's toRest, we'll need to put this
     // stuff somewhere else