X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FSingleton.h;h=c8cbea9f56fd09f38b0edf525824ef9b36717e80;hb=c9cbfdb7254cef993316a53e8ad11e8cf1c6f33f;hp=c377f3ad02c49c6b3cc2a6f233d7c80371edb15c;hpb=0416e1ea440f816d5543feb5e834f09906ddfcab;p=folly.git

diff --git a/folly/Singleton.h b/folly/Singleton.h
index c377f3ad..c8cbea9f 100644
--- a/folly/Singleton.h
+++ b/folly/Singleton.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -348,7 +348,7 @@ class SingletonVault {
     }
   };
 
-  explicit SingletonVault(Type type = Type::Relaxed) : type_(type) {}
+  explicit SingletonVault(Type type = Type::Strict) : type_(type) {}
 
   // Destructor is only called by unit tests to check destroyInstances.
   ~SingletonVault();
@@ -507,9 +507,12 @@ class SingletonVault {
       eagerInitSingletons_;
   folly::Synchronized<std::vector<detail::TypeDescriptor>> creationOrder_;
 
-  folly::Synchronized<State> state_;
+  // Using SharedMutexReadPriority is important here, because we want to make
+  // sure we don't block nested singleton creation happening concurrently with
+  // destroyInstances().
+  folly::Synchronized<State, folly::SharedMutexReadPriority> state_;
 
-  Type type_{Type::Relaxed};
+  Type type_;
 };
 
 // This is the wrapper class that most users actually interact with.