cmake: add checks to generate folly-config.h correctly

[folly.git] / folly / futures / Promise.h

diff --git a/folly/futures/Promise.h b/folly/futures/Promise.h
index b18f59b2808d59f5b365c6f890c5f87e3489ee43..359651324c19c15b3ce8a5907ed29a720b914543 100644 (file)
--- a/folly/futures/Promise.h
+++ b/folly/futures/Promise.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.
@@ -23,11 +23,25 @@
 namespace folly {
 
 // forward declaration
+template <class T>
+class SemiFuture;
 template <class T> class Future;
 
+namespace futures {
+namespace detail {
+template <class T>
+class FutureBase;
+struct EmptyConstruct {};
+template <typename T, typename F>
+class CoreCallbackState;
+} // namespace detail
+} // namespace futures
+
 template <class T>
 class Promise {
-public:
+ public:
+  static Promise<T> makeEmpty() noexcept; // equivalent to moved-from
+
   Promise();
   ~Promise();
 
@@ -39,8 +53,15 @@ public:
   Promise(Promise<T>&&) noexcept;
   Promise& operator=(Promise<T>&&) noexcept;
 
+  /** Return a SemiFuture tied to the shared core state. This can be called only
+    once, thereafter FutureAlreadyRetrieved exception will be raised. */
+  SemiFuture<T> getSemiFuture();
+
   /** Return a Future tied to the shared core state. This can be called only
-    once, thereafter Future already retrieved exception will be raised. */
+    once, thereafter FutureAlreadyRetrieved exception will be raised.
+    NOTE: This function is deprecated. Please use getSemiFuture and pass the
+          appropriate executor to .via on the returned SemiFuture to get a
+          valid Future where necessary. */
   Future<T> getFuture();
 
   /** Fulfill the Promise with an exception_wrapper */
@@ -93,11 +114,18 @@ public:
   template <class F>
   void setWith(F&& func);
 
-  bool isFulfilled();
+  bool isFulfilled() const noexcept;
 
-private:
+ private:
   typedef typename Future<T>::corePtr corePtr;
-  template <class> friend class Future;
+  template <class>
+  friend class futures::detail::FutureBase;
+  template <class>
+  friend class SemiFuture;
+  template <class>
+  friend class Future;
+  template <class, class>
+  friend class futures::detail::CoreCallbackState;
 
   // Whether the Future has been retrieved (a one-time operation).
   bool retrieved_;
@@ -105,12 +133,14 @@ private:
   // shared core state object
   corePtr core_;
 
+  explicit Promise(futures::detail::EmptyConstruct) noexcept;
+
   void throwIfFulfilled();
   void throwIfRetrieved();
   void detach();
 };
 
-}
+} // namespace folly
 
 #include <folly/futures/Future.h>
 #include <folly/futures/Promise-inl.h>