Mark future-core get-state members as const noexcept

Summary: [Folly] Mark future-core get-state members as `const noexcept`.

Reviewed By: andrewjcg

Differential Revision: D5014358

fbshipit-source-id: e39b0b63c59267a4ecfab5aac02e6d96ce2e7e00

folly/futures/Promise-inl.h

@@ -134,7 +134,7 @@ void Promise<T>::setWith(F&& func) {
 }
 
 template <class T>
-bool Promise<T>::isFulfilled() {
+bool Promise<T>::isFulfilled() const noexcept {
   if (core_) {
     return core_->hasResult();
   }

folly/futures/Promise.h

@@ -27,7 +27,7 @@ template <class T> class Future;
 
 template <class T>
 class Promise {
-public:
+ public:
   Promise();
   ~Promise();
 
@@ -93,9 +93,9 @@ 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;
 

folly/futures/detail/Core.h

@@ -101,7 +101,7 @@ class Core final {
   Core& operator=(Core&&) = delete;
 
   /// May call from any thread
-  bool hasResult() const {
+  bool hasResult() const noexcept {
     switch (fsm_.getState()) {
       case State::OnlyResult:
       case State::Armed:
@@ -115,7 +115,7 @@ class Core final {
   }
 
   /// May call from any thread
-  bool ready() const {
+  bool ready() const noexcept {
     return hasResult();
   }
 

folly/futures/detail/FSM.h

@@ -43,7 +43,7 @@ private:
 public:
   explicit FSM(Enum startState) : state_(startState) {}
 
-  Enum getState() const {
+  Enum getState() const noexcept {
     return state_.load(std::memory_order_acquire);
   }