r-value qualify Future::getVia for consistency with other get operations

Summary: getVia is destructive like other forms of get. This change r-value qualifies it to highlight that in code.

Reviewed By: yfeldblum

Differential Revision: D23603722

fbshipit-source-id: d2aecac3c6eb09e0fcf55a07e310114ebc13b932

folly/futures/Future-inl.h

@@ -2379,12 +2379,12 @@ Try<T> Future<T>::getTry(HighResDuration dur) && {
 }
 
 template <class T>
-T Future<T>::getVia(DrivableExecutor* e) {
+T Future<T>::getVia(DrivableExecutor* e) && {
   return std::move(waitVia(e).value());
 }
 
 template <class T>
-T Future<T>::getVia(TimedDrivableExecutor* e, HighResDuration dur) {
+T Future<T>::getVia(TimedDrivableExecutor* e, HighResDuration dur) && {
   waitVia(e, dur);
   if (!this->isReady()) {
     throw_exception<FutureTimeout>();

folly/futures/Future.h

@@ -1131,14 +1131,14 @@ class Future : private futures::detail::FutureBase<T> {
   /// Examples of DrivableExecutor include EventBase and ManualExecutor.
   ///
   /// Returns the fulfilled value (moved-out) or throws the fulfilled exception.
-  T getVia(DrivableExecutor* e);
+  T getVia(DrivableExecutor* e) &&;
 
   /// Call e->drive() repeatedly until the future is fulfilled, or `dur`
   /// elapses.
   ///
   /// Returns the fulfilled value (moved-out), throws the fulfilled exception,
   /// or on timeout throws FutureTimeout.
-  T getVia(TimedDrivableExecutor* e, HighResDuration dur);
+  T getVia(TimedDrivableExecutor* e, HighResDuration dur) &&;
 
   /// Call e->drive() repeatedly until the future is fulfilled. Examples
   /// of DrivableExecutor include EventBase and ManualExecutor. Returns a

folly/futures/test/SemiFutureTest.cpp

@@ -617,7 +617,7 @@ TEST(SemiFuture, DeferWithVia) {
   // Run "F" here inline in the calling thread
   auto tf = std::move(sf).via(&e2);
   p.setValue();
-  tf.getVia(&e2);
+  std::move(tf).getVia(&e2);
   ASSERT_EQ(innerResult, 17);
 }
 
@@ -630,7 +630,7 @@ TEST(SemiFuture, ChainingDefertoThen) {
   // Run "F" here inline in a task running on the eventbase
   auto tf = std::move(sf).via(&e2).thenValue([&](auto&&) { result = 42; });
   p.setValue();
-  tf.getVia(&e2);
+  std::move(tf).getVia(&e2);
   ASSERT_EQ(innerResult, 17);
   ASSERT_EQ(result, 42);
 }
@@ -671,7 +671,7 @@ TEST(SemiFuture, ChainingDefertoThenWithValue) {
   // Run "F" here inline in a task running on the eventbase
   auto tf = std::move(sf).via(&e2).thenValue([&](int a) { result = a; });
   p.setValue(7);
-  tf.getVia(&e2);
+  std::move(tf).getVia(&e2);
   ASSERT_EQ(innerResult, 7);
   ASSERT_EQ(result, 7);
 }
@@ -714,7 +714,7 @@ TEST(SemiFuture, DeferWithinContinuation) {
             });
       });
   p.setValue(7);
-  auto r = resultF.getVia(&e2);
+  auto r = std::move(resultF).getVia(&e2);
   ASSERT_EQ(r, 7);
   ASSERT_EQ(innerResult, 7);
   ASSERT_EQ(result, 7);

folly/futures/test/ViaTest.cpp

@@ -126,7 +126,7 @@ TEST_F(ViaFixture, threadHops) {
                  EXPECT_EQ(std::this_thread::get_id(), westThreadId);
                  return t.value();
                });
-  EXPECT_EQ(f.getVia(waiter.get()), 1);
+  EXPECT_EQ(std::move(f).getVia(waiter.get()), 1);
 }
 
 TEST_F(ViaFixture, chainVias) {
@@ -158,7 +158,7 @@ TEST_F(ViaFixture, chainVias) {
                  return val + 1;
                });
 
-  EXPECT_EQ(f.getVia(waiter.get()), 4);
+  EXPECT_EQ(std::move(f).getVia(waiter.get()), 4);
 }
 
 TEST_F(ViaFixture, bareViaAssignment) {
@@ -434,20 +434,20 @@ TEST(Via, getVia) {
     // non-void
     ManualExecutor x;
     auto f = via(&x).thenValue([](auto&&) { return true; });
-    EXPECT_TRUE(f.getVia(&x));
+    EXPECT_TRUE(std::move(f).getVia(&x));
   }
 
   {
     // void
     ManualExecutor x;
     auto f = via(&x).then();
-    f.getVia(&x);
+    std::move(f).getVia(&x);
   }
 
   {
     DummyDrivableExecutor x;
     auto f = makeFuture(true);
-    EXPECT_TRUE(f.getVia(&x));
+    EXPECT_TRUE(std::move(f).getVia(&x));
     EXPECT_FALSE(x.ran);
   }
 }
@@ -456,7 +456,8 @@ TEST(Via, SimpleTimedGetVia) {
   TimedDrivableExecutor e2;
   Promise<folly::Unit> p;
   auto f = p.getFuture();
-  EXPECT_THROW(f.getVia(&e2, std::chrono::seconds(1)), FutureTimeout);
+  EXPECT_THROW(
+      std::move(f).getVia(&e2, std::chrono::seconds(1)), FutureTimeout);
 }
 
 TEST(Via, getTryVia) {