folly: build with -Wunused-parameter

[folly.git] / folly / futures / Future-inl.h

diff --git a/folly/futures/Future-inl.h b/folly/futures/Future-inl.h
index eeb0e2e56e759308d0862afab33ce0a42ee11b41..091357ee5b23a796c14631cd2fcf001047b7e704 100644 (file)
--- a/folly/futures/Future-inl.h
+++ b/folly/futures/Future-inl.h
@@ -17,23 +17,38 @@
 #pragma once
 
 #include <algorithm>
+#include <cassert>
 #include <chrono>
 #include <random>
 #include <thread>
-
-#include <folly/experimental/fibers/Baton.h>
+#include <folly/Baton.h>
 #include <folly/Optional.h>
 #include <folly/Random.h>
 #include <folly/Traits.h>
 #include <folly/futures/detail/Core.h>
 #include <folly/futures/Timekeeper.h>
 
+#if defined(__ANDROID__) || defined(__APPLE__)
+#define FOLLY_FUTURE_USING_FIBER 0
+#else
+#define FOLLY_FUTURE_USING_FIBER 1
+#include <folly/experimental/fibers/Baton.h>
+#endif
+
 namespace folly {
 
 class Timekeeper;
 
 namespace detail {
-  Timekeeper* getTimekeeperSingleton();
+#if FOLLY_FUTURE_USING_FIBER
+typedef folly::fibers::Baton FutureBatonType;
+#else
+typedef folly::Baton<> FutureBatonType;
+#endif
+}
+
+namespace detail {
+  std::shared_ptr<Timekeeper> getTimekeeperSingleton();
 }
 
 template <class T>
@@ -589,7 +604,9 @@ namespace detail {
 
 template <typename T>
 struct CollectContext {
-  struct Nothing { explicit Nothing(int n) {} };
+  struct Nothing {
+    explicit Nothing(int /* n */) {}
+  };
 
   using Result = typename std::conditional<
     std::is_void<T>::value,
@@ -846,26 +863,29 @@ Future<T> unorderedReduce(It first, It last, T initial, F func) {
   auto ctx = std::make_shared<UnorderedReduceContext>(
     std::move(initial), std::move(func), std::distance(first, last));
 
-  mapSetCallback<ItT>(first, last, [ctx](size_t i, Try<ItT>&& t) {
-    folly::MoveWrapper<Try<ItT>> mt(std::move(t));
-    // Futures can be completed in any order, simultaneously.
-    // To make this non-blocking, we create a new Future chain in
-    // the order of completion to reduce the values.
-    // The spinlock just protects chaining a new Future, not actually
-    // executing the reduce, which should be really fast.
-    folly::MSLGuard lock(ctx->lock_);
-    ctx->memo_ = ctx->memo_.then([ctx, mt](T&& v) mutable {
-      // Either return a ItT&& or a Try<ItT>&& depending
-      // on the type of the argument of func.
-      return ctx->func_(std::move(v), mt->template get<IsTry::value, Arg&&>());
-    });
-    if (++ctx->numThens_ == ctx->numFutures_) {
-      // After reducing the value of the last Future, fulfill the Promise
-      ctx->memo_.setCallback_([ctx](Try<T>&& t2) {
-        ctx->promise_.setValue(std::move(t2));
+  mapSetCallback<ItT>(
+      first,
+      last,
+      [ctx](size_t /* i */, Try<ItT>&& t) {
+        folly::MoveWrapper<Try<ItT>> mt(std::move(t));
+        // Futures can be completed in any order, simultaneously.
+        // To make this non-blocking, we create a new Future chain in
+        // the order of completion to reduce the values.
+        // The spinlock just protects chaining a new Future, not actually
+        // executing the reduce, which should be really fast.
+        folly::MSLGuard lock(ctx->lock_);
+        ctx->memo_ = ctx->memo_.then([ctx, mt](T&& v) mutable {
+          // Either return a ItT&& or a Try<ItT>&& depending
+          // on the type of the argument of func.
+          return ctx->func_(std::move(v),
+                            mt->template get<IsTry::value, Arg&&>());
+        });
+        if (++ctx->numThens_ == ctx->numFutures_) {
+          // After reducing the value of the last Future, fulfill the Promise
+          ctx->memo_.setCallback_(
+              [ctx](Try<T>&& t2) { ctx->promise_.setValue(std::move(t2)); });
+        }
       });
-    }
-  });
 
   return ctx->promise_.getFuture();
 }
@@ -889,8 +909,10 @@ Future<T> Future<T>::within(Duration dur, E e, Timekeeper* tk) {
     std::atomic<bool> token {false};
   };
 
+  std::shared_ptr<Timekeeper> tks;
   if (!tk) {
-    tk = folly::detail::getTimekeeperSingleton();
+    tks = folly::detail::getTimekeeperSingleton();
+    tk = DCHECK_NOTNULL(tks.get());
   }
 
   auto ctx = std::make_shared<Context>(std::move(e));
@@ -935,19 +957,10 @@ void waitImpl(Future<T>& f) {
   // short-circuit if there's nothing to do
   if (f.isReady()) return;
 
-  folly::fibers::Baton baton;
-  f = f.then([&](Try<T> t) {
-    baton.post();
-    return makeFuture(std::move(t));
-  });
+  FutureBatonType baton;
+  f.setCallback_([&](const Try<T>& /* t */) { baton.post(); });
   baton.wait();
-
-  // There's a race here between the return here and the actual finishing of
-  // the future. f is completed, but the setup may not have finished on done
-  // after the baton has posted.
-  while (!f.isReady()) {
-    std::this_thread::yield();
-  }
+  assert(f.isReady());
 }
 
 template <class T>
@@ -955,19 +968,16 @@ void waitImpl(Future<T>& f, Duration dur) {
   // short-circuit if there's nothing to do
   if (f.isReady()) return;
 
-  auto baton = std::make_shared<folly::fibers::Baton>();
-  f = f.then([baton](Try<T> t) {
+  folly::MoveWrapper<Promise<T>> promise;
+  auto ret = promise->getFuture();
+  auto baton = std::make_shared<FutureBatonType>();
+  f.setCallback_([baton, promise](Try<T>&& t) mutable {
+    promise->setTry(std::move(t));
     baton->post();
-    return makeFuture(std::move(t));
   });
-
-  // Let's preserve the invariant that if we did not timeout (timed_wait returns
-  // true), then the returned Future is complete when it is returned to the
-  // caller. We need to wait out the race for that Future to complete.
+  f = std::move(ret);
   if (baton->timed_wait(dur)) {
-    while (!f.isReady()) {
-      std::this_thread::yield();
-    }
+    assert(f.isReady());
   }
 }