Always enable fiber support in futures

Summary:
[Folly] Always enable fiber support in futures.

(Note: this ignores all push blocking failures!)

Reviewed By: andriigrynenko

Differential Revision: D19229519

fbshipit-source-id: f0a034e9387c5ccad676a911213fab74364ca340

folly/fibers/BatchSemaphore.cpp

@@ -49,13 +49,9 @@ coro::Task<void> BatchSemaphore::co_wait(int64_t tokens) {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
 SemiFuture<Unit> BatchSemaphore::future_wait(int64_t tokens) {
   return future_wait_common(tokens);
 }
 
-#endif
-
 } // namespace fibers
 } // namespace folly

folly/fibers/BatchSemaphore.h

@@ -75,14 +75,10 @@ class BatchSemaphore : public SemaphoreBase {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
   /*
    * Wait for requested tokens in the semaphore.
    */
   SemiFuture<Unit> future_wait(int64_t tokens);
-
-#endif
 };
 
 } // namespace fibers

folly/fibers/FiberManager.cpp

@@ -28,6 +28,7 @@
 
 #include <folly/ConstexprMath.h>
 #include <folly/SingletonThreadLocal.h>
+#include <folly/portability/Config.h>
 #include <folly/portability/SysSyscall.h>
 #include <folly/portability/Unistd.h>
 #include <folly/synchronization/SanitizeThread.h>
@@ -329,7 +330,9 @@ static AsanUnpoisonMemoryRegionFuncPtr getUnpoisonMemoryRegionFunc() {
 
 #endif // FOLLY_SANITIZE_ADDRESS
 
-#ifndef _WIN32
+// TVOS and WatchOS platforms have SIGSTKSZ but not sigaltstack
+#if defined(SIGSTKSZ) && !FOLLY_APPLE_TVOS && !FOLLY_APPLE_WATCHOS
+
 namespace {
 
 // SIGSTKSZ (8 kB on our architectures) isn't always enough for
@@ -383,11 +386,19 @@ class ScopedAlternateSignalStack {
 };
 } // namespace
 
-void FiberManager::registerAlternateSignalStack() {
+void FiberManager::maybeRegisterAlternateSignalStack() {
   SingletonThreadLocal<ScopedAlternateSignalStack>::get();
 
   alternateSignalStackRegistered_ = true;
 }
+
+#else
+
+void FiberManager::maybeRegisterAlternateSignalStack() {
+  // no-op
+}
+
 #endif
+
 } // namespace fibers
 } // namespace folly

folly/fibers/FiberManagerInternal-inl.h

@@ -195,11 +195,9 @@ inline void FiberManager::loopUntilNoReady() {
 
 template <typename LoopFunc>
 void FiberManager::runFibersHelper(LoopFunc&& loopFunc) {
-#ifndef _WIN32
   if (UNLIKELY(!alternateSignalStackRegistered_)) {
-    registerAlternateSignalStack();
+    maybeRegisterAlternateSignalStack();
   }
-#endif
 
   // Support nested FiberManagers
   auto originalFiberManager = std::exchange(getCurrentFiberManager(), this);

folly/fibers/FiberManagerInternal.h

@@ -618,11 +618,9 @@ class FiberManager : public ::folly::Executor {
 
 #endif // FOLLY_SANITIZE_ADDRESS
 
-#ifndef _WIN32
   bool alternateSignalStackRegistered_{false};
 
-  void registerAlternateSignalStack();
-#endif
+  void maybeRegisterAlternateSignalStack();
 };
 
 /**

folly/fibers/Semaphore.cpp

@@ -187,8 +187,6 @@ coro::Task<void> Semaphore::co_wait() {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
 namespace {
 
 class FutureWaiter final : public fibers::Baton::Waiter {
@@ -230,8 +228,6 @@ SemiFuture<Unit> Semaphore::future_wait() {
   return makeSemiFuture();
 }
 
-#endif
-
 size_t Semaphore::getCapacity() const {
   return capacity_;
 }

folly/fibers/Semaphore.h

@@ -100,15 +100,11 @@ class Semaphore {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
   /*
    * Wait for capacity in the semaphore.
    */
   SemiFuture<Unit> future_wait();
 
-#endif
-
   size_t getCapacity() const;
 
  private:

folly/fibers/SemaphoreBase.cpp

@@ -163,8 +163,6 @@ coro::Task<void> SemaphoreBase::co_wait_common(int64_t tokens) {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
 namespace {
 
 class FutureWaiter final : public fibers::Baton::Waiter {
@@ -207,8 +205,6 @@ SemiFuture<Unit> SemaphoreBase::future_wait_common(int64_t tokens) {
   return makeSemiFuture();
 }
 
-#endif
-
 size_t SemaphoreBase::getCapacity() const {
   return capacity_;
 }

folly/fibers/SemaphoreBase.h

@@ -93,15 +93,11 @@ class SemaphoreBase {
 
 #endif
 
-#if FOLLY_FUTURE_USING_FIBER
-
   /*
    * Wait for request capacity in the semaphore.
    */
   SemiFuture<Unit> future_wait_common(int64_t tokens);
 
-#endif
-
   bool waitSlow(Waiter& waiter, int64_t tokens);
   bool signalSlow(int64_t tokens, int64_t oldVal);
 

folly/fibers/test/FibersTest.cpp

@@ -1737,11 +1737,7 @@ TEST(FiberManager, semaphore) {
                   sem.wait();
                   break;
                 case 1:
-#if FOLLY_FUTURE_USING_FIBER
                   sem.future_wait().get();
-#else
-                  sem.wait();
-#endif
                   break;
                 case 2: {
                   Semaphore::Waiter waiter;
@@ -1820,11 +1816,7 @@ TEST(FiberManager, batchSemaphore) {
                   sem.wait(tokens);
                   break;
                 case 1:
-#if FOLLY_FUTURE_USING_FIBER
                   sem.future_wait(tokens).get();
-#else
-                  sem.wait(tokens);
-#endif
                   break;
                 case 2: {
                   BatchSemaphore::Waiter waiter{tokens};

folly/futures/Future-inl.h

@@ -31,11 +31,6 @@
 #include <folly/executors/InlineExecutor.h>
 #include <folly/executors/QueuedImmediateExecutor.h>
 #include <folly/futures/detail/Core.h>
-#include <folly/synchronization/Baton.h>
-
-#if FOLLY_FUTURE_USING_FIBER
-#include <folly/fibers/Baton.h>
-#endif
 
 namespace folly {
 
@@ -43,11 +38,7 @@ class Timekeeper;
 
 namespace futures {
 namespace detail {
-#if FOLLY_FUTURE_USING_FIBER
 typedef folly::fibers::Baton FutureBatonType;
-#else
-typedef folly::Baton<> FutureBatonType;
-#endif
 } // namespace detail
 } // namespace futures
 
@@ -504,17 +495,13 @@ class WaitExecutor final : public folly::Executor {
 
   void drive() {
     baton_.wait();
-#if FOLLY_FUTURE_USING_FIBER
     fibers::runInMainContext([&]() {
-#endif
       baton_.reset();
       auto funcs = std::move(queue_.wlock()->funcs);
       for (auto& func : funcs) {
         std::exchange(func, nullptr)();
       }
-#if FOLLY_FUTURE_USING_FIBER
     });
-#endif
   }
 
   using Clock = std::chrono::steady_clock;
@@ -523,18 +510,14 @@ class WaitExecutor final : public folly::Executor {
     if (!baton_.try_wait_until(deadline)) {
       return false;
     }
-#if FOLLY_FUTURE_USING_FIBER
     return fibers::runInMainContext([&]() {
-#endif
       baton_.reset();
       auto funcs = std::move(queue_.wlock()->funcs);
       for (auto& func : funcs) {
         std::exchange(func, nullptr)();
       }
       return true;
-#if FOLLY_FUTURE_USING_FIBER
     });
-#endif
   }
 
   void detach() {

folly/futures/Future.cpp

@@ -39,8 +39,6 @@ Future<Unit> sleepUnsafe(HighResDuration dur, Timekeeper* tk) {
   return sleep(dur, tk).toUnsafeFuture();
 }
 
-#if FOLLY_FUTURE_USING_FIBER
-
 namespace {
 template <typename Ptr>
 class FutureWaiter : public fibers::Baton::Waiter {
@@ -76,8 +74,6 @@ SemiFuture<Unit> wait(std::shared_ptr<fibers::Baton> baton) {
   return sf;
 }
 
-#endif
-
 } // namespace futures
 
 #if FOLLY_USE_EXTERN_FUTURE_UNIT

folly/futures/Future.h

@@ -32,6 +32,7 @@
 #include <folly/Utility.h>
 #include <folly/executors/DrivableExecutor.h>
 #include <folly/executors/TimedDrivableExecutor.h>
+#include <folly/fibers/Baton.h>
 #include <folly/functional/Invoke.h>
 #include <folly/futures/Portability.h>
 #include <folly/futures/Promise.h>
@@ -108,14 +109,6 @@ class SemiFuture;
 template <class T>
 class FutureSplitter;
 
-#if FOLLY_FUTURE_USING_FIBER
-
-namespace fibers {
-class Baton;
-}
-
-#endif
-
 namespace futures {
 namespace detail {
 template <class T>
@@ -2171,13 +2164,9 @@ template <class F>
 auto when(bool p, F&& thunk)
     -> decltype(std::declval<invoke_result_t<F>>().unit());
 
-#if FOLLY_FUTURE_USING_FIBER
-
 SemiFuture<Unit> wait(std::unique_ptr<fibers::Baton> baton);
 SemiFuture<Unit> wait(std::shared_ptr<fibers::Baton> baton);
 
-#endif
-
 /**
  * Returns a lazy SemiFuture constructed by f, which also ensures that ensure is
  * called before completion.

folly/futures/Portability.h

@@ -17,9 +17,3 @@
 #pragma once
 
 #include <folly/Portability.h>
-
-#if FOLLY_MOBILE || defined(__APPLE__)
-#define FOLLY_FUTURE_USING_FIBER 0
-#else
-#define FOLLY_FUTURE_USING_FIBER 1
-#endif

folly/futures/test/FutureTest.cpp

@@ -1505,8 +1505,6 @@ TEST(Future, SimpleTimedGetTry) {
       std::move(sf).getTry(std::chrono::milliseconds(100)), FutureTimeout);
 }
 
-#if FOLLY_FUTURE_USING_FIBER
-
 TEST(Future, BatonWait) {
   auto baton = std::make_unique<fibers::Baton>();
   bool posted{false};
@@ -1524,5 +1522,3 @@ TEST(Future, BatonWait) {
       .getVia(&executor);
   EXPECT_TRUE(postFuture.isReady());
 }
-
-#endif