Enable KeepAlive support in ScopedEventBaseThread

Reviewed By: yfeldblum

Differential Revision: D18356211

fbshipit-source-id: ad2361c65260a1a09f8536d07e5447cfcf5cc552

folly/io/async/EventBase.h

@@ -132,6 +132,8 @@ class EventBase : public TimeoutManager,
                   public SequencedExecutor,
                   public ScheduledExecutor {
  public:
+  friend class ScopedEventBaseThread;
+
   using Func = folly::Function<void()>;
 
   /**

folly/io/async/ScopedEventBaseThread.h

@@ -60,6 +60,15 @@ class ScopedEventBaseThread : public IOExecutor, public SequencedExecutor {
     getEventBase()->add(std::move(func));
   }
 
+ protected:
+  bool keepAliveAcquire() override {
+    return getEventBase()->keepAliveAcquire();
+  }
+
+  void keepAliveRelease() override {
+    getEventBase()->keepAliveRelease();
+  }
+
  private:
   ScopedEventBaseThread(ScopedEventBaseThread&& other) = delete;
   ScopedEventBaseThread& operator=(ScopedEventBaseThread&& other) = delete;

folly/io/async/test/ScopedEventBaseThreadTest.cpp

@@ -20,6 +20,7 @@
 #include <string>
 
 #include <folly/Optional.h>
+#include <folly/futures/Promise.h>
 #include <folly/io/async/EventBaseManager.h>
 #include <folly/portability/GTest.h>
 #include <folly/synchronization/Baton.h>
@@ -87,3 +88,28 @@ TEST_F(ScopedEventBaseThreadTest, eb_dtor_in_io_thread) {
   sebt.clear();
   EXPECT_EQ(io_thread_id, eb_dtor_thread_id);
 }
+
+TEST_F(ScopedEventBaseThreadTest, keepalive) {
+  Baton<> started, done, reset;
+  folly::Executor::KeepAlive<> ex;
+  Promise<Unit> p;
+
+  std::thread t1([&] {
+    ScopedEventBaseThread sebt;
+    ex = &sebt;
+    started.post();
+  });
+
+  std::thread t2([&] {
+    started.wait();
+    p.getSemiFuture().via(ex).thenValue([&, ex](auto&&) { done.post(); });
+    ex.reset();
+    reset.post();
+  });
+
+  reset.wait();
+  p.setValue();
+  ASSERT_TRUE(done.try_wait_for(seconds(1)));
+  t1.join();
+  t2.join();
+}