}
namespace detail {
- std::shared_ptr<Timekeeper> getTimekeeperSingleton();
+std::shared_ptr<Timekeeper> getTimekeeperSingleton();
+
+// Guarantees that the stored functor is destructed before the stored promise
+// may be fulfilled. Assumes the stored functor to be noexcept-destructible.
+template <typename T, typename F>
+class CoreCallbackState {
+ public:
+ template <typename FF>
+ CoreCallbackState(Promise<T>&& promise, FF&& func) noexcept(
+ noexcept(F(std::declval<FF>())))
+ : func_(std::forward<FF>(func)), promise_(std::move(promise)) {
+ assert(before_barrier());
+ }
+
+ CoreCallbackState(CoreCallbackState&& that) noexcept(
+ noexcept(F(std::declval<F>()))) {
+ if (that.before_barrier()) {
+ new (&func_) F(std::move(that.func_));
+ promise_ = that.stealPromise();
+ }
+ }
+
+ CoreCallbackState& operator=(CoreCallbackState&&) = delete;
+
+ ~CoreCallbackState() {
+ if (before_barrier()) {
+ stealPromise();
+ }
+ }
+
+ template <typename... Args>
+ auto invoke(Args&&... args) noexcept(
+ noexcept(std::declval<F&&>()(std::declval<Args&&>()...))) {
+ assert(before_barrier());
+ return std::move(func_)(std::forward<Args>(args)...);
+ }
+
+ void setTry(Try<T>&& t) {
+ stealPromise().setTry(std::move(t));
+ }
+
+ void setException(exception_wrapper&& ew) {
+ stealPromise().setException(std::move(ew));
+ }
+
+ Promise<T> stealPromise() noexcept {
+ assert(before_barrier());
+ func_.~F();
+ return std::move(promise_);
+ }
+
+ private:
+ bool before_barrier() const noexcept {
+ return !promise_.isFulfilled();
+ }
+
+ union {
+ F func_;
+ };
+ Promise<T> promise_{detail::EmptyConstruct{}};
+};
+
+template <typename T, typename F>
+inline auto makeCoreCallbackState(Promise<T>&& p, F&& f) noexcept(
+ noexcept(CoreCallbackState<T, _t<std::decay<F>>>(
+ std::declval<Promise<T>&&>(),
+ std::declval<F&&>()))) {
+ return CoreCallbackState<T, _t<std::decay<F>>>(
+ std::move(p), std::forward<F>(f));
+}
}
template <class T>
in the destruction of the Future used to create it.
*/
setCallback_(
- [ func = std::forward<F>(func), pm = std::move(p) ](Try<T> && t) mutable {
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> && t) mutable {
if (!isTry && t.hasException()) {
- pm.setException(std::move(t.exception()));
+ state.setException(std::move(t.exception()));
} else {
- pm.setWith([&]() {
- return std::move(func)(t.template get<isTry, Args>()...);
- });
+ state.setTry(makeTryWith(
+ [&] { return state.invoke(t.template get<isTry, Args>()...); }));
}
});
auto f = p.getFuture();
f.core_->setExecutorNoLock(getExecutor());
- setCallback_([ func = std::forward<F>(func), pm = std::move(p) ](
- Try<T> && t) mutable {
- auto ew = [&] {
- if (!isTry && t.hasException()) {
- return std::move(t.exception());
- } else {
- try {
- auto f2 = std::move(func)(t.template get<isTry, Args>()...);
- // that didn't throw, now we can steal p
- f2.setCallback_([p = std::move(pm)](Try<B> && b) mutable {
- p.setTry(std::move(b));
- });
- return exception_wrapper();
- } catch (const std::exception& e) {
- return exception_wrapper(std::current_exception(), e);
- } catch (...) {
- return exception_wrapper(std::current_exception());
+ setCallback_(
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> && t) mutable {
+ auto ew = [&] {
+ if (!isTry && t.hasException()) {
+ return std::move(t.exception());
+ } else {
+ try {
+ auto f2 = state.invoke(t.template get<isTry, Args>()...);
+ // that didn't throw, now we can steal p
+ f2.setCallback_([p = state.stealPromise()](Try<B> && b) mutable {
+ p.setTry(std::move(b));
+ });
+ return exception_wrapper();
+ } catch (const std::exception& e) {
+ return exception_wrapper(std::current_exception(), e);
+ } catch (...) {
+ return exception_wrapper(std::current_exception());
+ }
+ }
+ }();
+ if (ew) {
+ state.setException(std::move(ew));
}
- }
- }();
- if (ew) {
- pm.setException(std::move(ew));
- }
- });
+ });
return f;
}
auto f = p.getFuture();
setCallback_(
- [ func = std::forward<F>(func), pm = std::move(p) ](Try<T> && t) mutable {
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> && t) mutable {
if (!t.template withException<Exn>([&](Exn& e) {
- pm.setWith([&] { return std::move(func)(e); });
+ state.setTry(makeTryWith([&] { return state.invoke(e); }));
})) {
- pm.setTry(std::move(t));
+ state.setTry(std::move(t));
}
});
Promise<T> p;
auto f = p.getFuture();
- setCallback_([ pm = std::move(p), func = std::forward<F>(func) ](
- Try<T> && t) mutable {
- if (!t.template withException<Exn>([&](Exn& e) {
- auto ew = [&] {
- try {
- auto f2 = std::move(func)(e);
- f2.setCallback_([pm = std::move(pm)](Try<T> && t2) mutable {
- pm.setTry(std::move(t2));
- });
- return exception_wrapper();
- } catch (const std::exception& e2) {
- return exception_wrapper(std::current_exception(), e2);
- } catch (...) {
- return exception_wrapper(std::current_exception());
- }
- }();
- if (ew) {
- pm.setException(std::move(ew));
- }
- })) {
- pm.setTry(std::move(t));
- }
- });
+ setCallback_(
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> && t) mutable {
+ if (!t.template withException<Exn>([&](Exn& e) {
+ auto ew = [&] {
+ try {
+ auto f2 = state.invoke(e);
+ f2.setCallback_([p = state.stealPromise()](
+ Try<T> && t2) mutable { p.setTry(std::move(t2)); });
+ return exception_wrapper();
+ } catch (const std::exception& e2) {
+ return exception_wrapper(std::current_exception(), e2);
+ } catch (...) {
+ return exception_wrapper(std::current_exception());
+ }
+ }();
+ if (ew) {
+ state.setException(std::move(ew));
+ }
+ })) {
+ state.setTry(std::move(t));
+ }
+ });
return f;
}
Promise<T> p;
auto f = p.getFuture();
setCallback_(
- [ pm = std::move(p), func = std::forward<F>(func) ](Try<T> t) mutable {
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> t) mutable {
if (t.hasException()) {
auto ew = [&] {
try {
- auto f2 = std::move(func)(std::move(t.exception()));
- f2.setCallback_([pm = std::move(pm)](Try<T> t2) mutable {
- pm.setTry(std::move(t2));
+ auto f2 = state.invoke(std::move(t.exception()));
+ f2.setCallback_([p = state.stealPromise()](Try<T> t2) mutable {
+ p.setTry(std::move(t2));
});
return exception_wrapper();
} catch (const std::exception& e2) {
}
}();
if (ew) {
- pm.setException(std::move(ew));
+ state.setException(std::move(ew));
}
} else {
- pm.setTry(std::move(t));
+ state.setTry(std::move(t));
}
});
Promise<T> p;
auto f = p.getFuture();
setCallback_(
- [ pm = std::move(p), func = std::forward<F>(func) ](Try<T> t) mutable {
+ [state = detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> t) mutable {
if (t.hasException()) {
- pm.setWith([&] { return std::move(func)(std::move(t.exception())); });
+ state.setTry(makeTryWith(
+ [&] { return state.invoke(std::move(t.exception())); }));
} else {
- pm.setTry(std::move(t));
+ state.setTry(std::move(t));
}
});
--- /dev/null
+/*
+ * Copyright 2017 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <folly/futures/Future.h>
+
+#include <thread>
+
+#include <folly/futures/test/TestExecutor.h>
+#include <folly/portability/GTest.h>
+
+using namespace folly;
+
+namespace {
+
+/***
+ * The basic premise is to check that the callback passed to then or onError
+ * is destructed before wait returns on the resulting future.
+ *
+ * The approach is to use callbacks where the destructor sleeps 500ms and then
+ * mutates a counter allocated on the caller stack. The caller checks the
+ * counter immediately after calling wait. Were the callback not destructed
+ * before wait returns, then we would very likely see an unchanged counter just
+ * after wait returns. But if, as we expect, the callback were destructed
+ * before wait returns, then we must be guaranteed to see a mutated counter
+ * just after wait returns.
+ *
+ * Note that the failure condition is not strictly guaranteed under load. :(
+ */
+class CallbackLifetimeTest : public testing::Test {
+ public:
+ using CounterPtr = std::unique_ptr<size_t>;
+
+ static bool kRaiseWillThrow() {
+ return true;
+ }
+ static constexpr auto kDelay() {
+ return std::chrono::milliseconds(500);
+ }
+
+ auto mkC() {
+ return std::make_unique<size_t>(0);
+ }
+ auto mkCGuard(CounterPtr& ptr) {
+ return makeGuard([&] {
+ /* sleep override */ std::this_thread::sleep_for(kDelay());
+ ++*ptr;
+ });
+ }
+
+ static void raise() {
+ if (kRaiseWillThrow()) { // to avoid marking [[noreturn]]
+ throw std::runtime_error("raise");
+ }
+ }
+ static Future<Unit> raiseFut() {
+ raise();
+ return makeFuture();
+ }
+
+ TestExecutor executor{2}; // need at least 2 threads for internal futures
+};
+}
+
+TEST_F(CallbackLifetimeTest, thenReturnsValue) {
+ auto c = mkC();
+ via(&executor).then([_ = mkCGuard(c)]{}).wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, thenReturnsValueThrows) {
+ auto c = mkC();
+ via(&executor).then([_ = mkCGuard(c)] { raise(); }).wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, thenReturnsFuture) {
+ auto c = mkC();
+ via(&executor).then([_ = mkCGuard(c)] { return makeFuture(); }).wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, thenReturnsFutureThrows) {
+ auto c = mkC();
+ via(&executor).then([_ = mkCGuard(c)] { return raiseFut(); }).wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsValueMatch) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::exception&){})
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsValueMatchThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::exception&) { raise(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsValueWrong) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::logic_error&){})
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsValueWrongThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::logic_error&) { raise(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsFutureMatch) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::exception&) { return makeFuture(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsFutureMatchThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::exception&) { return raiseFut(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsFutureWrong) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::logic_error&) { return makeFuture(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesExnReturnsFutureWrongThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](std::logic_error&) { return raiseFut(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesWrapReturnsValue) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](exception_wrapper &&){})
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesWrapReturnsValueThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](exception_wrapper &&) { raise(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesWrapReturnsFuture) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](exception_wrapper &&) { return makeFuture(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
+
+TEST_F(CallbackLifetimeTest, onErrorTakesWrapReturnsFutureThrows) {
+ auto c = mkC();
+ via(&executor)
+ .then(raise)
+ .onError([_ = mkCGuard(c)](exception_wrapper &&) { return raiseFut(); })
+ .wait();
+ EXPECT_EQ(1, *c);
+}
projects / folly.git / commitdiff