// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "mojo/public/cpp/bindings/sync_handle_registry.h"

#include <memory>

#include "base/containers/span.h"
#include "base/functional/bind.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/waitable_event.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace mojo {

class SyncHandleRegistryTest : public testing::Test {
 public:
  SyncHandleRegistryTest() : registry_(SyncHandleRegistry::current()) {}

  SyncHandleRegistryTest(const SyncHandleRegistryTest&) = delete;
  SyncHandleRegistryTest& operator=(const SyncHandleRegistryTest&) = delete;

  const scoped_refptr<SyncHandleRegistry>& registry() { return registry_; }

 private:
  scoped_refptr<SyncHandleRegistry> registry_;
};

TEST_F(SyncHandleRegistryTest, DuplicateEventRegistration) {
  bool called1 = false;
  bool called2 = false;
  auto callback = [](bool* called) { *called = true; };

  base::WaitableEvent e(base::WaitableEvent::ResetPolicy::MANUAL,
                        base::WaitableEvent::InitialState::SIGNALED);
  SyncHandleRegistry::EventCallbackSubscription subscription1 =
      registry()->RegisterEvent(&e, base::BindRepeating(callback, &called1));
  SyncHandleRegistry::EventCallbackSubscription subscription2 =
      registry()->RegisterEvent(&e, base::BindRepeating(callback, &called2));

  const bool* stop_flags[] = {&called1, &called2};
  registry()->Wait(stop_flags);

  EXPECT_TRUE(called1);
  EXPECT_TRUE(called2);
  subscription1.reset();

  called1 = false;
  called2 = false;

  registry()->Wait(stop_flags);

  EXPECT_FALSE(called1);
  EXPECT_TRUE(called2);
}

TEST_F(SyncHandleRegistryTest, UnregisterDuplicateEventInNestedWait) {
  base::WaitableEvent e(base::WaitableEvent::ResetPolicy::MANUAL,
                        base::WaitableEvent::InitialState::SIGNALED);
  bool called1 = false;
  bool called2 = false;
  bool called3 = false;

  SyncHandleRegistry::EventCallbackSubscription subscription1 =
      registry()->RegisterEvent(
          &e,
          base::BindRepeating([](bool* called) { *called = true; }, &called1));
  SyncHandleRegistry::EventCallbackSubscription subscription2 =
      registry()->RegisterEvent(
          &e,
          base::BindRepeating(
              [](SyncHandleRegistry::EventCallbackSubscription* subscription,
                 bool* called) {
                subscription->reset();
                *called = true;
              },
              &subscription1, &called2));
  SyncHandleRegistry::EventCallbackSubscription subscription3 =
      registry()->RegisterEvent(
          &e,
          base::BindRepeating([](bool* called) { *called = true; }, &called3));

  const bool* stop_flags[] = {&called1, &called2, &called3};
  registry()->Wait(stop_flags);

  // We don't make any assumptions about the order in which callbacks run, so
  // we can't check |called1| - it may or may not get set depending on internal
  // details. All we know is |called2| should be set, and a subsequent wait
  // should definitely NOT set |called1|.
  EXPECT_TRUE(called2);
  EXPECT_TRUE(called3);

  called1 = false;
  called2 = false;
  called3 = false;

  subscription2.reset();
  registry()->Wait(stop_flags);

  EXPECT_FALSE(called1);
  EXPECT_FALSE(called2);
  EXPECT_TRUE(called3);
}

TEST_F(SyncHandleRegistryTest, UnregisterAndRegisterForNewEventInCallback) {
  auto e = std::make_unique<base::WaitableEvent>(
      base::WaitableEvent::ResetPolicy::MANUAL,
      base::WaitableEvent::InitialState::SIGNALED);
  bool called = false;
  SyncHandleRegistry::EventCallbackSubscription subscription;
  auto callback = base::BindRepeating(
      [](std::unique_ptr<base::WaitableEvent>* e,
         SyncHandleRegistry::EventCallbackSubscription* subscription,
         scoped_refptr<SyncHandleRegistry> registry, bool* called) {
        EXPECT_FALSE(*called);

        subscription->reset();
        e->reset();
        *called = true;

        base::WaitableEvent nested_event(
            base::WaitableEvent::ResetPolicy::MANUAL,
            base::WaitableEvent::InitialState::SIGNALED);
        bool nested_called = false;
        SyncHandleRegistry::EventCallbackSubscription nested_subscription =
            registry->RegisterEvent(
                &nested_event,
                base::BindRepeating([](bool* called) { *called = true; },
                                    &nested_called));
        const bool* stop_flag = &nested_called;
        registry->Wait(base::span_from_ref(stop_flag));
      },
      &e, &subscription, registry(), &called);

  subscription = registry()->RegisterEvent(e.get(), callback);

  const bool* stop_flag = &called;
  registry()->Wait(base::span_from_ref(stop_flag));
  EXPECT_TRUE(called);
}

TEST_F(SyncHandleRegistryTest, UnregisterAndRegisterForSameEventInCallback) {
  base::WaitableEvent e(base::WaitableEvent::ResetPolicy::MANUAL,
                        base::WaitableEvent::InitialState::SIGNALED);
  bool called = false;
  SyncHandleRegistry::EventCallbackSubscription subscription;
  auto callback = base::BindRepeating(
      [](base::WaitableEvent* e,
         SyncHandleRegistry::EventCallbackSubscription* subscription,
         scoped_refptr<SyncHandleRegistry> registry, bool* called) {
        EXPECT_FALSE(*called);

        subscription->reset();
        *called = true;

        bool nested_called = false;
        SyncHandleRegistry::EventCallbackSubscription nested_subscription =
            registry->RegisterEvent(
                e, base::BindRepeating([](bool* called) { *called = true; },
                                       &nested_called));
        const bool* stop_flag = &nested_called;
        registry->Wait(base::span_from_ref(stop_flag));

        EXPECT_TRUE(nested_called);
      },
      &e, &subscription, registry(), &called);

  subscription = registry()->RegisterEvent(&e, callback);

  const bool* stop_flag = &called;
  registry()->Wait(base::span_from_ref(stop_flag));
  EXPECT_TRUE(called);
}

TEST_F(SyncHandleRegistryTest, RegisterDuplicateEventFromWithinCallback) {
  base::WaitableEvent e(base::WaitableEvent::ResetPolicy::MANUAL,
                        base::WaitableEvent::InitialState::SIGNALED);
  bool called = false;
  int call_count = 0;
  auto callback = base::BindRepeating(
      [](base::WaitableEvent* e, scoped_refptr<SyncHandleRegistry> registry,
         bool* called, int* call_count) {
        // Don't re-enter.
        ++(*call_count);
        if (*called) {
          return;
        }

        *called = true;

        bool called2 = false;
        SyncHandleRegistry::EventCallbackSubscription nested_subscription =
            registry->RegisterEvent(
                e, base::BindRepeating([](bool* called) { *called = true; },
                                       &called2));

        const bool* stop_flag = &called2;
        registry->Wait(base::span_from_ref(stop_flag));
      },
      &e, registry(), &called, &call_count);

  SyncHandleRegistry::EventCallbackSubscription subscription =
      registry()->RegisterEvent(&e, callback);

  const bool* stop_flag = &called;
  registry()->Wait(base::span_from_ref(stop_flag));
  EXPECT_TRUE(called);
  EXPECT_EQ(2, call_count);
}

TEST_F(SyncHandleRegistryTest, UnregisterUniqueEventInNestedWait) {
  auto e1 = std::make_unique<base::WaitableEvent>(
      base::WaitableEvent::ResetPolicy::MANUAL,
      base::WaitableEvent::InitialState::NOT_SIGNALED);
  base::WaitableEvent e2(base::WaitableEvent::ResetPolicy::MANUAL,
                         base::WaitableEvent::InitialState::SIGNALED);
  bool called1 = false;
  bool called2 = false;

  SyncHandleRegistry::EventCallbackSubscription subscription1 =
      registry()->RegisterEvent(
          e1.get(),
          base::BindRepeating([](bool* called) { *called = true; }, &called1));
  auto callback2 = base::BindRepeating(
      [](std::unique_ptr<base::WaitableEvent>* e1,
         SyncHandleRegistry::EventCallbackSubscription* subscription,
         scoped_refptr<SyncHandleRegistry> registry, bool* called) {
        // Prevent re-entrancy.
        if (*called) {
          return;
        }

        subscription->reset();
        *called = true;
        e1->reset();

        // Nest another wait.
        bool called3 = false;
        base::WaitableEvent e3(base::WaitableEvent::ResetPolicy::MANUAL,
                               base::WaitableEvent::InitialState::SIGNALED);
        SyncHandleRegistry::EventCallbackSubscription nested_subscription =
            registry->RegisterEvent(
                &e3, base::BindRepeating([](bool* called) { *called = true; },
                                         &called3));

        // This nested Wait() must not attempt to wait on |e1| since it has
        // been unregistered. This would crash otherwise, since |e1| has been
        // deleted. See http://crbug.com/761097.
        const bool* stop_flags[] = {&called3};
        registry->Wait(stop_flags);

        EXPECT_TRUE(called3);
      },
      &e1, &subscription1, registry(), &called2);

  SyncHandleRegistry::EventCallbackSubscription subscription2 =
      registry()->RegisterEvent(&e2, callback2);

  const bool* stop_flags[] = {&called1, &called2};
  registry()->Wait(stop_flags);

  EXPECT_TRUE(called2);
}

}  // namespace mojo