NOT INTENDED FOR LANDING: A promises demo

components/scheduler/promises/thread_pool_promise_executor_unittest.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/scheduler/promises/thread_pool_promise_executor.h"
+
+#include "base/bind.h"
+#include "base/synchronization/waitable_event.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using testing::ElementsAre;
+using testing::WhenSorted;
+
+#if 0
+
+namespace promise {
+
+class ThreadPoolPromiseExecutorTest : public testing::Test {
+ public:
+  ThreadPoolPromiseExecutorTest() {}
+  ~ThreadPoolPromiseExecutorTest() override {}
+
+  void SetUp() override {
+    promise_executor_.reset(new internal::ThreadPoolPromiseExecutor());
+  }
+
+  scoped_ptr<internal::ThreadPoolPromiseExecutor> promise_executor_;
+};
+
+namespace {
+bool ReturnTrue() {
+  return true;
+}
+
+int ReturnOne() {
+  return 1;
+}
+
+int ReturnTwo() {
+  return 2;
+}
+
+int ReturnTen() {
+  return 10;
+}
+
+int AddOne(int i) {
+  return i + 1;
+}
+
+int CondTimesThree(int i, bool do_smth) {
+  if (do_smth)
+    return i * 3;
+  return i;
+}
+
+int ReturnZero() {
+  return 0;
+}
+
+scoped_refptr<Promise<int>> Choose(scoped_refptr<Promise<int>> p1,
+                                   scoped_refptr<Promise<int>> p2,
+                                   int i) {
+  return i ? p1 : p2;
+}
+
+void RecordOrder(int value, std::vector<int>* out_result) {
+  out_result->push_back(value);
+}
+
+void SignalWaitableEvent(base::WaitableEvent* waitable_event, int) {
+  waitable_event->Signal();
+}
+
+void SignalWaitableEventVoid(base::WaitableEvent* waitable_event) {
+  waitable_event->Signal();
+}
+
+}  // namespace
+
+TEST_F(ThreadPoolPromiseExecutorTest, NonVoidPromise) {
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<int>> promise(promise::Create(base::Bind(&ReturnOne)));
+
+  scoped_refptr<Promise<void>> wait_promise(
+      promise.Then(base::Bind(&SignalWaitableEvent, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+  EXPECT_EQ(1, promise->GetResolved());
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, RunAfter_OnePromise_AndThen) {
+  scoped_refptr<Promise<int>> promise(
+      promise::Create(base::Bind(&ReturnOne)).Then(base::Bind(&AddOne)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promise.Then(base::Bind(&SignalWaitableEvent, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+  EXPECT_EQ(2, promise->GetResolved());
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, RunAfter_TwoPromises_AndThen) {
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<int>> promise(
+      promise::All(promise::Create(base::Bind(&ReturnOne)),
+                   promise::Create(base::Bind(&ReturnTrue)))
+          .Then(base::Bind(&CondTimesThree)));
+
+  scoped_refptr<Promise<void>> wait_promise(
+      promise.Then(base::Bind(&SignalWaitableEvent, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+  EXPECT_EQ(3, promise->GetResolved());
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, ChainOfPromises) {
+  scoped_refptr<Promise<int>> promise(promise::Create(base::Bind(&ReturnOne))
+                                          .Then(base::Bind(&AddOne))
+                                          .Then(base::Bind(&AddOne))
+                                          .Then(base::Bind(&AddOne))
+                                          .Then(base::Bind(&AddOne)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promise.Then(base::Bind(&SignalWaitableEvent, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+  EXPECT_EQ(5, promise->GetResolved());
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, EagerTasksExecutedFirst) {
+  std::vector<int> run_order;
+
+  scoped_refptr<Promise<void>> promiseA(
+      promise::Create(base::Bind(&RecordOrder, 0, &run_order))
+          .Then(base::Bind(&RecordOrder, 1, &run_order))
+          .Then(base::Bind(&RecordOrder, 2, &run_order))
+          .Then(base::Bind(&RecordOrder, 3, &run_order))
+          .Then(base::Bind(&RecordOrder, 4, &run_order)));
+
+  scoped_refptr<Promise<void>> promiseB(
+      promise::Create(base::Bind(&RecordOrder, 10, &run_order))
+          .Then(base::Bind(&RecordOrder, 11, &run_order))
+          .Then(base::Bind(&RecordOrder, 12, &run_order))
+          .Then(base::Bind(&RecordOrder, 13, &run_order))
+          .Then(base::Bind(&RecordOrder, 14, &run_order)));
+
+  promiseB->SetEager(true);
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promise::All(promiseA, promiseB)
+          .Then(base::Bind(&SignalWaitableEventVoid, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+
+  EXPECT_THAT(run_order, ElementsAre(10, 11, 12, 13, 14, 0, 1, 2, 3, 4));
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, Cancel) {
+  /*std::vector<int> run_order;
+
+  scoped_refptr<Promise<void>> promise(promise::Create(
+      base::Bind(&RecordOrder, 1, &run_order)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promise.Then(base::Bind(&SignalWaitableEventVoid, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  wait_promise->Cancel();
+  event.Wait();
+
+  EXPECT_TRUE(run_order.empty());*/
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, CancelChainOfTasks) {
+  std::vector<int> run_order;
+
+  scoped_refptr<Promise<void>> promiseA(
+      promise::Create(base::Bind(&RecordOrder, 0, &run_order))
+          .Then(base::Bind(&RecordOrder, 1, &run_order))
+          .Then(base::Bind(&RecordOrder, 2, &run_order))
+          .Then(base::Bind(&RecordOrder, 3, &run_order))
+          .Then(base::Bind(&RecordOrder, 4, &run_order)));
+
+  scoped_refptr<Promise<void>> promiseB(
+      promise::Create(base::Bind(&RecordOrder, 10, &run_order))
+          .Then(base::Bind(&RecordOrder, 11, &run_order))
+          .Then(base::Bind(&RecordOrder, 12, &run_order))
+          .Then(base::Bind(&RecordOrder, 13, &run_order))
+          .Then(base::Bind(&RecordOrder, 14, &run_order)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promiseA.Then(base::Bind(&SignalWaitableEventVoid, &event)));
+
+  promise_executor_->StartResolve(promiseB.get());
+  promiseB->Cancel();
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+
+  EXPECT_THAT(run_order, ElementsAre(0, 1, 2, 3, 4));
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, CancelOneBranch) {
+  std::vector<int> run_order;
+
+  scoped_refptr<Promise<void>> promiseA(
+      promise::Create(base::Bind(&RecordOrder, 0, &run_order))
+          .Then(base::Bind(&RecordOrder, 1, &run_order)));
+
+  scoped_refptr<Promise<void>> promiseB(
+      promiseA.Then(base::Bind(&RecordOrder, 2, &run_order))
+          .Then(base::Bind(&RecordOrder, 3, &run_order)));
+
+  scoped_refptr<Promise<void>> promiseC(
+      promiseA.Then(base::Bind(&RecordOrder, 4, &run_order))
+          .Then(base::Bind(&RecordOrder, 5, &run_order)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promiseC.Then(base::Bind(&SignalWaitableEventVoid, &event)));
+
+  promise_executor_->StartResolve(promiseB.get());
+  promise_executor_->StartResolve(wait_promise.get());
+
+  promiseB->Cancel();
+
+  event.Wait();
+
+  EXPECT_THAT(run_order, ElementsAre(0, 1, 4, 5));
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, Choose) {
+  scoped_refptr<Promise<int>> promise_two(
+      promise::Create(base::Bind(&ReturnTwo)));
+  scoped_refptr<Promise<int>> promise_ten(
+      promise::Create(base::Bind(&ReturnTen)));
+  scoped_refptr<Promise<int>> promiseA(
+      promise::Create(base::Bind(&ReturnZero))
+          .Then(base::Bind(&Choose, promise_two, promise_ten)));
+
+  scoped_refptr<Promise<int>> promiseB(
+      promise::Create(base::Bind(&ReturnOne))
+          .Then(base::Bind(&Choose, promise_two, promise_ten)));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(
+      promise::All(promiseA, promiseB)
+          .Then(base::Bind(&SignalWaitableEventVoid, &event)));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+
+  EXPECT_EQ(10, promiseA->GetResolved());
+  EXPECT_EQ(2, promiseB->GetResolved());
+}
+/*
+TEST_F(ThreadPoolPromiseExecutorTest, ChooseAndAddOne) {
+  scoped_refptr<Promise<int>> promise_a(
+      promise::Create(base::Bind(&ReturnZero)));
+  scoped_refptr<Promise<int>> promise_b(
+      promise::Create(base::Bind(&ReturnOne)));
+  scoped_refptr<Promise<int>> promise_c(
+      promise::Create(base::Bind(&ReturnTen)));
+
+  scoped_refptr<Promise<int>> promise_d_zero(promise_executor_->RunAfter(
+      base::Bind(&Choose, promise_b, promise_c), promise_a));
+
+  scoped_refptr<Promise<int>> promise_d_one(promise_executor_->RunAfter(
+      base::Bind(&Choose, promise_b, promise_c), promise_b));
+
+  scoped_refptr<Promise<int>> promise_e(
+      promise_executor_->RunAfter(base::Bind(&AddOne), promise_d_zero));
+
+  scoped_refptr<Promise<int>> promise_f(
+      promise_executor_->RunAfter(base::Bind(&AddOne), promise_d_one));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(promise_executor_->RunAfter(
+      base::Bind(&SignalWaitableEventVoid, &event), promise_e, promise_f));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+
+  EXPECT_EQ(11, promise_e->GetResolved());
+  EXPECT_EQ(2, promise_f->GetResolved());
+}
+
+TEST_F(ThreadPoolPromiseExecutorTest, ChooseAndAddOne_ResolvedPromise) {
+  scoped_refptr<Promise<int>> promise_one(
+      promise::Create(base::Bind(&ReturnOne)));
+
+  scoped_refptr<Promise<int>> promise_zero(
+      promise::Create(base::Bind(&ReturnZero)));
+
+  scoped_refptr<Promise<int>> promise_a(promise_executor_->RunAfter(
+      base::Bind(&Choose,
+make_scoped_refptr(promise::Create<int>(1)),
+                 make_scoped_refptr(promise::Create<int>(10))),
+      promise_zero));
+
+  scoped_refptr<Promise<int>> promise_b(promise_executor_->RunAfter(
+      base::Bind(&Choose,
+make_scoped_refptr(promise::Create<int>(1)),
+                 make_scoped_refptr(promise::Create<int>(10))),
+      promise_one));
+
+  scoped_refptr<Promise<int>> promise_c(
+      promise_executor_->RunAfter(base::Bind(&AddOne), promise_a));
+
+  scoped_refptr<Promise<int>> promise_d(
+      promise_executor_->RunAfter(base::Bind(&AddOne), promise_b));
+
+  base::WaitableEvent event(true, false);
+  scoped_refptr<Promise<void>> wait_promise(promise_executor_->RunAfter(
+      base::Bind(&SignalWaitableEventVoid, &event), promise_c, promise_d));
+
+  promise_executor_->StartResolve(wait_promise.get());
+  event.Wait();
+
+  EXPECT_EQ(11, promise_c->GetResolved());
+  EXPECT_EQ(2, promise_d->GetResolved());
+}
+*/
+
+namespace {
+class BlockingResolveFixture {
+ public:
+  void Root() { run_order_.push_back("Root"); }
+
+  void L() { run_order_.push_back("L"); }
+
+  void LL() { run_order_.push_back("LL"); }
+
+  void LR() { run_order_.push_back("LR"); }
+
+  void R() { run_order_.push_back("R"); }
+
+  void RL() { run_order_.push_back("RL"); }
+
+  void RR() { run_order_.push_back("RL"); }
+
+  std::vector<std::string> run_order_;
+};
+}  // namespace
+
+/*
+TEST_F(ThreadPoolPromiseExecutorTest, BlockingResolve) {
+  BlockingResolveFixture fixture;
+
+  scoped_refptr<Promise<void>> promise_ll(promise::Create(
+      base::Bind(&BlockingResolveFixture::LL, base::Unretained(&fixture))));
+
+  scoped_refptr<Promise<void>> promise_lr(promise::Create(
+      base::Bind(&BlockingResolveFixture::LR, base::Unretained(&fixture))));
+
+  scoped_refptr<Promise<void>> promise_l(promise_executor_->RunAfter(
+      base::Bind(&BlockingResolveFixture::L, base::Unretained(&fixture)),
+      promise_ll, promise_lr));
+
+  scoped_refptr<Promise<void>> promise_rl(promise::Create(
+      base::Bind(&BlockingResolveFixture::RL, base::Unretained(&fixture))));
+
+  scoped_refptr<Promise<void>> promise_rr(promise::Create(
+      base::Bind(&BlockingResolveFixture::RR, base::Unretained(&fixture))));
+
+  scoped_refptr<Promise<void>> blocking_promise(
+      promise::Create<void>());
+
+  scoped_refptr<Promise<void>> promise_r(promise_executor_->RunAfter(
+      base::Bind(&BlockingResolveFixture::R, base::Unretained(&fixture)),
+      promise_rl, promise_rr, scoped_refptr<Promise<void>>(blocking_promise)));
+
+  scoped_refptr<Promise<void>> promise_root(promise_executor_->RunAfter(
+      base::Bind(&BlockingResolveFixture::Root, base::Unretained(&fixture)),
+      promise_l, promise_r));
+
+  promise_executor_->StartResolve(promise_root.get());
+  mock_task_runner_->RunUntilIdle();
+  EXPECT_THAT(fixture.run_order_,
+              WhenSorted(ElementsAre(std::string("L"), std::string("LL"),
+                                     std::string("LR"), std::string("RL"),
+                                     std::string("RL"))));
+
+  fixture.run_order_.clear();
+  blocking_promise.Resolve();
+  mock_task_runner_->RunUntilIdle();
+  EXPECT_THAT(fixture.run_order_,
+              ElementsAre(std::string("R"), std::string("Root")));
+}
+
+namespace {
+scoped_refptr<Promise<void>> GenerateNewTask(PromiseExecutor* executor,
+                                             std::vector<int>* out_result) {
+  out_result->push_back(1);
+
+  scoped_refptr<Promise<void>> promise0(
+      executor->promise::Create(base::Bind(&RecordOrder, 2, out_result)));
+
+  return executor->RunAfter(base::Bind(&RecordOrder, 3, out_result), promise0);
+}
+}  // namespace
+
+TEST_F(ThreadPoolPromiseExecutorTest, NewPromiseFromWithinPromise) {
+  std::vector<int> run_order;
+
+  scoped_refptr<Promise<void>> promise0(promise::Create(
+      base::Bind(&RecordOrder, 0, &run_order)));
+
+  scoped_refptr<Promise<void>> promise1(promise_executor_->RunAfter(
+      base::Bind(&GenerateNewTask, base::Unretained(promise_executor_.get()),
+                 &run_order),
+      promise0));
+
+  scoped_refptr<Promise<void>> promise4(promise_executor_->RunAfter(
+      base::Bind(&RecordOrder, 4, &run_order), promise1));
+
+  promise_executor_->StartResolve(promise4.get());
+
+  mock_task_runner_->RunUntilIdle();
+
+  EXPECT_THAT(run_order, ElementsAre(0, 1, 2, 3, 4));
+}*/
+
+}  // namespace promise
+
+#endif