Add {CancelableTaskManager} to handle {Cancelable} concurrent tasks.

test/unittests/cancelable-tasks-unittest.cc

+// Copyright 2015 the V8 project 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 "src/base/atomicops.h"
+#include "src/base/platform/platform.h"
+#include "src/cancelable-task.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+class TestTask : public Task, public Cancelable {
+ public:
+  enum Mode { kDoNothing, kWaitTillCanceledAgain, kCheckNotRun };
+
+  TestTask(CancelableTaskManager* parent, base::AtomicWord* result,
+           Mode mode = kDoNothing)
+      : Cancelable(parent), result_(result), mode_(mode) {}
+
+  // Task overrides.
+  void Run() final {
+    if (TryRun()) {
+      RunInternal();
+    }
+  }
+
+ private:
+  void RunInternal() {
+    base::Release_Store(result_, id());
+
+    switch (mode_) {
+      case kWaitTillCanceledAgain:
+        // Simple busy wait until the main thread tried to cancel.
+        while (CancelAttempts() == 0) {
+        }
+        break;
+      case kCheckNotRun:
+        // Check that we never execute {RunInternal}.
+        EXPECT_TRUE(false);
+        break;
+      default:
+        break;
+    }
+  }
+
+  base::AtomicWord* result_;
+  Mode mode_;
+};
+
+
+class SequentialRunner {
+ public:
+  explicit SequentialRunner(TestTask* task) : task_(task) {}
+
+  void Run() {
+    task_->Run();
+    delete task_;
+  }
+
+ private:
+  TestTask* task_;
+};
+
+
+class ThreadedRunner final : public base::Thread {
+ public:
+  explicit ThreadedRunner(TestTask* task)
+      : Thread(Options("runner thread")), task_(task) {}
+
+  virtual void Run() {
+    task_->Run();
+    delete task_;
+  }
+
+ private:
+  TestTask* task_;
+};
+
+
+typedef base::AtomicWord ResultType;
+
+
+intptr_t GetValue(ResultType* result) { return base::Acquire_Load(result); }
+
+}  // namespace
+
+
+TEST(CancelableTask, EmptyCancelableTaskManager) {
+  CancelableTaskManager manager;
+  manager.CancelAndWait();
+}
+
+
+TEST(CancelableTask, SequentialCancelAndWait) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  SequentialRunner runner1(
+      new TestTask(&manager, &result1, TestTask::kCheckNotRun));
+  EXPECT_EQ(GetValue(&result1), 0);
+  manager.CancelAndWait();
+  EXPECT_EQ(GetValue(&result1), 0);
+  runner1.Run();  // Run to avoid leaking the Task.
+  EXPECT_EQ(GetValue(&result1), 0);
+}
+
+
+TEST(CancelableTask, SequentialMultipleTasks) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  ResultType result2 = 0;
+  TestTask* task1 = new TestTask(&manager, &result1);
+  TestTask* task2 = new TestTask(&manager, &result2);
+  SequentialRunner runner1(task1);
+  SequentialRunner runner2(task2);
+  EXPECT_EQ(task1->id(), 1);
+  EXPECT_EQ(task2->id(), 2);
+
+  EXPECT_EQ(GetValue(&result1), 0);
+  runner1.Run();  // Don't touch task1 after running it.
+  EXPECT_EQ(GetValue(&result1), 1);
+
+  EXPECT_EQ(GetValue(&result2), 0);
+  runner2.Run();  // Don't touch task2 after running it.
+  EXPECT_EQ(GetValue(&result2), 2);
+
+  manager.CancelAndWait();
+  EXPECT_FALSE(manager.Remove(1));
+  EXPECT_FALSE(manager.Remove(2));
+}
+
+
+TEST(CancelableTask, ThreadedMultipleTasksStarted) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  ResultType result2 = 0;
+  TestTask* task1 =
+      new TestTask(&manager, &result1, TestTask::kWaitTillCanceledAgain);
+  TestTask* task2 =
+      new TestTask(&manager, &result2, TestTask::kWaitTillCanceledAgain);
+  ThreadedRunner runner1(task1);
+  ThreadedRunner runner2(task2);
+  runner1.Start();
+  runner2.Start();
+  // Busy wait on result to make sure both tasks are done.
+  while ((GetValue(&result1) == 0) || (GetValue(&result2) == 0)) {
+  }
+  manager.CancelAndWait();
+  runner1.Join();
+  runner2.Join();
+  EXPECT_EQ(GetValue(&result1), 1);
+  EXPECT_EQ(GetValue(&result2), 2);
+}
+
+
+TEST(CancelableTask, ThreadedMultipleTasksNotRun) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  ResultType result2 = 0;
+  TestTask* task1 = new TestTask(&manager, &result1, TestTask::kCheckNotRun);
+  TestTask* task2 = new TestTask(&manager, &result2, TestTask::kCheckNotRun);
+  ThreadedRunner runner1(task1);
+  ThreadedRunner runner2(task2);
+  manager.CancelAndWait();
+  // Tasks are canceled, hence the runner will bail out and not update result.
+  runner1.Start();
+  runner2.Start();
+  runner1.Join();
+  runner2.Join();
+  EXPECT_EQ(GetValue(&result1), 0);
+  EXPECT_EQ(GetValue(&result2), 0);
+}
+
+
+TEST(CancelableTask, RemoveBeforeCancelAndWait) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  TestTask* task1 = new TestTask(&manager, &result1, TestTask::kCheckNotRun);
+  ThreadedRunner runner1(task1);
+  uint32_t id = task1->id();
+  EXPECT_EQ(id, 1);
+  EXPECT_TRUE(manager.Remove(id));
+  runner1.Start();
+  runner1.Join();
+  manager.CancelAndWait();
+  EXPECT_EQ(GetValue(&result1), 0);
+}
+
+
+TEST(CancelableTask, RemoveAfterCancelAndWait) {
+  CancelableTaskManager manager;
+  ResultType result1 = 0;
+  TestTask* task1 = new TestTask(&manager, &result1);
+  ThreadedRunner runner1(task1);
+  uint32_t id = task1->id();
+  EXPECT_EQ(id, 1);
+  runner1.Start();
+  runner1.Join();
+  manager.CancelAndWait();
+  EXPECT_FALSE(manager.Remove(id));
+  EXPECT_EQ(GetValue(&result1), 1);
+}
+
+
+TEST(CancelableTask, RemoveUnmanagedId) {
+  CancelableTaskManager manager;
+  EXPECT_FALSE(manager.Remove(1));
+  EXPECT_FALSE(manager.Remove(2));
+  manager.CancelAndWait();
+  EXPECT_FALSE(manager.Remove(1));
+  EXPECT_FALSE(manager.Remove(3));
+}
+
+}  // namespace internal
+}  // namespace v8