// Copyright 2013 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 "cc/resources/worker_pool.h"

#include "base/time/time.h"
#include "cc/base/completion_event.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace cc {

namespace {

static const int kTimeLimitMillis = 2000;
static const int kWarmupRuns = 5;
static const int kTimeCheckInterval = 10;

class PerfWorkerPoolTaskImpl : public internal::WorkerPoolTask {
 public:
  // Overridden from internal::WorkerPoolTask:
  virtual void RunOnWorkerThread(unsigned thread_index) OVERRIDE {}
  virtual void CompleteOnOriginThread() OVERRIDE {}

 private:
  virtual ~PerfWorkerPoolTaskImpl() {}
};

class PerfControlWorkerPoolTaskImpl : public internal::WorkerPoolTask {
 public:
  PerfControlWorkerPoolTaskImpl() : did_start_(new CompletionEvent),
                                    can_finish_(new CompletionEvent) {}

  // Overridden from internal::WorkerPoolTask:
  virtual void RunOnWorkerThread(unsigned thread_index) OVERRIDE {
    did_start_->Signal();
    can_finish_->Wait();
  }
  virtual void CompleteOnOriginThread() OVERRIDE {}

  void WaitForTaskToStartRunning() {
    did_start_->Wait();
  }

  void AllowTaskToFinish() {
    can_finish_->Signal();
  }

 private:
  virtual ~PerfControlWorkerPoolTaskImpl() {}

  scoped_ptr<CompletionEvent> did_start_;
  scoped_ptr<CompletionEvent> can_finish_;

  DISALLOW_COPY_AND_ASSIGN(PerfControlWorkerPoolTaskImpl);
};

class PerfWorkerPool : public WorkerPool {
 public:
  PerfWorkerPool() : WorkerPool(1, "test") {}
  virtual ~PerfWorkerPool() {}

  static scoped_ptr<PerfWorkerPool> Create() {
    return make_scoped_ptr(new PerfWorkerPool);
  }

  void ScheduleTasks(internal::WorkerPoolTask* root_task,
                     internal::WorkerPoolTask* leaf_task,
                     unsigned max_depth,
                     unsigned num_children_per_node) {
    TaskVector tasks;
    TaskGraph graph;

    scoped_ptr<internal::GraphNode> root_node;
    if (root_task)
      root_node = make_scoped_ptr(new internal::GraphNode(root_task, 0u));

    scoped_ptr<internal::GraphNode> leaf_node;
    if (leaf_task)
      leaf_node = make_scoped_ptr(new internal::GraphNode(leaf_task, 0u));

    if (max_depth) {
      BuildTaskGraph(&tasks,
                     &graph,
                     root_node.get(),
                     leaf_node.get(),
                     0,
                     max_depth,
                     num_children_per_node);
    }

    if (leaf_node)
      graph.set(leaf_task, leaf_node.Pass());

    if (root_node)
      graph.set(root_task, root_node.Pass());

    SetTaskGraph(&graph);

    tasks_.swap(tasks);
  }

 private:
  typedef std::vector<scoped_refptr<internal::WorkerPoolTask> > TaskVector;

  void BuildTaskGraph(TaskVector* tasks,
                      TaskGraph* graph,
                      internal::GraphNode* dependent_node,
                      internal::GraphNode* leaf_node,
                      unsigned current_depth,
                      unsigned max_depth,
                      unsigned num_children_per_node) {
    scoped_refptr<PerfWorkerPoolTaskImpl> task(new PerfWorkerPoolTaskImpl);
    scoped_ptr<internal::GraphNode> node(
        new internal::GraphNode(task.get(), 0u));

    if (current_depth < max_depth) {
      for (unsigned i = 0; i < num_children_per_node; ++i) {
        BuildTaskGraph(tasks,
                       graph,
                       node.get(),
                       leaf_node,
                       current_depth + 1,
                       max_depth,
                       num_children_per_node);
      }
    } else if (leaf_node) {
      leaf_node->add_dependent(node.get());
      node->add_dependency();
    }

    if (dependent_node) {
      node->add_dependent(dependent_node);
      dependent_node->add_dependency();
    }
    graph->set(task.get(), node.Pass());
    tasks->push_back(task.get());
  }

  TaskVector tasks_;

  DISALLOW_COPY_AND_ASSIGN(PerfWorkerPool);
};

class WorkerPoolPerfTest : public testing::Test {
 public:
  WorkerPoolPerfTest() : num_runs_(0) {}

  // Overridden from testing::Test:
  virtual void SetUp() OVERRIDE {
    worker_pool_ = PerfWorkerPool::Create();
  }
  virtual void TearDown() OVERRIDE {
    worker_pool_->Shutdown();
    worker_pool_->CheckForCompletedTasks();
  }

  void EndTest() {
    elapsed_ = base::TimeTicks::HighResNow() - start_time_;
  }

  void AfterTest(const std::string test_name) {
    // Format matches chrome/test/perf/perf_test.h:PrintResult
    printf("*RESULT %s: %.2f runs/s\n",
           test_name.c_str(),
           num_runs_ / elapsed_.InSecondsF());
  }

  bool DidRun() {
    ++num_runs_;
    if (num_runs_ == kWarmupRuns)
      start_time_ = base::TimeTicks::HighResNow();

    if (!start_time_.is_null() && (num_runs_ % kTimeCheckInterval) == 0) {
      base::TimeDelta elapsed = base::TimeTicks::HighResNow() - start_time_;
      if (elapsed >= base::TimeDelta::FromMilliseconds(kTimeLimitMillis)) {
        elapsed_ = elapsed;
        return false;
      }
    }

    return true;
  }

  void RunScheduleTasksTest(const std::string test_name,
                            unsigned max_depth,
                            unsigned num_children_per_node) {
    start_time_ = base::TimeTicks();
    num_runs_ = 0;
    do {
      scoped_refptr<PerfControlWorkerPoolTaskImpl> leaf_task(
          new PerfControlWorkerPoolTaskImpl);
      worker_pool_->ScheduleTasks(
          NULL, leaf_task.get(), max_depth, num_children_per_node);
      leaf_task->WaitForTaskToStartRunning();
      worker_pool_->ScheduleTasks(NULL, NULL, 0, 0);
      worker_pool_->CheckForCompletedTasks();
      leaf_task->AllowTaskToFinish();
    } while (DidRun());

    AfterTest(test_name);
  }

  void RunExecuteTasksTest(const std::string test_name,
                           unsigned max_depth,
                           unsigned num_children_per_node) {
    start_time_ = base::TimeTicks();
    num_runs_ = 0;
    do {
      scoped_refptr<PerfControlWorkerPoolTaskImpl> root_task(
          new PerfControlWorkerPoolTaskImpl);
      worker_pool_->ScheduleTasks(
          root_task.get(), NULL, max_depth, num_children_per_node);
      root_task->WaitForTaskToStartRunning();
      root_task->AllowTaskToFinish();
      worker_pool_->CheckForCompletedTasks();
    } while (DidRun());

    AfterTest(test_name);
  }

 protected:
  scoped_ptr<PerfWorkerPool> worker_pool_;
  base::TimeTicks start_time_;
  base::TimeDelta elapsed_;
  int num_runs_;
};

TEST_F(WorkerPoolPerfTest, ScheduleTasks) {
  RunScheduleTasksTest("schedule_tasks_1_10", 1, 10);
  RunScheduleTasksTest("schedule_tasks_1_1000", 1, 1000);
  RunScheduleTasksTest("schedule_tasks_2_10", 2, 10);
  RunScheduleTasksTest("schedule_tasks_5_5", 5, 5);
  RunScheduleTasksTest("schedule_tasks_10_2", 10, 2);
  RunScheduleTasksTest("schedule_tasks_1000_1", 1000, 1);
  RunScheduleTasksTest("schedule_tasks_10_1", 10, 1);
}

TEST_F(WorkerPoolPerfTest, ExecuteTasks) {
  RunExecuteTasksTest("execute_tasks_1_10", 1, 10);
  RunExecuteTasksTest("execute_tasks_1_1000", 1, 1000);
  RunExecuteTasksTest("execute_tasks_2_10", 2, 10);
  RunExecuteTasksTest("execute_tasks_5_5", 5, 5);
  RunExecuteTasksTest("execute_tasks_10_2", 10, 2);
  RunExecuteTasksTest("execute_tasks_1000_1", 1000, 1);
  RunExecuteTasksTest("execute_tasks_10_1", 10, 1);
}

}  // namespace

}  // namespace cc