/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.

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 "paddle/framework/channel.h"

#include <chrono>
#include <thread>

#include "gtest/gtest.h"

using paddle::framework::Channel;
using paddle::framework::MakeChannel;
using paddle::framework::CloseChannel;

TEST(Channel, MakeAndClose) {
  using paddle::framework::details::Buffered;
  using paddle::framework::details::UnBuffered;
  {
    // MakeChannel should return a buffered channel is buffer_size > 0.
    auto ch = MakeChannel<int>(10);
    EXPECT_NE(dynamic_cast<Buffered<int> *>(ch), nullptr);
    EXPECT_EQ(dynamic_cast<UnBuffered<int> *>(ch), nullptr);
    CloseChannel(ch);
    delete ch;
  }
  {
    // MakeChannel should return an un-buffered channel is buffer_size = 0.
    auto ch = MakeChannel<int>(0);
    EXPECT_EQ(dynamic_cast<Buffered<int> *>(ch), nullptr);
    EXPECT_NE(dynamic_cast<UnBuffered<int> *>(ch), nullptr);
    CloseChannel(ch);
    delete ch;
  }
}

TEST(Channel, SufficientBufferSizeDoesntBlock) {
  const size_t buffer_size = 10;
  auto ch = MakeChannel<size_t>(buffer_size);
  for (size_t i = 0; i < buffer_size; ++i) {
    ch->Send(&i);  // should not block
  }

  size_t out;
  for (size_t i = 0; i < buffer_size; ++i) {
    ch->Receive(&out);  // should not block
    EXPECT_EQ(out, i);
  }
  CloseChannel(ch);
  delete ch;
}

TEST(Channel, ConcurrentSendNonConcurrentReceiveWithSufficientBufferSize) {
  const size_t buffer_size = 10;
  auto ch = MakeChannel<size_t>(buffer_size);
  size_t sum = 0;
  std::thread t([&]() {
    // Try to write more than buffer size.
    for (size_t i = 0; i < 2 * buffer_size; ++i) {
      ch->Send(&i);  // should not block
      sum += i;
    }
  });
  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.5 sec
  EXPECT_EQ(sum, 45U);

  CloseChannel(ch);
  t.join();
  delete ch;
}

TEST(Channel, SimpleUnbufferedChannelTest) {
  auto ch = MakeChannel<int>(0);
  unsigned sum_send = 0;
  std::thread t([&]() {
    for (int i = 0; i < 5; i++) {
      ch->Send(&i);
      sum_send += i;
    }
  });
  for (int i = 0; i < 5; i++) {
    int recv;
    ch->Receive(&recv);
    EXPECT_EQ(recv, i);
  }

  CloseChannel(ch);
  t.join();
  EXPECT_EQ(sum_send, 10U);
  delete ch;
}

// This tests that closing an unbuffered channel also unblocks
//  unblocks any receivers waiting for senders
TEST(Channel, UnbufferedChannelCloseUnblocksReceiversTest) {
  auto ch = MakeChannel<int>(0);
  size_t num_threads = 5;
  std::thread t[num_threads];
  bool thread_ended[num_threads];

  // Launches threads that try to read and are blocked becausew of no writers
  for (size_t i = 0; i < num_threads; i++) {
    thread_ended[i] = false;
    t[i] = std::thread(
        [&](bool *p) {
          int data;
          ch->Receive(&data);
          *p = true;
        },
        &thread_ended[i]);
  }
  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec

  // Verify that all the threads are blocked
  for (size_t i = 0; i < num_threads; i++) {
    EXPECT_EQ(thread_ended[i], false);
  }

  // Explicitly close the thread
  // This should unblock all receivers
  CloseChannel(ch);

  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec

  // Verify that all threads got unblocked
  for (size_t i = 0; i < num_threads; i++) {
    EXPECT_EQ(thread_ended[i], true);
  }

  for (size_t i = 0; i < num_threads; i++) t[i].join();
  delete ch;
}

// This tests that closing an unbuffered channel also unblocks
//  unblocks any senders waiting for senders
TEST(Channel, UnbufferedChannelCloseUnblocksSendersTest) {
  auto ch = MakeChannel<int>(0);
  size_t num_threads = 5;
  std::thread t[num_threads];
  bool thread_ended[num_threads];

  // Launches threads that try to read and are blocked becausew of no writers
  for (size_t i = 0; i < num_threads; i++) {
    thread_ended[i] = false;
    t[i] = std::thread(
        [&](bool *p) {
          int data = 10;
          ch->Send(&data);
          *p = true;
        },
        &thread_ended[i]);
  }
  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec

  // Verify that all the threads are blocked
  for (size_t i = 0; i < num_threads; i++) {
    EXPECT_EQ(thread_ended[i], false);
  }

  // Explicitly close the thread
  // This should unblock all receivers
  CloseChannel(ch);

  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec

  // Verify that all threads got unblocked
  for (size_t i = 0; i < num_threads; i++) {
    EXPECT_EQ(thread_ended[i], true);
  }

  for (size_t i = 0; i < num_threads; i++) t[i].join();
  delete ch;
}

TEST(Channel, UnbufferedLessReceiveMoreSendTest) {
  auto ch = MakeChannel<int>(0);
  unsigned sum_send = 0;
  // Send should block after three iterations
  // since we only have three receivers.
  std::thread t([&]() {
    // Try to send more number of times
    // than receivers
    for (int i = 0; i < 4; i++) {
      ch->Send(&i);
      sum_send += i;
    }
  });
  for (int i = 0; i < 3; i++) {
    int recv;
    ch->Receive(&recv);
    EXPECT_EQ(recv, i);
  }
  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.5 sec
  EXPECT_EQ(sum_send, 3U);

  CloseChannel(ch);
  t.join();
  delete ch;
}