////////////////////////////////////////////////////////////////////////////////
/// @brief test suite for arangodb::cache::Rebalancer
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2017 ArangoDB GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Daniel H. Larkin
/// @author Copyright 2017, ArangoDB GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "Cache/Rebalancer.h"
#include "Basics/Common.h"
#include "Basics/voc-errors.h"
#include "Cache/Common.h"
#include "Cache/Manager.h"
#include "Cache/PlainCache.h"
#include "Cache/Transaction.h"
#include "Cache/TransactionalCache.h"
#include "Random/RandomGenerator.h"

#include "MockScheduler.h"
#include "gtest/gtest.h"

#include <stdint.h>
#include <queue>
#include <string>
#include <thread>
#include <vector>

using namespace arangodb;
using namespace arangodb::cache;

// long-running

TEST(CacheRebalancerTest, test_rebalancing_with_plaincache_LongRunning) {
  RandomGenerator::initialize(RandomGenerator::RandomType::MERSENNE);
  MockScheduler scheduler(4);
  auto postFn = [&scheduler](std::function<void()> fn) -> bool {
    scheduler.post(fn);
    return true;
  };
  Manager manager(postFn, 128 * 1024 * 1024);
  Rebalancer rebalancer(&manager);

  size_t cacheCount = 4;
  size_t threadCount = 4;
  std::vector<std::shared_ptr<Cache>> caches;
  for (size_t i = 0; i < cacheCount; i++) {
    caches.emplace_back(manager.createCache(CacheType::Plain));
  }

  std::atomic<bool> doneRebalancing(false);
  auto rebalanceWorker = [&rebalancer, &doneRebalancing]() -> void {
    while (!doneRebalancing) {
      int status = rebalancer.rebalance();
      if (status != TRI_ERROR_ARANGO_BUSY) {
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
      } else {
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
      }
    }
  };
  auto rebalancerThread = new std::thread(rebalanceWorker);

  uint64_t chunkSize = 4 * 1024 * 1024;
  uint64_t initialInserts = 1 * 1024 * 1024;
  uint64_t operationCount = 4 * 1024 * 1024;
  std::atomic<uint64_t> hitCount(0);
  std::atomic<uint64_t> missCount(0);
  auto worker = [&caches, cacheCount, initialInserts, operationCount, &hitCount,
                 &missCount](uint64_t lower, uint64_t upper) -> void {
    // fill with some initial data
    for (uint64_t i = 0; i < initialInserts; i++) {
      uint64_t item = lower + i;
      size_t cacheIndex = item % cacheCount;
      CachedValue* value =
          CachedValue::construct(&item, sizeof(uint64_t), &item, sizeof(uint64_t));
      TRI_ASSERT(value != nullptr);
      auto status = caches[cacheIndex]->insert(value);
      if (status.fail()) {
        delete value;
      }
    }

    // initialize valid range for keys that *might* be in cache
    uint64_t validLower = lower;
    uint64_t validUpper = lower + initialInserts - 1;

    // commence mixed workload
    for (uint64_t i = 0; i < operationCount; i++) {
      uint32_t r = RandomGenerator::interval(static_cast<uint32_t>(99UL));

      if (r >= 99) {  // remove something
        if (validLower == validUpper) {
          continue;  // removed too much
        }

        uint64_t item = validLower++;
        size_t cacheIndex = item % cacheCount;

        caches[cacheIndex]->remove(&item, sizeof(uint64_t));
      } else if (r >= 95) {  // insert something
        if (validUpper == upper) {
          continue;  // already maxed out range
        }

        uint64_t item = ++validUpper;
        size_t cacheIndex = item % cacheCount;
        CachedValue* value =
            CachedValue::construct(&item, sizeof(uint64_t), &item, sizeof(uint64_t));
        TRI_ASSERT(value != nullptr);
        auto status = caches[cacheIndex]->insert(value);
        if (status.fail()) {
          delete value;
        }
      } else {  // lookup something
        uint64_t item = RandomGenerator::interval(static_cast<int64_t>(validLower),
                                                  static_cast<int64_t>(validUpper));
        size_t cacheIndex = item % cacheCount;

        Finding f = caches[cacheIndex]->find(&item, sizeof(uint64_t));
        if (f.found()) {
          hitCount++;
          TRI_ASSERT(f.value() != nullptr);
          TRI_ASSERT(f.value()->sameKey(&item, sizeof(uint64_t)));
        } else {
          missCount++;
          TRI_ASSERT(f.value() == nullptr);
        }
      }
    }
  };

  std::vector<std::thread*> threads;
  // dispatch threads
  for (size_t i = 0; i < threadCount; i++) {
    uint64_t lower = i * chunkSize;
    uint64_t upper = ((i + 1) * chunkSize) - 1;
    threads.push_back(new std::thread(worker, lower, upper));
  }

  // join threads
  for (auto t : threads) {
    t->join();
    delete t;
  }

  doneRebalancing = true;
  rebalancerThread->join();
  delete rebalancerThread;

  for (auto cache : caches) {
    manager.destroyCache(cache);
  }

  RandomGenerator::shutdown();
}

TEST(CacheRebalancerTest, test_rebalancing_with_transactionalcache_LongRunning) {
  RandomGenerator::initialize(RandomGenerator::RandomType::MERSENNE);
  MockScheduler scheduler(4);
  auto postFn = [&scheduler](std::function<void()> fn) -> bool {
    scheduler.post(fn);
    return true;
  };
  Manager manager(postFn, 128 * 1024 * 1024);
  Rebalancer rebalancer(&manager);

  size_t cacheCount = 4;
  size_t threadCount = 4;
  std::vector<std::shared_ptr<Cache>> caches;
  for (size_t i = 0; i < cacheCount; i++) {
    caches.emplace_back(manager.createCache(CacheType::Transactional));
  }

  bool doneRebalancing = false;
  auto rebalanceWorker = [&rebalancer, &doneRebalancing]() -> void {
    while (!doneRebalancing) {
      int status = rebalancer.rebalance();
      if (status != TRI_ERROR_ARANGO_BUSY) {
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
      } else {
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
      }
    }
  };
  auto rebalancerThread = new std::thread(rebalanceWorker);

  uint64_t chunkSize = 4 * 1024 * 1024;
  uint64_t initialInserts = 1 * 1024 * 1024;
  uint64_t operationCount = 4 * 1024 * 1024;
  std::atomic<uint64_t> hitCount(0);
  std::atomic<uint64_t> missCount(0);
  auto worker = [&manager, &caches, cacheCount, initialInserts, operationCount,
                 &hitCount, &missCount](uint64_t lower, uint64_t upper) -> void {
    Transaction* tx = manager.beginTransaction(false);
    // fill with some initial data
    for (uint64_t i = 0; i < initialInserts; i++) {
      uint64_t item = lower + i;
      size_t cacheIndex = item % cacheCount;
      CachedValue* value =
          CachedValue::construct(&item, sizeof(uint64_t), &item, sizeof(uint64_t));
      TRI_ASSERT(value != nullptr);
      auto status = caches[cacheIndex]->insert(value);
      if (status.fail()) {
        delete value;
      }
    }

    // initialize valid range for keys that *might* be in cache
    uint64_t validLower = lower;
    uint64_t validUpper = lower + initialInserts - 1;
    uint64_t blacklistUpper = validUpper;

    // commence mixed workload
    for (uint64_t i = 0; i < operationCount; i++) {
      uint32_t r = RandomGenerator::interval(static_cast<uint32_t>(99UL));

      if (r >= 99) {  // remove something
        if (validLower == validUpper) {
          continue;  // removed too much
        }

        uint64_t item = validLower++;
        size_t cacheIndex = item % cacheCount;

        caches[cacheIndex]->remove(&item, sizeof(uint64_t));
      } else if (r >= 90) {  // insert something
        if (validUpper == upper) {
          continue;  // already maxed out range
        }

        uint64_t item = ++validUpper;
        if (validUpper > blacklistUpper) {
          blacklistUpper = validUpper;
        }
        size_t cacheIndex = item % cacheCount;
        CachedValue* value =
            CachedValue::construct(&item, sizeof(uint64_t), &item, sizeof(uint64_t));
        TRI_ASSERT(value != nullptr);
        auto status = caches[cacheIndex]->insert(value);
        if (status.fail()) {
          delete value;
        }
      } else if (r >= 80) {  // blacklist something
        if (blacklistUpper == upper) {
          continue;  // already maxed out range
        }

        uint64_t item = ++blacklistUpper;
        size_t cacheIndex = item % cacheCount;
        caches[cacheIndex]->blacklist(&item, sizeof(uint64_t));
      } else {  // lookup something
        uint64_t item = RandomGenerator::interval(static_cast<int64_t>(validLower),
                                                  static_cast<int64_t>(validUpper));
        size_t cacheIndex = item % cacheCount;

        Finding f = caches[cacheIndex]->find(&item, sizeof(uint64_t));
        if (f.found()) {
          hitCount++;
          TRI_ASSERT(f.value() != nullptr);
          TRI_ASSERT(f.value()->sameKey(&item, sizeof(uint64_t)));
        } else {
          missCount++;
          TRI_ASSERT(f.value() == nullptr);
        }
      }
    }
    manager.endTransaction(tx);
  };

  std::vector<std::thread*> threads;
  // dispatch threads
  for (size_t i = 0; i < threadCount; i++) {
    uint64_t lower = i * chunkSize;
    uint64_t upper = ((i + 1) * chunkSize) - 1;
    threads.push_back(new std::thread(worker, lower, upper));
  }

  // join threads
  for (auto t : threads) {
    t->join();
    delete t;
  }

  doneRebalancing = true;
  rebalancerThread->join();
  delete rebalancerThread;

  for (auto cache : caches) {
    manager.destroyCache(cache);
  }

  RandomGenerator::shutdown();
}