GD: Add ListMap and LruCache

        "observer_registry_test.cc",

        "link_key_unittest.cc",

        "init_flags_test.cc",

        "list_map_test.cc",

        "lru_cache_test.cc",

    ],

}

/*

 * Copyright 2020 The Android Open Source Project

 *

 * 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.

 */

#pragma once

#include <functional>

#include <iterator>

#include <list>

#include <mutex>

#include <optional>

#include <thread>

#include <type_traits>

#include <unordered_map>

#include "os/log.h"

namespace bluetooth {

namespace common {

// A map that maintains order of its element as a list. An element that is put earlier will appear before an element

// that is put later when iterating through this map's entries. Keys must be unique.

//

// Performance:

//   - Key look-up and modification is O(1)

//   - Value operated by replacement, no in-place modification

//   - Memory consumption is:

//     O(2*capacity*sizeof(K) + capacity*(sizeof(nullptr)+sizeof(V)))

//   - NOT THREAD SAFE

//

// Template:

//   - Key key

//   - T value

template <typename Key, typename T>

class ListMap {

 public:

  using value_type = std::pair<const Key, T>;

  // different from c++17 node_type on purpose as we want node to be copyable

  using node_type = std::pair<Key, T>;

  using iterator = typename std::list<value_type>::iterator;

  using const_iterator = typename std::list<value_type>::const_iterator;

  // Constructor of the list map

  ListMap() = default;

  // for move

  ListMap(ListMap&& other) noexcept = default;

  ListMap& operator=(ListMap&& other) noexcept = default;

  // copy-constructor

  // iterators in key_map_ cannot be copied directly

  ListMap(const ListMap& other) : node_list_(other.node_list_) {

    for (auto iter = node_list_.begin(); iter != node_list_.end(); iter++) {

      key_map_.emplace(iter->first, iter);

    }

  }

  // copy-assignment

  // iterators in key_map_ cannot be copied directly

  ListMap& operator=(const ListMap& other) {

    if (&other == this) {

      return *this;

    }

    node_list_ = other.node_list_;

    key_map_.clear();

    for (auto iter = node_list_.begin(); iter != node_list_.end(); iter++) {

      key_map_.emplace(iter->first, iter);

    }

    return *this;

  }

  ~ListMap() {

    clear();

  }

  // Clear the list map

  void clear() {

    key_map_.clear();

    node_list_.clear();

  }

  // const version of find()

  const_iterator find(const Key& key) const {

    return const_cast<ListMap*>(this)->find(key);

  }

  // Get the value of a key. Return iterator to the item if found, end() if not found

  iterator find(const Key& key) {

    auto map_iterator = key_map_.find(key);

    if (map_iterator == key_map_.end()) {

      return end();

    }

    return map_iterator->second;

  }

  // Check if key exist in the map. Return true if key exist in map, false if not.

  bool contains(const Key& key) const {

    return find(key) != end();

  }

  // Try emplace an element before a specific position |pos| of the list map. If the |key| already exists, does nothing.

  // Moved arguments won't be moved when key already exists. Return <iterator, true> when key does not exist, <iterator,

  // false> when key exist and iterator is the position where it was placed.

  template <class... Args>

  std::pair<iterator, bool> try_emplace(const_iterator pos, const Key& key, Args&&... args) {

    auto map_iterator = key_map_.find(key);

    if (map_iterator != key_map_.end()) {

      return std::make_pair(end(), false);

    }

    auto list_iterator = node_list_.emplace(pos, key, std::forward<Args>(args)...);

    key_map_.emplace(key, list_iterator);

    return std::make_pair(list_iterator, true);

  }

  // Try emplace an element before the end of the list map. If the key already exists, does nothing. Moved arguments

  // won't be moved when key already exists return <iterator, true> when key does not exist, <iterator, false> when key

  // exist and iterator is the position where it was placed

  template <class... Args>

  std::pair<iterator, bool> try_emplace_back(const Key& key, Args&&... args) {

    return try_emplace(end(), key, std::forward<Args>(args)...);

  }

  // Put a key-value pair to the map before position. If key already exist, |pos| will be ignored and existing value

  // will be replaced

  void insert_or_assign(const_iterator pos, const Key& key, T value) {

    auto map_iterator = key_map_.find(key);

    if (map_iterator != key_map_.end()) {

      map_iterator->second->second = std::move(value);

      return;

    }

    auto list_iterator = node_list_.emplace(pos, key, std::move(value));

    key_map_.emplace(key, list_iterator);

  }

  // Put a key-value pair to the tail of the map or replace the current value without moving the key if key exists

  void insert_or_assign(const Key& key, T value) {

    insert_or_assign(end(), key, std::move(value));

  }

  // STL splice, same as std::list::splice

  // - pos: element before which the content will be inserted

  // - other: another container to transfer the content from

  // - it: the element to transfer from other to *this

  void splice(const_iterator pos, ListMap<Key, T>& other, const_iterator it) {

    if (&other != this) {

      auto map_node = other.key_map_.extract(it->first);

      key_map_.insert(std::move(map_node));

    }

    node_list_.splice(pos, other.node_list_, it);

  }

  // Remove a key from the list map and return removed value if key exits, std::nullopt if not. The return value will be

  // evaluated to true in a boolean context if a value is contained by std::optional, false otherwise.

  std::optional<node_type> extract(const Key& key) {

    auto map_iterator = key_map_.find(key);

    if (map_iterator == key_map_.end()) {

      return std::nullopt;

    }

    std::optional<node_type> removed_node(std::move(*map_iterator->second));

    node_list_.erase(map_iterator->second);

    key_map_.erase(map_iterator);

    return removed_node;

  }

  // Remove an iterator pointed item from the list map and return the iterator immediately after the erased item

  iterator erase(const_iterator iter) {

    key_map_.erase(iter->first);

    return node_list_.erase(iter);

  }

  // Return size of the list map

  inline size_t size() const {

    return node_list_.size();

  }

  // Return iterator interface for begin

  inline iterator begin() {

    return node_list_.begin();

  }

  // Iterator interface for begin, const

  inline const_iterator begin() const {

    return node_list_.begin();

  }

  // Iterator interface for end

  inline iterator end() {

    return node_list_.end();

  }

  // Iterator interface for end, const

  inline const_iterator end() const {

    return node_list_.end();

  }

 private:

  std::list<value_type> node_list_;

  std::unordered_map<Key, iterator> key_map_;

};

}  // namespace common

}  // namespace bluetooth

 No newline at end of file

/*

 * Copyright 2020 The Android Open Source Project

 *

 * 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 <chrono>

#include <memory>

#include <gmock/gmock.h>

#include <gtest/gtest.h>

#include "common/list_map.h"

namespace testing {

using bluetooth::common::ListMap;

TEST(ListMapTest, empty_test) {

  ListMap<int, int> list_map;

  EXPECT_EQ(list_map.size(), 0);

  EXPECT_EQ(list_map.find(42), list_map.end());

  list_map.clear();  // should not crash

  EXPECT_EQ(list_map.find(42), list_map.end());

  EXPECT_FALSE(list_map.contains(42));

  EXPECT_FALSE(list_map.extract(42));

}

TEST(ListMapTest, copy_test) {

  ListMap<int, std::shared_ptr<int>> list_map;

  list_map.insert_or_assign(1, std::make_shared<int>(100));

  auto iter = list_map.find(1);

  EXPECT_EQ(*iter->second, 100);

  ListMap<int, std::shared_ptr<int>> new_list_map = list_map;

  iter = new_list_map.find(1);

  EXPECT_EQ(*iter->second, 100);

  *iter->second = 300;

  iter = new_list_map.find(1);

  EXPECT_EQ(*iter->second, 300);

  // Since copy is used, shared_ptr should increase count

  EXPECT_EQ(iter->second.use_count(), 2);

}

TEST(ListMapTest, move_test) {

  ListMap<int, std::shared_ptr<int>> list_map;

  list_map.insert_or_assign(1, std::make_shared<int>(100));

  auto iter = list_map.find(1);

  EXPECT_EQ(*iter->second, 100);

  ListMap<int, std::shared_ptr<int>> new_list_map = std::move(list_map);

  iter = new_list_map.find(1);

  EXPECT_EQ(*iter->second, 100);

  *iter->second = 300;

  iter = new_list_map.find(1);

  EXPECT_EQ(*iter->second, 300);

  // Since move is used, shared_ptr should not increase count

  EXPECT_EQ(iter->second.use_count(), 1);

}

TEST(ListMapTest, move_insert_unique_ptr_test) {

  ListMap<int, std::unique_ptr<int>> list_map;

  list_map.insert_or_assign(1, std::make_unique<int>(100));

  auto iter = list_map.find(1);

  EXPECT_EQ(*iter->second, 100);

  list_map.insert_or_assign(1, std::make_unique<int>(400));

  iter = list_map.find(1);

  EXPECT_EQ(*iter->second, 400);

}

TEST(ListMapTest, move_insert_list_map_test) {

  ListMap<int, ListMap<int, int>> list_map;

  ListMap<int, int> m1;

  m1.insert_or_assign(1, 100);

  list_map.insert_or_assign(1, std::move(m1));

  auto iter = list_map.find(1);

  EXPECT_THAT(iter->second, ElementsAre(Pair(1, 100)));

  ListMap<int, int> m2;

  m2.insert_or_assign(2, 200);

  list_map.insert_or_assign(1, std::move(m2));

  iter = list_map.find(1);

  EXPECT_THAT(iter->second, ElementsAre(Pair(2, 200)));

}

TEST(ListMapTest, erase_one_item_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  list_map.insert_or_assign(3, 30);

  auto iter = list_map.find(2);

  iter = list_map.erase(iter);

  EXPECT_EQ(iter->first, 3);

  EXPECT_EQ(iter->second, 30);

}

TEST(ListMapTest, erase_in_for_loop_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  list_map.insert_or_assign(3, 30);

  for (auto iter = list_map.begin(); iter != list_map.end();) {

    if (iter->first == 2) {

      iter = list_map.erase(iter);

    } else {

      ++iter;

    }

  }

  EXPECT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(3, 30)));

}

TEST(ListMapTest, splice_different_list_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  list_map.insert_or_assign(3, 30);

  ListMap<int, int> list_map_2;

  list_map_2.insert_or_assign(4, 40);

  list_map_2.insert_or_assign(5, 50);

  list_map.splice(list_map.find(2), list_map_2, list_map_2.find(4));

  EXPECT_EQ(list_map_2.find(4), list_map_2.end());

  auto iter = list_map.find(4);

  EXPECT_NE(iter, list_map.end());

  EXPECT_EQ(iter->second, 40);

  EXPECT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(4, 40), Pair(2, 20), Pair(3, 30)));

}

TEST(ListMapTest, splice_same_list_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  list_map.insert_or_assign(3, 30);

  list_map.splice(list_map.find(2), list_map, list_map.find(3));

  EXPECT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(3, 30), Pair(2, 20)));

  list_map.extract(2);

  list_map.insert_or_assign(list_map.begin(), 4, 40);

  EXPECT_THAT(list_map, ElementsAre(Pair(4, 40), Pair(1, 10), Pair(3, 30)));

  auto iter = list_map.find(4);

  EXPECT_EQ(iter->second, 40);

  list_map.splice(list_map.begin(), list_map, list_map.find(4));

  list_map.splice(list_map.begin(), list_map, list_map.find(3));

  list_map.splice(list_map.begin(), list_map, list_map.find(1));

  EXPECT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(3, 30), Pair(4, 40)));

  iter = list_map.find(4);

  EXPECT_EQ(iter->second, 40);

  iter = list_map.find(3);

  EXPECT_EQ(iter->second, 30);

}

TEST(ListMapTest, put_get_and_contains_key_test) {

  ListMap<int, int> list_map;

  EXPECT_EQ(list_map.size(), 0);

  EXPECT_EQ(list_map.find(42), list_map.end());

  EXPECT_FALSE(list_map.contains(42));

  list_map.insert_or_assign(56, 200);

  EXPECT_EQ(list_map.find(42), list_map.end());

  EXPECT_FALSE(list_map.contains(42));

  auto iter = list_map.find(56);

  EXPECT_NE(iter, list_map.end());

  EXPECT_TRUE(list_map.contains(56));

  EXPECT_EQ(iter->second, 200);

  EXPECT_TRUE(list_map.extract(56));

  EXPECT_FALSE(list_map.contains(56));

}

TEST(ListMapTest, try_emplace_at_position_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  auto iter = list_map.find(2);

  EXPECT_EQ(iter->second, 20);

  auto result = list_map.try_emplace(iter, 42, 420);

  EXPECT_TRUE(result.second);

  iter = list_map.find(42);

  EXPECT_EQ(iter->second, 420);

  EXPECT_EQ(iter, result.first);

  ASSERT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(42, 420), Pair(2, 20)));

  EXPECT_FALSE(list_map.try_emplace(result.first, 42, 420).second);

}

TEST(ListMapTest, try_emplace_back_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  auto result = list_map.try_emplace_back(42, 420);

  EXPECT_TRUE(result.second);

  auto iter = list_map.find(42);

  EXPECT_EQ(iter->second, 420);

  EXPECT_EQ(iter, result.first);

  ASSERT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(2, 20), Pair(42, 420)));

  EXPECT_FALSE(list_map.try_emplace_back(42, 420).second);

}

TEST(ListMapTest, insert_at_position_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  auto iter = list_map.find(2);

  EXPECT_EQ(iter->second, 20);

  list_map.insert_or_assign(iter, 42, 420);

  iter = list_map.find(42);

  EXPECT_EQ(iter->second, 420);

  ASSERT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(42, 420), Pair(2, 20)));

}

TEST(ListMapTest, in_place_modification_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  auto iter = list_map.find(2);

  iter->second = 200;

  ASSERT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(2, 200)));

}

TEST(ListMapTest, get_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  auto iter = list_map.find(1);

  EXPECT_NE(iter, list_map.end());

  EXPECT_EQ(iter->second, 10);

}

TEST(ListMapTest, remove_test) {

  ListMap<int, int> list_map;

  for (int key = 0; key <= 30; key++) {

    list_map.insert_or_assign(key, key * 100);

  }

  for (int key = 0; key <= 30; key++) {

    EXPECT_TRUE(list_map.contains(key));

  }

  for (int key = 0; key <= 30; key++) {

    auto removed = list_map.extract(key);

    EXPECT_TRUE(removed);

    EXPECT_EQ(*removed, std::make_pair(key, key * 100));

  }

  for (int key = 0; key <= 30; key++) {

    EXPECT_FALSE(list_map.contains(key));

  }

}

TEST(ListMapTest, clear_test) {

  ListMap<int, int> list_map;

  for (int key = 0; key < 10; key++) {

    list_map.insert_or_assign(key, key * 100);

  }

  for (int key = 0; key < 10; key++) {

    EXPECT_TRUE(list_map.contains(key));

  }

  list_map.clear();

  for (int key = 0; key < 10; key++) {

    EXPECT_FALSE(list_map.contains(key));

  }

  for (int key = 0; key < 10; key++) {

    list_map.insert_or_assign(key, key * 1000);

  }

  for (int key = 0; key < 10; key++) {

    EXPECT_TRUE(list_map.contains(key));

  }

}

TEST(ListMapTest, container_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  ASSERT_THAT(list_map, ElementsAre(Pair(1, 10), Pair(2, 20)));

}

TEST(ListMapTest, iterator_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  std::list<std::pair<int, int>> list(list_map.begin(), list_map.end());

  ASSERT_THAT(list, ElementsAre(Pair(1, 10), Pair(2, 20)));

}

TEST(ListMapTest, for_loop_test) {

  ListMap<int, int> list_map;

  list_map.insert_or_assign(1, 10);

  list_map.insert_or_assign(2, 20);

  std::list<std::pair<int, int>> list;

  for (const auto& node : list_map) {

    list.emplace_back(node);

  }

  ASSERT_THAT(list, ElementsAre(Pair(1, 10), Pair(2, 20)));

  list.clear();

  for (auto& node : list_map) {

    list.emplace_back(node);

    node.second = node.second * 2;

  }

  ASSERT_THAT(list, ElementsAre(Pair(1, 10), Pair(2, 20)));

  list.clear();

  for (const auto& node : list_map) {

    list.emplace_back(node);

  }

  ASSERT_THAT(list, ElementsAre(Pair(1, 20), Pair(2, 40)));

}

TEST(ListMapTest, pressure_test) {

  auto started = std::chrono::high_resolution_clock::now();

  int num_entries = 0xFFFF;  // 2^16 = 65535

  ListMap<int, int> list_map;

  // fill the list_map

  for (int key = 0; key < num_entries; key++) {

    list_map.insert_or_assign(key, key);

  }

  // make sure the list_map is full

  for (int key = 0; key < num_entries; key++) {

    EXPECT_TRUE(list_map.contains(key));

  }

  // clear the entire list_map

  for (int key = 0; key < num_entries; key++) {

    auto iter = list_map.find(key);

    EXPECT_NE(iter, list_map.end());

    EXPECT_EQ(iter->second, key);

    EXPECT_TRUE(list_map.extract(key));

  }

  EXPECT_EQ(list_map.size(), 0);

  // test execution time

  auto done = std::chrono::high_resolution_clock::now();

  int execution_time = std::chrono::duration_cast<std::chrono::microseconds>(done - started).count();

  // Shouldn't be more than 1000ms

  int execution_time_per_cycle_us = 10;

  EXPECT_LT(execution_time, execution_time_per_cycle_us * num_entries);

}

}  // namespace testing