diff --git a/tdutils/CMakeLists.txt b/tdutils/CMakeLists.txt
index 406e64f7..7f53b2a8 100644
--- a/tdutils/CMakeLists.txt
+++ b/tdutils/CMakeLists.txt
@@ -105,7 +105,6 @@ set(TDUTILS_SOURCE
   td/utils/tests.cpp
   td/utils/Time.cpp
   td/utils/Timer.cpp
-  td/utils/tests.cpp
   td/utils/tl_parsers.cpp
   td/utils/translit.cpp
   td/utils/unicode.cpp
@@ -185,6 +184,9 @@ set(TDUTILS_SOURCE
   td/utils/format.h
   td/utils/Gzip.h
   td/utils/GzipByteFlow.h
+  td/utils/Hash.h
+  td/utils/HashMap.h
+  td/utils/HashSet.h
   td/utils/HazardPointers.h
   td/utils/Heap.h
   td/utils/Hints.h
@@ -298,8 +300,7 @@ if (CRC32C_FOUND)
   target_link_libraries(tdutils PRIVATE crc32c)
 endif()
 if (ABSL_FOUND)
-  #target_link_libraries(tdutils PRIVATE absl::base absl::time)
-  target_link_libraries_system(tdutils absl::base absl::container absl::hash )
+  target_link_libraries(tdutils absl::base absl::container absl::hash)
 endif()
 
 if (WIN32 AND WINGETOPT_FOUND)
diff --git a/tdutils/td/utils/ConcurrentHashTable.h b/tdutils/td/utils/ConcurrentHashTable.h
new file mode 100644
index 00000000..b2299458
--- /dev/null
+++ b/tdutils/td/utils/ConcurrentHashTable.h
@@ -0,0 +1,315 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/HazardPointers.h"
+
+#include <mutex>
+#include <atomic>
+#include <condition_variable>
+#include <vector>
+// AtomicHashArray<KeyT, ValueT>
+// Building block for other conurrent hash maps
+//
+// Support one operation:
+//  template <class F>
+//  bool with_value(KeyT key, bool should_create, F &&func);
+//
+//  Finds slot for key, and call func(value)
+//  Creates slot if shoul_create is true.
+//  Returns true if func was called.
+//
+//  Concurrent calls with same key may result in concurrent calls of func(value)
+//  It is resposibility of caller to handle such races.
+//
+//  Key should already be random
+//  It is resposibility of caller to provide unique random key.
+//  One may use injective hash function, or handle collisions on some other way.
+
+namespace td {
+template <class KeyT, class ValueT>
+class AtomicHashArray {
+ public:
+  AtomicHashArray(size_t n) : nodes_(n) {
+  }
+  struct Node {
+    std::atomic<KeyT> key{KeyT{}};
+    ValueT value{};
+  };
+  size_t size() const {
+    return nodes_.size();
+  }
+  Node &node_at(size_t i) {
+    return nodes_[i];
+  }
+  static KeyT empty_key() {
+    return KeyT{};
+  }
+
+  template <class F>
+  bool with_value(KeyT key, bool should_create, F &&f) {
+    DCHECK(key != empty_key());
+    size_t pos = static_cast<size_t>(key) % nodes_.size();
+    size_t n = std::min(std::max(size_t(300), nodes_.size() / 16 + 2), nodes_.size());
+
+    for (size_t i = 0; i < n; i++) {
+      pos++;
+      if (pos >= nodes_.size()) {
+        pos = 0;
+      }
+      auto &node = nodes_[pos];
+      while (true) {
+        auto node_key = node.key.load(std::memory_order_acquire);
+        if (node_key == empty_key()) {
+          if (!should_create) {
+            return false;
+          }
+          KeyT expected_key = empty_key();
+          if (node.key.compare_exchange_strong(expected_key, key, std::memory_order_relaxed,
+                                               std::memory_order_relaxed)) {
+            f(node.value);
+            return true;
+          }
+        } else if (node_key == key) {
+          f(node.value);
+          return true;
+        } else {
+          break;
+        }
+      }
+    }
+    return false;
+  }
+
+ private:
+  std::vector<Node> nodes_;
+};
+
+// Simple concurrent hash map with multiple limitations
+template <class KeyT, class ValueT>
+class ConcurrentHashMap {
+  using HashMap = AtomicHashArray<KeyT, std::atomic<ValueT>>;
+  static td::HazardPointers<HashMap> hp_;
+
+ public:
+  ConcurrentHashMap(size_t n = 32) {
+    n = 1;
+    hash_map_.store(make_unique<HashMap>(n).release());
+  }
+  ConcurrentHashMap(const ConcurrentHashMap &) = delete;
+  ConcurrentHashMap &operator=(const ConcurrentHashMap &) = delete;
+  ConcurrentHashMap(ConcurrentHashMap &&) = delete;
+  ConcurrentHashMap &operator=(ConcurrentHashMap &&) = delete;
+  ~ConcurrentHashMap() {
+    td::unique_ptr<HashMap>(hash_map_.load());
+  }
+
+  static std::string get_name() {
+    return "ConcurrrentHashMap";
+  }
+
+  static KeyT empty_key() {
+    return KeyT{};
+  }
+  static ValueT empty_value() {
+    return ValueT{};
+  }
+  static ValueT migrate_value() {
+    return (ValueT)(1);  // c-style convertion because reinterpret_cast<int>(1) is CE in MSVC
+  }
+
+  ValueT insert(KeyT key, ValueT value) {
+    CHECK(key != empty_key());
+    CHECK(value != migrate_value());
+    typename HazardPointers<HashMap>::Holder holder(hp_, get_thread_id(), 0);
+    while (true) {
+      auto hash_map = holder.protect(hash_map_);
+      if (!hash_map) {
+        do_migrate(nullptr);
+        continue;
+      }
+
+      bool ok = false;
+      ValueT inserted_value;
+      hash_map->with_value(key, true, [&](auto &node_value) {
+        ValueT expected_value = this->empty_value();
+        if (node_value.compare_exchange_strong(expected_value, value, std::memory_order_release,
+                                               std::memory_order_acquire)) {
+          ok = true;
+          inserted_value = value;
+        } else {
+          if (expected_value == this->migrate_value()) {
+            ok = false;
+          } else {
+            ok = true;
+            inserted_value = expected_value;
+          }
+        }
+      });
+      if (ok) {
+        return inserted_value;
+      }
+      do_migrate(hash_map);
+    }
+  }
+  ValueT find(KeyT key, ValueT value) {
+    typename HazardPointers<HashMap>::Holder holder(hp_, get_thread_id(), 0);
+    while (true) {
+      auto hash_map = holder.protect(hash_map_);
+      if (!hash_map) {
+        do_migrate(nullptr);
+        continue;
+      }
+
+      bool has_value = hash_map->with_value(
+          key, false, [&](auto &node_value) { value = node_value.load(std::memory_order_acquire); });
+      if (!has_value || value != migrate_value()) {
+        return value;
+      }
+      do_migrate(hash_map);
+    }
+  }
+  template <class F>
+  void for_each(F &&f) {
+    auto hash_map = hash_map_.load();
+    CHECK(hash_map);
+    auto size = hash_map->size();
+    for (size_t i = 0; i < size; i++) {
+      auto &node = hash_map->node_at(i);
+      auto key = node.key.load(std::memory_order_relaxed);
+      auto value = node.value.load(std::memory_order_relaxed);
+
+      if (key != empty_key()) {
+        CHECK(value != migrate_value());
+        if (value != empty_value()) {
+          f(key, value);
+        }
+      }
+    }
+  }
+
+ private:
+  // use no padding intentionally
+  std::atomic<HashMap *> hash_map_{nullptr};
+
+  std::mutex migrate_mutex_;
+  std::condition_variable migrate_cv_;
+
+  int migrate_cnt_{0};
+  int migrate_generation_{0};
+  HashMap *migrate_from_hash_map_{nullptr};
+  HashMap *migrate_to_hash_map_{nullptr};
+  struct Task {
+    size_t begin;
+    size_t end;
+    bool empty() const {
+      return begin >= end;
+    }
+    size_t size() const {
+      if (empty()) {
+        return 0;
+      }
+      return end - begin;
+    }
+  };
+
+  struct TaskCreator {
+    size_t chunk_size;
+    size_t size;
+    std::atomic<size_t> pos{0};
+    Task create() {
+      auto i = pos++;
+      auto begin = i * chunk_size;
+      auto end = begin + chunk_size;
+      if (end > size) {
+        end = size;
+      }
+      return {begin, end};
+    }
+  };
+  TaskCreator task_creator;
+
+  void do_migrate(HashMap *ptr) {
+    //LOG(ERROR) << "do migrate: " << ptr;
+    std::unique_lock<std::mutex> lock(migrate_mutex_);
+    if (hash_map_.load() != ptr) {
+      return;
+    }
+    init_migrate();
+    CHECK(!ptr || migrate_from_hash_map_ == ptr);
+    migrate_cnt_++;
+    auto migrate_generation = migrate_generation_;
+    lock.unlock();
+
+    run_migrate();
+
+    lock.lock();
+    migrate_cnt_--;
+    if (migrate_cnt_ == 0) {
+      finish_migrate();
+    }
+    migrate_cv_.wait(lock, [&] { return migrate_generation_ != migrate_generation; });
+  }
+
+  void finish_migrate() {
+    //LOG(ERROR) << "finish_migrate";
+    hash_map_.store(migrate_to_hash_map_);
+    hp_.retire(get_thread_id(), migrate_from_hash_map_);
+    migrate_from_hash_map_ = nullptr;
+    migrate_to_hash_map_ = nullptr;
+    migrate_generation_++;
+    migrate_cv_.notify_all();
+  }
+
+  void init_migrate() {
+    if (migrate_from_hash_map_ != nullptr) {
+      return;
+    }
+    //LOG(ERROR) << "init_migrate";
+    CHECK(migrate_cnt_ == 0);
+    migrate_generation_++;
+    migrate_from_hash_map_ = hash_map_.exchange(nullptr);
+    auto new_size = migrate_from_hash_map_->size() * 2;
+    migrate_to_hash_map_ = make_unique<HashMap>(new_size).release();
+    task_creator.chunk_size = 100;
+    task_creator.size = migrate_from_hash_map_->size();
+    task_creator.pos = 0;
+  }
+
+  void run_migrate() {
+    //LOG(ERROR) << "run_migrate";
+    size_t cnt = 0;
+    while (true) {
+      auto task = task_creator.create();
+      cnt += task.size();
+      if (task.empty()) {
+        break;
+      }
+      run_task(task);
+    }
+    //LOG(ERROR) << "run_migrate " << cnt;
+  }
+
+  void run_task(Task task) {
+    for (auto i = task.begin; i < task.end; i++) {
+      auto &node = migrate_from_hash_map_->node_at(i);
+      auto old_value = node.value.exchange(migrate_value(), std::memory_order_acq_rel);
+      if (old_value == 0) {
+        continue;
+      }
+      auto node_key = node.key.load(std::memory_order_relaxed);
+      //LOG(ERROR) << node_key << " " << node_key;
+      auto ok = migrate_to_hash_map_->with_value(
+          node_key, true, [&](auto &node_value) { node_value.store(old_value, std::memory_order_relaxed); });
+      LOG_CHECK(ok) << "migration overflow";
+    }
+  }
+};
+
+template <class KeyT, class ValueT>
+td::HazardPointers<typename ConcurrentHashMap<KeyT, ValueT>::HashMap> ConcurrentHashMap<KeyT, ValueT>::hp_(64);
+}  // namespace td
diff --git a/tdutils/td/utils/EpochBasedMemoryReclamation.h b/tdutils/td/utils/EpochBasedMemoryReclamation.h
new file mode 100644
index 00000000..7c288ed5
--- /dev/null
+++ b/tdutils/td/utils/EpochBasedMemoryReclamation.h
@@ -0,0 +1,196 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/common.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/sleep.h"
+#include "td/utils/port/thread.h"
+
+namespace td {
+template <class T>
+class EpochBasedMemoryReclamation {
+ public:
+  EpochBasedMemoryReclamation(const EpochBasedMemoryReclamation &other) = delete;
+  EpochBasedMemoryReclamation &operator=(const EpochBasedMemoryReclamation &other) = delete;
+  EpochBasedMemoryReclamation(EpochBasedMemoryReclamation &&other) = delete;
+  EpochBasedMemoryReclamation &operator=(EpochBasedMemoryReclamation &&other) = delete;
+
+  class Locker {
+   public:
+    Locker(size_t thread_id, EpochBasedMemoryReclamation *ebmr) : thread_id_(thread_id), ebmr_(ebmr) {
+    }
+    Locker(const Locker &other) = delete;
+    Locker &operator=(const Locker &other) = delete;
+    Locker(Locker &&other) = default;
+    Locker &operator=(Locker &&other) = delete;
+
+    ~Locker() {
+      if (ebmr_) {
+        retire_sync();
+        unlock();
+        ebmr_.release();
+      }
+    }
+    void lock() {
+      DCHECK(ebmr_);
+      ebmr_->lock(thread_id_);
+    }
+    void unlock() {
+      DCHECK(ebmr_);
+      ebmr_->unlock(thread_id_);
+    }
+
+    void retire_sync() {
+      ebmr_->retire_sync(thread_id_);
+    }
+
+    void retire() {
+      ebmr_->retire(thread_id_);
+    }
+
+    void retire(T *ptr) {
+      ebmr_->retire(thread_id_, ptr);
+    }
+
+   private:
+    size_t thread_id_;
+    struct Never {
+      template <class S>
+      void operator()(S *) const {
+        UNREACHABLE();
+      }
+    };
+    std::unique_ptr<EpochBasedMemoryReclamation, Never> ebmr_;
+  };
+
+  explicit EpochBasedMemoryReclamation(size_t threads_n) : threads_(threads_n) {
+  }
+
+  Locker get_locker(size_t thread_id) {
+    return Locker{thread_id, this};
+  }
+
+  size_t to_delete_size_unsafe() const {
+    size_t res = 0;
+    for (auto &thread : threads_) {
+      LOG(ERROR) << "---" << thread.epoch.load() / 2;
+      for (size_t i = 0; i < MAX_BAGS; i++) {
+        res += thread.to_delete[i].size();
+        LOG(ERROR) << thread.to_delete[i].size();
+      }
+    }
+    return res;
+  }
+
+ private:
+  friend class Locker;
+  static constexpr size_t MAX_BAGS = 3;
+  struct ThreadData {
+    std::atomic<int64> epoch{1};
+    char pad[TD_CONCURRENCY_PAD - sizeof(epoch)];
+
+    size_t to_skip{0};
+    size_t checked_thread_i{0};
+    size_t bag_i{0};
+    std::vector<unique_ptr<T>> to_delete[MAX_BAGS];
+    char pad2[TD_CONCURRENCY_PAD - sizeof(to_delete)];
+
+    void rotate_bags() {
+      bag_i = (bag_i + 1) % MAX_BAGS;
+      to_delete[bag_i].clear();
+    }
+
+    void set_epoch(int64 new_epoch) {
+      //LOG(ERROR) << new_epoch;
+      if (epoch.load(std::memory_order_relaxed) / 2 != new_epoch) {
+        checked_thread_i = 0;
+        to_skip = 0;
+        rotate_bags();
+      }
+      epoch = new_epoch * 2;
+    }
+
+    void idle() {
+      epoch.store(epoch.load(std::memory_order_relaxed) | 1);
+    }
+
+    size_t undeleted() const {
+      size_t res = 0;
+      for (size_t i = 0; i < MAX_BAGS; i++) {
+        res += to_delete[i].size();
+      }
+      return res;
+    }
+  };
+  std::vector<ThreadData> threads_;
+  char pad[TD_CONCURRENCY_PAD - sizeof(threads_)];
+
+  std::atomic<int64> epoch_{1};
+  char pad2[TD_CONCURRENCY_PAD - sizeof(epoch_)];
+
+  void lock(size_t thread_id) {
+    auto &data = threads_[thread_id];
+    auto epoch = epoch_.load();
+    data.set_epoch(epoch);
+
+    if (data.to_skip == 0) {
+      data.to_skip = 30;
+      step_check(data);
+    } else {
+      data.to_skip--;
+    }
+  }
+
+  void unlock(size_t thread_id) {
+    //LOG(ERROR) << "UNLOCK";
+    auto &data = threads_[thread_id];
+    data.idle();
+  }
+
+  bool step_check(ThreadData &data) {
+    auto epoch = data.epoch.load(std::memory_order_relaxed) / 2;
+    auto checked_thread_epoch = threads_[data.checked_thread_i].epoch.load();
+    if (checked_thread_epoch % 2 == 1 || checked_thread_epoch / 2 == epoch) {
+      data.checked_thread_i++;
+      if (data.checked_thread_i == threads_.size()) {
+        if (epoch_.compare_exchange_strong(epoch, epoch + 1)) {
+          data.set_epoch(epoch + 1);
+        } else {
+          data.set_epoch(epoch);
+        }
+      }
+      return true;
+    }
+    return false;
+  }
+
+  void retire_sync(size_t thread_id) {
+    auto &data = threads_[thread_id];
+
+    while (true) {
+      retire(thread_id);
+      data.idle();
+      if (data.undeleted() == 0) {
+        break;
+      }
+      usleep_for(1000);
+    }
+  }
+
+  void retire(size_t thread_id) {
+    auto &data = threads_[thread_id];
+    data.set_epoch(epoch_.load());
+    while (step_check(data) && data.undeleted() != 0) {
+    }
+  }
+
+  void retire(size_t thread_id, T *ptr) {
+    auto &data = threads_[thread_id];
+    data.to_delete[data.bag_i].push_back(unique_ptr<T>{ptr});
+  }
+};
+}  // namespace td
diff --git a/tdutils/td/utils/Hash.h b/tdutils/td/utils/Hash.h
new file mode 100644
index 00000000..345933f5
--- /dev/null
+++ b/tdutils/td/utils/Hash.h
@@ -0,0 +1,73 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+
+#if TD_HAVE_ABSL
+#include <absl/hash/hash.h>
+#endif
+
+namespace td {
+// A simple wrapper for absl::flat_hash_map, std::unordered_map and probably some our implementaion of hash map in
+// the future
+
+// We will introduce out own Hashing utility like an absl one.
+class Hasher {
+ public:
+  Hasher() = default;
+  Hasher(size_t init_value) : hash_(init_value) {
+  }
+  std::size_t finalize() {
+    return hash_;
+  }
+
+  static Hasher combine(Hasher hasher, size_t value) {
+    hasher.hash_ ^= value;
+    return hasher;
+  }
+
+  template <class A, class B>
+  static Hasher combine(Hasher hasher, const std::pair<A, B> &value) {
+    hasher = AbslHashValue(std::move(hasher), value.first);
+    hasher = AbslHashValue(std::move(hasher), value.first);
+    return hasher;
+  }
+
+ private:
+  std::size_t hash_{0};
+};
+
+template <class IgnoreT>
+class TdHash {
+ public:
+  template <class T>
+  std::size_t operator()(const T &value) const noexcept {
+    return AbslHashValue(Hasher(), value).finalize();
+  }
+};
+
+#if TD_HAVE_ABSL
+template <class T>
+using AbslHash = absl::Hash<T>;
+#endif
+
+// default hash implementations
+template <class H, class T>
+decltype(H::combine(std::declval<H>(), std::declval<T>())) AbslHashValue(H hasher, const T &value) {
+  return H::combine(std::move(hasher), value);
+}
+
+#if TD_HAVE_ABSL
+template <class T>
+using Hash = AbslHash<T>;
+#else
+template <class T>
+using Hash = TdHash<T>;
+#endif
+
+}  // namespace td
diff --git a/tdutils/td/utils/HashMap.h b/tdutils/td/utils/HashMap.h
new file mode 100644
index 00000000..66991de3
--- /dev/null
+++ b/tdutils/td/utils/HashMap.h
@@ -0,0 +1,24 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Hash.h"
+
+#if TD_HAVE_ABSL
+#include <absl/container/flat_hash_map.h>
+#else
+#include <unordered_map>
+#endif
+namespace td {
+#if TD_HAVE_ABSL
+template <class Key, class Value, class H = Hash<Key>>
+using HashMap = absl::flat_hash_map<Key, Value, H>;
+#else
+template <class Key, class Value, class H = Hash<Key>>
+using HashMap = std::unordered_map<Key, Value, H>;
+#endif
+}  // namespace td
diff --git a/tdutils/td/utils/HashSet.h b/tdutils/td/utils/HashSet.h
new file mode 100644
index 00000000..bb0ae4c2
--- /dev/null
+++ b/tdutils/td/utils/HashSet.h
@@ -0,0 +1,24 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Hash.h"
+
+#if TD_HAVE_ABSL
+#include <absl/container/flat_hash_set.h>
+#else
+#include <unordered_set>
+#endif
+namespace td {
+#if TD_HAVE_ABSL
+template <class Key, class H = Hash<Key>>
+using HashSet = absl::flat_hash_set<Key, H>;
+#else
+template <class Key, class H = Hash<Key>>
+using HashSet = std::unordered_set<Key, H>;
+#endif
+}  // namespace td
diff --git a/tdutils/td/utils/MpmcQueue.cpp b/tdutils/td/utils/MpmcQueue.cpp
new file mode 100644
index 00000000..f6fb48e0
--- /dev/null
+++ b/tdutils/td/utils/MpmcQueue.cpp
@@ -0,0 +1,10 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/MpmcQueue.h"
+namespace td {
+detail::MpmcStat stat_;
+}
diff --git a/tdutils/td/utils/OptionsParser.cpp b/tdutils/td/utils/OptionsParser.cpp
new file mode 100644
index 00000000..f1d9a3b2
--- /dev/null
+++ b/tdutils/td/utils/OptionsParser.cpp
@@ -0,0 +1,129 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/OptionsParser.h"
+
+#if TD_HAVE_GETOPT
+#include "getopt.h"
+#endif
+
+#if !TD_WINDOWS
+#include <getopt.h>
+#include <unistd.h>
+#endif
+
+namespace td {
+void OptionsParser::set_description(std::string description) {
+  description_ = std::move(description);
+}
+
+void OptionsParser::add_option(Option::Type type, char short_key, Slice long_key, Slice description,
+                               std::function<Status(Slice)> callback) {
+  options_.push_back(Option{type, short_key, long_key.str(), description.str(), std::move(callback)});
+}
+
+void OptionsParser::add_option(char short_key, Slice long_key, Slice description,
+                               std::function<Status(Slice)> callback) {
+  add_option(Option::Type::Arg, short_key, long_key, description, std::move(callback));
+}
+
+void OptionsParser::add_option(char short_key, Slice long_key, Slice description,
+                               std::function<Status(void)> callback) {
+  // Ouch. There must be some better way
+  add_option(Option::Type::NoArg, short_key, long_key, description,
+             std::bind([](std::function<Status(void)> &func, Slice) { return func(); }, std::move(callback),
+                       std::placeholders::_1));
+}
+
+Result<int> OptionsParser::run(int argc, char *argv[]) {
+#if TD_HAVE_GETOPT
+  char buff[1024];
+  StringBuilder sb(MutableSlice{buff, sizeof(buff)});
+  for (auto &opt : options_) {
+    CHECK(opt.type != Option::OptionalArg);
+    sb << opt.short_key;
+    if (opt.type == Option::Arg) {
+      sb << ":";
+    }
+  }
+  if (sb.is_error()) {
+    return Status::Error("Can't parse options");
+  }
+  CSlice short_options = sb.as_cslice();
+
+  vector<option> long_options;
+  for (auto &opt : options_) {
+    if (opt.long_key.empty()) {
+      continue;
+    }
+    option o;
+    o.flag = nullptr;
+    o.val = opt.short_key;
+    o.has_arg = opt.type == Option::Arg ? required_argument : no_argument;
+    o.name = opt.long_key.c_str();
+    long_options.push_back(o);
+  }
+  long_options.push_back({nullptr, 0, nullptr, 0});
+
+  while (true) {
+    int opt_i = getopt_long(argc, argv, short_options.c_str(), &long_options[0], nullptr);
+    if (opt_i == ':') {
+      return Status::Error("Missing argument");
+    }
+    if (opt_i == '?') {
+      return Status::Error("Unrecognized option");
+    }
+    if (opt_i == -1) {
+      break;
+    }
+    bool found = false;
+    for (auto &opt : options_) {
+      if (opt.short_key == opt_i) {
+        Slice arg;
+        if (opt.type == Option::Arg) {
+          arg = Slice(optarg);
+        }
+        auto status = opt.arg_callback(arg);
+        if (status.is_error()) {
+          return std::move(status);
+        }
+        found = true;
+        break;
+      }
+    }
+    if (!found) {
+      return Status::Error("Unknown argument");
+    }
+  }
+  return optind;
+#else
+  return -1;
+#endif
+}
+
+StringBuilder &operator<<(StringBuilder &sb, const OptionsParser &o) {
+  sb << o.description_ << "\n";
+  for (auto &opt : o.options_) {
+    sb << "-" << opt.short_key;
+    if (!opt.long_key.empty()) {
+      sb << "|--" << opt.long_key;
+    }
+    if (opt.type == OptionsParser::Option::OptionalArg) {
+      sb << "[";
+    }
+    if (opt.type != OptionsParser::Option::NoArg) {
+      sb << "<arg>";
+    }
+    if (opt.type == OptionsParser::Option::OptionalArg) {
+      sb << "]";
+    }
+    sb << "\t" << opt.description;
+    sb << "\n";
+  }
+  return sb;
+}
+
+}  // namespace td
diff --git a/tdutils/td/utils/ThreadSafeCounter.h b/tdutils/td/utils/ThreadSafeCounter.h
new file mode 100644
index 00000000..4e4caf57
--- /dev/null
+++ b/tdutils/td/utils/ThreadSafeCounter.h
@@ -0,0 +1,47 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+#include "td/utils/port/thread.h"
+#include "td/utils/port/thread_local.h"
+#include "td/utils/int_types.h"
+
+#include <atomic>
+#include <array>
+
+namespace td {
+class ThreadSafeCounter {
+ public:
+  void add(int64 diff) {
+    auto &node = thread_local_node();
+    node.count_.store(node.count_.load(std::memory_order_relaxed) + diff, std::memory_order_relaxed);
+  }
+
+  int64 sum() const {
+    int n = max_thread_id_.load();
+    int64 res = 0;
+    for (int i = 0; i < n; i++) {
+      res += nodes_[i].count_.load();
+    }
+    return res;
+  }
+
+ private:
+  struct Node {
+    std::atomic<int64> count_{0};
+    char padding[128];
+  };
+  static constexpr int MAX_THREAD_ID = 128;
+  std::atomic<int> max_thread_id_{MAX_THREAD_ID};
+  std::array<Node, MAX_THREAD_ID> nodes_;
+
+  Node &thread_local_node() {
+    auto thread_id = get_thread_id();
+    CHECK(0 <= thread_id && static_cast<size_t>(thread_id) < nodes_.size());
+    return nodes_[thread_id];
+  }
+};
+}  // namespace td
diff --git a/tdutils/td/utils/port/IoSlice.h b/tdutils/td/utils/port/IoSlice.h
new file mode 100644
index 00000000..9e6c4775
--- /dev/null
+++ b/tdutils/td/utils/port/IoSlice.h
@@ -0,0 +1,34 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/Slice.h"
+#include "td/utils/Span.h"
+
+#if TD_PORT_POSIX
+#include <sys/uio.h>
+#endif
+
+namespace td {
+#if TD_PORT_POSIX
+using IoSlice = struct iovec;
+inline IoSlice as_io_slice(Slice slice) {
+  IoSlice res;
+  res.iov_len = slice.size();
+  res.iov_base = const_cast<char *>(slice.data());
+  return res;
+}
+inline Slice as_slice(const IoSlice io_slice) {
+  return Slice(reinterpret_cast<const char *>(io_slice.iov_base), io_slice.iov_len);
+}
+#else
+using IoSlice = Slice;
+inline IoSlice as_io_slice(Slice slice) {
+  return slice;
+}
+#endif
+}  // namespace td
diff --git a/tdutils/td/utils/port/MemoryMapping.cpp b/tdutils/td/utils/port/MemoryMapping.cpp
new file mode 100644
index 00000000..af9939bb
--- /dev/null
+++ b/tdutils/td/utils/port/MemoryMapping.cpp
@@ -0,0 +1,109 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/MemoryMapping.h"
+
+#include "td/utils/misc.h"
+
+// TODO:
+// windows,
+// anonymous map
+// huge pages?
+#if TD_WINDOWS
+#else
+#include <sys/mman.h>
+#include <unistd.h>
+#endif
+
+namespace td {
+namespace detail {
+class MemoryMappingImpl {
+ public:
+  MemoryMappingImpl(MutableSlice data, int64 offset) : data_(data), offset_(offset) {
+  }
+  Slice as_slice() const {
+    return data_.substr(narrow_cast<size_t>(offset_));
+  }
+  MutableSlice as_mutable_slice() const {
+    return {};
+  }
+
+ private:
+  MutableSlice data_;
+  int64 offset_;
+};
+
+Result<int64> get_page_size() {
+#if TD_WINDOWS
+  return Status::Error("Unimplemented");
+#else
+  static Result<int64> page_size = []() -> Result<int64> {
+    auto page_size = sysconf(_SC_PAGESIZE);
+    if (page_size < 0) {
+      return OS_ERROR("Can't load page size from sysconf");
+    }
+    return page_size;
+  }();
+  return page_size.clone();
+#endif
+}
+}  // namespace detail
+
+Result<MemoryMapping> MemoryMapping::create_anonymous(const MemoryMapping::Options &options) {
+  return Status::Error("Unsupported yet");
+}
+Result<MemoryMapping> MemoryMapping::create_from_file(const FileFd &file_fd, const MemoryMapping::Options &options) {
+#if TD_WINDOWS
+  return Status::Error("Unsupported yet");
+#else
+  if (file_fd.empty()) {
+    return Status::Error("Can't create memory mapping: file is empty");
+  }
+  TRY_RESULT(stat, file_fd.stat());
+  auto fd = file_fd.get_native_fd().fd();
+  auto begin = options.offset;
+  if (begin < 0) {
+    return Status::Error(PSLICE() << "Can't create memory mapping: negative offset " << options.offset);
+  }
+
+  int64 end;
+  if (options.size < 0) {
+    end = stat.size_;
+  } else {
+    end = begin + stat.size_;
+  }
+
+  TRY_RESULT(page_size, detail::get_page_size());
+  auto fixed_begin = begin / page_size * page_size;
+
+  auto data_offset = begin - fixed_begin;
+  auto data_size = end - fixed_begin;
+
+  void *data = mmap(nullptr, data_size, PROT_READ, MAP_PRIVATE, fd, fixed_begin);
+  if (data == MAP_FAILED) {
+    return OS_ERROR("mmap call failed");
+  }
+
+  return MemoryMapping(std::make_unique<detail::MemoryMappingImpl>(
+      MutableSlice(reinterpret_cast<char *>(data), data_size), data_offset));
+#endif
+}
+
+MemoryMapping::MemoryMapping(MemoryMapping &&other) = default;
+MemoryMapping &MemoryMapping::operator=(MemoryMapping &&other) = default;
+MemoryMapping::~MemoryMapping() = default;
+
+MemoryMapping::MemoryMapping(std::unique_ptr<detail::MemoryMappingImpl> impl) : impl_(std::move(impl)) {
+}
+Slice MemoryMapping::as_slice() const {
+  return impl_->as_slice();
+}
+MutableSlice MemoryMapping::as_mutable_slice() {
+  return impl_->as_mutable_slice();
+}
+
+}  // namespace td
+
diff --git a/tdutils/td/utils/port/MemoryMapping.h b/tdutils/td/utils/port/MemoryMapping.h
new file mode 100644
index 00000000..9e462c73
--- /dev/null
+++ b/tdutils/td/utils/port/MemoryMapping.h
@@ -0,0 +1,53 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/port/FileFd.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Status.h"
+
+namespace td {
+namespace detail {
+class MemoryMappingImpl;
+}
+
+class MemoryMapping {
+ public:
+  struct Options {
+    int64 offset{0};
+    int64 size{-1};
+
+    Options() {
+    }
+    Options &with_offset(int64 new_offset) {
+      offset = new_offset;
+      return *this;
+    }
+    Options &with_size(int64 new_size) {
+      size = new_size;
+      return *this;
+    }
+  };
+
+  static Result<MemoryMapping> create_anonymous(const Options &options = {});
+  static Result<MemoryMapping> create_from_file(const FileFd &file, const Options &options = {});
+
+  Slice as_slice() const;
+  MutableSlice as_mutable_slice();  // returns empty slice if memory is read-only
+
+  MemoryMapping(const MemoryMapping &other) = delete;
+  const MemoryMapping &operator=(const MemoryMapping &other) = delete;
+  MemoryMapping(MemoryMapping &&other);
+  MemoryMapping &operator=(MemoryMapping &&other);
+  ~MemoryMapping();
+
+ private:
+  std::unique_ptr<detail::MemoryMappingImpl> impl_;
+  explicit MemoryMapping(std::unique_ptr<detail::MemoryMappingImpl> impl);
+};
+}  // namespace td
diff --git a/tdutils/td/utils/port/stacktrace.cpp b/tdutils/td/utils/port/stacktrace.cpp
new file mode 100644
index 00000000..331d6197
--- /dev/null
+++ b/tdutils/td/utils/port/stacktrace.cpp
@@ -0,0 +1,105 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/port/stacktrace.h"
+#include "td/utils/port/signals.h"
+
+#if !TD_WINDOWS && !TD_ANDROID && !TD_FREEBSD
+#include <execinfo.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#if TD_LINUX
+#include <sys/prctl.h>
+#endif
+
+#endif
+
+namespace td {
+namespace {
+void print_backtrace(void) {
+#if !TD_WINDOWS && !TD_ANDROID && !TD_FREEBSD
+  void *buffer[128];
+  int nptrs = backtrace(buffer, 128);
+  td::signal_safe_write("------- Stack Backtrace -------\n", false);
+  backtrace_symbols_fd(buffer, nptrs, 2);
+  td::signal_safe_write("-------------------------------\n", false);
+#endif
+}
+void print_backtrace_gdb(void) {
+#if !TD_WINDOWS && !TD_DARWIN && !TD_ANDROID
+  char pid_buf[30], *pid_buf_begin = pid_buf + sizeof(pid_buf);
+  pid_t pid = getpid();
+  *--pid_buf_begin = '\0';
+  do {
+    *--pid_buf_begin = static_cast<char>(pid % 10 + '0');
+    pid /= 10;
+  } while (pid > 0);
+
+  char name_buf[512];
+  ssize_t res = readlink("/proc/self/exe", name_buf, 511);  // TODO works only under Linux
+  if (res >= 0) {
+    name_buf[res] = 0;
+
+#if TD_LINUX
+    if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) < 0) {
+      td::signal_safe_write("Can't set dumpable\n");
+      return;
+    }
+#if defined(PR_SET_PTRACER)
+    // We can't use td::EventFd because we are in a signal handler
+    int fds[2];
+    bool need_set_ptracer = true;
+    if (pipe(fds) < 0) {
+      need_set_ptracer = false;
+      td::signal_safe_write("Can't create a pipe\n");
+    }
+#endif
+#endif
+
+    int child_pid = fork();
+    if (child_pid < 0) {
+      td::signal_safe_write("Can't fork() to run gdb\n");
+      return;
+    }
+    if (!child_pid) {
+#if TD_LINUX && defined(PR_SET_PTRACER)
+      if (need_set_ptracer) {
+        char c;
+        read(fds[0], &c, 1);
+      }
+#endif
+      dup2(2, 1);  // redirect output to stderr
+      execlp("gdb", "gdb", "--batch", "-n", "-ex", "thread", "-ex", "thread apply all bt full", name_buf, pid_buf_begin,
+             NULL);
+      return;
+    } else {
+#if TD_LINUX && defined(PR_SET_PTRACER)
+      if (need_set_ptracer) {
+        if (prctl(PR_SET_PTRACER, child_pid, 0, 0, 0) < 0) {
+          td::signal_safe_write("Can't set ptracer\n");
+        }
+        if (write(fds[1], "a", 1) != 1) {
+          td::signal_safe_write("Can't write to pipe\n");
+        }
+      }
+#endif
+      waitpid(child_pid, nullptr, 0);
+    }
+  } else {
+    td::signal_safe_write("Can't get name of executable file to pass to gdb\n");
+  }
+#endif
+}
+}  // namespace
+
+void Stacktrace::print_to_stderr(const PrintOptions &options) {
+  if (options.use_gdb) {
+    print_backtrace_gdb();
+  }
+  print_backtrace();
+}
+}  // namespace td
diff --git a/tdutils/td/utils/port/stacktrace.h b/tdutils/td/utils/port/stacktrace.h
new file mode 100644
index 00000000..2f978514
--- /dev/null
+++ b/tdutils/td/utils/port/stacktrace.h
@@ -0,0 +1,19 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+namespace td {
+class Stacktrace {
+ public:
+  struct PrintOptions {
+    bool use_gdb = false;
+    PrintOptions() {
+    }
+  };
+  static void print_to_stderr(const PrintOptions &options = PrintOptions());
+};
+
+}  // namespace td
diff --git a/tdutils/td/utils/uint128.h b/tdutils/td/utils/uint128.h
new file mode 100644
index 00000000..03a79ccf
--- /dev/null
+++ b/tdutils/td/utils/uint128.h
@@ -0,0 +1,270 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/bits.h"
+namespace td {
+
+class uint128_emulated {
+ public:
+  using uint128 = uint128_emulated;
+  uint128_emulated(uint64 hi, uint64 lo) : hi_(hi), lo_(lo) {
+  }
+  uint128_emulated(uint64 lo) : uint128_emulated(0, lo) {
+  }
+  uint128_emulated() = default;
+  uint64 hi() const {
+    return hi_;
+  }
+  uint64 lo() const {
+    return lo_;
+  }
+  static uint128 from_signed(int64 x) {
+    if (x >= 0) {
+      return uint128(0, x);
+    }
+    return uint128(std::numeric_limits<uint64>::max(), static_cast<uint64>(x));
+  }
+
+  uint128 add(uint128 other) const {
+    uint128 res(other.hi() + hi(), other.lo() + lo());
+    if (res.lo() < lo()) {
+      res.hi_++;
+    }
+    return res;
+  }
+
+  uint128 shl(int cnt) const {
+    if (cnt >= 128) {
+      return uint128();
+    }
+    if (cnt == 0) {
+      return *this;
+    }
+    if (cnt < 64) {
+      return uint128((hi() << cnt) | (lo() >> (64 - cnt)), lo() << cnt);
+    }
+    return uint128(lo() << (cnt - 64), 0);
+  }
+  uint128 shr(int cnt) const {
+    if (cnt >= 128) {
+      return uint128();
+    }
+    if (cnt == 0) {
+      return *this;
+    }
+    if (cnt < 64) {
+      return uint128(hi() >> cnt, (lo() >> cnt) | (hi() << (64 - cnt)));
+    }
+    return uint128(0, hi() >> (cnt - 64));
+  }
+
+  uint128 mult(uint128 other) const {
+    uint64 a_lo = lo() & 0xffffffff;
+    uint64 a_hi = lo() >> 32;
+    uint64 b_lo = other.lo() & 0xffffffff;
+    uint64 b_hi = other.lo() >> 32;
+    uint128 res(lo() * other.hi() + hi() * other.lo() + a_hi * b_hi, a_lo * b_lo);
+    uint128 add1(0, a_lo * b_hi);
+    uint128 add2(0, a_hi * b_lo);
+    return res.add(add1.shl(32)).add(add2.shl(32));
+  }
+  uint128 mult(uint64 other) const {
+    return mult(uint128(0, other));
+  }
+  uint128 mult_signed(int64 other) const {
+    return mult(uint128::from_signed(other));
+  }
+  bool is_zero() const {
+    return lo() == 0 && hi() == 0;
+  }
+  uint128 sub(uint128 other) const {
+    uint32 carry = 0;
+    if (other.lo() > lo()) {
+      carry = 1;
+    }
+    return uint128(hi() - other.hi() - carry, lo() - other.lo());
+  }
+  void divmod(uint128 other, uint128 *div_res, uint128 *mod_res) const {
+    CHECK(!other.is_zero());
+
+    auto from = *this;
+    auto ctz = from.count_leading_zeroes();
+    auto other_ctz = other.count_leading_zeroes();
+    if (ctz > other_ctz) {
+      *div_res = uint128();
+      *mod_res = from;
+      return;
+    }
+    auto shift = other_ctz - ctz;
+    auto res = uint128();
+    for (int i = shift; i >= 0; i--) {
+      auto sub = other.shl(i);
+      res = res.shl(1);
+      if (from.greater_or_equal(sub)) {
+        from = from.sub(sub);
+        res = res.set_lower_bit();
+      }
+    }
+
+    *div_res = res;
+    *mod_res = from;
+  }
+  uint128 div(uint128 other) const {
+    uint128 a, b;
+    divmod(other, &a, &b);
+    return a;
+  }
+  uint128 mod(uint128 other) const {
+    uint128 a, b;
+    divmod(other, &a, &b);
+    return b;
+  }
+
+  void divmod_signed(int64 y, int64 *quot, int64 *rem) const {
+    CHECK(y != 0);
+    auto x = *this;
+    int x_sgn = x.is_negative();
+    int y_sgn = y < 0;
+    if (x_sgn) {
+      x = x.negate();
+    }
+    uint128 uy = from_signed(y);
+    if (uy.is_negative()) {
+      uy = uy.negate();
+    }
+
+    uint128 t_quot, t_mod;
+    x.divmod(uy, &t_quot, &t_mod);
+    *quot = t_quot.lo();
+    *rem = t_mod.lo();
+    if (x_sgn != y_sgn) {
+      *quot = -*quot;
+    }
+    if (x_sgn) {
+      *rem = -*rem;
+    }
+  }
+
+ private:
+  uint64 hi_{0};
+  uint64 lo_{0};
+
+  bool is_negative() const {
+    return static_cast<int64>(hi_) < 0;
+  }
+
+  int32 count_leading_zeroes() const {
+    if (hi() == 0) {
+      return 64 + count_leading_zeroes64(lo());
+    }
+    return count_leading_zeroes64(hi());
+  }
+  uint128 set_lower_bit() const {
+    return uint128(hi(), lo() | 1);
+  }
+  bool greater_or_equal(uint128 other) const {
+    return hi() > other.hi() || (hi() == other.hi() && lo() >= other.lo());
+  }
+  uint128 negate() const {
+    uint128 res(~hi(), ~lo() + 1);
+    if (res.lo() == 0) {
+      return uint128(res.hi() + 1, 0);
+    }
+    return res;
+  }
+};
+#if TD_HAVE_INT128
+class uint128_intrinsic {
+ public:
+  using ValueT = unsigned __int128;
+  using uint128 = uint128_intrinsic;
+  explicit uint128_intrinsic(ValueT value) : value_(value) {
+  }
+  uint128_intrinsic(uint64 hi, uint64 lo) : value_((ValueT(hi) << 64) | lo) {
+  }
+  uint128_intrinsic() = default;
+
+  static uint128 from_signed(int64 x) {
+    return uint128(static_cast<ValueT>(x));
+  }
+  uint64 hi() const {
+    return uint64(value() >> 64);
+  }
+  uint64 lo() const {
+    return uint64(value() & std::numeric_limits<uint64>::max());
+  }
+
+  uint128 add(uint128 other) const {
+    return uint128(value() + other.value());
+  }
+  uint128 sub(uint128 other) const {
+    return uint128(value() - other.value());
+  }
+
+  uint128 shl(int cnt) const {
+    if (cnt >= 128) {
+      return uint128();
+    }
+    return uint128(value() << cnt);
+  }
+
+  uint128 shr(int cnt) const {
+    if (cnt >= 128) {
+      return uint128();
+    }
+    return uint128(value() >> cnt);
+  }
+
+  uint128 mult(uint128 other) const {
+    return uint128(value() * other.value());
+  }
+  uint128 mult(uint64 other) const {
+    return uint128(value() * other);
+  }
+  uint128 mult_signed(int64 other) const {
+    return uint128(value() * other);
+  }
+  bool is_zero() const {
+    return value() == 0;
+  }
+  void divmod(uint128 other, uint128 *div_res, uint128 *mod_res) const {
+    CHECK(!other.is_zero());
+    *div_res = uint128(value() / other.value());
+    *mod_res = uint128(value() % other.value());
+  }
+  uint128 div(uint128 other) const {
+    CHECK(!other.is_zero());
+    return uint128(value() / other.value());
+  }
+  uint128 mod(uint128 other) const {
+    CHECK(!other.is_zero());
+    return uint128(value() % other.value());
+  }
+  void divmod_signed(int64 y, int64 *quot, int64 *rem) const {
+    CHECK(y != 0);
+    *quot = (int64)(signed_value() / y);
+    *rem = (int64)(signed_value() % y);
+  }
+
+ private:
+  unsigned __int128 value_{0};
+  ValueT value() const {
+    return value_;
+  }
+  __int128 signed_value() const {
+    return static_cast<__int128>(value());
+  }
+};
+#endif
+#if TD_HAVE_INT128
+using uint128 = uint128_intrinsic;
+#else
+using uint128 = uint128_emulated;
+#endif
+}  // namespace td
diff --git a/tdutils/test/ConcurrentHashMap.cpp b/tdutils/test/ConcurrentHashMap.cpp
new file mode 100644
index 00000000..3d72472f
--- /dev/null
+++ b/tdutils/test/ConcurrentHashMap.cpp
@@ -0,0 +1,242 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <cstdio>
+#include "td/utils/tests.h"
+#include "td/utils/benchmark.h"
+#include "td/utils/SpinLock.h"
+#include "td/utils/HazardPointers.h"
+#include "td/utils/ConcurrentHashTable.h"
+#include <algorithm>
+
+#if TD_HAVE_ABSL
+#include <absl/container/flat_hash_map.h>
+#else
+#include <unordered_map>
+#endif
+
+#if TD_WITH_JUNCTION
+#include <third-party/libcuckoo/libcuckoo/cuckoohash_map.hh>
+#endif
+
+#if TD_WITH_JUNCTION
+#include <junction/ConcurrentMap_Grampa.h>
+#include <junction/ConcurrentMap_Linear.h>
+#include <junction/ConcurrentMap_Leapfrog.h>
+#endif
+namespace td {
+
+// Non resizable HashMap. Just an example
+template <class KeyT, class ValueT>
+class ArrayHashMap {
+ public:
+  ArrayHashMap(size_t n) : array_(n) {
+  }
+  struct Node {
+    std::atomic<KeyT> key{KeyT{}};
+    std::atomic<ValueT> value{};
+  };
+  static std::string get_name() {
+    return "ArrayHashMap";
+  }
+  KeyT empty_key() const {
+    return KeyT{};
+  }
+
+  void insert(KeyT key, ValueT value) {
+    array_.with_value(key, true, [&](auto &node_value) { node_value.store(value, std::memory_order_release); });
+  }
+  ValueT find(KeyT key, ValueT value) {
+    array_.with_value(key, false, [&](auto &node_value) { value = node_value.load(std::memory_order_acquire); });
+    return value;
+  }
+
+ private:
+  AtomicHashArray<KeyT, std::atomic<ValueT>> array_;
+};
+
+template <class KeyT, class ValueT>
+class ConcurrentHashMapMutex {
+ public:
+  ConcurrentHashMapMutex(size_t) {
+  }
+  static std::string get_name() {
+    return "ConcurrentHashMapMutex";
+  }
+  void insert(KeyT key, ValueT value) {
+    std::unique_lock<std::mutex> lock(mutex_);
+    hash_map_.emplace(key, value);
+  }
+  ValueT find(KeyT key, ValueT default_value) {
+    std::unique_lock<std::mutex> lock(mutex_);
+    auto it = hash_map_.find(key);
+    if (it == hash_map_.end()) {
+      return default_value;
+    }
+    return it->second;
+  }
+
+ private:
+  std::mutex mutex_;
+#if TD_HAVE_ABSL
+  absl::flat_hash_map<KeyT, ValueT> hash_map_;
+#else
+  std::unordered_map<KeyT, ValueT> hash_map_;
+#endif
+};
+template <class KeyT, class ValueT>
+class ConcurrentHashMapSpinlock {
+ public:
+  ConcurrentHashMapSpinlock(size_t) {
+  }
+  static std::string get_name() {
+    return "ConcurrentHashMapSpinlock";
+  }
+  void insert(KeyT key, ValueT value) {
+    auto guard = spinlock_.lock();
+    hash_map_.emplace(key, value);
+  }
+  ValueT find(KeyT key, ValueT default_value) {
+    auto guard = spinlock_.lock();
+    auto it = hash_map_.find(key);
+    if (it == hash_map_.end()) {
+      return default_value;
+    }
+    return it->second;
+  }
+
+ private:
+  td::SpinLock spinlock_;
+#if TD_HAVE_ABSL
+  absl::flat_hash_map<KeyT, ValueT> hash_map_;
+#else
+  std::unordered_map<KeyT, ValueT> hash_map_;
+#endif
+};
+#if TD_WITH_LIBCUCKOO
+template <class KeyT, class ValueT>
+class ConcurrentHashMapLibcuckoo {
+ public:
+  ConcurrentHashMapLibcuckoo(size_t) {
+  }
+  static std::string get_name() {
+    return "ConcurrentHashMapLibcuckoo";
+  }
+  void insert(KeyT key, ValueT value) {
+    hash_map_.insert(key, value);
+  }
+  ValueT find(KeyT key, ValueT default_value) {
+    hash_map_.find(key, default_value);
+    return default_value;
+  }
+
+ private:
+  cuckoohash_map<KeyT, ValueT> hash_map_;
+};
+#endif
+#if TD_WITH_JUNCTION
+template <class KeyT, class ValueT>
+class ConcurrentHashMapJunction {
+ public:
+  ConcurrentHashMapJunction(size_t size) : hash_map_() {
+  }
+  static std::string get_name() {
+    return "ConcurrentHashMapJunction";
+  }
+  void insert(KeyT key, ValueT value) {
+    hash_map_.assign(key, value);
+  }
+  ValueT find(KeyT key, ValueT default_value) {
+    return hash_map_.get(key);
+  }
+  ~ConcurrentHashMapJunction() {
+    junction::DefaultQSBR.flush();
+  }
+
+ private:
+  junction::ConcurrentMap_Leapfrog<KeyT, ValueT> hash_map_;
+};
+#endif
+}  // namespace td
+
+template <class HashMap>
+class HashMapBenchmark : public td::Benchmark {
+  struct Query {
+    int key;
+    int value;
+  };
+  std::vector<Query> queries;
+  std::unique_ptr<HashMap> hash_map;
+
+  size_t threads_n = 16;
+  int mod_;
+  constexpr static size_t mul_ = 7273;  //1000000000 + 7;
+  int n_;
+
+ public:
+  HashMapBenchmark(size_t threads_n) : threads_n(threads_n) {
+  }
+  std::string get_description() const override {
+    return hash_map->get_name();
+  }
+  void start_up_n(int n) override {
+    n *= (int)threads_n;
+    n_ = n;
+    hash_map = std::make_unique<HashMap>(n * 2);
+  }
+
+  void run(int n) override {
+    n = n_;
+    std::vector<td::thread> threads;
+
+    for (size_t i = 0; i < threads_n; i++) {
+      size_t l = n * i / threads_n;
+      size_t r = n * (i + 1) / threads_n;
+      threads.emplace_back([l, r, this] {
+        for (size_t i = l; i < r; i++) {
+          auto x = int((i + 1) * mul_ % n_) + 3;
+          auto y = int(i + 2);
+          hash_map->insert(x, y);
+        }
+      });
+    }
+    for (auto &thread : threads) {
+      thread.join();
+    }
+  }
+
+  void tear_down() override {
+    for (int i = 0; i < n_; i++) {
+      auto x = int((i + 1) * mul_ % n_) + 3;
+      auto y = int(i + 2);
+      ASSERT_EQ(y, hash_map->find(x, -1));
+    }
+    queries.clear();
+    hash_map.reset();
+  }
+
+ private:
+};
+
+template <class HashMap>
+void bench_hash_map() {
+  td::bench(HashMapBenchmark<HashMap>(16));
+  td::bench(HashMapBenchmark<HashMap>(1));
+}
+
+TEST(ConcurrentHashMap, Benchmark) {
+  bench_hash_map<td::ConcurrentHashMap<int, int>>();
+  bench_hash_map<td::ArrayHashMap<int, int>>();
+  bench_hash_map<td::ConcurrentHashMapSpinlock<int, int>>();
+  bench_hash_map<td::ConcurrentHashMapMutex<int, int>>();
+#if TD_WITH_LIBCUCKOO
+  bench_hash_map<td::ConcurrentHashMapLibcuckoo<int, int>>();
+#endif
+#if TD_WITH_JUNCTION
+  bench_hash_map<td::ConcurrentHashMapJunction<int, int>>();
+#endif
+}
+
diff --git a/tdutils/test/EpochBasedMemoryReclamation.cpp b/tdutils/test/EpochBasedMemoryReclamation.cpp
new file mode 100644
index 00000000..de409d97
--- /dev/null
+++ b/tdutils/test/EpochBasedMemoryReclamation.cpp
@@ -0,0 +1,67 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2019
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#include "td/utils/EpochBasedMemoryReclamation.h"
+#include "td/utils/logging.h"
+#include "td/utils/port/thread.h"
+#include "td/utils/Random.h"
+#include "td/utils/tests.h"
+
+#include <atomic>
+
+#if !TD_THREAD_UNSUPPORTED
+TEST(EpochBaseMemoryReclamation, stress) {
+  struct Node {
+    std::atomic<std::string *> name_;
+    char pad[64];
+  };
+
+  int threads_n = 10;
+  std::vector<Node> nodes(threads_n);
+  td::EpochBasedMemoryReclamation<std::string> ebmr(threads_n + 1);
+  auto locker = ebmr.get_locker(threads_n);
+  locker.lock();
+  locker.unlock();
+  std::vector<td::thread> threads(threads_n);
+  int thread_id = 0;
+  for (auto &thread : threads) {
+    thread = td::thread([&, thread_id] {
+      auto locker = ebmr.get_locker(thread_id);
+      locker.lock();
+      for (int i = 0; i < 1000000; i++) {
+        auto &node = nodes[td::Random::fast(0, threads_n - 1)];
+        auto *str = node.name_.load(std::memory_order_acquire);
+        if (str) {
+          CHECK(*str == "one" || *str == "twotwo");
+        }
+        if ((i + 1) % 100 == 0) {
+          locker.retire();
+        }
+        if (td::Random::fast(0, 5) == 0) {
+          std::string *new_str = new std::string(td::Random::fast(0, 1) == 0 ? "one" : "twotwo");
+          if (node.name_.compare_exchange_strong(str, new_str, std::memory_order_acq_rel)) {
+            locker.retire(str);
+          } else {
+            delete new_str;
+          }
+        }
+      }
+      locker.retire_sync();
+      locker.unlock();
+    });
+    thread_id++;
+  }
+  for (auto &thread : threads) {
+    thread.join();
+  }
+  LOG(ERROR) << "Undeleted pointers: " << ebmr.to_delete_size_unsafe();
+  //CHECK(static_cast<int>(ebmr.to_delete_size_unsafe()) <= threads_n * threads_n);
+  for (int i = 0; i < threads_n; i++) {
+    ebmr.get_locker(i).retire_sync();
+  }
+  CHECK(ebmr.to_delete_size_unsafe() == 0);
+}
+#endif  //!TD_THREAD_UNSUPPORTED