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tdutils/td/utils/ThreadLocalStorage.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#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 {
+template <class T>
+class ThreadLocalStorage {
+ public:
+  T& get() {
+    return thread_local_node().value;
+  }
+
+  template <class F>
+  void for_each(F&& f) {
+    int n = max_thread_id_.load();
+    for (int i = 0; i < n; i++) {
+      f(nodes_[i].value);
+    }
+  }
+  template <class F>
+  void for_each(F&& f) const {
+    int n = max_thread_id_.load();
+    for (int i = 0; i < n; i++) {
+      f(nodes_[i].value);
+    }
+  }
+
+ private:
+  struct Node {
+    T value{};
+    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