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tdutils/td/utils/CancellationToken.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 <atomic>
+#include <memory>
+
+namespace td {
+
+namespace detail {
+struct RawCancellationToken {
+  std::atomic<bool> is_cancelled_{false};
+};
+}  // namespace detail
+
+class CancellationToken {
+ public:
+  explicit operator bool() const {
+    return token_->is_cancelled_.load(std::memory_order_acquire);
+  }
+  explicit CancellationToken(std::shared_ptr<detail::RawCancellationToken> token) : token_(std::move(token)) {
+  }
+
+ private:
+  std::shared_ptr<detail::RawCancellationToken> token_;
+};
+
+class CancellationTokenSource {
+ public:
+  CancellationTokenSource() = default;
+  CancellationTokenSource(CancellationTokenSource &&other) : token_(std::move(other.token_)) {
+  }
+  CancellationTokenSource &operator=(CancellationTokenSource &&other) {
+    cancel();
+    token_ = std::move(other.token_);
+    return *this;
+  }
+  CancellationTokenSource(const CancellationTokenSource &other) = delete;
+  CancellationTokenSource &operator=(const CancellationTokenSource &other) = delete;
+  ~CancellationTokenSource() {
+    cancel();
+  }
+
+  CancellationToken get_cancellation_token() {
+    if (!token_) {
+      token_ = std::make_shared<detail::RawCancellationToken>();
+    }
+    return CancellationToken(token_);
+  }
+  void cancel() {
+    if (!token_) {
+      return;
+    }
+    token_->is_cancelled_.store(true, std::memory_order_release);
+    token_.reset();
+  }
+
+ private:
+  std::shared_ptr<detail::RawCancellationToken> token_;
+};
+
+}  // namespace td