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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2026
//
// 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 <atomic>
#include <memory>
namespace td {
namespace detail {
struct RawCancellationToken {
std::atomic<bool> is_canceled_{false};
};
} // namespace detail
class CancellationToken {
public:
explicit operator bool() const noexcept {
// empty CancellationToken is never canceled
if (!token_) {
return false;
}
return token_->is_canceled_.load(std::memory_order_acquire);
}
CancellationToken() = default;
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) noexcept : token_(std::move(other.token_)) {
}
CancellationTokenSource &operator=(CancellationTokenSource &&other) noexcept {
cancel();
token_ = std::move(other.token_);
return *this;
}
CancellationTokenSource(const CancellationTokenSource &) = delete;
CancellationTokenSource &operator=(const CancellationTokenSource &) = 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_canceled_.store(true, std::memory_order_release);
token_.reset();
}
private:
std::shared_ptr<detail::RawCancellationToken> token_;
};
} // namespace td
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