// Copyright (c), ETH Zurich and UNC Chapel Hill.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//
//     * Neither the name of ETH Zurich and UNC Chapel Hill nor the names of
//       its contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

#pragma once

#include <atomic>
#include <csignal>

namespace colmap {

// Thread-safe cancellation state for cooperative cancellation of long-running
// operations. Cancellation tokens are single-use and remain cancelled once a
// cancellation request has been made.
class CancellationToken {
 public:
  void Cancel();
  bool IsCancelled() const;

 private:
  std::atomic<bool> is_cancelled_{false};
};

// Scoped handler for process interruption signals. The handler only records
// the first signal so that normal code can perform cleanup at a safe point. A
// second signal terminates the process immediately.
class ScopedSignalHandler {
 public:
  ScopedSignalHandler();
  ~ScopedSignalHandler();

  ScopedSignalHandler(const ScopedSignalHandler&) = delete;
  ScopedSignalHandler& operator=(const ScopedSignalHandler&) = delete;

  int ReceivedSignal() const;
  int GetExitCode() const;

  static bool IsInterruptRequested();

 private:
  using SignalHandler = void (*)(int);

  SignalHandler previous_sigint_handler_ = SIG_DFL;
  SignalHandler previous_sigterm_handler_ = SIG_DFL;
};

}  // namespace colmap
