child_process.hpp

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#pragma once
 
/// @file userver/engine/subprocess/child_process.hpp
/// @brief @copybrief engine::subprocess::ChildProcess
 
#include <chrono>
#include <memory>
 
#include <userver/compiler/select.hpp>
#include <userver/engine/deadline.hpp>
#include <userver/engine/subprocess/child_process_status.hpp>
#include <userver/utils/fast_pimpl.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace engine::subprocess {
 
class ChildProcessImpl;
 
class ChildProcess final {
 public:
  /// @cond
  explicit ChildProcess(ChildProcessImpl&& impl) noexcept;
  /// @endcond
 
  ChildProcess(ChildProcess&&) noexcept;
  ChildProcess& operator=(ChildProcess&&) noexcept;
 
  /// Does not terminate the child process (just detaches from it).
  ~ChildProcess();
 
  /// Returns pid of the child process.
  int GetPid() const;
 
  /// Wait for the child process to terminate.
  /// Ignores cancellations of the current task.
  void Wait();
 
  /// Wait for the child process to terminate.
  /// Returns if this did not happen for the specified timeout duration.
  template <typename Rep, typename Period>
  [[nodiscard]] bool WaitFor(std::chrono::duration<Rep, Period> duration) {
    return WaitUntil(Deadline::FromDuration(duration));
  }
 
  /// Wait for the child process to terminate.
  /// Returns if this did not happen until the specified time point has been
  /// reached.
  template <typename Clock, typename Duration>
  [[nodiscard]] bool WaitUntil(std::chrono::time_point<Clock, Duration> until) {
    return WaitUntil(Deadline::FromTimePoint(until));
  }
 
  /// Wait for the child process to terminate.
  /// Returns if this did not happen until the specified Deadline has been
  /// reached.
  [[nodiscard]] bool WaitUntil(Deadline deadline);
 
  /// Wait for the child process to terminate.
  /// Returns `ChildProcessStatus` of finished subprocess.
  [[nodiscard]] ChildProcessStatus Get();
 
  /// Send a signal to the child process.
  void SendSignal(int signum);
 
 private:
  static constexpr std::size_t kImplSize =
      compiler::SelectSize().For64Bit(24).For32Bit(12);
  static constexpr std::size_t kImplAlignment = alignof(void*);
  utils::FastPimpl<ChildProcessImpl, kImplSize, kImplAlignment> impl_;
};
 
}  // namespace engine::subprocess
 
USERVER_NAMESPACE_END