//===-- SelectHelper.h ------------------------------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#ifndef LLDB_UTILITY_SELECTHELPER_H

#define LLDB_UTILITY_SELECTHELPER_H

#include "lldb/Utility/Status.h"

#include "lldb/lldb-types.h"

#include "llvm/ADT/DenseMap.h"

#include <chrono>

#include <optional>

class SelectHelper {

public:

  // Defaults to infinite wait for select unless you call SetTimeout()

  SelectHelper();

  // Call SetTimeout() before calling SelectHelper::Select() to set the timeout

  // based on the current time + the timeout. This allows multiple calls to

  // SelectHelper::Select() without having to worry about the absolute timeout

  // as this class manages to set the relative timeout correctly.

  void SetTimeout(const std::chrono::microseconds &timeout);

  // Call the FDSet*() functions before calling SelectHelper::Select() to set

  // the file descriptors that we will watch for when calling select. This will

  // cause FD_SET() to be called prior to calling select using the "fd"

  // provided.

  void FDSetRead(lldb::socket_t fd);

  void FDSetWrite(lldb::socket_t fd);

  void FDSetError(lldb::socket_t fd);

  // Call the FDIsSet*() functions after calling SelectHelper::Select() to

  // check which file descriptors are ready for read/write/error. This will

  // contain the result of FD_ISSET after calling select for a given file

  // descriptor.

  bool FDIsSetRead(lldb::socket_t fd) const;

  bool FDIsSetWrite(lldb::socket_t fd) const;

  bool FDIsSetError(lldb::socket_t fd) const;

  // Call the system's select() to wait for descriptors using timeout provided

  // in a call the SelectHelper::SetTimeout(), or infinite wait if no timeout

  // was set.

  lldb_private::Status Select();

protected:

  struct FDInfo {

    FDInfo()

        : read_set(false), write_set(false), error_set(false),

          read_is_set(false), write_is_set(false), error_is_set(false) {}

    void PrepareForSelect() {

      read_is_set = false;

      write_is_set = false;

      error_is_set = false;

    }

    bool read_set : 1, write_set : 1, error_set : 1, read_is_set : 1,

        write_is_set : 1, error_is_set : 1;

  };

  llvm::DenseMap<lldb::socket_t, FDInfo> m_fd_map;

  std::optional<std::chrono::steady_clock::time_point> m_end_time;

};

#endif // LLDB_UTILITY_SELECTHELPER_H