//===-- MainLoopPosix.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_HOST_POSIX_MAINLOOPPOSIX_H

#define LLDB_HOST_POSIX_MAINLOOPPOSIX_H

#include "lldb/Host/Config.h"

#include "lldb/Host/MainLoopBase.h"

#include "lldb/Host/Pipe.h"

#include "llvm/ADT/DenseMap.h"

#include <atomic>

#include <csignal>

#include <list>

#include <vector>

namespace lldb_private {

// Implementation of the MainLoopBase class. It can monitor file descriptors for

// readability using ppoll, kqueue, or pselect. In addition to the common base,

// this class provides the ability to invoke a given handler when a signal is

// received.

class MainLoopPosix : public MainLoopBase {

private:

  class SignalHandle;

public:

  typedef std::unique_ptr<SignalHandle> SignalHandleUP;

  MainLoopPosix();

  ~MainLoopPosix() override;

  ReadHandleUP RegisterReadObject(const lldb::IOObjectSP &object_sp,

                                  const Callback &callback,

                                  Status &error) override;

  // Listening for signals from multiple MainLoop instances is perfectly safe

  // as long as they don't try to listen for the same signal. The callback

  // function is invoked when the control returns to the Run() function, not

  // when the hander is executed. This mean that you can treat the callback as

  // a normal function and perform things which would not be safe in a signal

  // handler. However, since the callback is not invoked synchronously, you

  // cannot use this mechanism to handle SIGSEGV and the like.

  SignalHandleUP RegisterSignal(int signo, const Callback &callback,

                                Status &error);

  Status Run() override;

protected:

  void UnregisterReadObject(IOObject::WaitableHandle handle) override;

  void UnregisterSignal(int signo, std::list<Callback>::iterator callback_it);

  void TriggerPendingCallbacks() override;

private:

  void ProcessReadObject(IOObject::WaitableHandle handle);

  void ProcessSignal(int signo);

  class SignalHandle {

  public:

    ~SignalHandle() { m_mainloop.UnregisterSignal(m_signo, m_callback_it); }

  private:

    SignalHandle(MainLoopPosix &mainloop, int signo,

                 std::list<Callback>::iterator callback_it)

        : m_mainloop(mainloop), m_signo(signo), m_callback_it(callback_it) {}

    MainLoopPosix &m_mainloop;

    int m_signo;

    std::list<Callback>::iterator m_callback_it;

    friend class MainLoopPosix;

    SignalHandle(const SignalHandle &) = delete;

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

  };

  struct SignalInfo {

    std::list<Callback> callbacks;

    struct sigaction old_action;

    bool was_blocked : 1;

  };

  class RunImpl;

  llvm::DenseMap<IOObject::WaitableHandle, Callback> m_read_fds;

  llvm::DenseMap<int, SignalInfo> m_signals;

  Pipe m_trigger_pipe;

  std::atomic<bool> m_triggering;

#if HAVE_SYS_EVENT_H

  int m_kqueue;

#endif

};

} // namespace lldb_private

#endif // LLDB_HOST_POSIX_MAINLOOPPOSIX_H