////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2024 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include "child-list.h"
#include "oct-syscalls.h"

OCTAVE_BEGIN_NAMESPACE(octave)

void child_list::remove (pid_t pid)
{
  m_list.remove_if ([pid] (const child& oc) { return oc.m_pid == pid; });
}

void
child_list::child_list::insert (pid_t pid, child::child_event_handler f)
{
  m_list.append (child (pid, f));
}

void
child_list::reap ()
{
  // Mark the record for PID invalid.

  for (auto& oc : m_list)
    {
      // The call to the child::child_event_handler might
      // invalidate the iterator (for example, by calling
      // child_list::remove), so we increment the iterator
      // here.

      if (oc.m_have_status)
        {
          oc.m_have_status = 0;

          child::child_event_handler f = oc.m_handler;

          if (f && f (oc.m_pid, oc.m_status))
            oc.m_pid = -1;
        }
    }

  // Remove PIDs that have completed above.
  remove (-1);
}

// Wait on our children and record any changes in their status.

bool
child_list::wait ()
{
  bool retval = false;

  for (auto& oc : m_list)
    {
      pid_t pid = oc.m_pid;

      if (pid > 0)
        {
          int status;

          if (sys::waitpid (pid, &status, sys::wnohang ()) > 0)
            {
              oc.m_have_status = 1;

              oc.m_status = status;

              retval = true;

              break;
            }
        }
    }

  return retval;
}

OCTAVE_END_NAMESPACE(octave)