child-list.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2021 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/>.
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////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include "child-list.h"
#include "oct-syscalls.h"
 
namespace octave
{
  class pid_equal
  {
  public:
 
    pid_equal (pid_t v) : val (v) { }
 
    bool operator () (const child& oc) const { return oc.pid == val; }
 
  private:
 
    pid_t val;
  };
 
  void child_list::remove (pid_t pid)
  {
    m_list.remove_if (pid_equal (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 (void)
  {
    // 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.have_status)
          {
            oc.have_status = 0;
 
            child::child_event_handler f = oc.handler;
 
            if (f && f (oc.pid, oc.status))
              oc.pid = -1;
          }
      }
 
    // ??
    remove (-1);
  }
 
  // Wait on our children and record any changes in their status.
 
  bool child_list::wait (void)
  {
    bool retval = false;
 
    for (auto& oc : m_list)
      {
        pid_t pid = oc.pid;
 
        if (pid > 0)
          {
            int status;
 
            if (sys::waitpid (pid, &status, sys::wnohang ()) > 0)
              {
                oc.have_status = 1;
 
                oc.status = status;
 
                retval = true;
 
                break;
              }
          }
      }
 
    return retval;
  }
}