1/*
2 Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
3
4 This file is part of libzmq, the ZeroMQ core engine in C++.
5
6 libzmq is free software; you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 As a special exception, the Contributors give you permission to link
12 this library with independent modules to produce an executable,
13 regardless of the license terms of these independent modules, and to
14 copy and distribute the resulting executable under terms of your choice,
15 provided that you also meet, for each linked independent module, the
16 terms and conditions of the license of that module. An independent
17 module is a module which is not derived from or based on this library.
18 If you modify this library, you must extend this exception to your
19 version of the library.
20
21 libzmq is distributed in the hope that it will be useful, but WITHOUT
22 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
23 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
24 License for more details.
25
26 You should have received a copy of the GNU Lesser General Public License
27 along with this program. If not, see <http://www.gnu.org/licenses/>.
28*/
29
30#ifndef __ZMQ_SIGNALER_HPP_INCLUDED__
31#define __ZMQ_SIGNALER_HPP_INCLUDED__
32
33#ifdef HAVE_FORK
34#include <unistd.h>
35#endif
36
37#include "fd.hpp"
38#include "macros.hpp"
39
40namespace zmq
41{
42// This is a cross-platform equivalent to signal_fd. However, as opposed
43// to signal_fd there can be at most one signal in the signaler at any
44// given moment. Attempt to send a signal before receiving the previous
45// one will result in undefined behaviour.
46
47class signaler_t
48{
49 public:
50 signaler_t ();
51 ~signaler_t ();
52
53 // Returns the socket/file descriptor
54 // May return retired_fd if the signaler could not be initialized.
55 fd_t get_fd () const;
56 void send ();
57 int wait (int timeout_);
58 void recv ();
59 int recv_failable ();
60
61 bool valid () const;
62
63#ifdef HAVE_FORK
64 // close the file descriptors in a forked child process so that they
65 // do not interfere with the context in the parent process.
66 void forked ();
67#endif
68
69 private:
70 // Underlying write & read file descriptor
71 // Will be -1 if an error occurred during initialization, e.g. we
72 // exceeded the number of available handles
73 fd_t _w;
74 fd_t _r;
75
76#ifdef HAVE_FORK
77 // the process that created this context. Used to detect forking.
78 pid_t pid;
79 // idempotent close of file descriptors that is safe to use by destructor
80 // and forked().
81 void close_internal ();
82#endif
83
84 ZMQ_NON_COPYABLE_NOR_MOVABLE (signaler_t)
85};
86}
87
88#endif
89