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#include "precompiled.hpp"
31#include "mailbox_safe.hpp"
32#include "clock.hpp"
33#include "err.hpp"
34
35#include <algorithm>
36
37zmq::mailbox_safe_t::mailbox_safe_t (mutex_t *sync_) : _sync (sync_)
38{
39 // Get the pipe into passive state. That way, if the users starts by
40 // polling on the associated file descriptor it will get woken up when
41 // new command is posted.
42 const bool ok = _cpipe.check_read ();
43 zmq_assert (!ok);
44}
45
46zmq::mailbox_safe_t::~mailbox_safe_t ()
47{
48 // TODO: Retrieve and deallocate commands inside the cpipe.
49
50 // Work around problem that other threads might still be in our
51 // send() method, by waiting on the mutex before disappearing.
52 _sync->lock ();
53 _sync->unlock ();
54}
55
56void zmq::mailbox_safe_t::add_signaler (signaler_t *signaler_)
57{
58 _signalers.push_back (signaler_);
59}
60
61void zmq::mailbox_safe_t::remove_signaler (signaler_t *signaler_)
62{
63 // TODO: make a copy of array and signal outside the lock
64 const std::vector<zmq::signaler_t *>::iterator end = _signalers.end ();
65 std::vector<signaler_t *>::iterator it =
66 std::find (_signalers.begin (), end, signaler_);
67
68 if (it != end)
69 _signalers.erase (it);
70}
71
72void zmq::mailbox_safe_t::clear_signalers ()
73{
74 _signalers.clear ();
75}
76
77void zmq::mailbox_safe_t::send (const command_t &cmd_)
78{
79 _sync->lock ();
80 _cpipe.write (cmd_, false);
81 const bool ok = _cpipe.flush ();
82
83 if (!ok) {
84 _cond_var.broadcast ();
85
86 for (std::vector<signaler_t *>::iterator it = _signalers.begin (),
87 end = _signalers.end ();
88 it != end; ++it) {
89 (*it)->send ();
90 }
91 }
92
93 _sync->unlock ();
94}
95
96int zmq::mailbox_safe_t::recv (command_t *cmd_, int timeout_)
97{
98 // Try to get the command straight away.
99 if (_cpipe.read (cmd_))
100 return 0;
101
102 // If the timeout is zero, it will be quicker to release the lock, giving other a chance to send a command
103 // and immediately relock it.
104 if (timeout_ == 0) {
105 _sync->unlock ();
106 _sync->lock ();
107 } else {
108 // Wait for signal from the command sender.
109 int rc = _cond_var.wait (_sync, timeout_);
110 if (rc == -1) {
111 errno_assert (errno == EAGAIN || errno == EINTR);
112 return -1;
113 }
114 }
115
116 // Another thread may already fetch the command
117 const bool ok = _cpipe.read (cmd_);
118
119 if (!ok) {
120 errno = EAGAIN;
121 return -1;
122 }
123
124 return 0;
125}
126