1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_MULTI_SOCKET_MONITOR_HXX
#define MPD_MULTI_SOCKET_MONITOR_HXX
#include "check.h"
#include "IdleMonitor.hxx"
#include "TimerEvent.hxx"
#include "SocketMonitor.hxx"
#include "util/Compiler.h"
#include <forward_list>
#include <iterator>
#include <assert.h>
#ifndef _WIN32
struct pollfd;
#endif
class EventLoop;
/**
* Similar to #SocketMonitor, but monitors multiple sockets. To use
* it, implement the methods PrepareSockets() and DispatchSockets().
* In PrepareSockets(), use UpdateSocketList() and AddSocket().
* DispatchSockets() will be called if at least one socket is ready.
*/
class MultiSocketMonitor : IdleMonitor
{
class SingleFD final : public SocketMonitor {
MultiSocketMonitor &multi;
unsigned revents;
public:
SingleFD(MultiSocketMonitor &_multi, SocketDescriptor _fd,
unsigned events) noexcept
:SocketMonitor(_fd, _multi.GetEventLoop()),
multi(_multi), revents(0) {
Schedule(events);
}
SocketDescriptor GetSocket() const noexcept {
return SocketMonitor::GetSocket();
}
unsigned GetEvents() const noexcept {
return SocketMonitor::GetScheduledFlags();
}
void SetEvents(unsigned _events) noexcept {
revents &= _events;
SocketMonitor::Schedule(_events);
}
unsigned GetReturnedEvents() const noexcept {
return revents;
}
void ClearReturnedEvents() noexcept {
revents = 0;
}
protected:
bool OnSocketReady(unsigned flags) noexcept override {
revents = flags;
multi.SetReady();
return true;
}
};
friend class SingleFD;
TimerEvent timeout_event;
/**
* DispatchSockets() should be called.
*/
bool ready = false;
/**
* PrepareSockets() should be called.
*
* Note that this doesn't need to be initialized by the
* constructor; this class is activated with the first
* InvalidateSockets() call, which initializes this flag.
*/
bool refresh;
std::forward_list<SingleFD> fds;
public:
static constexpr unsigned READ = SocketMonitor::READ;
static constexpr unsigned WRITE = SocketMonitor::WRITE;
static constexpr unsigned ERROR = SocketMonitor::ERROR;
static constexpr unsigned HANGUP = SocketMonitor::HANGUP;
MultiSocketMonitor(EventLoop &_loop) noexcept;
using IdleMonitor::GetEventLoop;
/**
* Clear the socket list and disable all #EventLoop
* registrations. Run this in the #EventLoop thread before
* destroying this object.
*
* Later, this object can be reused and reactivated by calling
* InvalidateSockets().
*
* Note that this class doesn't have a destructor which calls
* this method, because this would be racy and thus pointless:
* at the time ~MultiSocketMonitor() is called, our virtual
* methods have been morphed to be pure again, and in the
* meantime the #EventLoop thread could invoke those pure
* methods.
*/
void Reset() noexcept;
/**
* Invalidate the socket list. A call to PrepareSockets() is
* scheduled which will then update the list.
*/
void InvalidateSockets() noexcept {
refresh = true;
IdleMonitor::Schedule();
}
/**
* Add one socket to the list of monitored sockets.
*
* May only be called from PrepareSockets().
*/
void AddSocket(SocketDescriptor fd, unsigned events) noexcept {
fds.emplace_front(*this, fd, events);
}
/**
* Remove all sockets.
*
* May only be called from PrepareSockets().
*/
void ClearSocketList() noexcept;
/**
* Update the known sockets by invoking the given function for
* each one; its return value is the events bit mask. A
* return value of 0 means the socket will be removed from the
* list.
*
* May only be called from PrepareSockets().
*/
template<typename E>
void UpdateSocketList(E &&e) noexcept {
for (auto prev = fds.before_begin(), end = fds.end(),
i = std::next(prev);
i != end; i = std::next(prev)) {
assert(i->GetEvents() != 0);
unsigned events = e(i->GetSocket());
if (events != 0) {
i->SetEvents(events);
prev = i;
} else {
fds.erase_after(prev);
}
}
}
#ifndef _WIN32
/**
* Replace the socket list with the given file descriptors.
* The given pollfd array will be modified by this method.
*
* May only be called from PrepareSockets().
*/
void ReplaceSocketList(pollfd *pfds, unsigned n) noexcept;
#endif
protected:
/**
* Override this method and update the socket registrations.
* To do that, call AddSocket(), ClearSocketList(),
* UpdateSocketList() and ReplaceSocketList().
*
* @return timeout or a negative value for no timeout
*/
virtual std::chrono::steady_clock::duration PrepareSockets() noexcept = 0;
/**
* At least one socket is ready or the timeout has expired.
* This method should be used to perform I/O.
*/
virtual void DispatchSockets() noexcept = 0;
private:
void SetReady() noexcept {
ready = true;
IdleMonitor::Schedule();
}
void Prepare() noexcept;
void OnTimeout() noexcept {
SetReady();
IdleMonitor::Schedule();
}
virtual void OnIdle() noexcept final;
};
#endif
|
