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1 : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 : // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
4 : // Use of this source code is governed by a BSD-style license that can be
5 : // found in the LICENSE file.
6 :
7 : #ifndef BASE_MESSAGE_PUMP_LIBEVENT_H_
8 : #define BASE_MESSAGE_PUMP_LIBEVENT_H_
9 :
10 : #include "base/message_pump.h"
11 : #include "base/time.h"
12 : #include "mozilla/UniquePtr.h"
13 :
14 : // Declare structs we need from libevent.h rather than including it
15 : struct event_base;
16 : struct event;
17 :
18 : class nsDependentCSubstring;
19 :
20 : namespace base {
21 :
22 : // Class to monitor sockets and issue callbacks when sockets are ready for I/O
23 : // TODO(dkegel): add support for background file IO somehow
24 : class MessagePumpLibevent : public MessagePump {
25 : public:
26 :
27 : // Object returned by WatchFileDescriptor to manage further watching.
28 : class FileDescriptorWatcher {
29 : public:
30 : FileDescriptorWatcher();
31 : ~FileDescriptorWatcher(); // Implicitly calls StopWatchingFileDescriptor.
32 :
33 : // NOTE: These methods aren't called StartWatching()/StopWatching() to
34 : // avoid confusion with the win32 ObjectWatcher class.
35 :
36 : // Stop watching the FD, always safe to call. No-op if there's nothing
37 : // to do.
38 : bool StopWatchingFileDescriptor();
39 :
40 : private:
41 : // Called by MessagePumpLibevent, ownership of |e| is transferred to this
42 : // object.
43 : void Init(event* e, bool is_persistent);
44 :
45 : // Used by MessagePumpLibevent to take ownership of event_.
46 : event *ReleaseEvent();
47 : friend class MessagePumpLibevent;
48 :
49 : private:
50 : bool is_persistent_; // false if this event is one-shot.
51 : event* event_;
52 : DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
53 : };
54 :
55 : // Used with WatchFileDescptor to asynchronously monitor the I/O readiness of
56 : // a File Descriptor.
57 44 : class Watcher {
58 : public:
59 13 : virtual ~Watcher() {}
60 : // Called from MessageLoop::Run when an FD can be read from/written to
61 : // without blocking
62 : virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
63 : virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;
64 : };
65 :
66 : MessagePumpLibevent();
67 :
68 : enum Mode {
69 : WATCH_READ = 1 << 0,
70 : WATCH_WRITE = 1 << 1,
71 : WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
72 : };
73 :
74 : // Have the current thread's message loop watch for a a situation in which
75 : // reading/writing to the FD can be performed without Blocking.
76 : // Callers must provide a preallocated FileDescriptorWatcher object which
77 : // can later be used to manage the Lifetime of this event.
78 : // If a FileDescriptorWatcher is passed in which is already attached to
79 : // an event, then the effect is cumulative i.e. after the call |controller|
80 : // will watch both the previous event and the new one.
81 : // If an error occurs while calling this method in a cumulative fashion, the
82 : // event previously attached to |controller| is aborted.
83 : // Returns true on success.
84 : // TODO(dkegel): switch to edge-triggered readiness notification
85 : bool WatchFileDescriptor(int fd,
86 : bool persistent,
87 : Mode mode,
88 : FileDescriptorWatcher *controller,
89 : Watcher *delegate);
90 :
91 :
92 : // This is analagous to FileDescriptorWatcher above, which really is
93 : // just a wrapper around libevent's |struct event|. This class acts
94 : // as a sort of "scoped event watcher" in that it guarantees that
95 : // when this class is out of scope, the signal-event it wraps is
96 : // removed from libevent's guts.
97 : //
98 : // XXX/cjones: this isn't my favorite API, but preserving it in
99 : // order to match code above
100 : class SignalEvent {
101 : friend class MessagePumpLibevent;
102 :
103 : public:
104 : SignalEvent();
105 : ~SignalEvent(); // implicitly calls StopCatching()
106 :
107 : // Have libevent forget this event.
108 : bool StopCatching();
109 :
110 : private:
111 : void Init(event* e);
112 : event* ReleaseEvent();
113 :
114 : event* event_;
115 :
116 : DISALLOW_COPY_AND_ASSIGN(SignalEvent);
117 : };
118 :
119 0 : class SignalWatcher {
120 : public:
121 0 : virtual ~SignalWatcher() {}
122 : // Called from MessageLoop::Run when |sig| has been delivered to
123 : // this process
124 : virtual void OnSignal(int sig) = 0;
125 : };
126 :
127 : // Have the current thread's message loop catch the signal |sig|.
128 : // Multiple watchers can catch the same signal; they're all notified
129 : // upon its delivery. Callers must provide a preallocated
130 : // SignalEvent object which can be used to manage the lifetime of
131 : // this event. Returns true on success.
132 : bool CatchSignal(int sig,
133 : SignalEvent* sigevent,
134 : SignalWatcher* delegate);
135 :
136 :
137 : // MessagePump methods:
138 : virtual void Run(Delegate* delegate) override;
139 : virtual void Quit() override;
140 : virtual void ScheduleWork() override;
141 : virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
142 :
143 : protected:
144 :
145 : virtual ~MessagePumpLibevent();
146 :
147 : private:
148 :
149 : // Risky part of constructor. Returns true on success.
150 : bool Init();
151 :
152 : // This flag is set to false when Run should return.
153 : bool keep_running_;
154 :
155 : // This flag is set when inside Run.
156 : bool in_run_;
157 :
158 : // The time at which we should call DoDelayedWork.
159 : TimeTicks delayed_work_time_;
160 :
161 : // Libevent dispatcher. Watches all sockets registered with it, and sends
162 : // readiness callbacks when a socket is ready for I/O.
163 : event_base* event_base_;
164 :
165 : // Called by libevent to tell us a registered FD can be read/written to.
166 : static void OnLibeventNotification(int fd, short flags,
167 : void* context);
168 :
169 : // Called by libevent upon receiving a signal
170 : static void OnLibeventSignalNotification(int sig, short flags,
171 : void* context);
172 :
173 : // Unix pipe used to implement ScheduleWork()
174 : // ... callback; called by libevent inside Run() when pipe is ready to read
175 : static void OnWakeup(int socket, short flags, void* context);
176 : // ... write end; ScheduleWork() writes a single byte to it
177 : int wakeup_pipe_in_;
178 : // ... read end; OnWakeup reads it and then breaks Run() out of its sleep
179 : int wakeup_pipe_out_;
180 : // ... libevent wrapper for read end
181 : event* wakeup_event_;
182 :
183 : DISALLOW_COPY_AND_ASSIGN(MessagePumpLibevent);
184 : };
185 :
186 : /**
187 : * LineWatcher overrides OnFileCanReadWithoutBlocking. It separates the read
188 : * data by mTerminator and passes each line to OnLineRead.
189 : */
190 : class LineWatcher : public MessagePumpLibevent::Watcher
191 : {
192 : public:
193 : LineWatcher(char aTerminator, int aBufferSize) : mReceivedIndex(0),
194 : mBufferSize(aBufferSize),
195 : mTerminator(aTerminator)
196 : {
197 : mReceiveBuffer = mozilla::MakeUnique<char[]>(mBufferSize);
198 : }
199 :
200 : ~LineWatcher() {}
201 :
202 : protected:
203 : /**
204 : * OnError will be called when |read| returns error. Derived class should
205 : * implement this function to handle error cases when needed.
206 : */
207 0 : virtual void OnError() {}
208 : virtual void OnLineRead(int aFd, nsDependentCSubstring& aMessage) = 0;
209 0 : virtual void OnFileCanWriteWithoutBlocking(int /* aFd */) override {}
210 : private:
211 : virtual void OnFileCanReadWithoutBlocking(int aFd) final override;
212 :
213 : mozilla::UniquePtr<char[]> mReceiveBuffer;
214 : int mReceivedIndex;
215 : int mBufferSize;
216 : char mTerminator;
217 : };
218 : } // namespace base
219 :
220 : #endif // BASE_MESSAGE_PUMP_LIBEVENT_H_
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