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| 1 // Copyright (c) 2008 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "base/message_pump_libevent.h" |
| 6 |
| 7 #include "base/logging.h" |
| 8 #include "base/time.h" |
| 9 #include "third_party/libevent/event.h" |
| 10 |
| 11 #include <fcntl.h> |
| 12 |
| 13 namespace base { |
| 14 |
| 15 // Return 0 on success |
| 16 // Too small a function to bother putting in a library? |
| 17 static int SetNonBlocking(int fd) |
| 18 { |
| 19 int flags = fcntl(fd, F_GETFL, 0); |
| 20 if (-1 == flags) |
| 21 flags = 0; |
| 22 return fcntl(fd, F_SETFL, flags | O_NONBLOCK); |
| 23 } |
| 24 |
| 25 // Called if a byte is received on the wakeup pipe. |
| 26 void MessagePumpLibevent::OnWakeup(int socket, short flags, void* context) { |
| 27 |
| 28 base::MessagePumpLibevent* that = |
| 29 static_cast<base::MessagePumpLibevent*>(context); |
| 30 DCHECK(that->wakeup_pipe_out_ == socket); |
| 31 |
| 32 // Remove and discard the wakeup byte. |
| 33 char buf; |
| 34 int nread = read(socket, &buf, 1); |
| 35 DCHECK(nread == 1); |
| 36 // Tell libevent to break out of inner loop. |
| 37 event_base_loopbreak(that->event_base_); |
| 38 } |
| 39 |
| 40 MessagePumpLibevent::MessagePumpLibevent() |
| 41 : keep_running_(true), |
| 42 in_run_(false), |
| 43 wakeup_pipe_in_(-1), |
| 44 wakeup_pipe_out_(-1), |
| 45 event_base_(event_base_new()) { |
| 46 if (!Init()) |
| 47 NOTREACHED(); |
| 48 } |
| 49 |
| 50 bool MessagePumpLibevent::Init() { |
| 51 int fds[2]; |
| 52 if (pipe(fds)) |
| 53 return false; |
| 54 if (SetNonBlocking(fds[0])) |
| 55 return false; |
| 56 if (SetNonBlocking(fds[1])) |
| 57 return false; |
| 58 wakeup_pipe_out_ = fds[0]; |
| 59 wakeup_pipe_in_ = fds[1]; |
| 60 |
| 61 wakeup_event_ = new event; |
| 62 event_set(wakeup_event_, wakeup_pipe_out_, EV_READ | EV_PERSIST, |
| 63 OnWakeup, this); |
| 64 event_base_set(event_base_, wakeup_event_); |
| 65 |
| 66 if (event_add(wakeup_event_, 0)) |
| 67 return false; |
| 68 return true; |
| 69 } |
| 70 |
| 71 MessagePumpLibevent::~MessagePumpLibevent() { |
| 72 DCHECK(wakeup_event_); |
| 73 DCHECK(event_base_); |
| 74 event_del(wakeup_event_); |
| 75 delete wakeup_event_; |
| 76 event_base_free(event_base_); |
| 77 } |
| 78 |
| 79 void MessagePumpLibevent::WatchSocket(int socket, short interest_mask, |
| 80 event* e, Watcher* watcher) { |
| 81 |
| 82 // Set current interest mask and message pump for this event |
| 83 event_set(e, socket, interest_mask, OnReadinessNotification, watcher); |
| 84 |
| 85 // Tell libevent which message pump this socket will belong to when we add it. |
| 86 event_base_set(event_base_, e); |
| 87 |
| 88 // Add this socket to the list of monitored sockets. |
| 89 if (event_add(e, NULL)) |
| 90 NOTREACHED(); |
| 91 } |
| 92 |
| 93 void MessagePumpLibevent::UnwatchSocket(event* e) { |
| 94 // Remove this socket from the list of monitored sockets. |
| 95 if (event_del(e)) |
| 96 NOTREACHED(); |
| 97 } |
| 98 |
| 99 void MessagePumpLibevent::OnReadinessNotification(int socket, short flags, |
| 100 void* context) { |
| 101 // The given socket is ready for I/O. |
| 102 // Tell the owner what kind of I/O the socket is ready for. |
| 103 Watcher* watcher = static_cast<Watcher*>(context); |
| 104 watcher->OnSocketReady(flags); |
| 105 } |
| 106 |
| 107 // Reentrant! |
| 108 void MessagePumpLibevent::Run(Delegate* delegate) { |
| 109 DCHECK(keep_running_) << "Quit must have been called outside of Run!"; |
| 110 |
| 111 bool old_in_run = in_run_; |
| 112 in_run_ = true; |
| 113 |
| 114 for (;;) { |
| 115 bool did_work = delegate->DoWork(); |
| 116 if (!keep_running_) |
| 117 break; |
| 118 |
| 119 did_work |= delegate->DoDelayedWork(&delayed_work_time_); |
| 120 if (!keep_running_) |
| 121 break; |
| 122 |
| 123 if (did_work) |
| 124 continue; |
| 125 |
| 126 did_work = delegate->DoIdleWork(); |
| 127 if (!keep_running_) |
| 128 break; |
| 129 |
| 130 if (did_work) |
| 131 continue; |
| 132 |
| 133 // EVLOOP_ONCE tells libevent to only block once, |
| 134 // but to service all pending events when it wakes up. |
| 135 if (delayed_work_time_.is_null()) { |
| 136 event_base_loop(event_base_, EVLOOP_ONCE); |
| 137 } else { |
| 138 TimeDelta delay = delayed_work_time_ - Time::Now(); |
| 139 if (delay > TimeDelta()) { |
| 140 struct timeval poll_tv; |
| 141 poll_tv.tv_sec = delay.InSeconds(); |
| 142 poll_tv.tv_usec = delay.InMicroseconds() % Time::kMicrosecondsPerSecond; |
| 143 event_base_loopexit(event_base_, &poll_tv); |
| 144 event_base_loop(event_base_, EVLOOP_ONCE); |
| 145 } else { |
| 146 // It looks like delayed_work_time_ indicates a time in the past, so we |
| 147 // need to call DoDelayedWork now. |
| 148 delayed_work_time_ = Time(); |
| 149 } |
| 150 } |
| 151 } |
| 152 |
| 153 keep_running_ = true; |
| 154 in_run_ = old_in_run; |
| 155 } |
| 156 |
| 157 void MessagePumpLibevent::Quit() { |
| 158 DCHECK(in_run_); |
| 159 // Tell both libevent and Run that they should break out of their loops. |
| 160 keep_running_ = false; |
| 161 ScheduleWork(); |
| 162 } |
| 163 |
| 164 void MessagePumpLibevent::ScheduleWork() { |
| 165 // Tell libevent (in a threadsafe way) that it should break out of its loop. |
| 166 char buf = 0; |
| 167 int nwrite = write(wakeup_pipe_in_, &buf, 1); |
| 168 DCHECK(nwrite == 1); |
| 169 } |
| 170 |
| 171 void MessagePumpLibevent::ScheduleDelayedWork(const Time& delayed_work_time) { |
| 172 // We know that we can't be blocked on Wait right now since this method can |
| 173 // only be called on the same thread as Run, so we only need to update our |
| 174 // record of how long to sleep when we do sleep. |
| 175 delayed_work_time_ = delayed_work_time; |
| 176 } |
| 177 |
| 178 } // namespace base |
| 179 |
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