Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 1 | // Copyright (c) 2012 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 | #ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_LIBEVENT_H_ |
| 6 | #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_LIBEVENT_H_ |
| 7 | |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 8 | #include "base/compiler_specific.h" |
Alex Vakulenko | 0d205d7 | 2016-01-15 13:02:14 -0800 | [diff] [blame] | 9 | #include "base/macros.h" |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 10 | #include "base/message_loop/message_pump.h" |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 11 | #include "base/threading/thread_checker.h" |
| 12 | #include "base/time/time.h" |
| 13 | |
| 14 | // Declare structs we need from libevent.h rather than including it |
| 15 | struct event_base; |
| 16 | struct event; |
| 17 | |
| 18 | namespace base { |
| 19 | |
| 20 | // Class to monitor sockets and issue callbacks when sockets are ready for I/O |
| 21 | // TODO(dkegel): add support for background file IO somehow |
| 22 | class BASE_EXPORT MessagePumpLibevent : public MessagePump { |
| 23 | public: |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 24 | // Used with WatchFileDescriptor to asynchronously monitor the I/O readiness |
| 25 | // of a file descriptor. |
| 26 | class Watcher { |
| 27 | public: |
| 28 | // Called from MessageLoop::Run when an FD can be read from/written to |
| 29 | // without blocking |
| 30 | virtual void OnFileCanReadWithoutBlocking(int fd) = 0; |
| 31 | virtual void OnFileCanWriteWithoutBlocking(int fd) = 0; |
| 32 | |
| 33 | protected: |
| 34 | virtual ~Watcher() {} |
| 35 | }; |
| 36 | |
| 37 | // Object returned by WatchFileDescriptor to manage further watching. |
| 38 | class FileDescriptorWatcher { |
| 39 | public: |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 40 | FileDescriptorWatcher(); |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 41 | ~FileDescriptorWatcher(); // Implicitly calls StopWatchingFileDescriptor. |
| 42 | |
| 43 | // NOTE: These methods aren't called StartWatching()/StopWatching() to |
| 44 | // avoid confusion with the win32 ObjectWatcher class. |
| 45 | |
| 46 | // Stop watching the FD, always safe to call. No-op if there's nothing |
| 47 | // to do. |
| 48 | bool StopWatchingFileDescriptor(); |
| 49 | |
| 50 | private: |
| 51 | friend class MessagePumpLibevent; |
| 52 | friend class MessagePumpLibeventTest; |
| 53 | |
| 54 | // Called by MessagePumpLibevent, ownership of |e| is transferred to this |
| 55 | // object. |
| 56 | void Init(event* e); |
| 57 | |
| 58 | // Used by MessagePumpLibevent to take ownership of event_. |
| 59 | event* ReleaseEvent(); |
| 60 | |
| 61 | void set_pump(MessagePumpLibevent* pump) { pump_ = pump; } |
| 62 | MessagePumpLibevent* pump() const { return pump_; } |
| 63 | |
| 64 | void set_watcher(Watcher* watcher) { watcher_ = watcher; } |
| 65 | |
| 66 | void OnFileCanReadWithoutBlocking(int fd, MessagePumpLibevent* pump); |
| 67 | void OnFileCanWriteWithoutBlocking(int fd, MessagePumpLibevent* pump); |
| 68 | |
| 69 | event* event_; |
| 70 | MessagePumpLibevent* pump_; |
| 71 | Watcher* watcher_; |
Alex Vakulenko | 0d205d7 | 2016-01-15 13:02:14 -0800 | [diff] [blame] | 72 | // If this pointer is non-NULL, the pointee is set to true in the |
| 73 | // destructor. |
| 74 | bool* was_destroyed_; |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 75 | |
| 76 | DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher); |
| 77 | }; |
| 78 | |
| 79 | enum Mode { |
| 80 | WATCH_READ = 1 << 0, |
| 81 | WATCH_WRITE = 1 << 1, |
| 82 | WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE |
| 83 | }; |
| 84 | |
| 85 | MessagePumpLibevent(); |
| 86 | ~MessagePumpLibevent() override; |
| 87 | |
| 88 | // Have the current thread's message loop watch for a a situation in which |
| 89 | // reading/writing to the FD can be performed without blocking. |
| 90 | // Callers must provide a preallocated FileDescriptorWatcher object which |
| 91 | // can later be used to manage the lifetime of this event. |
| 92 | // If a FileDescriptorWatcher is passed in which is already attached to |
| 93 | // an event, then the effect is cumulative i.e. after the call |controller| |
| 94 | // will watch both the previous event and the new one. |
| 95 | // If an error occurs while calling this method in a cumulative fashion, the |
| 96 | // event previously attached to |controller| is aborted. |
| 97 | // Returns true on success. |
| 98 | // Must be called on the same thread the message_pump is running on. |
| 99 | // TODO(dkegel): switch to edge-triggered readiness notification |
| 100 | bool WatchFileDescriptor(int fd, |
| 101 | bool persistent, |
| 102 | int mode, |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 103 | FileDescriptorWatcher *controller, |
| 104 | Watcher *delegate); |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 105 | |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 106 | // MessagePump methods: |
| 107 | void Run(Delegate* delegate) override; |
| 108 | void Quit() override; |
| 109 | void ScheduleWork() override; |
| 110 | void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override; |
| 111 | |
| 112 | private: |
| 113 | friend class MessagePumpLibeventTest; |
| 114 | |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 115 | void WillProcessIOEvent(); |
| 116 | void DidProcessIOEvent(); |
| 117 | |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 118 | // Risky part of constructor. Returns true on success. |
| 119 | bool Init(); |
| 120 | |
| 121 | // Called by libevent to tell us a registered FD can be read/written to. |
Luis Hector Chavez | e5b2c6f | 2017-07-26 17:33:47 +0000 | [diff] [blame] | 122 | static void OnLibeventNotification(int fd, short flags, |
| 123 | void* context); |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 124 | |
| 125 | // Unix pipe used to implement ScheduleWork() |
| 126 | // ... callback; called by libevent inside Run() when pipe is ready to read |
| 127 | static void OnWakeup(int socket, short flags, void* context); |
| 128 | |
| 129 | // This flag is set to false when Run should return. |
| 130 | bool keep_running_; |
| 131 | |
| 132 | // This flag is set when inside Run. |
| 133 | bool in_run_; |
| 134 | |
| 135 | // This flag is set if libevent has processed I/O events. |
| 136 | bool processed_io_events_; |
| 137 | |
| 138 | // The time at which we should call DoDelayedWork. |
| 139 | TimeTicks delayed_work_time_; |
| 140 | |
| 141 | // Libevent dispatcher. Watches all sockets registered with it, and sends |
| 142 | // readiness callbacks when a socket is ready for I/O. |
| 143 | event_base* event_base_; |
| 144 | |
| 145 | // ... write end; ScheduleWork() writes a single byte to it |
| 146 | int wakeup_pipe_in_; |
| 147 | // ... read end; OnWakeup reads it and then breaks Run() out of its sleep |
| 148 | int wakeup_pipe_out_; |
| 149 | // ... libevent wrapper for read end |
| 150 | event* wakeup_event_; |
| 151 | |
Daniel Erat | b8cf949 | 2015-07-06 13:18:13 -0600 | [diff] [blame] | 152 | ThreadChecker watch_file_descriptor_caller_checker_; |
| 153 | DISALLOW_COPY_AND_ASSIGN(MessagePumpLibevent); |
| 154 | }; |
| 155 | |
| 156 | } // namespace base |
| 157 | |
| 158 | #endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_LIBEVENT_H_ |