1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef SIMPLE_PERF_IOEVENT_LOOP_H_
18 #define SIMPLE_PERF_IOEVENT_LOOP_H_
19 
20 #include <time.h>
21 
22 #include <functional>
23 #include <memory>
24 #include <vector>
25 
26 struct IOEvent;
27 typedef IOEvent* IOEventRef;
28 struct event_base;
29 
30 // IOEventLoop is a class wrapper of libevent, it monitors events happened,
31 // and calls the corresponding callbacks. Possible events are: file ready to
32 // read, file ready to write, signal happens, periodic timer timeout.
33 class IOEventLoop {
34  public:
35   IOEventLoop();
36   ~IOEventLoop();
37 
38   // Register a read Event, so [callback] is called when [fd] can be read
39   // without blocking. If registered successfully, return the reference
40   // to control the Event, otherwise return nullptr.
41   IOEventRef AddReadEvent(int fd, const std::function<bool()>& callback);
42 
43   // Register a write Event, so [callback] is called when [fd] can be written
44   // without blocking.
45   IOEventRef AddWriteEvent(int fd, const std::function<bool()>& callback);
46 
47   // Register a signal Event, so [callback] is called each time signal [sig]
48   // happens.
49   bool AddSignalEvent(int sig, const std::function<bool()>& callback);
50 
51   // Register a vector of signal Events.
52   bool AddSignalEvents(std::vector<int> sigs,
53                        const std::function<bool()>& callback);
54 
55   // Register a periodic Event, so [callback] is called periodically every
56   // [duration].
57   bool AddPeriodicEvent(timeval duration,
58                         const std::function<bool()>& callback);
59 
60   // Run a loop polling for Events. It only exits when ExitLoop() is called
61   // in a callback function of registered Events.
62   bool RunLoop();
63 
64   // Exit the loop started by RunLoop().
65   bool ExitLoop();
66 
67   // Disable an Event, which can be enabled later.
68   static bool DisableEvent(IOEventRef ref);
69   // Enable a disabled Event.
70   static bool EnableEvent(IOEventRef ref);
71 
72   // Unregister an Event.
73   static bool DelEvent(IOEventRef ref);
74 
75  private:
76   bool EnsureInit();
77   IOEventRef AddEvent(int fd_or_sig, short events, timeval* timeout,
78                       const std::function<bool()>& callback);
79   static void EventCallbackFn(int, short, void*);
80 
81   event_base* ebase_;
82   std::vector<std::unique_ptr<IOEvent>> events_;
83   bool has_error_;
84 };
85 
86 #endif  // SIMPLE_PERF_IOEVENT_LOOP_H_
87