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 <stdint.h>
21 #include <time.h>
22 
23 #include <functional>
24 #include <memory>
25 #include <vector>
26 
27 struct event_base;
28 
29 namespace simpleperf {
30 
31 struct IOEvent;
32 typedef IOEvent* IOEventRef;
33 
34 // IOEventLoop is a class wrapper of libevent, it monitors events happened,
35 // and calls the corresponding callbacks. Possible events are: file ready to
36 // read, file ready to write, signal happens, periodic timer timeout.
37 class IOEventLoop {
38  public:
39   IOEventLoop();
40   ~IOEventLoop();
41 
42   // Use precise timer for periodic events which want precision in ms.
43   bool UsePreciseTimer();
44 
45   // Register a read Event, so [callback] is called when [fd] can be read
46   // without blocking. If registered successfully, return the reference
47   // to control the Event, otherwise return nullptr.
48   IOEventRef AddReadEvent(int fd, const std::function<bool()>& callback);
49 
50   // Register a write Event, so [callback] is called when [fd] can be written
51   // without blocking.
52   IOEventRef AddWriteEvent(int fd, const std::function<bool()>& callback);
53 
54   // Register a signal Event, so [callback] is called each time signal [sig]
55   // happens.
56   bool AddSignalEvent(int sig, const std::function<bool()>& callback);
57 
58   // Register a vector of signal Events.
59   bool AddSignalEvents(std::vector<int> sigs, const std::function<bool()>& callback);
60 
61   // Register a periodic Event, so [callback] is called periodically every
62   // [duration].
63   IOEventRef AddPeriodicEvent(timeval duration, const std::function<bool()>& callback);
64 
65   // Run a loop polling for Events. It only exits when ExitLoop() is called
66   // in a callback function of registered Events.
67   bool RunLoop();
68 
69   // Exit the loop started by RunLoop().
70   bool ExitLoop();
71 
72   // Disable an Event, which can be enabled later.
73   static bool DisableEvent(IOEventRef ref);
74   // Enable a disabled Event.
75   static bool EnableEvent(IOEventRef ref);
76 
77   // Unregister an Event.
78   static bool DelEvent(IOEventRef ref);
79 
80  private:
81   bool EnsureInit();
82   IOEventRef AddEvent(int fd_or_sig, int16_t events, timeval* timeout,
83                       const std::function<bool()>& callback);
84   static void EventCallbackFn(int, int16_t, void*);
85 
86   event_base* ebase_;
87   std::vector<std::unique_ptr<IOEvent>> events_;
88   bool has_error_;
89   bool use_precise_timer_;
90   bool in_loop_;
91 };
92 
93 }  // namespace simpleperf
94 
95 #endif  // SIMPLE_PERF_IOEVENT_LOOP_H_
96