1#ifndef ANDROID_DVR_SERVICES_DISPLAYD_EPOLL_EVENT_DISPATCHER_H_
2#define ANDROID_DVR_SERVICES_DISPLAYD_EPOLL_EVENT_DISPATCHER_H_
3
4#include <sys/epoll.h>
5
6#include <atomic>
7#include <functional>
8#include <mutex>
9#include <thread>
10#include <unordered_map>
11#include <vector>
12
13#include <pdx/file_handle.h>
14#include <pdx/status.h>
15
16namespace android {
17namespace dvr {
18
19class EpollEventDispatcher {
20 public:
21  // Function type for event handlers. The handler receives a bitmask of the
22  // epoll events that occurred on the file descriptor associated with the
23  // handler.
24  using Handler = std::function<void(int)>;
25
26  EpollEventDispatcher();
27  ~EpollEventDispatcher();
28
29  // |handler| is called on the internal dispatch thread when |fd| is signaled
30  // by events in |event_mask|.
31  pdx::Status<void> AddEventHandler(int fd, int event_mask, Handler handler);
32  pdx::Status<void> RemoveEventHandler(int fd);
33
34  void Stop();
35
36 private:
37  void EventThread();
38
39  std::thread thread_;
40  std::atomic<bool> exit_thread_{false};
41
42  // Protects handlers_ and removed_handlers_ and serializes operations on
43  // epoll_fd_ and event_fd_.
44  std::mutex lock_;
45
46  // Maintains a map of fds to event handlers. This is primarily to keep any
47  // references alive that may be bound in the std::function instances. It is
48  // not used at dispatch time to avoid performance problems with different
49  // versions of std::unordered_map.
50  std::unordered_map<int, Handler> handlers_;
51
52  // List of fds to be removed from the map. The actual removal is performed
53  // by the event dispatch thread to avoid races.
54  std::vector<int> removed_handlers_;
55
56  pdx::LocalHandle epoll_fd_;
57  pdx::LocalHandle event_fd_;
58};
59
60}  // namespace dvr
61}  // namespace android
62
63#endif  // ANDROID_DVR_SERVICES_DISPLAYD_EPOLL_EVENT_DISPATCHER_H_
64