Support epoll in PhysicalSocketServer.

webrtc/base/physicalsocketserver.h

Index: webrtc/base/physicalsocketserver.h
diff --git a/webrtc/base/physicalsocketserver.h b/webrtc/base/physicalsocketserver.h
index 5f843da20c78879181f7bc09bd1fddcc26691f9c..61bb7ca3c3ed89a3748e0a88f08f530c95dabdb1 100644
--- a/webrtc/base/physicalsocketserver.h
+++ b/webrtc/base/physicalsocketserver.h
@@ -11,7 +11,13 @@
 #ifndef WEBRTC_BASE_PHYSICALSOCKETSERVER_H__
 #define WEBRTC_BASE_PHYSICALSOCKETSERVER_H__
 
+#if defined(WEBRTC_POSIX) && defined(WEBRTC_LINUX)
+#include <sys/epoll.h>
+#define WEBRTC_USE_EPOLL 1
+#endif
+
 #include <memory>
+#include <set>
 #include <vector>
 
 #include "webrtc/base/nethelpers.h"
@@ -76,6 +82,7 @@ class PhysicalSocketServer : public SocketServer {
 
   void Add(Dispatcher* dispatcher);
   void Remove(Dispatcher* dispatcher);
+  void Update(Dispatcher* dispatcher);
 
 #if defined(WEBRTC_POSIX)
   // Sets the function to be executed in response to the specified POSIX signal.
@@ -96,15 +103,35 @@ class PhysicalSocketServer : public SocketServer {
 
  private:
   typedef std::vector<Dispatcher*> DispatcherList;
+  typedef std::set<Dispatcher*> DispatcherSet;
   typedef std::vector<size_t*> IteratorList;
 
 #if defined(WEBRTC_POSIX)
+  bool WaitSelect(int cms, bool process_io);
+  void AddRemovePendingDispatchers();
   static bool InstallSignal(int signum, void (*handler)(int));
 
   std::unique_ptr<PosixSignalDispatcher> signal_dispatcher_;
-#endif
+#endif  // WEBRTC_POSIX
+#if defined(WEBRTC_USE_EPOLL)
+  void AddEpoll(Dispatcher* dispatcher);
+  void RemoveEpoll(Dispatcher* dispatcher);
+  void UpdateEpoll(Dispatcher* dispatcher);
+  bool WaitEpoll(int cms);
+  bool WaitPoll(int cms, Dispatcher* dispatcher);
+
+  int epoll_fd_ = INVALID_SOCKET;
+  std::vector<struct epoll_event> epoll_events_;
+#endif  // WEBRTC_USE_EPOLL
+#if defined(WEBRTC_WIN)
   DispatcherList dispatchers_;
   IteratorList iterators_;
+#else
+  DispatcherSet dispatchers_;
+  DispatcherSet pending_add_dispatchers_;
+  DispatcherSet pending_remove_dispatchers_;
+  bool processing_dispatchers_ = false;
+#endif

[Taylor Brandstetter, 2017/05/30 22:05:50]

This code is going to confusing to maintain if |dispatchers_| can be either a
set or a list, and different strategies are used for handling modifications
while iterating. Would it be easier now to switch to using a set everywhere,
using "pending_remove_dispatchers_" for the Windows code as well? If not, can
you leave a comment explaining why not, and describing what would need to be
done?

[joachim, 2017/05/31 17:18:03]

I agree. As commented before, I wanted to switch the Windows code to use the
same set in a separate CL, but did it in this now.

   Signaler* signal_wakeup_;
   CriticalSection crit_;
   bool fWait_;
@@ -172,9 +199,9 @@ class PhysicalSocket : public AsyncSocket, public sigslot::has_slots<> {
   void MaybeRemapSendError();
 
   uint8_t enabled_events() const { return enabled_events_; }
-  void SetEnabledEvents(uint8_t events);
-  void EnableEvents(uint8_t events);
-  void DisableEvents(uint8_t events);
+  virtual void SetEnabledEvents(uint8_t events);
+  virtual void EnableEvents(uint8_t events);
+  virtual void DisableEvents(uint8_t events);
 
   static int TranslateOption(Option opt, int* slevel, int* sopt);
 
@@ -220,13 +247,28 @@ class SocketDispatcher : public Dispatcher, public PhysicalSocket {
 
   int Close() override;
 
-#if defined(WEBRTC_WIN)
+#if defined(WEBRTC_USE_EPOLL)
+ protected:
+  void StartBatchedEventUpdates();
+  void FinishBatchedEventUpdates();
+
+  void SetEnabledEvents(uint8_t events) override;
+  void EnableEvents(uint8_t events) override;
+  void DisableEvents(uint8_t events) override;
+#endif
+
  private:
+#if defined(WEBRTC_WIN)
   static int next_id_;
   int id_;
   bool signal_close_;
   int signal_err_;
 #endif // WEBRTC_WIN
+#if defined(WEBRTC_USE_EPOLL)
+  void MaybeUpdateDispatcher(uint8_t old_events);
+
+  int saved_enabled_events_ = -1;
+#endif
 };
 
 } // namespace rtc