Support epoll in PhysicalSocketServer.

webrtc/base/physicalsocketserver.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #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"
 #include "webrtc/base/socketserver.h"
 #include "webrtc/base/criticalsection.h"
 
 #if defined(WEBRTC_POSIX)
 typedef int SOCKET;
 #endif // WEBRTC_POSIX
 
@@ skipping 44 matching lines @@
 
   // Internal Factory for Accept (virtual so it can be overwritten in tests).
   virtual AsyncSocket* WrapSocket(SOCKET s);
 
   // SocketServer:
   bool Wait(int cms, bool process_io) override;
   void WakeUp() override;
 
   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.
   // The function is executed from inside Wait() using the "self-pipe trick"--
   // regardless of which thread receives the signal--and hence can safely
   // manipulate user-level data structures.
   // "handler" may be SIG_IGN, SIG_DFL, or a user-specified function, just like
   // with signal(2).
   // Only one PhysicalSocketServer should have user-level signal handlers.
   // Dispatching signals on multiple PhysicalSocketServers is not reliable.
   // The signal mask is not modified. It is the caller's responsibily to
   // maintain it as desired.
   virtual bool SetPosixSignalHandler(int signum, void (*handler)(int));
 
  protected:
   Dispatcher* signal_dispatcher();
 #endif
 
  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_;
 #if defined(WEBRTC_WIN)
   WSAEVENT socket_ev_;
 #endif
 };
 
 class PhysicalSocket : public AsyncSocket, public sigslot::has_slots<> {
  public:
@@ skipping 47 matching lines @@
   // Make virtual so ::sendto can be overwritten in tests.
   virtual int DoSendTo(SOCKET socket, const char* buf, int len, int flags,
                        const struct sockaddr* dest_addr, socklen_t addrlen);
 
   void OnResolveResult(AsyncResolverInterface* resolver);
 
   void UpdateLastError();
   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);
 
   PhysicalSocketServer* ss_;
   SOCKET s_;
   bool udp_;
   CriticalSection crit_;
   int error_ GUARDED_BY(crit_);
   ConnState state_;
   AsyncResolver* resolver_;
@@ skipping 25 matching lines @@
   int GetDescriptor() override;
   bool IsDescriptorClosed() override;
 #endif
 
   uint32_t GetRequestedEvents() override;
   void OnPreEvent(uint32_t ff) override;
   void OnEvent(uint32_t ff, int err) override;
 
   int Close() override;
 
+#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)
- private:
   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
 
 #endif // WEBRTC_BASE_PHYSICALSOCKETSERVER_H__