Add config to prune TURN ports

webrtc/p2p/base/portallocator.h

Index: webrtc/p2p/base/portallocator.h
diff --git a/webrtc/p2p/base/portallocator.h b/webrtc/p2p/base/portallocator.h
index 6a32b9668f882ddc245f4f2af9bc3683ced930a4..106e86e4a697c969422c09b49d9b60128d4491df 100644
--- a/webrtc/p2p/base/portallocator.h
+++ b/webrtc/p2p/base/portallocator.h
@@ -178,6 +178,11 @@ class PortAllocatorSession : public sigslot::has_slots<> {
   sigslot::signal2<PortAllocatorSession*,
                    const std::vector<Candidate>&> SignalCandidatesReady;
   sigslot::signal1<PortAllocatorSession*> SignalCandidatesAllocationDone;
+  // A TURN port is pruned if a higher-priority TURN port becomes ready
+  // (pairable). When it is pruned, it will not be used for creating
+  // connections and its candidates will not be sent to the remote side
+  // if they have not been sent.
+  sigslot::signal2<PortAllocatorSession*, PortInterface*> SignalPortPruned;

[Taylor Brandstetter, 2016/06/29 20:57:35]

I realize this may be too large of a change to the CL, but I don't think the
port pruning logic should go in BasicPortAllocator. This means if someone wants
to use their own PortAllocator, they have to implement their own pruning logic.
It would be better in my opinion if PortAllocator just gathers ports/candidates,
and P2PTransportChannel decides which ones to use.

[Taylor Brandstetter, 2016/06/29 22:15:24]

Actually I take this back. It may be fine as is. One advantage of having the
PortAllocator filter ports is that it can stop allocating ports it realizes it
no longer needs, saving packets. And if this is standardized, it very well may
be an option on the IceGatherer, not the IceTransport. So it's probably fine to
leave it the way it is. Hopefully you haven't already started changing it, or
I'd feel really bad...

[honghaiz3, 2016/06/29 22:53:29]

I haven't done that yet. 
I think there is benefit to do it here as you pointed out. 
Plus, it is more natural to do it here because PortAllocator manages ports. 

 
   virtual uint32_t generation() { return generation_; }
   virtual void set_generation(uint32_t generation) { generation_ = generation; }
@@ -253,7 +258,8 @@ class PortAllocator : public sigslot::has_slots<> {
   // pooled sessions will be either created or destroyed as necessary.
   void SetConfiguration(const ServerAddresses& stun_servers,
                         const std::vector<RelayServerConfig>& turn_servers,
-                        int candidate_pool_size);
+                        int candidate_pool_size,
+                        bool prune_turn_ports);
 
   const ServerAddresses& stun_servers() const { return stun_servers_; }
 
@@ -327,6 +333,8 @@ class PortAllocator : public sigslot::has_slots<> {
     candidate_filter_ = filter;
   }
 
+  bool prune_turn_ports() const { return prune_turn_ports_; }
+
   // Gets/Sets the Origin value used for WebRTC STUN requests.
   const std::string& origin() const { return origin_; }
   void set_origin(const std::string& origin) { origin_ = origin; }
@@ -357,6 +365,7 @@ class PortAllocator : public sigslot::has_slots<> {
   // both owned by this class and taken by TakePooledSession.
   int allocated_pooled_session_count_ = 0;
   std::deque<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
+  bool prune_turn_ports_;
 };
 
 }  // namespace cricket