Making candidate pool size behave as decided in JSEP.

webrtc/p2p/base/portallocator.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.
  */
 
@@ skipping 288 matching lines @@
 class PortAllocator : public sigslot::has_slots<> {
  public:
   PortAllocator() :
       flags_(kDefaultPortAllocatorFlags),
       min_port_(0),
       max_port_(0),
       step_delay_(kDefaultStepDelay),
       allow_tcp_listen_(true),
       candidate_filter_(CF_ALL) {
   }
+
   virtual ~PortAllocator() {}
 
   // This should be called on the PortAllocator's thread before the
   // PortAllocator is used. Subclasses may override this if necessary.
   virtual void Initialize() {}
 
   // Set STUN and TURN servers to be used in future sessions, and set
   // candidate pool size, as described in JSEP.
   //
-  // If the servers are changing and the candidate pool size is nonzero,
-  // existing pooled sessions will be destroyed and new ones created.
+  // If the servers are changing, and the candidate pool size is nonzero, and
+  // FreezeCandidatePool hasn't been called, existing pooled sessions will be
+  // destroyed and new ones created.
   //
-  // If the servers are not changing but the candidate pool size is,
-  // pooled sessions will be either created or destroyed as necessary.
+  // If the servers are not changing but the candidate pool size is, and
+  // FreezeCandidatePool hasn't been called, pooled sessions will be either
+  // created or destroyed as necessary.
   //
   // Returns true if the configuration could successfully be changed.
   bool SetConfiguration(const ServerAddresses& stun_servers,
                         const std::vector<RelayServerConfig>& turn_servers,
                         int candidate_pool_size,
                         bool prune_turn_ports);
 
   const ServerAddresses& stun_servers() const { return stun_servers_; }
 
   const std::vector<RelayServerConfig>& turn_servers() const {
@@ skipping 22 matching lines @@
   // If no pooled sessions are available, returns null.
   std::unique_ptr<PortAllocatorSession> TakePooledSession(
       const std::string& content_name,
       int component,
       const std::string& ice_ufrag,
       const std::string& ice_pwd);
 
   // Returns the next session that would be returned by TakePooledSession.
   const PortAllocatorSession* GetPooledSession() const;
 
+  // After FreezeCandidatePool is called, changing the candidate pool size will
+  // no longer be allowed, and changing ICE servers will not cause pooled
+  // sessions to be recreated.
+  //
+  // Expected to be called when SetLocalDescription is called on a
+  // PeerConnection. Can be called safely on any thread as long as not
+  // simultaneously with SetConfiguration.
+  void FreezeCandidatePool();
+
+  // Discard any remaining pooled sessions.
+  void DiscardCandidatePool();
+
   uint32_t flags() const { return flags_; }
   void set_flags(uint32_t flags) { flags_ = flags; }
 
   // Gets/Sets the port range to use when choosing client ports.
   int min_port() const { return min_port_; }
   int max_port() const { return max_port_; }
   bool SetPortRange(int min_port, int max_port) {
     if (min_port > max_port) {
       return false;
     }
@@ skipping 47 matching lines @@
   uint32_t step_delay_;
   bool allow_tcp_listen_;
   uint32_t candidate_filter_;
   std::string origin_;
 
  private:
   ServerAddresses stun_servers_;
   std::vector<RelayServerConfig> turn_servers_;
   int candidate_pool_size_ = 0;  // Last value passed into SetConfiguration.
   std::deque<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
+  bool candidate_pool_frozen_ = false;
   bool prune_turn_ports_ = false;
 
   webrtc::MetricsObserverInterface* metrics_observer_ = nullptr;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_PORTALLOCATOR_H_