Makes migration on write error asynchronous to avoid reentrancy issues

net/quic/chromium/quic_chromium_client_session.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // A client specific QuicSession subclass.  This class owns the underlying
 // QuicConnection and QuicConnectionHelper objects.  The connection stores
 // a non-owning pointer to the helper so this session needs to ensure that
 // the helper outlives the connection.
 
 #ifndef NET_QUIC_QUIC_CHROMIUM_CLIENT_SESSION_H_
@@ skipping 235 matching lines @@
 
   // Returns true if |hostname| may be pooled onto this session.  If this
   // is a secure QUIC session, then |hostname| must match the certificate
   // presented during the handshake.
   bool CanPool(const std::string& hostname, PrivacyMode privacy_mode) const;
 
   const QuicServerId& server_id() const { return server_id_; }
 
   QuicDisabledReason disabled_reason() const { return disabled_reason_; }
 
+  // Attempts to migrate session when a write error is encountered.
+  void MigrateSessionOnWriteError();
+
+  // Helper method that writes a packet on the new socket after
+  // migration completes. If not null, the packet_ member is written,
+  // otherwise a PING packet is written.
+  void WriteToNewSocket();
+
   // Migrates session onto new socket, i.e., starts reading from
   // |socket| in addition to any previous sockets, and sets |writer|
   // to be the new default writer. Returns true if socket was
   // successfully added to the session and the session was
-  // successfully migrated to using the new socket. If not null,
-  // |packet| is sent on the new network, else a PING frame is
-  // sent. Returns true on successful migration, or false if number of
-  // migrations exceeds kMaxReadersPerQuicSession.  Takes ownership of
-  // |socket|, |reader|, and |writer|.
+  // successfully migrated to using the new socket. Returns true on
+  // successful migration, or false if number of migrations exceeds
+  // kMaxReadersPerQuicSession. Takes ownership of |socket|, |reader|,
+  // and |writer|.
   bool MigrateToSocket(std::unique_ptr<DatagramClientSocket> socket,
                        std::unique_ptr<QuicChromiumPacketReader> reader,
-                       std::unique_ptr<QuicChromiumPacketWriter> writer,
-                       scoped_refptr<StringIOBuffer> packet);
+                       std::unique_ptr<QuicChromiumPacketWriter> writer);
 
   // Populates network error details for this session.
   void PopulateNetErrorDetails(NetErrorDetails* details);
 
   // Returns current default socket. This is the socket over which all
   // QUIC packets are sent. This default socket can change, so do not store the
   // returned socket.
   const DatagramClientSocket* GetDefaultSocket() const;
 
   bool IsAuthorized(const std::string& hostname) override;
@@ skipping 79 matching lines @@
   // True when the session is going away, and streams may no longer be created
   // on this session. Existing stream will continue to be processed.
   bool going_away_;
   // True when the session receives a go away from server due to port migration.
   bool port_migration_detected_;
   QuicDisabledReason disabled_reason_;
   TokenBindingSignatureMap token_binding_signatures_;
   // UMA histogram counters for streams pushed to this session.
   int streams_pushed_count_;
   int streams_pushed_and_claimed_count_;
-  // Return value from packet rewrite packet on new socket. Used
-  // during connection migration on socket write error.
-  int error_code_from_rewrite_;
-  bool use_error_code_from_rewrite_;
+  // Stores packet that witnesses socket write error. This packet is
+  // written to a new socket after migration completes.
+  scoped_refptr<StringIOBuffer> packet_;
+  // TODO(jri): Replace use of migration_pending_ sockets_.size().
+  // When a task is posted for MigrateSessionOnError, pass in
+  // sockets_.size(). Then in MigrateSessionOnError, check to see if
+  // the current sockets_.size() == the passed in value.
+  bool migration_pending_;  // True while migration is underway.
   base::WeakPtrFactory<QuicChromiumClientSession> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicChromiumClientSession);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CHROMIUM_CLIENT_SESSION_H_