DNS: Per-network-type and Finch-variable timeouts

net/dns/dns_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.
 
 #ifndef NET_DNS_DNS_SESSION_H_
 #define NET_DNS_DNS_SESSION_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/bucket_ranges.h"
 #include "base/time/time.h"
 #include "net/base/net_export.h"
+#include "net/base/network_change_notifier.h"
 #include "net/base/rand_callback.h"
 #include "net/dns/dns_config_service.h"
 #include "net/dns/dns_socket_pool.h"
 
 namespace base {
 class BucketRanges;
 class SampleVector;
 }
 
 namespace net {
 
 class ClientSocketFactory;
 class DatagramClientSocket;
 class NetLog;
 class StreamSocket;
 
 // Session parameters and state shared between DNS transactions.
 // Ref-counted so that DnsClient::Request can keep working in absence of
 // DnsClient. A DnsSession must be recreated when DnsConfig changes.
 class NET_EXPORT_PRIVATE DnsSession
-    : NON_EXPORTED_BASE(public base::RefCounted<DnsSession>) {
+    : NON_EXPORTED_BASE(public base::RefCounted<DnsSession>),
+      public NetworkChangeNotifier::ConnectionTypeObserver {
  public:
   typedef base::Callback<int()> RandCallback;
 
   class NET_EXPORT_PRIVATE SocketLease {
    public:
     SocketLease(scoped_refptr<DnsSession> session,
                 unsigned server_index,
                 scoped_ptr<DatagramClientSocket> socket);
     ~SocketLease();
 
@@ skipping 53 matching lines @@
   scoped_ptr<SocketLease> AllocateSocket(unsigned server_index,
                                          const NetLog::Source& source);
 
   // Creates a StreamSocket from the factory for a transaction over TCP. These
   // sockets are not pooled.
   scoped_ptr<StreamSocket> CreateTCPSocket(unsigned server_index,
                                            const NetLog::Source& source);
 
  private:
   friend class base::RefCounted<DnsSession>;
-  ~DnsSession();
+  ~DnsSession() override;
+
+  void UpdateTimeouts(NetworkChangeNotifier::ConnectionType type);
+  void InitializeServerStats();
 
   // Release a socket.
   void FreeSocket(unsigned server_index,
                   scoped_ptr<DatagramClientSocket> socket);
 
   // Return the timeout using the TCP timeout method.
   base::TimeDelta NextTimeoutFromJacobson(unsigned server_index, int attempt);
 
   // Compute the timeout using the histogram method.
   base::TimeDelta NextTimeoutFromHistogram(unsigned server_index, int attempt);
 
+  // NetworkChangeNotifier::ConnectionTypeObserver:
+  void OnConnectionTypeChanged(
+      NetworkChangeNotifier::ConnectionType type) override;
+
   const DnsConfig config_;
   scoped_ptr<DnsSocketPool> socket_pool_;
   RandCallback rand_callback_;
   NetLog* net_log_;
 
   // Current index into |config_.nameservers| to begin resolution with.
   int server_index_;
 
+  base::TimeDelta initial_timeout_;
+  base::TimeDelta max_timeout_;
+
   struct ServerStats;
 
   // Track runtime statistics of each DNS server.
   std::vector<scoped_ptr<ServerStats>> server_stats_;
 
   // Buckets shared for all |ServerStats::rtt_histogram|.
   struct RttBuckets : public base::BucketRanges {
     RttBuckets();
   };
   static base::LazyInstance<RttBuckets>::Leaky rtt_buckets_;
 
   DISALLOW_COPY_AND_ASSIGN(DnsSession);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_DNS_SESSION_H_