net/dns/dns_socket_pool.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_DNS_DNS_SOCKET_POOL_H_
   6 #define NET_DNS_DNS_SOCKET_POOL_H_
   7
   8 #include <vector>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "net/base/net_export.h"
  12 #include "net/log/net_log.h"
  13
  14 namespace net {
  15
  16 class ClientSocketFactory;
  17 class DatagramClientSocket;
  18 class IPEndPoint;
  19 class NetLog;
  20 class StreamSocket;
  21
  22 // A DnsSocketPool is an abstraction layer around a ClientSocketFactory that
  23 // allows preallocation, reuse, or other strategies to manage sockets connected
  24 // to DNS servers.
  25 class NET_EXPORT_PRIVATE DnsSocketPool {
  26  public:
  27   virtual ~DnsSocketPool() { }
  28
  29   // Creates a DnsSocketPool that implements the default strategy for managing
  30   // sockets.  (This varies by platform; see DnsSocketPoolImpl in
  31   // dns_socket_pool.cc for details.)
  32   static scoped_ptr<DnsSocketPool> CreateDefault(
  33       ClientSocketFactory* factory);
  34
  35   // Creates a DnsSocketPool that implements a "null" strategy -- no sockets are
  36   // preallocated, allocation requests are satisfied by calling the factory
  37   // directly, and returned sockets are deleted immediately.
  38   static scoped_ptr<DnsSocketPool> CreateNull(
  39       ClientSocketFactory* factory);
  40
  41   // Initializes the DnsSocketPool.  |nameservers| is the list of nameservers
  42   // for which the DnsSocketPool will manage sockets; |net_log| is the NetLog
  43   // used when constructing sockets with the factory.
  44   //
  45   // Initialize may not be called more than once, and must be called before
  46   // calling AllocateSocket or FreeSocket.
  47   virtual void Initialize(
  48       const std::vector<IPEndPoint>* nameservers,
  49       NetLog* net_log) = 0;
  50
  51   // Allocates a socket that is already connected to the nameserver referenced
  52   // by |server_index|.  May return a scoped_ptr to NULL if no sockets are
  53   // available to reuse and the factory fails to produce a socket (or produces
  54   // one on which Connect fails).
  55   virtual scoped_ptr<DatagramClientSocket> AllocateSocket(
  56       unsigned server_index) = 0;
  57
  58   // Frees a socket allocated by AllocateSocket.  |server_index| must be the
  59   // same index passed to AllocateSocket.
  60   virtual void FreeSocket(
  61       unsigned server_index,
  62       scoped_ptr<DatagramClientSocket> socket) = 0;
  63
  64   // Creates a StreamSocket from the factory for a transaction over TCP. These
  65   // sockets are not pooled.
  66   scoped_ptr<StreamSocket> CreateTCPSocket(
  67       unsigned server_index,
  68       const NetLog::Source& source);
  69
  70  protected:
  71   DnsSocketPool(ClientSocketFactory* socket_factory);
  72
  73   void InitializeInternal(
  74       const std::vector<IPEndPoint>* nameservers,
  75       NetLog* net_log);
  76
  77   scoped_ptr<DatagramClientSocket> CreateConnectedSocket(
  78       unsigned server_index);
  79
  80  private:
  81   ClientSocketFactory* socket_factory_;
  82   NetLog* net_log_;
  83   const std::vector<IPEndPoint>* nameservers_;
  84   bool initialized_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(DnsSocketPool);
  87 };
  88
  89 } // namespace net
  90
  91 #endif // NET_DNS_DNS_SOCKET_POOL_H_