net/dns/single_request_host_resolver.h

   1 // Copyright (c) 2011 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_SINGLE_REQUEST_HOST_RESOLVER_H_
   6 #define NET_DNS_SINGLE_REQUEST_HOST_RESOLVER_H_
   7
   8 #include "base/basictypes.h"
   9
  10 #include "net/base/completion_callback.h"
  11 #include "net/base/net_export.h"
  12 #include "net/base/request_priority.h"
  13 #include "net/dns/host_resolver.h"
  14
  15 namespace net {
  16
  17 class AddressList;
  18 class BoundNetLog;
  19
  20 // This class represents the task of resolving a hostname (or IP address
  21 // literal) to an AddressList object.  It wraps HostResolver to resolve only a
  22 // single hostname at a time and cancels this request when going out of scope.
  23 class NET_EXPORT SingleRequestHostResolver {
  24  public:
  25   // |resolver| must remain valid for the lifetime of |this|.
  26   explicit SingleRequestHostResolver(HostResolver* resolver);
  27
  28   // If a completion callback is pending when the resolver is destroyed, the
  29   // host resolution is cancelled, and the completion callback will not be
  30   // called.
  31   ~SingleRequestHostResolver();
  32
  33   // Resolves the given hostname (or IP address literal), filling out the
  34   // |addresses| object upon success. See HostResolver::Resolve() for details.
  35   int Resolve(const HostResolver::RequestInfo& info,
  36               RequestPriority priority,
  37               AddressList* addresses,
  38               const CompletionCallback& callback,
  39               const BoundNetLog& net_log);
  40
  41   // Cancels the in-progress request, if any. This prevents the callback
  42   // from being invoked. Resolve() can be called again after cancelling.
  43   void Cancel();
  44
  45  private:
  46   // Callback for when the request to |resolver_| completes, so we dispatch
  47   // to the user's callback.
  48   void OnResolveCompletion(int result);
  49
  50   // The actual host resolver that will handle the request.
  51   HostResolver* const resolver_;
  52
  53   // The current request (if any).
  54   HostResolver::RequestHandle cur_request_;
  55   CompletionCallback cur_request_callback_;
  56
  57   // Completion callback for when request to |resolver_| completes.
  58   CompletionCallback callback_;
  59
  60   DISALLOW_COPY_AND_ASSIGN(SingleRequestHostResolver);
  61 };
  62
  63 }  // namespace net
  64
  65 #endif  // NET_DNS_SINGLE_REQUEST_HOST_RESOLVER_H_