single_request_host_resolver.h revision 2a99a7e74a7f215066514fe81d2bfa6639d9eddd 
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 "net/dns/host_resolver.h"
9
10namespace net {
11
12// This class represents the task of resolving a hostname (or IP address
13// literal) to an AddressList object.  It wraps HostResolver to resolve only a
14// single hostname at a time and cancels this request when going out of scope.
15class NET_EXPORT SingleRequestHostResolver {
16 public:
17  // |resolver| must remain valid for the lifetime of |this|.
18  explicit SingleRequestHostResolver(HostResolver* resolver);
19
20  // If a completion callback is pending when the resolver is destroyed, the
21  // host resolution is cancelled, and the completion callback will not be
22  // called.
23  ~SingleRequestHostResolver();
24
25  // Resolves the given hostname (or IP address literal), filling out the
26  // |addresses| object upon success. See HostResolver::Resolve() for details.
27  int Resolve(const HostResolver::RequestInfo& info,
28              AddressList* addresses,
29              const CompletionCallback& callback,
30              const BoundNetLog& net_log);
31
32  // Cancels the in-progress request, if any. This prevents the callback
33  // from being invoked. Resolve() can be called again after cancelling.
34  void Cancel();
35
36 private:
37  // Callback for when the request to |resolver_| completes, so we dispatch
38  // to the user's callback.
39  void OnResolveCompletion(int result);
40
41  // The actual host resolver that will handle the request.
42  HostResolver* const resolver_;
43
44  // The current request (if any).
45  HostResolver::RequestHandle cur_request_;
46  CompletionCallback cur_request_callback_;
47
48  // Completion callback for when request to |resolver_| completes.
49  CompletionCallback callback_;
50
51  DISALLOW_COPY_AND_ASSIGN(SingleRequestHostResolver);
52};
53
54}  // namespace net
55
56#endif  // NET_DNS_SINGLE_REQUEST_HOST_RESOLVER_H_
57