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      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 
     10 namespace 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.
     15 class 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