net/dns/single_request_host_resolver.cc

   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 #include "net/dns/single_request_host_resolver.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/logging.h"
  11 #include "net/base/net_errors.h"
  12
  13 namespace net {
  14
  15 SingleRequestHostResolver::SingleRequestHostResolver(HostResolver* resolver)
  16     : resolver_(resolver),
  17       cur_request_(NULL),
  18       callback_(
  19           base::Bind(&SingleRequestHostResolver::OnResolveCompletion,
  20                      base::Unretained(this))) {
  21   DCHECK(resolver_ != NULL);
  22 }
  23
  24 SingleRequestHostResolver::~SingleRequestHostResolver() {
  25   Cancel();
  26 }
  27
  28 int SingleRequestHostResolver::Resolve(const HostResolver::RequestInfo& info,
  29                                        RequestPriority priority,
  30                                        AddressList* addresses,
  31                                        const CompletionCallback& callback,
  32                                        const BoundNetLog& net_log) {
  33   DCHECK(addresses);
  34   DCHECK_EQ(false, callback.is_null());
  35   DCHECK(cur_request_callback_.is_null()) << "resolver already in use";
  36
  37   HostResolver::RequestHandle request = NULL;
  38
  39   // We need to be notified of completion before |callback| is called, so that
  40   // we can clear out |cur_request_*|.
  41   CompletionCallback transient_callback =
  42       callback.is_null() ? CompletionCallback() : callback_;
  43
  44   int rv = resolver_->Resolve(
  45       info, priority, addresses, transient_callback, &request, net_log);
  46
  47   if (rv == ERR_IO_PENDING) {
  48     DCHECK_EQ(false, callback.is_null());
  49     // Cleared in OnResolveCompletion().
  50     cur_request_ = request;
  51     cur_request_callback_ = callback;
  52   }
  53
  54   return rv;
  55 }
  56
  57 void SingleRequestHostResolver::Cancel() {
  58   if (!cur_request_callback_.is_null()) {
  59     resolver_->CancelRequest(cur_request_);
  60     cur_request_ = NULL;
  61     cur_request_callback_.Reset();
  62   }
  63 }
  64
  65 void SingleRequestHostResolver::OnResolveCompletion(int result) {
  66   DCHECK(cur_request_);
  67   DCHECK_EQ(false, cur_request_callback_.is_null());
  68
  69   CompletionCallback callback = cur_request_callback_;
  70
  71   // Clear the outstanding request information.
  72   cur_request_ = NULL;
  73   cur_request_callback_.Reset();
  74
  75   // Call the user's original callback.
  76   callback.Run(result);
  77 }
  78
  79 }  // namespace net