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 "base/profiler/scoped_tracker.h"
  12 #include "net/base/net_errors.h"
  13
  14 namespace net {
  15
  16 SingleRequestHostResolver::SingleRequestHostResolver(HostResolver* resolver)
  17     : resolver_(resolver),
  18       cur_request_(NULL),
  19       callback_(
  20           base::Bind(&SingleRequestHostResolver::OnResolveCompletion,
  21                      base::Unretained(this))) {
  22   DCHECK(resolver_ != NULL);
  23 }
  24
  25 SingleRequestHostResolver::~SingleRequestHostResolver() {
  26   Cancel();
  27 }
  28
  29 int SingleRequestHostResolver::Resolve(const HostResolver::RequestInfo& info,
  30                                        RequestPriority priority,
  31                                        AddressList* addresses,
  32                                        const CompletionCallback& callback,
  33                                        const BoundNetLog& net_log) {
  34   DCHECK(addresses);
  35   DCHECK_EQ(false, callback.is_null());
  36   DCHECK(cur_request_callback_.is_null()) << "resolver already in use";
  37
  38   HostResolver::RequestHandle request = NULL;
  39
  40   // We need to be notified of completion before |callback| is called, so that
  41   // we can clear out |cur_request_*|.
  42   CompletionCallback transient_callback =
  43       callback.is_null() ? CompletionCallback() : callback_;
  44
  45   int rv = resolver_->Resolve(
  46       info, priority, addresses, transient_callback, &request, net_log);
  47
  48   if (rv == ERR_IO_PENDING) {
  49     DCHECK_EQ(false, callback.is_null());
  50     // Cleared in OnResolveCompletion().
  51     cur_request_ = request;
  52     cur_request_callback_ = callback;
  53   }
  54
  55   return rv;
  56 }
  57
  58 void SingleRequestHostResolver::Cancel() {
  59   if (!cur_request_callback_.is_null()) {
  60     resolver_->CancelRequest(cur_request_);
  61     cur_request_ = NULL;
  62     cur_request_callback_.Reset();
  63   }
  64 }
  65
  66 void SingleRequestHostResolver::OnResolveCompletion(int result) {
  67   // TODO(vadimt): Remove ScopedTracker below once crbug.com/436634 is fixed.
  68   tracked_objects::ScopedTracker tracking_profile(
  69       FROM_HERE_WITH_EXPLICIT_FUNCTION(
  70           "436634 SingleRequestHostResolver::OnResolveCompletion"));
  71
  72   DCHECK(cur_request_);
  73   DCHECK_EQ(false, cur_request_callback_.is_null());
  74
  75   CompletionCallback callback = cur_request_callback_;
  76
  77   // Clear the outstanding request information.
  78   cur_request_ = NULL;
  79   cur_request_callback_.Reset();
  80
  81   // Call the user's original callback.
  82   callback.Run(result);
  83 }
  84
  85 }  // namespace net