base/supports_user_data.cc

   1 // Copyright (c) 2012 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 "base/supports_user_data.h"
   6
   7 namespace base {
   8
   9 SupportsUserData::SupportsUserData() {
  10   // Harmless to construct on a different execution sequence to subsequent
  11   // usage.
  12   sequence_checker_.DetachFromSequence();
  13 }
  14
  15 SupportsUserData::Data* SupportsUserData::GetUserData(const void* key) const {
  16   DCHECK(sequence_checker_.CalledOnValidSequence());
  17   // Avoid null keys; they are too vulnerable to collision.
  18   DCHECK(key);
  19   DataMap::const_iterator found = user_data_.find(key);
  20   if (found != user_data_.end())
  21     return found->second.get();
  22   return nullptr;
  23 }
  24
  25 void SupportsUserData::SetUserData(const void* key,
  26                                    std::unique_ptr<Data> data) {
  27   DCHECK(sequence_checker_.CalledOnValidSequence());
  28   // Avoid null keys; they are too vulnerable to collision.
  29   DCHECK(key);
  30   user_data_[key] = std::move(data);
  31 }
  32
  33 void SupportsUserData::RemoveUserData(const void* key) {
  34   DCHECK(sequence_checker_.CalledOnValidSequence());
  35   user_data_.erase(key);
  36 }
  37
  38 void SupportsUserData::DetachFromSequence() {
  39   sequence_checker_.DetachFromSequence();
  40 }
  41
  42 SupportsUserData::~SupportsUserData() {
  43   DCHECK(sequence_checker_.CalledOnValidSequence() || user_data_.empty());
  44   DataMap local_user_data;
  45   user_data_.swap(local_user_data);
  46   // Now this->user_data_ is empty, and any destructors called transitively from
  47   // the destruction of |local_user_data| will see it that way instead of
  48   // examining a being-destroyed object.
  49 }
  50
  51 }  // namespace base