| // Copyright 2015 The Weave Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/states/state_change_queue.h" |
| |
| #include <base/logging.h> |
| |
| namespace weave { |
| |
| StateChangeQueue::StateChangeQueue(size_t max_queue_size) |
| : max_queue_size_(max_queue_size) { |
| CHECK_GT(max_queue_size_, 0U) << "Max queue size must not be zero"; |
| } |
| |
| bool StateChangeQueue::NotifyPropertiesUpdated( |
| base::Time timestamp, |
| const base::DictionaryValue& changed_properties) { |
| auto& stored_changes = state_changes_[timestamp]; |
| // Merge the old property set. |
| if (stored_changes) |
| stored_changes->MergeDictionary(&changed_properties); |
| else |
| stored_changes.reset(changed_properties.DeepCopy()); |
| |
| while (state_changes_.size() > max_queue_size_) { |
| // Queue is full. |
| // Merge the two oldest records into one. The merge strategy is: |
| // - Move non-existent properties from element [old] to [new]. |
| // - If both [old] and [new] specify the same property, |
| // keep the value of [new]. |
| // - Keep the timestamp of [new]. |
| auto element_old = state_changes_.begin(); |
| auto element_new = std::next(element_old); |
| // This will skip elements that exist in both [old] and [new]. |
| element_old->second->MergeDictionary(element_new->second.get()); |
| std::swap(element_old->second, element_new->second); |
| state_changes_.erase(element_old); |
| } |
| return true; |
| } |
| |
| std::vector<StateChange> StateChangeQueue::GetAndClearRecordedStateChanges() { |
| std::vector<StateChange> changes; |
| changes.reserve(state_changes_.size()); |
| for (auto& pair : state_changes_) { |
| changes.push_back(StateChange{pair.first, std::move(pair.second)}); |
| } |
| state_changes_.clear(); |
| return changes; |
| } |
| |
| } // namespace weave |