| // Copyright (C) 2013 Google Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "retriever.h" |
| |
| #include <libaddressinput/callback.h> |
| #include <libaddressinput/source.h> |
| #include <libaddressinput/storage.h> |
| #include <libaddressinput/util/basictypes.h> |
| #include <libaddressinput/util/scoped_ptr.h> |
| |
| #include <cassert> |
| #include <cstddef> |
| #include <string> |
| |
| #include "validating_storage.h" |
| |
| namespace i18n { |
| namespace addressinput { |
| |
| namespace { |
| |
| class Helper { |
| public: |
| // Does not take ownership of its parameters. |
| Helper(const std::string& key, |
| const Retriever::Callback& retrieved, |
| const Source& source, |
| ValidatingStorage* storage) |
| : retrieved_(retrieved), |
| source_(source), |
| storage_(storage), |
| fresh_data_ready_(BuildCallback(this, &Helper::OnFreshDataReady)), |
| validated_data_ready_( |
| BuildCallback(this, &Helper::OnValidatedDataReady)), |
| stale_data_() { |
| assert(storage_ != NULL); |
| storage_->Get(key, *validated_data_ready_); |
| } |
| |
| private: |
| ~Helper() {} |
| |
| void OnValidatedDataReady(bool success, |
| const std::string& key, |
| std::string* data) { |
| if (success) { |
| assert(data != NULL); |
| retrieved_(success, key, *data); |
| delete this; |
| } else { |
| // Validating storage returns (false, key, stale-data) for valid but stale |
| // data. If |data| is empty, however, then it's either missing or invalid. |
| if (data != NULL && !data->empty()) { |
| stale_data_ = *data; |
| } |
| source_.Get(key, *fresh_data_ready_); |
| } |
| delete data; |
| } |
| |
| void OnFreshDataReady(bool success, |
| const std::string& key, |
| std::string* data) { |
| if (success) { |
| assert(data != NULL); |
| retrieved_(true, key, *data); |
| storage_->Put(key, data); |
| data = NULL; // Deleted by Storage::Put(). |
| } else if (!stale_data_.empty()) { |
| // Reuse the stale data if a download fails. It's better to have slightly |
| // outdated validation rules than to suddenly lose validation ability. |
| retrieved_(true, key, stale_data_); |
| } else { |
| retrieved_(false, key, std::string()); |
| } |
| delete data; |
| delete this; |
| } |
| |
| const Retriever::Callback& retrieved_; |
| const Source& source_; |
| ValidatingStorage* storage_; |
| const scoped_ptr<const Source::Callback> fresh_data_ready_; |
| const scoped_ptr<const Storage::Callback> validated_data_ready_; |
| std::string stale_data_; |
| |
| DISALLOW_COPY_AND_ASSIGN(Helper); |
| }; |
| |
| } // namespace |
| |
| Retriever::Retriever(const Source* source, Storage* storage) |
| : source_(source), storage_(new ValidatingStorage(storage)) { |
| assert(source_ != NULL); |
| assert(storage_ != NULL); |
| } |
| |
| Retriever::~Retriever() {} |
| |
| void Retriever::Retrieve(const std::string& key, |
| const Callback& retrieved) const { |
| new Helper(key, retrieved, *source_, storage_.get()); |
| } |
| |
| } // namespace addressinput |
| } // namespace i18n |