| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 "value_schema_manager.h" |
| #include "value_schema_v0.h" |
| #include "value_schema_v1.h" |
| #include "value_schema_v2.h" |
| |
| namespace pegasus { |
| value_schema_manager::value_schema_manager() |
| { |
| /** |
| * If someone wants to add a new data version, he only need to implement the new value schema, |
| * and register it here. |
| */ |
| register_schema(dsn::make_unique<value_schema_v0>()); |
| register_schema(dsn::make_unique<value_schema_v1>()); |
| register_schema(dsn::make_unique<value_schema_v2>()); |
| } |
| |
| void value_schema_manager::register_schema(std::unique_ptr<value_schema> schema) |
| { |
| _schemas[schema->version()] = std::move(schema); |
| } |
| |
| value_schema *value_schema_manager::get_value_schema(uint32_t meta_cf_data_version, |
| dsn::string_view value) const |
| { |
| dsn::data_input input(value); |
| uint8_t first_byte = input.read_u8(); |
| // first bit = 1 means the data version is >= VERSION_2 |
| if (first_byte & 0x80) { |
| // In order to keep backward compatibility, we should return latest version if the data |
| // version in value is not found. In other words, it will work well in future version if it |
| // is compatible with latest version in current |
| auto schema = get_value_schema(first_byte & 0x7F); |
| if (nullptr == schema) { |
| return get_latest_value_schema(); |
| } |
| return schema; |
| } else { |
| auto schema = get_value_schema(meta_cf_data_version); |
| if (nullptr == schema) { |
| dassert_f(false, "data version({}) in meta cf is not supported", meta_cf_data_version); |
| } |
| return schema; |
| } |
| } |
| |
| value_schema *value_schema_manager::get_value_schema(uint32_t version) const |
| { |
| if (version >= _schemas.size()) { |
| return nullptr; |
| } |
| return _schemas[version].get(); |
| } |
| |
| value_schema *value_schema_manager::get_latest_value_schema() const |
| { |
| return _schemas.rbegin()->get(); |
| } |
| } // namespace pegasus |