| // Copyright 2016 The LUCI Authors. |
| // |
| // 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. |
| |
| // Package coordinator implements a minimal interface to the Coordinator service |
| // that is sufficient for Collector usage. |
| // |
| // The interface also serves as an API abstraction boundary between the current |
| // Coordinator service definition and the Collector's logic. |
| // |
| // # Cache |
| // |
| // Coordinator methods are called very heavily during Collector operation. In |
| // production, the Coordinator instance should be wrapped in a Cache structure |
| // to locally cache Coordinator's known state. |
| // |
| // The cache is responsible for two things: Firstly, it coalesces multiple |
| // pending requests for the same stream state into a single Coordinator request. |
| // Secondly, it maintains a cache of completed responses to short-circuit the |
| // Coordinator. |
| // |
| // Stream state is stored internally as a Promise. This Promise is evaluated by |
| // querying the Coordinator. This interface is hidden to callers. |
| package coordinator |
