go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/logdog/server/collector/coordinator/doc.go (about)

     1  // Copyright 2016 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package coordinator implements a minimal interface to the Coordinator service
    16  // that is sufficient for Collector usage.
    17  //
    18  // The interface also serves as an API abstraction boundary between the current
    19  // Coordinator service definition and the Collector's logic.
    20  //
    21  // # Cache
    22  //
    23  // Coordinator methods are called very heavily during Collector operation. In
    24  // production, the Coordinator instance should be wrapped in a Cache structure
    25  // to locally cache Coordinator's known state.
    26  //
    27  // The cache is responsible for two things: Firstly, it coalesces multiple
    28  // pending requests for the same stream state into a single Coordinator request.
    29  // Secondly, it maintains a cache of completed responses to short-circuit the
    30  // Coordinator.
    31  //
    32  // Stream state is stored internally as a Promise. This Promise is evaluated by
    33  // querying the Coordinator. This interface is hidden to callers.
    34  package coordinator