common_session/
lib.rs

1// Copyright 2023 Greptime Team
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
15use serde::{Deserialize, Serialize};
16use strum::{AsRefStr, Display, EnumString};
17
18/// Defines the read preference for frontend route operations,
19/// determining whether to read from the region leader or follower.
20#[derive(
21    Debug, Clone, Copy, Default, EnumString, Display, AsRefStr, PartialEq, Serialize, Deserialize,
22)]
23pub enum ReadPreference {
24    #[default]
25    // Reads all operations from the region leader. This is the default mode.
26    #[strum(serialize = "leader", to_string = "LEADER")]
27    Leader,
28}
29
30#[cfg(test)]
31mod tests {
32    use std::str::FromStr;
33
34    use crate::ReadPreference;
35
36    #[test]
37    fn test_read_preference() {
38        assert_eq!(ReadPreference::Leader.to_string(), "LEADER");
39
40        let read_preference = ReadPreference::from_str("LEADER").unwrap();
41        assert_eq!(read_preference, ReadPreference::Leader);
42
43        let read_preference = ReadPreference::from_str("leader").unwrap();
44        assert_eq!(read_preference, ReadPreference::Leader);
45
46        ReadPreference::from_str("follower").unwrap_err();
47    }
48}
common_session/lib.rs

common_session/
lib.rs
