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

common_session/
lib.rs
