meta_srv/selector/
lease_based.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 common_meta::affinity::AffinityFallback;
16use common_meta::peer::Peer;
17
18use crate::error::{self, Result};
19use crate::metasrv::SelectorContext;
20use crate::selector::common::{self, choose_items, filter_out_excluded_peers};
21use crate::selector::weighted_choose::{RandomWeightedChoose, WeightedItem};
22use crate::selector::{Selector, SelectorOptions};
23
24/// Select all alive datanodes based using a random weighted choose.
25#[derive(Default)]
26pub struct LeaseBasedSelector;
27
28impl LeaseBasedSelector {
29    async fn select_once(
30        &self,
31        ctx: &SelectorContext,
32        opts: &SelectorOptions<'_>,
33    ) -> Result<Vec<Peer>> {
34        // 1. get alive datanodes.
35        let alive_datanodes = common::active_schedulable_datanodes(ctx, opts.workload_filter)
36            .await?
37            .into_iter()
38            .filter(|node| {
39                opts.affinity
40                    .is_none_or(|requirements| ctx.affinity.matches(requirements, node))
41            })
42            .map(|node| node.peer)
43            .collect::<Vec<_>>();
44
45        // 2. compute weight array, but the weight of each item is the same.
46        let mut weight_array = alive_datanodes
47            .into_iter()
48            .map(|p| WeightedItem {
49                item: p,
50                weight: 1.0,
51            })
52            .collect();
53
54        // 3. choose peers by weight_array.
55        filter_out_excluded_peers(&mut weight_array, &opts.exclude_peer_ids);
56        let mut weighted_choose = RandomWeightedChoose::new(weight_array);
57        let selected = choose_items(opts, &mut weighted_choose)?;
58
59        Ok(selected)
60    }
61}
62
63#[async_trait::async_trait]
64impl Selector for LeaseBasedSelector {
65    type Context = SelectorContext;
66    type Output = Vec<Peer>;
67
68    async fn select(
69        &self,
70        ctx: &Self::Context,
71        mut opts: SelectorOptions<'_>,
72    ) -> Result<Self::Output> {
73        match self.select_once(ctx, &opts).await {
74            Err(error::Error::NoEnoughAvailableNode {
75                required,
76                available,
77                ..
78            }) if opts.affinity.is_some()
79                && ctx.affinity_fallback == AffinityFallback::Unconstrained
80                && available < required =>
81            {
82                opts.affinity = None;
83                self.select_once(ctx, &opts).await
84            }
85            result => result,
86        }
87    }
88}
meta_srv/selector/lease_based.rs

meta_srv/selector/
lease_based.rs
