lsm_tree/
descriptor_table.rs

1// Copyright (c) 2025-present, fjall-rs
2// This source code is licensed under both the Apache 2.0 and MIT License
3// (found in the LICENSE-* files in the repository)
4
5use crate::GlobalSegmentId;
6use quick_cache::{sync::Cache as QuickCache, UnitWeighter};
7use std::{fs::File, sync::Arc};
8
9const TAG_BLOCK: u8 = 0;
10const TAG_BLOB: u8 = 1;
11
12type Item = Arc<File>;
13
14#[derive(Eq, std::hash::Hash, PartialEq)]
15struct CacheKey(u8, u64, u64);
16
17/// Caches file descriptors to disk segments and blob files
18pub struct DescriptorTable {
19    inner: QuickCache<CacheKey, Item, UnitWeighter, rustc_hash::FxBuildHasher>,
20}
21
22impl DescriptorTable {
23    #[must_use]
24    pub fn new(capacity: usize) -> Self {
25        use quick_cache::sync::DefaultLifecycle;
26
27        #[allow(clippy::default_trait_access)]
28        let quick_cache = QuickCache::with(
29            1_000,
30            capacity as u64,
31            UnitWeighter,
32            Default::default(),
33            DefaultLifecycle::default(),
34        );
35
36        Self { inner: quick_cache }
37    }
38
39    #[doc(hidden)]
40    pub fn clear(&self) {
41        self.inner.clear();
42    }
43
44    #[must_use]
45    pub fn access_for_table(&self, id: &GlobalSegmentId) -> Option<Arc<File>> {
46        let key = CacheKey(TAG_BLOCK, id.tree_id(), id.segment_id());
47        self.inner.get(&key)
48    }
49
50    pub fn insert_for_table(&self, id: GlobalSegmentId, item: Item) {
51        let key = CacheKey(TAG_BLOCK, id.tree_id(), id.segment_id());
52        self.inner.insert(key, item);
53    }
54
55    #[must_use]
56    pub fn access_for_blob_file(&self, id: &GlobalSegmentId) -> Option<Arc<File>> {
57        let key = CacheKey(TAG_BLOB, id.tree_id(), id.segment_id());
58        self.inner.get(&key)
59    }
60
61    pub fn insert_for_blob_file(&self, id: GlobalSegmentId, item: Item) {
62        let key = CacheKey(TAG_BLOB, id.tree_id(), id.segment_id());
63        self.inner.insert(key, item);
64    }
65}
lsm_tree/descriptor_table.rs

lsm_tree/
descriptor_table.rs
