mysql_async/conn/
stmt_cache.rs

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1// Copyright (c) 2017 Anatoly Ikorsky
2//
3// Licensed under the Apache License, Version 2.0
4// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT
5// license <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. All files in the project carrying such notice may not be copied,
7// modified, or distributed except according to those terms.
8
9use lru::LruCache;
10use twox_hash::XxHash64;
11
12use std::{
13    borrow::Borrow,
14    collections::HashMap,
15    hash::{BuildHasherDefault, Hash},
16    sync::Arc,
17};
18
19use crate::queryable::stmt::StmtInner;
20
21#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
22pub struct QueryString(pub Arc<[u8]>);
23
24impl Borrow<[u8]> for QueryString {
25    fn borrow(&self) -> &[u8] {
26        self.0.as_ref()
27    }
28}
29
30impl PartialEq<[u8]> for QueryString {
31    fn eq(&self, other: &[u8]) -> bool {
32        self.0.as_ref() == other
33    }
34}
35
36pub struct Entry {
37    pub stmt: Arc<StmtInner>,
38    pub query: QueryString,
39}
40
41#[derive(Debug)]
42pub struct StmtCache {
43    cap: usize,
44    cache: LruCache<u32, Entry>,
45    query_map: HashMap<QueryString, u32, BuildHasherDefault<XxHash64>>,
46}
47
48impl StmtCache {
49    pub fn new(cap: usize) -> Self {
50        Self {
51            cap,
52            cache: LruCache::unbounded(),
53            query_map: Default::default(),
54        }
55    }
56
57    pub fn by_query<T>(&mut self, query: &T) -> Option<&Entry>
58    where
59        QueryString: Borrow<T>,
60        QueryString: PartialEq<T>,
61        T: Hash + Eq,
62        T: ?Sized,
63    {
64        let id = self.query_map.get(query).cloned();
65        match id {
66            Some(id) => self.cache.get(&id),
67            None => None,
68        }
69    }
70
71    pub fn put(&mut self, query: Arc<[u8]>, stmt: Arc<StmtInner>) -> Option<Arc<StmtInner>> {
72        if self.cap == 0 {
73            return None;
74        }
75
76        let query = QueryString(query);
77
78        self.query_map.insert(query.clone(), stmt.id());
79        self.cache.put(stmt.id(), Entry { stmt, query });
80
81        if self.cache.len() > self.cap {
82            if let Some((_, entry)) = self.cache.pop_lru() {
83                self.query_map.remove(entry.query.0.as_ref());
84                return Some(entry.stmt);
85            }
86        }
87
88        None
89    }
90
91    pub fn clear(&mut self) {
92        self.query_map.clear();
93        self.cache.clear();
94    }
95
96    pub fn remove(&mut self, id: u32) {
97        if let Some(entry) = self.cache.pop(&id) {
98            self.query_map.remove::<[u8]>(entry.query.borrow());
99        }
100    }
101
102    #[cfg(test)]
103    pub fn iter(&self) -> impl Iterator<Item = (&u32, &Entry)> {
104        self.cache.iter()
105    }
106
107    #[cfg(test)]
108    pub fn len(&self) -> usize {
109        self.cache.len()
110    }
111}
112
113impl super::Conn {
114    #[cfg(test)]
115    pub(crate) fn stmt_cache_ref(&self) -> &StmtCache {
116        &self.inner.stmt_cache
117    }
118
119    pub(crate) fn stmt_cache_mut(&mut self) -> &mut StmtCache {
120        &mut self.inner.stmt_cache
121    }
122
123    /// Caches the given statement.
124    ///
125    /// Returns LRU statement on cache capacity overflow.
126    pub(crate) fn cache_stmt(&mut self, stmt: &Arc<StmtInner>) -> Option<Arc<StmtInner>> {
127        let query = stmt.raw_query.clone();
128        if self.inner.opts.stmt_cache_size() > 0 {
129            self.stmt_cache_mut().put(query, stmt.clone())
130        } else {
131            None
132        }
133    }
134
135    /// Returns statement, if cached.
136    ///
137    /// `raw_query` is the query with `?` placeholders (not with `:<name>` placeholders).
138    pub(crate) fn get_cached_stmt(&mut self, raw_query: &[u8]) -> Option<Arc<StmtInner>> {
139        self.stmt_cache_mut()
140            .by_query(raw_query)
141            .map(|entry| entry.stmt.clone())
142    }
143}
mysql_async/conn/stmt_cache.rs

mysql_async/conn/
stmt_cache.rs
