kvsd 0.1.3

Simple key value store
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

use std::borrow::Borrow;
use std::collections::HashMap;
use std::hash::Hash;

use tokio::io::AsyncReadExt;

use crate::common::Result;
use crate::core::table::entry::Entry;

#[derive(Debug)]
pub(super) struct Index {
    // key to file offset mapping.
    entry_offsets: HashMap<String, usize>,
}

impl Index {
    pub(super) async fn from_reader<R: AsyncReadExt + Unpin>(mut reader: R) -> Result<Self> {
        let mut entries = HashMap::new();
        let mut pos: usize = 0;
        loop {
            match Entry::decode_from(&mut reader).await {
                Ok((n, entry)) => {
                    // Ignore deleted entry
                    if entry.is_active() {
                        entries.insert(entry.take_key(), pos);
                    } else {
                        // Remove as there should be entry left before deleted
                        entries.remove(entry.take_key().as_str());
                    }
                    pos = pos.checked_add(n).unwrap();
                }
                Err(err) if err.is_eof() => {
                    return Ok(Index::new(entries));
                }
                Err(err) => {
                    return Err(err);
                }
            }
        }
    }
    pub(super) fn add(&mut self, key: String, offset: usize) -> Option<usize> {
        self.entry_offsets.insert(key, offset)
    }

    pub(super) fn remove<Q>(&mut self, k: &Q) -> Option<usize>
    where
        String: Borrow<Q>,
        Q: Hash + Eq + ?Sized,
    {
        self.entry_offsets.remove(k)
    }

    pub(super) fn lookup_offset(&self, key: &str) -> Option<usize> {
        self.entry_offsets.get(key).cloned()
    }

    fn new(entry_offsets: HashMap<String, usize>) -> Self {
        Self { entry_offsets }
    }
}