rdb 0.3.0

Fast and efficient RDB parsing utility
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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161

use super::common::utils::{read_blob, read_exact, read_length};
use super::common::{
    read_list_pack_entry_as_string, read_list_pack_length, read_ziplist_entry_string,
    read_ziplist_metadata,
};
use crate::types::{RdbError, RdbResult, RdbValue};
use byteorder::{LittleEndian, ReadBytesExt};
use indexmap::IndexMap;
use std::io::{Cursor, Read};

pub fn read_hash<R: Read>(input: &mut R, key: &[u8], expiry: Option<u64>) -> RdbResult<RdbValue> {
    let mut hash_items = read_length(input)?;
    let mut values = IndexMap::new();

    while hash_items > 0 {
        let field = read_blob(input)?;
        let val = read_blob(input)?;
        values.insert(field, val);
        hash_items -= 1;
    }

    Ok(RdbValue::Hash {
        key: key.to_vec(),
        values,
        expiry,
    })
}

pub fn read_hash_ziplist<R: Read>(
    input: &mut R,
    key: &[u8],
    expiry: Option<u64>,
) -> RdbResult<RdbValue> {
    let ziplist = read_blob(input)?;
    let mut reader = Cursor::new(ziplist);
    let (_zlbytes, _zltail, zllen) = read_ziplist_metadata(&mut reader)?;

    assert!(zllen % 2 == 0);
    let zllen = zllen / 2;

    let mut values = IndexMap::new();

    for _ in 0..zllen {
        let field = read_ziplist_entry_string(&mut reader)?;
        let value = read_ziplist_entry_string(&mut reader)?;
        values.insert(field, value);
    }

    let last_byte = reader.read_u8()?;
    if last_byte != 0xFF {
        return Err(RdbError::ParsingError {
            context: "read_hash_ziplist",
            message: format!("Unknown encoding value: {}", last_byte),
        });
    }

    Ok(RdbValue::Hash {
        key: key.to_vec(),
        values,
        expiry,
    })
}

pub fn read_hash_zipmap<R: Read>(
    input: &mut R,
    key: &[u8],
    expiry: Option<u64>,
) -> RdbResult<RdbValue> {
    let zipmap = read_blob(input)?;
    let mut reader = Cursor::new(zipmap);

    let zmlen = reader.read_u8()?;

    let mut length: i32;
    if zmlen <= 254 {
        length = zmlen as i32;
    } else {
        length = -1;
    }

    let mut values = IndexMap::new();

    loop {
        let next_byte = reader.read_u8()?;

        if next_byte == 0xFF {
            break; // End of list.
        }

        let field = read_zipmap_entry(next_byte, &mut reader)?;

        let next_byte = reader.read_u8()?;
        let _free = reader.read_u8()?;
        let value = read_zipmap_entry(next_byte, &mut reader)?;

        values.insert(field, value);

        if length > 0 {
            length -= 1;
        }

        if length == 0 {
            let last_byte = reader.read_u8()?;

            if last_byte != 0xFF {
                return Err(RdbError::ParsingError {
                    context: "read_hash_zipmap",
                    message: format!("Unknown encoding value: {}", last_byte),
                });
            }
            break;
        }
    }

    Ok(RdbValue::Hash {
        key: key.to_vec(),
        values,
        expiry,
    })
}

fn read_zipmap_entry<T: Read>(next_byte: u8, zipmap: &mut T) -> RdbResult<Vec<u8>> {
    let elem_len = match next_byte {
        253 => zipmap.read_u32::<LittleEndian>().unwrap(),
        254 | 255 => {
            return Err(RdbError::ParsingError {
                context: "read_zipmap_entry",
                message: format!("Unknown encoding value: {}", next_byte),
            });
        }
        _ => next_byte as u32,
    };

    read_exact(zipmap, elem_len as usize)
}

pub fn read_hash_list_pack<R: Read>(
    input: &mut R,
    key: &[u8],
    expiry: Option<u64>,
) -> RdbResult<RdbValue> {
    let listpack = read_blob(input)?;
    let mut cursor = 0;
    let size = read_list_pack_length(&listpack, &mut cursor);

    let mut values = IndexMap::new();
    let mut reader = Cursor::new(listpack);
    reader.set_position(cursor as u64);

    for _ in 0..size / 2 {
        let field = read_list_pack_entry_as_string(&mut reader)?;
        let value = read_list_pack_entry_as_string(&mut reader)?;
        values.insert(field, value);
    }

    Ok(RdbValue::Hash {
        key: key.to_vec(),
        values,
        expiry,
    })
}