risingwave_storage/hummock/
value.rs

1// Copyright 2025 RisingWave Labs
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 std::fmt::Debug;
16
17use bytes::{Buf, BufMut, Bytes};
18
19use super::{HummockError, HummockResult};
20
21pub const VALUE_DELETE: u8 = 1 << 0;
22pub const VALUE_PUT: u8 = 0;
23
24/// [`HummockValue`] can be created on either a `Vec<u8>` or a `&[u8]`.
25///
26/// Its encoding is a 1-byte flag + storage value. For `Put`, storage value contains both value meta
27/// and user value. For `Delete`, storage value contains only value meta.
28#[derive(Clone)]
29pub enum HummockValue<T> {
30    Put(T),
31    Delete,
32}
33
34impl<T: AsRef<[u8]>> Debug for HummockValue<T> {
35    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
36        match &self {
37            HummockValue::Put(v) => {
38                write!(f, "HummockValue {{ PUT, {} }}", hex::encode(v.as_ref()))
39            }
40            HummockValue::Delete => write!(f, "HummockValue {{ DELETE }}"),
41        }
42    }
43}
44
45impl<T> Copy for HummockValue<T> where T: Copy {}
46
47#[cfg(any(test, feature = "test"))]
48impl<T: PartialEq> PartialEq for HummockValue<T> {
49    fn eq(&self, other: &Self) -> bool {
50        match (self, other) {
51            (Self::Put(l0), Self::Put(r0)) => l0.eq(r0),
52            (Self::Delete, Self::Delete) => true,
53            _ => false,
54        }
55    }
56}
57
58#[cfg(any(test, feature = "test"))]
59impl<T: Eq> Eq for HummockValue<T> {}
60
61impl<T> HummockValue<T>
62where
63    T: AsRef<[u8]>,
64{
65    pub fn encoded_len(&self) -> usize {
66        match self {
67            HummockValue::Put(val) => 1 + val.as_ref().len(),
68            HummockValue::Delete => 1,
69        }
70    }
71
72    /// Encodes the object
73    pub fn encode(&self, buffer: &mut impl BufMut) {
74        match self {
75            HummockValue::Put(val) => {
76                // set flag
77                buffer.put_u8(VALUE_PUT);
78                buffer.put_slice(val.as_ref());
79            }
80            HummockValue::Delete => {
81                // set flag
82                buffer.put_u8(VALUE_DELETE);
83            }
84        }
85    }
86
87    /// Gets the user value out of the `HummockValue`. If the current value is `Delete`, `None` will
88    /// be returned.
89    pub fn into_user_value(self) -> Option<T> {
90        match self {
91            Self::Put(val) => Some(val),
92            Self::Delete => None,
93        }
94    }
95
96    pub fn is_delete(&self) -> bool {
97        matches!(self, Self::Delete)
98    }
99
100    pub fn put(data: T) -> Self {
101        Self::Put(data)
102    }
103
104    pub fn delete() -> Self {
105        Self::Delete
106    }
107}
108
109impl HummockValue<Vec<u8>> {
110    /// Decodes the object from `Vec<u8>`.
111    pub fn decode(buffer: &mut impl Buf) -> HummockResult<Self> {
112        if buffer.remaining() == 0 {
113            return Err(HummockError::decode_error("empty value"));
114        }
115        match buffer.get_u8() {
116            VALUE_PUT => Ok(Self::Put(Vec::from(buffer.chunk()))),
117            VALUE_DELETE => Ok(Self::Delete),
118            _ => Err(HummockError::decode_error("non-empty but format error")),
119        }
120    }
121}
122
123impl<B: AsRef<[u8]>> HummockValue<B> {
124    pub fn as_slice(&self) -> HummockValue<&[u8]> {
125        match self {
126            HummockValue::Put(data) => HummockValue::Put(data.as_ref()),
127            HummockValue::Delete => HummockValue::Delete,
128        }
129    }
130}
131
132impl<'a> HummockValue<&'a [u8]> {
133    /// Decodes the object from `&[u8]`.
134    pub fn from_slice(mut buffer: &'a [u8]) -> HummockResult<Self> {
135        if buffer.remaining() == 0 {
136            return Err(HummockError::decode_error("empty value"));
137        }
138        match buffer.get_u8() {
139            VALUE_PUT => Ok(Self::Put(buffer)),
140            VALUE_DELETE => Ok(Self::Delete),
141            _ => Err(HummockError::decode_error("non-empty but format error")),
142        }
143    }
144
145    /// Copies `self` into [`HummockValue<Bytes>`].
146    pub fn to_bytes(self) -> HummockValue<Bytes> {
147        match self {
148            HummockValue::Put(value) => HummockValue::Put(Bytes::copy_from_slice(value)),
149            HummockValue::Delete => HummockValue::Delete,
150        }
151    }
152}
153
154impl HummockValue<Bytes> {
155    pub fn to_vec(&self) -> HummockValue<Vec<u8>> {
156        match self {
157            HummockValue::Put(data) => HummockValue::Put(data.to_vec()),
158            HummockValue::Delete => HummockValue::Delete,
159        }
160    }
161}
162
163impl From<HummockValue<Vec<u8>>> for HummockValue<Bytes> {
164    fn from(data: HummockValue<Vec<u8>>) -> Self {
165        match data {
166            HummockValue::Put(data) => HummockValue::Put(data.into()),
167            HummockValue::Delete => HummockValue::Delete,
168        }
169    }
170}
171
172#[cfg(test)]
173mod tests {
174    use super::*;
175    #[test]
176    fn test_vec_decode_encode() {
177        let mut result = vec![];
178        HummockValue::Put(b"233333".to_vec()).encode(&mut result);
179        assert_eq!(
180            HummockValue::Put(b"233333".to_vec()),
181            HummockValue::decode(&mut &result[..]).unwrap()
182        );
183    }
184
185    #[test]
186    fn test_slice_decode_encode() {
187        let mut result = vec![];
188        HummockValue::Put(b"233333".to_vec()).encode(&mut result);
189        assert_eq!(
190            HummockValue::Put(b"233333".as_slice()),
191            HummockValue::from_slice(&result).unwrap()
192        );
193    }
194}
risingwave_storage/hummock/value.rs

risingwave_storage/hummock/
value.rs
