cassandra_protocol/
compression.rs

1/// CDRS support traffic compression as it is described in [Apache
2/// Cassandra protocol](
3/// https://github.com/apache/cassandra/blob/trunk/doc/native_protocol_v4.spec#L790)
4///
5/// Before being used, client and server must agree on a compression algorithm to
6/// use, which is done in the STARTUP message. As a consequence, a STARTUP message
7/// must never be compressed.  However, once the STARTUP envelope has been received
8/// by the server, messages can be compressed (including the response to the STARTUP
9/// request).
10use derive_more::Display;
11use snap::raw::{Decoder, Encoder};
12use std::convert::{From, TryInto};
13use std::error::Error;
14use std::fmt;
15use std::io;
16use std::result;
17
18type Result<T> = result::Result<T, CompressionError>;
19
20pub const LZ4: &str = "lz4";
21pub const SNAPPY: &str = "snappy";
22
23/// An error which may occur during encoding or decoding frame body. As there are only two types
24/// of compressors it contains two related enum options.
25#[derive(Debug)]
26pub enum CompressionError {
27    /// Snappy error.
28    Snappy(snap::Error),
29    /// Lz4 error.
30    Lz4(io::Error),
31}
32
33impl fmt::Display for CompressionError {
34    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
35        match *self {
36            CompressionError::Snappy(ref err) => write!(f, "Snappy Error: {err:?}"),
37            CompressionError::Lz4(ref err) => write!(f, "Lz4 Error: {err:?}"),
38        }
39    }
40}
41
42impl Error for CompressionError {
43    fn source(&self) -> Option<&(dyn Error + 'static)> {
44        match *self {
45            CompressionError::Snappy(ref err) => Some(err),
46            CompressionError::Lz4(ref err) => Some(err),
47        }
48    }
49}
50
51impl Clone for CompressionError {
52    fn clone(&self) -> Self {
53        match self {
54            CompressionError::Snappy(error) => CompressionError::Snappy(error.clone()),
55            CompressionError::Lz4(error) => CompressionError::Lz4(io::Error::new(
56                error.kind(),
57                error
58                    .get_ref()
59                    .map(|error| error.to_string())
60                    .unwrap_or_default(),
61            )),
62        }
63    }
64}
65
66/// Enum which represents a type of compression. Only non-startup frame's body can be compressed.
67#[derive(Debug, PartialEq, Clone, Copy, Eq, Ord, PartialOrd, Hash, Display)]
68pub enum Compression {
69    /// [lz4](https://code.google.com/p/lz4/) compression
70    Lz4,
71    /// [snappy](https://code.google.com/p/snappy/) compression
72    Snappy,
73    /// No compression
74    None,
75}
76
77impl Compression {
78    /// It encodes `bytes` basing on type of `Compression`..
79    ///
80    /// # Examples
81    ///
82    /// ```
83    ///    use cassandra_protocol::compression::Compression;
84    ///
85    ///   let snappy_compression = Compression::Snappy;
86    ///   let bytes = String::from("Hello World").into_bytes().to_vec();
87    ///   let encoded = snappy_compression.encode(&bytes).unwrap();
88    ///   assert_eq!(snappy_compression.decode(encoded).unwrap(), bytes);
89    ///
90    /// ```
91    pub fn encode(&self, bytes: &[u8]) -> Result<Vec<u8>> {
92        match *self {
93            Compression::Lz4 => Compression::encode_lz4(bytes),
94            Compression::Snappy => Compression::encode_snappy(bytes),
95            Compression::None => Ok(bytes.into()),
96        }
97    }
98
99    /// Checks if current compression actually compresses data.
100    #[inline]
101    pub fn is_compressed(self) -> bool {
102        self != Compression::None
103    }
104
105    /// It decodes `bytes` basing on type of compression.
106    pub fn decode(&self, bytes: Vec<u8>) -> Result<Vec<u8>> {
107        match *self {
108            Compression::Lz4 => Compression::decode_lz4(bytes),
109            Compression::Snappy => Compression::decode_snappy(bytes),
110            Compression::None => Ok(bytes),
111        }
112    }
113
114    /// It transforms compression method into a `&str`.
115    pub fn as_str(&self) -> Option<&'static str> {
116        match *self {
117            Compression::Lz4 => Some(LZ4),
118            Compression::Snappy => Some(SNAPPY),
119            Compression::None => None,
120        }
121    }
122
123    fn encode_snappy(bytes: &[u8]) -> Result<Vec<u8>> {
124        let mut encoder = Encoder::new();
125        encoder
126            .compress_vec(bytes)
127            .map_err(CompressionError::Snappy)
128    }
129
130    fn decode_snappy(bytes: Vec<u8>) -> Result<Vec<u8>> {
131        let mut decoder = Decoder::new();
132        decoder
133            .decompress_vec(bytes.as_slice())
134            .map_err(CompressionError::Snappy)
135    }
136
137    fn encode_lz4(bytes: &[u8]) -> Result<Vec<u8>> {
138        let len = 4 + lz4_flex::block::get_maximum_output_size(bytes.len());
139        assert!(len <= i32::MAX as usize);
140
141        let mut result = vec![0; len];
142
143        let len = bytes.len() as i32;
144        result[..4].copy_from_slice(&len.to_be_bytes());
145
146        let compressed_len = lz4_flex::compress_into(bytes, &mut result[4..])
147            .map_err(|error| CompressionError::Lz4(io::Error::new(io::ErrorKind::Other, error)))?;
148
149        result.truncate(4 + compressed_len);
150        Ok(result)
151    }
152
153    fn decode_lz4(bytes: Vec<u8>) -> Result<Vec<u8>> {
154        let uncompressed_size =
155            i32::from_be_bytes(bytes[..4].try_into().map_err(|error| {
156                CompressionError::Lz4(io::Error::new(io::ErrorKind::Other, error))
157            })?);
158
159        lz4_flex::decompress(&bytes[4..], uncompressed_size as usize)
160            .map_err(|error| CompressionError::Lz4(io::Error::new(io::ErrorKind::Other, error)))
161    }
162}
163
164impl From<String> for Compression {
165    /// It converts `String` into `Compression`. If string is neither `lz4` nor `snappy` then
166    /// `Compression::None` will be returned
167    fn from(compression_string: String) -> Compression {
168        Compression::from(compression_string.as_str())
169    }
170}
171
172impl Compression {
173    /// It converts `Compression` into `String`. If compression is `None` then empty string will be
174    /// returned
175    pub fn to_protocol_string(self) -> String {
176        match self {
177            Compression::Lz4 => "LZ4".to_string(),
178            Compression::Snappy => "SNAPPY".to_string(),
179            Compression::None => "NONE".to_string(),
180        }
181    }
182
183    pub fn from_protocol_string(protocol_string: &str) -> std::result::Result<Self, String> {
184        match protocol_string {
185            "lz4" | "LZ4" => Ok(Compression::Lz4),
186            "snappy" | "SNAPPY" => Ok(Compression::Snappy),
187            "none" | "NONE" => Ok(Compression::None),
188            _ => Err("Unknown compression".to_string()),
189        }
190    }
191}
192
193impl<'a> From<&'a str> for Compression {
194    /// It converts `str` into `Compression`. If string is neither `lz4` nor `snappy` then
195    /// `Compression::None` will be returned
196    fn from(compression_str: &'a str) -> Compression {
197        match compression_str {
198            LZ4 => Compression::Lz4,
199            SNAPPY => Compression::Snappy,
200            _ => Compression::None,
201        }
202    }
203}
204
205#[cfg(test)]
206mod tests {
207    use super::*;
208
209    #[test]
210    fn test_compression_to_protocol_string() {
211        let lz4 = Compression::Lz4;
212        assert_eq!("LZ4", lz4.to_protocol_string());
213
214        let snappy = Compression::Snappy;
215        assert_eq!("SNAPPY", snappy.to_protocol_string());
216
217        let none = Compression::None;
218        assert_eq!("NONE", none.to_protocol_string());
219    }
220
221    #[test]
222    fn test_compression_from_protocol_str() {
223        let lz4 = "lz4";
224        assert_eq!(
225            Compression::from_protocol_string(lz4).unwrap(),
226            Compression::Lz4
227        );
228
229        let lz4 = "LZ4";
230        assert_eq!(
231            Compression::from_protocol_string(lz4).unwrap(),
232            Compression::Lz4
233        );
234
235        let snappy = "snappy";
236        assert_eq!(
237            Compression::from_protocol_string(snappy).unwrap(),
238            Compression::Snappy
239        );
240
241        let snappy = "SNAPPY";
242        assert_eq!(
243            Compression::from_protocol_string(snappy).unwrap(),
244            Compression::Snappy
245        );
246
247        let none = "none";
248        assert_eq!(
249            Compression::from_protocol_string(none).unwrap(),
250            Compression::None
251        );
252
253        let none = "NONE";
254        assert_eq!(
255            Compression::from_protocol_string(none).unwrap(),
256            Compression::None
257        );
258    }
259
260    #[test]
261    fn test_compression_from_string() {
262        let lz4 = "lz4".to_string();
263        assert_eq!(Compression::from(lz4), Compression::Lz4);
264        let snappy = "snappy".to_string();
265        assert_eq!(Compression::from(snappy), Compression::Snappy);
266        let none = "x".to_string();
267        assert_eq!(Compression::from(none), Compression::None);
268    }
269
270    #[test]
271    fn test_compression_encode_snappy() {
272        let snappy_compression = Compression::Snappy;
273        let bytes = String::from("Hello World").into_bytes().to_vec();
274        snappy_compression
275            .encode(&bytes)
276            .expect("Should work without exceptions");
277    }
278
279    #[test]
280    fn test_compression_decode_snappy() {
281        let snappy_compression = Compression::Snappy;
282        let bytes = String::from("Hello World").into_bytes().to_vec();
283        let encoded = snappy_compression.encode(&bytes).unwrap();
284        assert_eq!(snappy_compression.decode(encoded).unwrap(), bytes);
285    }
286
287    #[test]
288    fn test_compression_encode_lz4() {
289        let snappy_compression = Compression::Lz4;
290        let bytes = String::from("Hello World").into_bytes().to_vec();
291        snappy_compression
292            .encode(&bytes)
293            .expect("Should work without exceptions");
294    }
295
296    #[test]
297    fn test_compression_decode_lz4() {
298        let lz4_compression = Compression::Lz4;
299        let bytes = String::from("Hello World").into_bytes().to_vec();
300        let encoded = lz4_compression.encode(&bytes).unwrap();
301        assert_eq!(lz4_compression.decode(encoded).unwrap(), bytes);
302    }
303
304    #[test]
305    fn test_compression_encode_none() {
306        let none_compression = Compression::None;
307        let bytes = String::from("Hello World").into_bytes().to_vec();
308        none_compression
309            .encode(&bytes)
310            .expect("Should work without exceptions");
311    }
312
313    #[test]
314    fn test_compression_decode_none() {
315        let none_compression = Compression::None;
316        let bytes = String::from("Hello World").into_bytes().to_vec();
317        let encoded = none_compression.encode(&bytes).unwrap();
318        assert_eq!(none_compression.decode(encoded).unwrap(), bytes);
319    }
320
321    #[test]
322    fn test_compression_decode_lz4_with_invalid_input() {
323        let lz4_compression = Compression::Lz4;
324        let decode = lz4_compression.decode(vec![0, 0, 0, 0x7f]);
325        assert!(decode.is_err());
326    }
327
328    #[test]
329    fn test_compression_encode_snappy_with_non_utf8() {
330        let snappy_compression = Compression::Snappy;
331        let v = vec![0xff, 0xff];
332        let encoded = snappy_compression
333            .encode(&v)
334            .expect("Should work without exceptions");
335        assert_eq!(snappy_compression.decode(encoded).unwrap(), v);
336    }
337}
cassandra_protocol/compression.rs

cassandra_protocol/
compression.rs
