aurora_db/wal/
log.rs

1use crate::error::{AuroraError, Result};
2use serde::{Deserialize, Serialize};
3use std::fs::{File, OpenOptions};
4use std::io::{self, BufReader, BufWriter, Read, Seek, SeekFrom, Write};
5use std::path::PathBuf;
6use std::time::SystemTime;
7
8#[derive(Serialize, Deserialize)]
9pub struct LogEntry {
10    timestamp: u64,
11    operation: Operation,
12    key: String,
13    value: Option<Vec<u8>>,
14}
15
16#[derive(Serialize, Deserialize)]
17pub enum Operation {
18    Put,
19    Delete,
20    BeginTx,
21    CommitTx,
22    RollbackTx,
23}
24
25pub struct WriteAheadLog {
26    file: BufWriter<File>,
27    _path: PathBuf,
28}
29
30impl WriteAheadLog {
31    pub fn new(path: &str) -> Result<Self> {
32        let path = PathBuf::from(path);
33        let wal_path = path.with_extension("wal");
34        
35        let file = BufWriter::new(
36            OpenOptions::new()
37                .create(true)
38                .read(true)
39                .write(true)
40                .append(true)
41                .open(&wal_path)?
42        );
43
44        Ok(Self {
45            file,
46            _path: wal_path,
47        })
48    }
49
50    pub fn append(&mut self, operation: Operation, key: &str, value: Option<&[u8]>) -> Result<()> {
51        let timestamp = SystemTime::now()
52            .duration_since(SystemTime::UNIX_EPOCH)
53            .map_err(|e| AuroraError::Protocol(e.to_string()))?
54            .as_secs();
55
56        let entry = LogEntry {
57            timestamp,
58            operation,
59            key: key.to_string(),
60            value: value.map(|v| v.to_vec()),
61        };
62
63        let serialized = bincode::serialize(&entry)
64            .map_err(|e| AuroraError::Protocol(e.to_string()))?;
65        let len = serialized.len() as u32;
66        
67        self.file.write_all(&len.to_le_bytes())?;
68        self.file.write_all(&serialized)?;
69        self.file.flush()?;
70        
71        Ok(())
72    }
73
74    pub fn recover(&mut self) -> Result<Vec<LogEntry>> {
75        let mut file = self.file.get_ref();
76        file.seek(SeekFrom::Start(0))?;
77        let mut reader = BufReader::new(file);
78        let mut entries = Vec::new();
79
80        loop {
81            let mut len_bytes = [0u8; 4];
82            match reader.read_exact(&mut len_bytes) {
83                Ok(_) => {
84                    let len = u32::from_le_bytes(len_bytes) as usize;
85                    let mut buffer = vec![0u8; len];
86                    reader.read_exact(&mut buffer)?;
87                    let entry: LogEntry = bincode::deserialize(&buffer)
88                        .map_err(|e| AuroraError::Protocol(e.to_string()))?;
89                    entries.push(entry);
90                }
91                Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof => break,
92                Err(e) => return Err(e.into()),
93            }
94        }
95
96        Ok(entries)
97    }
98
99    pub fn truncate(&mut self) -> Result<()> {
100        let file = self.file.get_mut();
101        file.set_len(0)?;
102        file.sync_all()?;
103        file.seek(SeekFrom::Start(0))?;
104        Ok(())
105    }
106}
107
108#[cfg(test)]
109mod tests {
110    use super::*;
111    use tempfile::tempdir;
112
113    #[test]
114    fn test_log_operations() -> Result<()> {
115        let temp_dir = tempdir()?;
116        let log_path = temp_dir.path().join("test.wal");
117        let mut wal = WriteAheadLog::new(log_path.to_str().unwrap())?;
118
119        // Test append operations
120        wal.append(Operation::Put, "test_key", Some(b"test_value"))?;
121        wal.append(Operation::BeginTx, "", None)?;
122        wal.append(Operation::CommitTx, "", None)?;
123
124        // Test recovery
125        let entries = wal.recover()?;
126        assert_eq!(entries.len(), 3);
127        
128        assert!(matches!(entries[0].operation, Operation::Put));
129        assert_eq!(entries[0].key, "test_key");
130        assert_eq!(entries[0].value.as_ref().unwrap(), b"test_value");
131
132        assert!(matches!(entries[1].operation, Operation::BeginTx));
133        assert!(matches!(entries[2].operation, Operation::CommitTx));
134
135        Ok(())
136    }
137
138    #[test]
139    fn test_truncate() -> Result<()> {
140        let temp_dir = tempdir()?;
141        let log_path = temp_dir.path().join("test.wal");
142        let mut wal = WriteAheadLog::new(log_path.to_str().unwrap())?;
143
144        // Write some entries
145        wal.append(Operation::Put, "key1", Some(b"value1"))?;
146        wal.append(Operation::Put, "key2", Some(b"value2"))?;
147
148        // Truncate the log
149        wal.truncate()?;
150
151        // Verify log is empty
152        let entries = wal.recover()?;
153        assert_eq!(entries.len(), 0);
154
155        Ok(())
156    }
157
158    #[test]
159    fn test_transaction_operations() -> Result<()> {
160        let temp_dir = tempdir()?;
161        let log_path = temp_dir.path().join("test.wal");
162        let mut wal = WriteAheadLog::new(log_path.to_str().unwrap())?;
163
164        // Test transaction sequence
165        wal.append(Operation::BeginTx, "", None)?;
166        wal.append(Operation::Put, "tx_key1", Some(b"tx_value1"))?;
167        wal.append(Operation::Put, "tx_key2", Some(b"tx_value2"))?;
168        wal.append(Operation::CommitTx, "", None)?;
169
170        let entries = wal.recover()?;
171        assert_eq!(entries.len(), 4);
172
173        assert!(matches!(entries[0].operation, Operation::BeginTx));
174        assert!(matches!(entries[1].operation, Operation::Put));
175        assert!(matches!(entries[2].operation, Operation::Put));
176        assert!(matches!(entries[3].operation, Operation::CommitTx));
177
178        Ok(())
179    }
180
181    #[test]
182    fn test_rollback_operation() -> Result<()> {
183        let temp_dir = tempdir()?;
184        let log_path = temp_dir.path().join("test.wal");
185        let mut wal = WriteAheadLog::new(log_path.to_str().unwrap())?;
186        // Test rollback sequence
187        wal.append(Operation::BeginTx, "", None)?;
188        wal.append(Operation::Put, "key_to_rollback", Some(b"value"))?;
189        wal.append(Operation::RollbackTx, "", None)?;
190
191        let entries = wal.recover()?;
192        assert_eq!(entries.len(), 3);
193
194        assert!(matches!(entries[0].operation, Operation::BeginTx));
195        assert!(matches!(entries[1].operation, Operation::Put));
196        assert!(matches!(entries[2].operation, Operation::RollbackTx));
197
198        Ok(())
199    }
200
201    #[test]
202    fn test_large_values() -> Result<()> {
203        let temp_dir = tempdir()?;
204        let log_path = temp_dir.path().join("test.wal");
205        let mut wal = WriteAheadLog::new(log_path.to_str().unwrap())?;
206
207        // Test with a larger value
208        let large_value = vec![0u8; 1024 * 1024]; // 1MB
209        wal.append(Operation::Put, "large_key", Some(&large_value))?;
210
211        let entries = wal.recover()?;
212        assert_eq!(entries.len(), 1);
213        assert_eq!(entries[0].value.as_ref().unwrap().len(), large_value.len());
214
215        Ok(())
216    }
217
218    #[test]
219    fn test_invalid_path() {
220        let result = WriteAheadLog::new("/nonexistent/directory/test.wal");
221        assert!(result.is_err());
222    }
223}
aurora_db/wal/log.rs

aurora_db/wal/
log.rs
