redb/tree_store/page_store/
in_memory_backend.rs

1use crate::StorageBackend;
2use std::io;
3use std::sync::*;
4
5/// Acts as temporal in-memory database storage.
6#[derive(Debug, Default)]
7pub struct InMemoryBackend(RwLock<Vec<u8>>);
8
9impl InMemoryBackend {
10    fn out_of_range() -> io::Error {
11        io::Error::new(io::ErrorKind::InvalidInput, "Index out-of-range.")
12    }
13}
14
15impl InMemoryBackend {
16    /// Creates a new, empty memory backend.
17    pub fn new() -> Self {
18        Self::default()
19    }
20
21    /// Gets a read guard for this backend.
22    fn read(&self) -> RwLockReadGuard<'_, Vec<u8>> {
23        self.0.read().expect("Could not acquire read lock.")
24    }
25
26    /// Gets a write guard for this backend.
27    fn write(&self) -> RwLockWriteGuard<'_, Vec<u8>> {
28        self.0.write().expect("Could not acquire write lock.")
29    }
30}
31
32impl StorageBackend for InMemoryBackend {
33    fn len(&self) -> Result<u64, io::Error> {
34        Ok(self.read().len() as u64)
35    }
36
37    fn read(&self, offset: u64, len: usize) -> Result<Vec<u8>, io::Error> {
38        let guard = self.read();
39        let offset = usize::try_from(offset).map_err(|_| Self::out_of_range())?;
40        if offset + len <= guard.len() {
41            Ok(guard[offset..offset + len].to_owned())
42        } else {
43            Err(Self::out_of_range())
44        }
45    }
46
47    fn set_len(&self, len: u64) -> Result<(), io::Error> {
48        let mut guard = self.write();
49        let len = usize::try_from(len).map_err(|_| Self::out_of_range())?;
50        if guard.len() < len {
51            let additional = len - guard.len();
52            guard.reserve(additional);
53            for _ in 0..additional {
54                guard.push(0);
55            }
56        } else {
57            guard.truncate(len);
58        }
59
60        Ok(())
61    }
62
63    fn sync_data(&self, _: bool) -> Result<(), io::Error> {
64        Ok(())
65    }
66
67    fn write(&self, offset: u64, data: &[u8]) -> Result<(), io::Error> {
68        let mut guard = self.write();
69        let offset = usize::try_from(offset).map_err(|_| Self::out_of_range())?;
70        if offset + data.len() <= guard.len() {
71            guard[offset..offset + data.len()].copy_from_slice(data);
72            Ok(())
73        } else {
74            Err(Self::out_of_range())
75        }
76    }
77}
redb/tree_store/page_store/in_memory_backend.rs

redb/tree_store/page_store/
in_memory_backend.rs
