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
|
use crate::chunk::DataChunk;
use crate::chunkid::ChunkId;
use crate::chunkmeta::ChunkMeta;
use std::path::{Path, PathBuf};
/// Store chunks, with metadata, persistently.
///
/// The chunks and their metadata are stored persistently on disk
/// under a directory specified as the Store struct is created. To
/// store or retrieve a chunk its identifier must be used.
pub struct Store {
dir: PathBuf,
}
impl Store {
/// Create a new Store to represent on-disk storage of chunks.x
pub fn new(dir: &Path) -> Self {
Store {
dir: dir.to_path_buf(),
}
}
// Construct name for a file in the store from chunk id and suffix.
fn filename(&self, id: &ChunkId, suffix: &str) -> PathBuf {
self.dir.join(format!("{}.{}", id, suffix))
}
/// Save a chunk into a store.
pub fn save(&self, id: &ChunkId, meta: &ChunkMeta, chunk: &DataChunk) -> anyhow::Result<()> {
std::fs::write(&self.filename(id, "meta"), meta.to_json())?;
std::fs::write(&self.filename(id, "data"), chunk.data())?;
Ok(())
}
/// Load a chunk's metadata from a store.
pub fn load_meta(&self, id: &ChunkId) -> anyhow::Result<ChunkMeta> {
let meta = std::fs::read(&self.filename(id, "meta"))?;
Ok(serde_json::from_slice(&meta)?)
}
/// Load a chunk from a store.
pub fn load(&self, id: &ChunkId) -> anyhow::Result<(ChunkMeta, DataChunk)> {
let meta = self.load_meta(id)?;
let data = std::fs::read(&self.filename(id, "data"))?;
Ok((meta, DataChunk::new(data)))
}
/// Delete a chunk from a store.
pub fn delete(&self, id: &ChunkId) -> anyhow::Result<()> {
std::fs::remove_file(&self.filename(id, "meta"))?;
std::fs::remove_file(&self.filename(id, "data"))?;
Ok(())
}
}
|