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use rmp_serde::{decode, encode};
use std::fmt::Debug;
use std::fs;
use std::marker::PhantomData;
use std::path::{Path, PathBuf};
extern crate serde;
use serde::{de::DeserializeOwned, Serialize};
pub struct Fsdb {
dir: PathBuf,
}
pub struct Bucket<V> {
dir: PathBuf,
max_file_name: Option<usize>,
_v: PhantomData<V>,
}
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("io error: {0}")]
Io(#[from] std::io::Error),
#[error("encode error: {0}")]
Encode(#[from] rmp_serde::encode::Error),
#[error("dncode error: {0}")]
Decode(#[from] rmp_serde::decode::Error),
}
type Result<T> = std::result::Result<T, Error>;
impl Fsdb {
pub fn new(dir: &str) -> Result<Self> {
if !Path::new(dir).exists() {
fs::create_dir_all(dir)?;
}
Ok(Self { dir: dir.into() })
}
pub fn bucket<V: Serialize + DeserializeOwned>(&self, p: &str) -> Result<Bucket<V>> {
let mut dir = self.dir.clone();
dir.push::<PathBuf>(p.into());
if !Path::new(&dir).exists() {
fs::create_dir(dir.clone())?;
}
Ok(Bucket {
dir: dir.into(),
max_file_name: None,
_v: PhantomData,
})
}
}
impl<V: Serialize + DeserializeOwned> Bucket<V> {
pub fn set_max_file_name(&mut self, x: usize) {
self.max_file_name = Some(x);
}
pub fn exists(&self, key: &str) -> bool {
let mut path = self.dir.clone();
path.push(self.maxify(key));
path.exists()
}
pub fn put(&self, key: &str, value: V) -> Result<()> {
let mut path = self.dir.clone();
path.push(self.maxify(key));
let mut f = fs::File::create(path.clone())?;
encode::write(&mut f, &value)?;
Ok(())
}
pub fn get(&self, key: &str) -> Result<V> {
let mut path = self.dir.clone();
path.push(self.maxify(key));
let f = fs::File::open(path)?;
Ok(decode::from_read(f)?)
}
pub fn remove(&self, key: &str) -> Result<()> {
let mut path = self.dir.clone();
path.push(self.maxify(key));
Ok(std::fs::remove_file(path)?)
}
pub fn list(&self) -> Result<Vec<String>> {
let path = self.dir.clone();
let paths = fs::read_dir(path)?;
let mut r = Vec::new();
paths.for_each(|name| {
if let Ok(na) = name {
if let Ok(n) = na.file_name().into_string() {
r.push(n);
}
}
});
Ok(r)
}
pub fn clear(&self) -> Result<()> {
let path = self.dir.clone();
Ok(fs::remove_dir_all(path)?)
}
fn maxify(&self, name: &str) -> String {
if let Some(max) = self.max_file_name {
let mut s = name.to_string();
s.truncate(max);
s
} else {
name.to_owned()
}
}
}
#[cfg(test)]
mod tests {
use crate::Fsdb;
use serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
struct Thing {
n: u8,
}
#[test]
fn test_db() {
let db = Fsdb::new("testdb").expect("fail Fsdb::new");
let mut b = db.bucket("hi").expect("fail bucket");
b.set_max_file_name(8);
let t1 = Thing { n: 1 };
b.put("keythatisverylong", t1.clone())
.expect("failed to save");
let t2: Thing = b.get("keythatisverylong").expect("fail to load");
println!("t {:?}", t2.clone());
assert_eq!(t1, t2);
let list = b.list().expect("fail list");
assert_eq!(list, vec!["keythati".to_string()]);
}
}