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/*
This file is part of jellything (https://codeberg.org/metamuffin/jellything)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2023 metamuffin <metamuffin.org>
*/
#![feature(lazy_cell)]
use base64::Engine;
use jellycommon::{config::GlobalConfig, AssetLocation};
use std::{fs::File, future::Future, path::PathBuf, sync::LazyLock};
use tokio::sync::Mutex;
pub static CONF: LazyLock<GlobalConfig> = LazyLock::new(|| {
serde_json::from_reader(
File::open(
std::env::args()
.nth(1)
.expect("First argument must specify the config.json to use."),
)
.unwrap(),
)
.unwrap()
});
pub fn cache_location(seed: &[&str]) -> (usize, AssetLocation) {
use sha2::Digest;
let mut d = sha2::Sha512::new();
for s in seed {
d.update(s.as_bytes());
d.update(b"\0");
}
let d = d.finalize();
let n = d[0] as usize | (d[1] as usize) << 8 | (d[2] as usize) << 16 | (d[3] as usize) << 24;
let fname = base64::engine::general_purpose::URL_SAFE.encode(d);
let fname = &fname[..22]; // about 128 bits
(n, AssetLocation::Cache(fname.into()))
}
const CACHE_GENERATION_BUCKET_COUNT: usize = 1024;
pub static CACHE_GENERATION_LOCKS: LazyLock<[Mutex<()>; CACHE_GENERATION_BUCKET_COUNT]> =
LazyLock::new(|| [(); CACHE_GENERATION_BUCKET_COUNT].map(|_| Mutex::new(())));
pub async fn async_cache_file<Fun, Fut>(
seed: &[&str],
generate: Fun,
) -> Result<AssetLocation, anyhow::Error>
where
Fun: FnOnce(tokio::fs::File) -> Fut,
Fut: Future<Output = Result<(), anyhow::Error>>,
{
let (bucket, location) = cache_location(seed);
// we need a lock even if it exists since somebody might be still in the process of writing.
let _guard = CACHE_GENERATION_LOCKS[bucket % CACHE_GENERATION_BUCKET_COUNT].lock();
let exists = tokio::fs::try_exists(location.path()).await?;
if !exists {
let f = tokio::fs::File::create(location.path()).await?;
generate(f).await?;
}
drop(_guard);
Ok(location)
}
pub fn cache_file<Fun>(seed: &[&str], mut generate: Fun) -> Result<AssetLocation, anyhow::Error>
where
Fun: FnMut(std::fs::File) -> Result<(), anyhow::Error>,
{
let (bucket, location) = cache_location(seed);
// we need a lock even if it exists since somebody might be still in the process of writing.
let _guard = CACHE_GENERATION_LOCKS[bucket % CACHE_GENERATION_BUCKET_COUNT].lock();
let exists = location.path().exists();
if !exists {
let f = std::fs::File::create(location.path())?;
generate(f)?;
}
drop(_guard);
Ok(location)
}
pub trait AssetLocationExt {
fn path(&self) -> PathBuf;
}
impl AssetLocationExt for AssetLocation {
fn path(&self) -> PathBuf {
match self {
AssetLocation::Assets(p) => CONF.asset_path.join(p),
AssetLocation::Cache(p) => CONF.cache_path.join(p),
AssetLocation::Library(p) => CONF.library_path.join(p),
}
}
}
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