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|
use std::collections::{HashMap, VecDeque};
use std::path::{Path, PathBuf};
use std::sync::mpsc::{self, TryRecvError};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;
use anyhow::{anyhow, Context, Result};
use crate::modes::{FileInfo, Preview, Users};
pub struct Previewer {
pub tx: mpsc::Sender<Option<PathBuf>>,
pub handle_receiver: thread::JoinHandle<Result<()>>,
pub handle_builder: thread::JoinHandle<Result<()>>,
}
impl Previewer {
pub fn new(preview_cache: Arc<Mutex<PreviewCache>>) -> Self {
let (tx, rx) = mpsc::channel::<Option<PathBuf>>();
let queue: Arc<Mutex<VecDeque<PathBuf>>> = Arc::new(Mutex::new(VecDeque::new()));
let queue2 = queue.clone();
let handle_receiver = thread::spawn(move || -> Result<()> {
loop {
match rx.try_recv() {
Ok(Some(path)) => match queue2.lock() {
Ok(mut queue) => {
queue.push_back(path);
drop(queue);
}
Err(error) => return Err(anyhow!("Error locking queue: {error}")),
},
Ok(_) | Err(TryRecvError::Disconnected) => {
crate::log_info!("terminating previewer");
break;
}
Err(TryRecvError::Empty) => {
thread::sleep(Duration::from_millis(33));
}
}
}
Ok(())
});
let handle_builder = thread::spawn(move || loop {
match queue.lock() {
Err(error) => return Err(anyhow!("error locking queue lock: {error}")),
Ok(mut queue) => {
match queue.pop_front() {
Some(path) => match preview_cache.lock() {
Ok(mut preview_cache) => {
preview_cache.update(&path)?;
drop(preview_cache);
}
Err(error) => {
return Err(anyhow!("Error locking preview_cache: {error}"))
}
},
None => {
thread::sleep(Duration::from_millis(33));
}
};
drop(queue);
}
}
});
Self {
tx,
handle_receiver,
handle_builder,
}
}
}
#[derive(Default)]
pub struct PreviewCache {
cache: HashMap<PathBuf, Preview>,
paths: Vec<PathBuf>,
}
impl PreviewCache {
const SIZE_LIMIT: usize = 100;
/// Returns an optional reference to the preview.
pub fn read(&self, path: &Path) -> Option<&Preview> {
self.cache.get(path)
}
/// True iff the cache aleady contains a preview of path.
///
/// # Errors
///
/// May fail if:
/// - FileInfo fail,
/// - Preview fail.
pub fn update(&mut self, path: &Path) -> Result<bool> {
if self.cache.contains_key(path) {
crate::log_info!("key {path} already in cache", path = path.display());
return Ok(false);
};
self.add_preview(path)?;
self.limit_size();
Ok(true)
}
pub fn add_made_preview(&mut self, path: &Path, preview: Preview) {
self.cache.insert(path.to_path_buf(), preview);
self.paths.push(path.to_path_buf());
self.limit_size();
}
fn add_preview(&mut self, path: &Path) -> Result<()> {
self.cache
.insert(path.to_path_buf(), Self::make_preview(path)?);
self.paths.push(path.to_path_buf());
crate::log_info!("added {path} to cache", path = path.display());
Ok(())
}
fn make_preview(path: &Path) -> Result<Preview> {
Preview::new(&FileInfo::from_path_with_name(
path,
&path.file_name().context("")?.to_string_lossy(),
&Users::default(),
)?)
}
fn limit_size(&mut self) {
if self.cache.len() > Self::SIZE_LIMIT {
let path = self.paths.remove(0);
self.cache.remove(&path);
}
}
}
|
