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//! Rustdoc's FileSystem abstraction module.
//!
//! On Windows this indirects IO into threads to work around performance issues
//! with Defender (and other similar virus scanners that do blocking operations).
//!
//! Only calls needed to permit this workaround have been abstracted: thus
//! fs::read is still done directly via the fs module; if in future rustdoc
//! needs to read-after-write from a file, then it would be added to this
//! abstraction.
use std::cmp::max;
use std::fs;
use std::io;
use std::path::{Path, PathBuf};
use std::string::ToString;
use std::sync::mpsc::Sender;
use std::thread::available_parallelism;
use threadpool::ThreadPool;
pub(crate) trait PathError {
fn new<S, P: AsRef<Path>>(e: S, path: P) -> Self
where
S: ToString + Sized;
}
pub(crate) struct DocFS {
sync_only: bool,
errors: Option<Sender<String>>,
pool: ThreadPool,
}
impl DocFS {
pub(crate) fn new(errors: Sender<String>) -> DocFS {
const MINIMUM_NB_THREADS: usize = 2;
DocFS {
sync_only: false,
errors: Some(errors),
pool: ThreadPool::new(
available_parallelism()
.map(|nb| max(nb.get(), MINIMUM_NB_THREADS))
.unwrap_or(MINIMUM_NB_THREADS),
),
}
}
pub(crate) fn set_sync_only(&mut self, sync_only: bool) {
self.sync_only = sync_only;
}
pub(crate) fn close(&mut self) {
self.errors = None;
}
pub(crate) fn create_dir_all<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
// For now, dir creation isn't a huge time consideration, do it
// synchronously, which avoids needing ordering between write() actions
// and directory creation.
fs::create_dir_all(path)
}
pub(crate) fn write<E>(
&self,
path: PathBuf,
contents: impl 'static + Send + AsRef<[u8]>,
) -> Result<(), E>
where
E: PathError,
{
if !self.sync_only {
// A possible future enhancement after more detailed profiling would
// be to create the file sync so errors are reported eagerly.
let sender = self.errors.clone().expect("can't write after closing");
self.pool.execute(move || {
fs::write(&path, contents).unwrap_or_else(|e| {
sender.send(format!("\"{path}\": {e}", path = path.display())).unwrap_or_else(
|_| panic!("failed to send error on \"{}\"", path.display()),
)
});
});
} else {
fs::write(&path, contents).map_err(|e| E::new(e, path))?;
}
Ok(())
}
}
impl Drop for DocFS {
fn drop(&mut self) {
self.pool.join();
}
}
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