rustdoc/
docfs.rs

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1//! Rustdoc's FileSystem abstraction module.
2//!
3//! On Windows this indirects IO into threads to work around performance issues
4//! with Defender (and other similar virus scanners that do blocking operations).
5//!
6//! Only calls needed to permit this workaround have been abstracted: thus
7//! fs::read is still done directly via the fs module; if in future rustdoc
8//! needs to read-after-write from a file, then it would be added to this
9//! abstraction.
10
11use std::cmp::max;
12use std::path::{Path, PathBuf};
13use std::sync::mpsc::Sender;
14use std::thread::available_parallelism;
15use std::{fs, io};
16
17use threadpool::ThreadPool;
18
19pub(crate) trait PathError {
20    fn new<S, P: AsRef<Path>>(e: S, path: P) -> Self
21    where
22        S: ToString + Sized;
23}
24
25pub(crate) struct DocFS {
26    sync_only: bool,
27    errors: Option<Sender<String>>,
28    pool: ThreadPool,
29}
30
31impl DocFS {
32    pub(crate) fn new(errors: Sender<String>) -> DocFS {
33        const MINIMUM_NB_THREADS: usize = 2;
34        DocFS {
35            sync_only: false,
36            errors: Some(errors),
37            pool: ThreadPool::new(
38                available_parallelism()
39                    .map(|nb| max(nb.get(), MINIMUM_NB_THREADS))
40                    .unwrap_or(MINIMUM_NB_THREADS),
41            ),
42        }
43    }
44
45    pub(crate) fn set_sync_only(&mut self, sync_only: bool) {
46        self.sync_only = sync_only;
47    }
48
49    pub(crate) fn close(&mut self) {
50        self.errors = None;
51    }
52
53    pub(crate) fn create_dir_all<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
54        // For now, dir creation isn't a huge time consideration, do it
55        // synchronously, which avoids needing ordering between write() actions
56        // and directory creation.
57        fs::create_dir_all(path)
58    }
59
60    pub(crate) fn write<E>(
61        &self,
62        path: PathBuf,
63        contents: impl 'static + Send + AsRef<[u8]>,
64    ) -> Result<(), E>
65    where
66        E: PathError,
67    {
68        if !self.sync_only {
69            // A possible future enhancement after more detailed profiling would
70            // be to create the file sync so errors are reported eagerly.
71            let sender = self.errors.clone().expect("can't write after closing");
72            self.pool.execute(move || {
73                fs::write(&path, contents).unwrap_or_else(|e| {
74                    sender.send(format!("\"{path}\": {e}", path = path.display())).unwrap_or_else(
75                        |_| panic!("failed to send error on \"{}\"", path.display()),
76                    )
77                });
78            });
79        } else {
80            fs::write(&path, contents).map_err(|e| E::new(e, path))?;
81        }
82
83        Ok(())
84    }
85}
86
87impl Drop for DocFS {
88    fn drop(&mut self) {
89        self.pool.join();
90    }
91}
rustdoc/docfs.rs

rustdoc/
docfs.rs
