Function read_file_bytes

src/sync.rs:55–72

Reads a file's bytes, absorbing transient Windows file locks. On Windows, antivirus scanners and the search indexer briefly open freshly written files with exclusive access; an unlucky open during that window fails with a sharing violation or "Access is denied" (os error 5) even though the file is readable milliseconds later. Callers treat read errors as "skip this file" or fail the whole sync, s

(path: &Path)

/// giving up. Other platforms read directly: `PermissionDenied` there is a
/// real ACL problem that retrying cannot fix.
fn read_file_bytes(path: &Path) -> std::io::Result<Vec<u8>> {
    const RETRY_DELAYS_MS: [u64; 4] = [10, 20, 40, 80];
    if !cfg!(windows) {
        return std::fs::read(path);
    }
    let mut delays = RETRY_DELAYS_MS.iter();
    loop {
        match std::fs::read(path) {
            Err(err) if is_transient_windows_file_lock(&err) => match delays.next() {
                Some(&delay_ms) => {
                    std::thread::sleep(std::time::Duration::from_millis(delay_ms));
                }
                None => return Err(err),
            },
            result => return result,
        }
    }
}

/// True for Windows errors that indicate another process is briefly holding
/// the file: `ERROR_SHARING_VIOLATION` (32) and `ERROR_LOCK_VIOLATION` (33)