/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at
https://mozilla.org/MPL/2.0/. */
//! Application logging facilities.
use crate::std::{
self,
path::Path,
sync::{Arc, Mutex},
};
/// Initialize logging and return a log target which can be used to change the destination of log
/// statements.
pub fn init() -> LogTarget {
let log_target_inner = LogTargetInner::default();
env_logger::builder()
.filter_level(log::LevelFilter::Warn)
.parse_env(
env_logger::Env::new()
.filter(ekey!("LOG"))
.write_style(ekey!("LOG_STYLE")),
)
.target(env_logger::fmt::Target::Pipe(Box::new(
log_target_inner.clone(),
)))
.init();
LogTarget {
inner: log_target_inner,
}
}
/// Controls the target of logging.
#[derive(Clone)]
pub struct LogTarget {
inner: LogTargetInner,
}
impl LogTarget {
/// Set the file to which log statements will be written.
pub fn set_file(&self, path: &Path) {
match std::fs::File::create(path) {
Ok(file) => {
if let Ok(mut guard) = self.inner.target.lock() {
*guard = Box::new(file);
}
}
Err(e) => log::error!("failed to retarget log to {}: {e}", path.display()),
}
}
}
/// A private inner class implements Write, allows creation, etc. Externally the `LogTarget`
only
/// supports changing the target and nothing else.
#[derive(Clone)]
struct LogTargetInner {
target: Arc<Mutex<Box<dyn std::io::Write + Send + 'static>>>,
}
impl Default for LogTargetInner {
fn default() -> Self {
LogTargetInner {
target: Arc::new(Mutex::new(Box::new(std::io::stderr()))),
}
}
}
impl std::io::Write for LogTargetInner {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
let Ok(mut guard) = self.target.lock() else {
// Pretend we wrote successfully.
return Ok(buf.len());
};
guard.write(buf)
}
fn flush(&mut self) -> std::io::Result<()> {
let Ok(mut guard) = self.target.lock() else {
// Pretend we flushed successfully.
return Ok(());
};
guard.flush()
}
}
