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use std::fs::File; use std::io; use std::io::prelude::*; use std::io::BufReader; use std::io::ErrorKind; use std::io::SeekFrom; use std::os::unix::fs::MetadataExt; use std::path::Path; use std::thread::sleep; use std::time::Duration; pub enum LogWatcherAction { None, SeekToEnd, } pub struct LogWatcher { filename: String, inode: u64, pos: u64, reader: BufReader<File>, finish: bool, } impl LogWatcher { pub fn register<P: AsRef<Path>>(filename: P) -> Result<LogWatcher, io::Error> { let f = match File::open(&filename) { Ok(x) => x, Err(err) => return Err(err), }; let metadata = match f.metadata() { Ok(x) => x, Err(err) => return Err(err), }; let mut reader = BufReader::new(f); let pos = metadata.len(); reader.seek(SeekFrom::Start(pos)).unwrap(); Ok(LogWatcher { filename: filename.as_ref().to_string_lossy().to_string(), inode: metadata.ino(), pos: pos, reader: reader, finish: false, }) } fn reopen_if_log_rotated<F: ?Sized>(&mut self, callback: &mut F) where F: FnMut(String) -> LogWatcherAction, { loop { match File::open(&self.filename) { Ok(x) => { let f = x; let metadata = match f.metadata() { Ok(m) => m, Err(_) => { sleep(Duration::new(1, 0)); continue; } }; if metadata.ino() != self.inode { self.finish = true; self.watch(callback); self.finish = false; println!("reloading log file"); self.reader = BufReader::new(f); self.pos = 0; self.inode = metadata.ino(); } else { sleep(Duration::new(1, 0)); } break; } Err(err) => { if err.kind() == ErrorKind::NotFound { sleep(Duration::new(1, 0)); continue; } } }; } } pub fn watch<F: ?Sized>(&mut self, callback: &mut F) where F: FnMut(String) -> LogWatcherAction, { loop { let mut line = String::new(); let resp = self.reader.read_line(&mut line); match resp { Ok(len) => { if len > 0 { self.pos += len as u64; self.reader.seek(SeekFrom::Start(self.pos)).unwrap(); match callback(line.replace("\n", "")) { LogWatcherAction::SeekToEnd => { println!("SeekToEnd"); self.reader.seek(SeekFrom::End(0)).unwrap(); } LogWatcherAction::None => {} } line.clear(); } else { if self.finish { break; } else { self.reopen_if_log_rotated(callback); self.reader.seek(SeekFrom::Start(self.pos)).unwrap(); } } } Err(err) => { println!("{}", err); } } } } }