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use async_std::{fs::File, io::BufReader, prelude::*, sync::Mutex, task};
use notify::event::{DataChange, ModifyKind};
use notify::{event::EventKind, RecommendedWatcher, RecursiveMode, Watcher};
use regex::RegexSet;
use shellexpand::tilde;
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::sync::{mpsc::channel, Arc};
//==== Errors
#[derive(Debug, thiserror::Error)]
pub enum ErrorKind {
#[error("failed to open file - {0}")]
FileOpenError(std::io::Error),
#[error("failed to seek file - {0}")]
FileSeekError(std::io::Error),
}
#[derive(Debug)]
pub struct LogError {
pub kind: ErrorKind,
// pub path: String,
}
impl LogError {
// Display the error message
pub fn display_error(&self) -> String {
match &self.kind {
ErrorKind::FileOpenError(err) => {
// format!("{:?} - {}", err, self.path)
format!("{:?}", err)
}
ErrorKind::FileSeekError(err) => {
// format!("{:?} - {}", err, self.path)
format!("{:?}", err)
}
}
}
}
impl std::fmt::Display for LogError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self.display_error())
}
}
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("event error - {0}")]
EventError(notify::Error),
#[error("failed to receive data - {0}")]
RecvError(std::sync::mpsc::RecvError),
}
//==== Events
pub struct LogEvent {
line: Option<String>,
log_error: Option<LogError>,
path: String,
// log_watcher: Arc<Mutex<LogWatcher>>,
}
impl LogEvent {
fn new(
path: String,
line: Option<String>,
error: Option<LogError>, /*, log_watcher:Arc<Mutex<LogWatcher>>*/
) -> Self {
Self {
path,
line,
log_error: error,
// log_watcher
}
}
// pub async fn change_file_path(&self, new_path: &str) -> Result<(), Error>{
// self.log_watcher.lock().await.change_file_path(&self.path, new_path).await
// }
//
// pub async fn stop_monitoring_file(&self) -> Result<(), Error>{
// self.log_watcher.lock().await.stop_monitoring_file(&self.path).await
// }
pub fn file_path(&self) -> &str {
self.path.as_str()
}
pub fn get_line(&self) -> Option<&String> {
self.line.as_ref()
}
pub fn get_log_error(&self) -> Option<&LogError> {
self.log_error.as_ref()
}
}
//==== Callback
pub type LogCallback =
Arc<dyn Fn(LogEvent) -> Pin<Box<dyn Future<Output = ()> + Send + Sync>> + Send + Sync>;
pub struct LogWatcher {
log_callbacks: Arc<Mutex<HashMap<String, (LogCallback, Option<RegexSet>)>>>,
watcher: Arc<Mutex<Option<RecommendedWatcher>>>,
}
impl LogWatcher {
pub fn new() -> Self {
Self {
log_callbacks: Arc::new(Mutex::new(HashMap::new())),
watcher: Arc::new(Mutex::new(None)),
}
}
pub async fn change_file_path(&mut self, old_path: &str, new_path: &str) -> Result<(), Error> {
// change into absolute path
let old_path = self.make_absolute_path(&Path::new(old_path));
let old_path = old_path.into_os_string().into_string().unwrap();
let callback = self.log_callbacks.lock().await.remove(&old_path);
if let Some(callback) = callback {
self.log_callbacks
.lock()
.await
.insert(new_path.to_owned(), callback);
let mut watcher = self.watcher.lock().await;
if let Some(watcher) = &mut *watcher {
watcher
.unwatch(Path::new(&old_path))
.map_err(|e| Error::EventError(e))?;
watcher
.watch(Path::new(new_path), RecursiveMode::NonRecursive)
.map_err(|e| Error::EventError(e))?;
}
}
Ok(())
}
pub async fn stop_monitoring_file(&mut self, path: &str) -> Result<(), Error> {
// change into absolute path
let path = self.make_absolute_path(&Path::new(path));
let path = path.into_os_string().into_string().unwrap();
self.log_callbacks.lock().await.remove(&path);
let mut watcher = self.watcher.lock().await;
if let Some(watcher) = &mut *watcher {
watcher
.unwatch(Path::new(&path))
.map_err(|e| Error::EventError(e))?;
}
Ok(())
}
// helper function to convert a relative path into an absolute path
fn make_absolute_path(&self, path: &Path) -> PathBuf {
let expanded_path = tilde(&path.to_string_lossy()).into_owned();
let expanded_path = Path::new(&expanded_path);
if expanded_path.is_absolute() {
expanded_path.to_path_buf()
} else {
std::env::current_dir().unwrap().join(expanded_path)
}
}
// register a file path and its associated callback function.
pub async fn register<P: AsRef<Path>, F, Fut>(
&mut self,
path: P,
callback: F,
patterns: Option<Vec<&str>>,
) where
F: Fn(LogEvent) -> Fut + Send + Sync + 'static,
Fut: std::future::Future<Output = ()> + Send + Sync + 'static,
{
let path = self.make_absolute_path(path.as_ref());
let path = path.into_os_string().into_string().unwrap();
let callback = Arc::new(
move |log_event: LogEvent| -> Pin<Box<dyn Future<Output = ()> + Send + Sync>> {
Box::pin(callback(log_event))
},
);
let regex_set = if let Some(patterns) = patterns {
Some(RegexSet::new(patterns).unwrap())
} else {
None
};
self.log_callbacks
.lock()
.await
.insert(path, (callback, regex_set));
}
// Start monitoring
pub async fn monitoring(&self, poll_interval: std::time::Duration) -> Result<(), Error> {
let (tx, rx) = channel();
let config = notify::Config::default().with_poll_interval(poll_interval);
let watcher: RecommendedWatcher = Watcher::new(tx, config).unwrap();
*self.watcher.lock().await = Some(watcher);
for path in self.log_callbacks.lock().await.keys() {
self.watcher
.lock()
.await
.as_mut()
.unwrap()
.watch(Path::new(&path), RecursiveMode::NonRecursive)
.map_err(|e| Error::EventError(e))?;
}
let file_positions = Arc::new(Mutex::new(HashMap::<String, u64>::new()));
loop {
match rx.recv() {
Ok(event) => match event {
Ok(event) => match event.kind {
EventKind::Modify(ModifyKind::Data(DataChange::Any)) => {
let paths = &event.paths;
for path in paths {
let path_str = path.clone().into_os_string().into_string().unwrap();
// clone the contianers
let log_callbacks = Arc::clone(&self.log_callbacks);
let file_positions_clone = Arc::clone(&file_positions);
task::spawn(async move {
// to avoid the deadlock
let log_callbacks = log_callbacks.lock().await;
if let Some((callback, regex_set)) =
log_callbacks.get(&path_str)
{
let callback = Arc::clone(callback);
let mut file_positions = file_positions_clone.lock().await;
let position = file_positions
.entry(path_str.clone())
.or_insert(std::u64::MAX);
// file open
match File::open(&path_str).await {
Ok(file) => {
let mut reader = BufReader::new(file);
let mut line = String::new();
// need to set initial position
if *position == std::u64::MAX {
*position = find_last_line(&mut reader).await;
}
// seek from *position
match reader
.seek(std::io::SeekFrom::Start(*position))
.await
{
Ok(_) => {
// check if a full line has been read
if reader
.read_line(&mut line)
.await
.unwrap()
> 0
&& line.ends_with('\n')
{
*position += line.len() as u64;
// remove trailing newline character, if present
// use the trim_end_matches
let line = line
.trim_end_matches(|c| {
c == '\n' || c == '\r'
})
.to_owned();
let notify = if let Some(regex_set) =
regex_set
{
if regex_set.is_match(&line) {
true
} else {
false
}
} else {
true
};
if notify {
let event = LogEvent::new(
path_str,
Some(line),
None,
);
callback(event).await;
}
}
}
Err(e) => {
let log_error = LogError {
kind: ErrorKind::FileSeekError(e),
};
let event = LogEvent::new(
path_str,
None,
Some(log_error),
);
callback(event).await;
}
}
}
Err(e) => {
let log_error = LogError {
kind: ErrorKind::FileOpenError(e),
};
let event =
LogEvent::new(path_str, None, Some(log_error));
callback(event).await;
}
}
}
});
}
}
_ => {}
},
Err(e) => return Err(Error::EventError(e)),
},
Err(e) => return Err(Error::RecvError(e)),
}
}
}
}
// find the position of last line.
async fn find_last_line(reader: &mut BufReader<File>) -> u64 {
let mut last_line_start = 0;
let mut last_line = String::new();
let mut current_position = 0;
while let Ok(len) = reader.read_line(&mut last_line).await {
if len == 0 || !last_line.ends_with('\n') {
break;
}
last_line_start = current_position;
current_position += len as u64;
last_line.clear();
}
last_line_start
}
#[cfg(test)]
mod tests {
use super::find_last_line;
use async_std::{fs::remove_file, fs::File, io::BufReader, prelude::*};
#[async_std::test]
async fn test_find_last_line() {
//
let filepath = "test-log.txt";
let _ = remove_file(filepath);
let mut file = File::create(filepath).await.unwrap();
file.write_all(b"0\n").await.unwrap();
file.write_all(b"1\n").await.unwrap();
file.write_all(b"2\n").await.unwrap();
file.write_all(b"3\n").await.unwrap();
file.flush().await.unwrap();
let ofile = File::open(&filepath).await.unwrap();
let mut reader = BufReader::new(ofile);
let position = find_last_line(&mut reader).await;
// assert last line position
assert_eq!(position, 6);
let mut line = String::new();
reader
.seek(std::io::SeekFrom::Start(position))
.await
.unwrap();
reader.read_line(&mut line).await.unwrap();
// assert last line
assert_eq!(line, "3\n");
let _ = remove_file(filepath).await; // Remove the file if it exists
}
#[async_std::test]
async fn test_log_watcher() {
let mut log_watcher = super::LogWatcher::new();
let log_file_1 = "test-log1.txt";
let log_file_2 = "test-log2.txt";
let log_file_3 = "test-log3.txt";
// create log files
let mut file_1 = File::create(log_file_1).await.unwrap();
let mut file_2 = File::create(log_file_2).await.unwrap();
let mut file_3 = File::create(log_file_3).await.unwrap();
log_watcher.register(log_file_1, |_| async {}, None).await;
log_watcher.register(log_file_2, |_| async {}, None).await;
// write data to log files
file_1.write_all(b"line 1\n").await.unwrap();
file_1.sync_all().await.unwrap();
file_2.write_all(b"line 2\n").await.unwrap();
file_2.sync_all().await.unwrap();
// stop monitoring log_file_1
log_watcher.stop_monitoring_file(log_file_1).await.unwrap();
// change the path of log_file_2 to log_file_3
log_watcher
.change_file_path(log_file_2, log_file_3)
.await
.unwrap();
// write data to log files
file_1.write_all(b"line 3\n").await.unwrap();
file_1.sync_all().await.unwrap();
file_3.write_all(b"line 4\n").await.unwrap();
file_3.sync_all().await.unwrap();
assert!(!log_watcher
.log_callbacks
.lock()
.await
.contains_key(log_file_1));
assert!(!log_watcher
.log_callbacks
.lock()
.await
.contains_key(log_file_2));
assert!(log_watcher
.log_callbacks
.lock()
.await
.contains_key(log_file_3));
// remove the test log files
remove_file(log_file_1).await.unwrap();
remove_file(log_file_2).await.unwrap();
remove_file(log_file_3).await.unwrap();
}
}