Logging #26
@ -7,6 +7,7 @@ mod test;
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use std::fmt::Display;
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use std::fs::OpenOptions;
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use std::io;
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use std::io::Write;
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use config::log::LogSettings;
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@ -24,45 +25,49 @@ use LogMessageType::GenericWarn;
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/**
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* Logs the given message.
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*
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* # Panics
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* Panics if readlock on [`config::CONFIG`] could not be acquired
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* or if another error occurs, such as a full disk.
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*/
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pub fn log_message(msg: &LogMessage, conf: &LogSettings, file: &str, line: u32, column: u32) {
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pub fn log_message(msg: &LogMessage, conf: &LogSettings, file: &str, line: u32, column: u32) -> Result<(), io::Error> {
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// Check if message may be logged according to config.
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let Some(log_line) = log_to_str(msg, conf, file, line, column) else {
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return;
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return Ok(());
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};
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// May panic if file cannot be opened or written to.
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conf.path().as_ref().map_or_else(
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|| {},
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|path| {
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let mut file = OpenOptions::new()
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// Log to file
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match conf.path().as_ref()
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{
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None => {/* Do not log to file */}
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Some(p) =>
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{
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let file = OpenOptions::new()
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.write(true)
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.append(true)
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.create(true)
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.open(path)
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.unwrap_or_else(|_| panic!("Could not open log file: {path:#?}"));
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writeln!(file, "{log_line}")
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.unwrap_or_else(|_| panic!("Could not write log to file: {path:#?}"));
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},
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);
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.open(p);
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let mut file = match file
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{
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Ok(f) => f,
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Err(e) => return Err(e),
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};
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match writeln!(file, "{log_line}")
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{
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Ok(_) => {},
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Err(e) => return Err(e),
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}
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}
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};
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if msg.1 <= Warning && *conf.stderr() {
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// May panic if writing to stderr fails.
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eprintln!("{log_line}");
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let mut stdout = io::stdout().lock();
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return writeln!(stdout, "{log_line}");
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} else if msg.1 >= Information && *conf.stdout() {
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// May panic if writing to stdout fails.
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println!("{log_line}");
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let mut stderr = io::stderr().lock();
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return writeln!(stderr, "{log_line}")
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}
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return Ok(());
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}
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/**
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* Return log line, if message may be logged according to [`config::log::LogSettings`].
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* # Panics
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* Panics if readlock on [`config::CONFIG`] could not be acquired
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* or if another error occurs, such as a full disk.
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*/
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#[must_use]
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pub fn log_to_str(
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@ -103,11 +108,12 @@ macro_rules! log {
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let conf = config::LOG_SETTINGS
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.read()
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.unwrap_or_else(|_| panic!("Failed aqcuire read lock on config!"));
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log_message($msg, &*conf, file!(), line!(), column!());
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let res = log_message($msg, &*conf, file!(), line!(), column!());
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drop(conf);
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res
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};
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($msg:expr, $config:expr) => {
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log_message($msg, $config, file!(), line!(), column!());
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log_message($msg, $config, file!(), line!(), column!())
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};
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}
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Reference in New Issue
Block a user
While logging is not a dependency of the program's main function, it is a crucial part of administrating it. If the program cannot log to stdout because the feature was disabled by the admin or due to some problem, it could lead to an edge case-where the program has no logging and cannot inform the sysadmin about errors.
Although I see how panicking is not the best solution. A controlled shutdown is preferable and a config Option allowing the sysadmin to set a limit on how many log-messages may be dropped within x time, without the service shutting down.
@hendrik
If the stdout was disabled, panicking wouldn't tell the admin about the error either. The whole program shutting down is not a good indicator for a failure, if not shutting down is a safe alternative. The program could also notify the admin via CLI, Internet, Email or many other ways that something went wrong while still keeping up its full functionality (as from the perspective of the user).
The error in this case is the inability to report about warnings. This edge-case happens, when there is absolutely no way of informing the sysadmin of other errors, including CLI and E-Mail, etc.
Let's assume the program detects something which could to serious data-loss in the future. The program should warn the sysadmin about it, but not yet shut down, unless the error is possibly imminent. But if all configured ways of logging and communicating with the sysadmin fail, the service should try to shut down to prevent data loss or other unintended behavior.
I would suggest the following:
But until then, I will remove the panic and spit something into stderr, ignoring the stderr setting.
See
e4baaa5f45