proxmox-backup/src/tools/file_logger.rs
Thomas Lamprecht 081c37cccf tools file logger: fix example and comments
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
2020-10-16 11:16:29 +02:00

109 lines
3.2 KiB
Rust

use anyhow::Error;
use std::io::Write;
/// Log messages with optional automatically added timestamps into files
///
/// Logs messages to file, and optionally to standard output.
///
///
/// #### Example:
/// ```
/// #[macro_use] extern crate proxmox_backup;
/// # use anyhow::{bail, format_err, Error};
/// use proxmox_backup::tools::{FileLogger, FileLogOptions};
///
/// # std::fs::remove_file("test.log");
/// let options = FileLogOptions {
/// to_stdout: true,
/// exclusive: true,
/// ..Default::default()
/// };
/// let mut log = FileLogger::new("test.log", options).unwrap();
/// flog!(log, "A simple log: {}", "Hello!");
/// ```
#[derive(Debug, Default)]
/// Options to control the behavior of a ['FileLogger'] instance
pub struct FileLogOptions {
/// Open underlying log file in append mode, useful when multiple concurrent processes
/// want to log to the same file (e.g., HTTP access log). Note that it is only atomic
/// for writes smaller than the PIPE_BUF (4k on Linux).
/// Inside the same process you may need to still use an mutex, for shared access.
pub append: bool,
/// Open underlying log file as readable
pub read: bool,
/// If set, ensure that the file is newly created or error out if already existing.
pub exclusive: bool,
/// Duplicate logged messages to STDOUT, like tee
pub to_stdout: bool,
/// Prefix messages logged to the file with the current local time as RFC 3339
pub prefix_time: bool,
}
#[derive(Debug)]
pub struct FileLogger {
file: std::fs::File,
options: FileLogOptions,
}
/// Log messages to [FileLogger](tools/struct.FileLogger.html)
#[macro_export]
macro_rules! flog {
($log:expr, $($arg:tt)*) => ({
$log.log(format!($($arg)*));
})
}
impl FileLogger {
pub fn new<P: AsRef<std::path::Path>>(
file_name: P,
options: FileLogOptions,
) -> Result<Self, Error> {
let file = std::fs::OpenOptions::new()
.read(options.read)
.write(true)
.append(options.append)
.create_new(options.exclusive)
.create(!options.exclusive)
.open(file_name)?;
Ok(Self { file, options })
}
pub fn log<S: AsRef<str>>(&mut self, msg: S) {
let msg = msg.as_ref();
if self.options.to_stdout {
let mut stdout = std::io::stdout();
stdout.write_all(msg.as_bytes()).unwrap();
stdout.write_all(b"\n").unwrap();
}
let now = proxmox::tools::time::epoch_i64();
let rfc3339 = proxmox::tools::time::epoch_to_rfc3339(now).unwrap();
let line = if self.options.prefix_time {
format!("{}: {}\n", rfc3339, msg)
} else {
format!("{}\n", msg)
};
self.file.write_all(line.as_bytes()).unwrap();
}
}
impl std::io::Write for FileLogger {
fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
if self.options.to_stdout {
let _ = std::io::stdout().write(buf);
}
self.file.write(buf)
}
fn flush(&mut self) -> Result<(), std::io::Error> {
if self.options.to_stdout {
let _ = std::io::stdout().flush();
}
self.file.flush()
}
}