Replace logging backend to log4rs and add log rotation (#1789)

* Replace logging backend to flexi-logger and add log rotation
* Changed flexi_logger to log4rs
* Disable logging level filtering in Root logger
* Support different logging levels for file and stdout
* Don't log messages from modules other than Grin-related
* Fix formatting
* Place backed up compressed log copies into log file directory
* Increase default log file size to 16 MiB
* Add comment to config file on log_max_size option

util/src/types.rs

@@ -14,11 +14,9 @@
 
 //! Logging configuration types
 
-/// Log level types, as slog's don't implement serialize
+/// Log level types
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub enum LogLevel {
-	/// Critical
-	Critical,
 	/// Error
 	Error,
 	/// Warning
@@ -46,6 +44,8 @@ pub struct LoggingConfig {
 	pub log_file_path: String,
 	/// Whether to append to log or replace
 	pub log_file_append: bool,
+	/// Size of the log in bytes to rotate over (optional)
+	pub log_max_size: Option<u64>,
 	/// Whether the tui is running (optional)
 	pub tui_running: Option<bool>,
 }
@@ -59,6 +59,7 @@ impl Default for LoggingConfig {
 			file_log_level: LogLevel::Debug,
 			log_file_path: String::from("grin.log"),
 			log_file_append: true,
+			log_max_size: Some(1024 * 1024 * 16), // 16 megabytes default
 			tui_running: None,
 		}
 	}