Add migration to config_file_version = 2 (#3634)

* Add config_file_version and migration to version 2

* Generate `config_file_version = 2` as default

config/src/comments.rs

@@ -19,7 +19,7 @@ use std::collections::HashMap;
 fn comments() -> HashMap<String, String> {
 	let mut retval = HashMap::new();
 	retval.insert(
-		"[server]".to_string(),
+		"config_file_version".to_string(),
 		"
 # Generated Server Configuration File for Grin
 #
@@ -31,7 +31,13 @@ fn comments() -> HashMap<String, String> {
 # -[user home]/.grin
 #
 
-#########################################
+"
+		.to_string(),
+	);
+
+	retval.insert(
+		"[server]".to_string(),
+		"#########################################
 ### SERVER CONFIGURATION              ###
 #########################################
 
@@ -323,7 +329,6 @@ fn comments() -> HashMap<String, String> {
 		"accept_fee_base".to_string(),
 		"
 #base fee that's accepted into the pool
-#a setting to 1000000 will be overridden to 500000 to respect the fixfees RFC
 "
 		.to_string(),
 	);

config/src/config.rs

@@ -20,7 +20,6 @@ use std::env;
 use std::fs::{self, File};
 use std::io::prelude::*;
 use std::io::BufReader;
-use std::io::Read;
 use std::path::PathBuf;
 
 use crate::comments::insert_comments;
@@ -141,6 +140,7 @@ pub fn initial_setup_server(chain_type: &global::ChainTypes) -> Result<GlobalCon
 impl Default for ConfigMembers {
 	fn default() -> ConfigMembers {
 		ConfigMembers {
+			config_file_version: Some(2),
 			server: ServerConfig::default(),
 			logging: Some(LoggingConfig::default()),
 		}
@@ -222,10 +222,14 @@ impl GlobalConfig {
 
 	/// Read config
 	fn read_config(mut self) -> Result<GlobalConfig, ConfigError> {
-		let mut file = File::open(self.config_file_path.as_mut().unwrap())?;
-		let mut contents = String::new();
-		file.read_to_string(&mut contents)?;
-		let fixed = GlobalConfig::fix_warning_level(contents);
+		let config_file_path = self.config_file_path.as_ref().unwrap();
+		let contents = fs::read_to_string(config_file_path)?;
+		let migrated = GlobalConfig::migrate_config_file_version_none_to_2(contents.clone());
+		if contents != migrated {
+			fs::write(config_file_path, &migrated)?;
+		}
+
+		let fixed = GlobalConfig::fix_warning_level(migrated);
 		let decoded: Result<ConfigMembers, toml::de::Error> = toml::from_str(&fixed);
 		match decoded {
 			Ok(gc) => {
@@ -305,6 +309,47 @@ impl GlobalConfig {
 		Ok(())
 	}
 
+	/// This migration does the following:
+	/// - Adds "config_file_version = 2"
+	/// - If server.pool_config.accept_fee_base is 1000000, change it to 500000
+	/// - Remove "#a setting to 1000000 will be overridden to 500000 to respect the fixfees RFC"
+	fn migrate_config_file_version_none_to_2(config_str: String) -> String {
+		// Parse existing config and return unchanged if not eligible for migration
+
+		let mut config: ConfigMembers =
+			toml::from_str(&GlobalConfig::fix_warning_level(config_str.clone())).unwrap();
+		if config.config_file_version != None {
+			return config_str;
+		}
+
+		// Apply changes both textually and structurally
+
+		let config_str = config_str.replace("\n#########################################\n### SERVER CONFIGURATION              ###", "\nconfig_file_version = 2\n\n#########################################\n### SERVER CONFIGURATION              ###");
+		config.config_file_version = Some(2);
+
+		let config_str = config_str.replace(
+			"\naccept_fee_base = 1000000\n",
+			"\naccept_fee_base = 500000\n",
+		);
+		if config.server.pool_config.accept_fee_base == 1000000 {
+			config.server.pool_config.accept_fee_base = 500000;
+		}
+
+		let config_str = config_str.replace(
+			"\n#a setting to 1000000 will be overridden to 500000 to respect the fixfees RFC\n",
+			"\n",
+		);
+
+		// Verify equivalence
+
+		assert_eq!(
+			config,
+			toml::from_str(&GlobalConfig::fix_warning_level(config_str.clone())).unwrap()
+		);
+
+		config_str
+	}
+
 	// For forwards compatibility old config needs `Warning` log level changed to standard log::Level `WARN`
 	fn fix_warning_level(conf: String) -> String {
 		conf.replace("Warning", "WARN")

config/src/types.rs

@@ -88,6 +88,8 @@ pub struct GlobalConfig {
 /// want serialised or deserialised
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
 pub struct ConfigMembers {
+	/// Config file version (None == version 1)
+	pub config_file_version: Option<u32>,
 	/// Server config
 	#[serde(default)]
 	pub server: ServerConfig,

src/bin/grin.rs

@@ -167,11 +167,7 @@ fn real_main() -> i32 {
 		.server
 		.pool_config
 		.accept_fee_base;
-	let fix_afb = match afb {
-		1_000_000 => 500_000,
-		_ => afb,
-	};
-	global::init_global_accept_fee_base(fix_afb);
+	global::init_global_accept_fee_base(afb);
 	info!("Accept Fee Base: {:?}", global::get_accept_fee_base());
 	global::init_global_future_time_limit(config.members.unwrap().server.future_time_limit);
 	info!("Future Time Limit: {:?}", global::get_future_time_limit());