Consolidate config defaults

Use #[serde(default)] to provide default values for missing
configuration options during deserialization.  This typically makes use
of the type's Default trait, but we also specify a couple default
functions for standard types when a custom default is desired.

Also make number_of_queries optional to bring its semantics into
alignment with the documentation in the README.md.  I think it was
accidentally specified as a required option.

Author: davisjc

src/config.rs

@@ -51,6 +51,14 @@ pub enum QueryDiscoveryMode {
     External,
 }
 
+fn default_lock_file() -> String {
+    "/tmp/readyset_scheduler.lock".to_string()
+}
+
+fn default_number_of_queries() -> u16 {
+    10
+}
+
 #[derive(Deserialize, Clone, Debug)]
 pub struct Config {
     pub proxysql_user: String,
@@ -61,14 +69,22 @@ pub struct Config {
     pub readyset_password: String,
     pub source_hostgroup: u16,
     pub readyset_hostgroup: u16,
-    pub warmup_time_s: Option<u16>,
-    pub lock_file: Option<String>,
-    pub operation_mode: Option<OperationMode>,
+    #[serde(default)]
+    pub warmup_time_s: u16,
+    #[serde(default = "default_lock_file")]
+    pub lock_file: String,
+    #[serde(default)]
+    pub operation_mode: OperationMode,
+    #[serde(default = "default_number_of_queries")]
     pub number_of_queries: u16,
-    pub query_discovery_mode: Option<QueryDiscoveryMode>,
-    pub query_discovery_min_execution: Option<u64>,
-    pub query_discovery_min_row_sent: Option<u64>,
-    pub log_verbosity: Option<MessageType>,
+    #[serde(default)]
+    pub query_discovery_mode: QueryDiscoveryMode,
+    #[serde(default)]
+    pub query_discovery_min_execution: u64,
+    #[serde(default)]
+    pub query_discovery_min_row_sent: u64,
+    #[serde(default)]
+    pub log_verbosity: MessageType,
 }
 
 pub fn read_config_file(path: &str) -> Result<String, std::io::Error> {

src/main.rs

@@ -5,9 +5,8 @@ mod queries;
 mod readyset;
 
 use clap::Parser;
-use config::read_config_file;
+use config::{read_config_file, OperationMode};
 use file_guard::Lock;
-use messages::MessageType;
 use mysql::{Conn, OptsBuilder};
 use proxysql::ProxySQL;
 use std::fs::OpenOptions;
@@ -29,30 +28,19 @@ fn main() {
     let args = Args::parse();
     let config_file = read_config_file(&args.config).expect("Failed to read config file");
     let config = config::parse_config_file(&config_file).expect("Failed to parse config file");
-    messages::set_log_verbosity(config.clone().log_verbosity.unwrap_or(MessageType::Note));
+    messages::set_log_verbosity(config.log_verbosity);
     messages::print_info("Running readyset_scheduler");
     let file = match OpenOptions::new()
         .read(true)
         .write(true)
         .create(true)
         .truncate(true)
-        .open(
-            config
-                .clone()
-                .lock_file
-                .unwrap_or("/tmp/readyset_scheduler.lock".to_string()),
-        ) {
+        .open(&config.lock_file)
+    {
         Ok(file) => file,
         Err(err) => {
             messages::print_error(
-                format!(
-                    "Failed to open lock file {}: {}",
-                    config
-                        .lock_file
-                        .unwrap_or("/tmp/readyset_scheduler.lock".to_string()),
-                    err
-                )
-                .as_str(),
+                format!("Failed to open lock file {}: {}", config.lock_file, err).as_str(),
             );
             std::process::exit(1);
         }
@@ -68,19 +56,14 @@ fn main() {
 
     let mut proxysql = ProxySQL::new(&config, args.dry_run);
 
-    let running_mode = match config.operation_mode {
-        Some(mode) => mode,
-        None => config::OperationMode::All,
-    };
-
-    if running_mode == config::OperationMode::HealthCheck
-        || running_mode == config::OperationMode::All
+    if config.operation_mode == OperationMode::HealthCheck
+        || config.operation_mode == OperationMode::All
     {
         proxysql.health_check();
     }
 
-    if running_mode == config::OperationMode::QueryDiscovery
-        || running_mode == config::OperationMode::All
+    if config.operation_mode == OperationMode::QueryDiscovery
+        || config.operation_mode == OperationMode::All
     {
         let mut conn = Conn::new(
             OptsBuilder::new()

src/proxysql.rs

@@ -60,7 +60,7 @@ impl ProxySQL {
         ProxySQL {
             conn,
             readyset_hostgroup: config.readyset_hostgroup,
-            warmup_time_s: config.warmup_time_s.unwrap_or(0),
+            warmup_time_s: config.warmup_time_s,
             readysets,
             dry_run,
         }

src/queries.rs

@@ -96,11 +96,9 @@ impl QueryDiscovery {
     /// A new QueryDiscovery struct.
     pub fn new(config: &Config) -> Self {
         QueryDiscovery {
-            query_discovery_mode: config
-                .query_discovery_mode
-                .unwrap_or(QueryDiscoveryMode::CountStar),
-            query_discovery_min_execution: config.query_discovery_min_execution.unwrap_or(0),
-            query_discovery_min_rows_sent: config.query_discovery_min_row_sent.unwrap_or(0),
+            query_discovery_mode: config.query_discovery_mode,
+            query_discovery_min_execution: config.query_discovery_min_execution,
+            query_discovery_min_rows_sent: config.query_discovery_min_row_sent,
             source_hostgroup: config.source_hostgroup,
             readyset_user: config.readyset_user.clone(),
             number_of_queries: config.number_of_queries,