[BE] Re-enable database pool for latency measuring

backend/src/main.rs

@@ -1,6 +1,10 @@
 use cors::Cors;
+use once_cell::sync::OnceCell;
 use sqlx::Connection;
+use sqlx::MySql;
 use sqlx::MySqlConnection;
+use sqlx::Pool;
+use sqlx::mysql::MySqlPoolOptions;
 use std::env;
 use std::time::Instant;
 
@@ -14,12 +18,14 @@ mod online_classroom;
 
 pub mod json_result;
 
+static DB: OnceCell<Pool<MySql>> = OnceCell::new();
+
 /// Opens & returns a connection to the database
 ///
 /// We don't use a connection pool because it often times out,
 /// we don't have a lot of traffic and reiniting the pool would
 /// require to change a lot of code in multiple places.
-pub async fn db() -> Result<MySqlConnection, String> {
+pub async fn db() -> Result<&'static Pool<MySql>, String> {
     /*
        Init DB and set it as a global variable
     * /
@@ -39,6 +45,53 @@ pub async fn db() -> Result<MySqlConnection, String> {
             Err("Error connecting to DB".to_string())
         }
     }
+    // */
+
+    let attempts = 3;
+
+    for _ in 0..attempts {
+        match DB.get() {
+            Some(db) => return Ok(db),
+            None => {
+                log::info!("DB not initialized, initializing from db()");
+                let _ = init_db().await;
+            }
+        }
+    }
+
+    log::error!("Failed to initialize DB after {} attempts", attempts);
+    Err("Failed to initialize DB".to_string())
+}
+
+pub async fn init_db() -> Result<(), String> {
+    /*
+       Init DB and set it as a global variable
+    */
+    let db_url = match env::var("DATABASE_URL") {
+        Ok(url) => url,
+        Err(_) => return Err("env DATABASE_URL not found".to_string()),
+    };
+
+    let start = Instant::now();
+    let pool = MySqlPoolOptions::new()
+        .max_connections(5)
+        .connect(db_url.as_str())
+        .await;
+    log::info!("DB Pool connection took: {:?} ms", start.elapsed().as_millis());
+
+    match pool {
+        Ok(pool) => match DB.set(pool) {
+            Ok(_) => Ok(()),
+            Err(_) => {
+                log::error!("Failed to set DB global variable");
+                Err("Failed to set DB".to_string())
+            }
+        },
+        Err(e) => {
+            log::error!("Error connecting to DB: {}", e);
+            Err("Error connecting to DB".to_string())
+        }
+    }
 }
 
 #[launch]

backend/src/model/course.rs

@@ -36,7 +36,7 @@ impl Course {
         };
 
         let results = sqlx::query!("SELECT * FROM course")
-            .fetch_all(&mut db)
+            .fetch_all(db)
             .await;
 
         let results = match results {
@@ -73,7 +73,7 @@ impl Course {
             "SELECT course_name FROM course WHERE course_id = ?",
             course_id
         )
-        .fetch_one(&mut db)
+        .fetch_one(db)
         .await;
 
         match res {

backend/src/model/custom_label.rs

@@ -20,7 +20,7 @@ impl CustomLabel {
             FROM custom_label
             "#,
         )
-        .fetch_all(&mut db)
+        .fetch_all(db)
         .await;
 
         match result {
@@ -42,7 +42,7 @@ impl CustomLabel {
             "SELECT custom_label_id FROM custom_label WHERE custom_label_value = ?",
             value
         )
-        .fetch_all(&mut db)
+        .fetch_all(db)
         .await;
 
         let result = match result {
@@ -72,7 +72,7 @@ impl CustomLabel {
             "INSERT INTO custom_label (custom_label_value) VALUES (?)",
             value
         )
-        .execute(&mut db)
+        .execute(db)
         .await;
 
         if let Err(err) = result {

backend/src/model/person.rs

@@ -36,16 +36,19 @@ pub struct Person {
 
 impl Person {
     pub async fn get_by_dni(dni: i32) -> Result<Person, DBError> {
-        let mut db = match db().await {
+        let db = match db().await {
             Ok(db) => db,
             Err(reason) => return Err(DBError::Str(reason)),
         };
 
         let start = Instant::now();
         let result = sqlx::query_as!(Person, "SELECT * FROM person WHERE person_dni = ?", dni)
-            .fetch_one(&mut db)
+            .fetch_one(db)
             .await;
-        log::info!("DB query (person by dni) took: {:?} ms", start.elapsed().as_millis());
+        log::info!(
+            "DB query (person by dni) took: {:?} ms",
+            start.elapsed().as_millis()
+        );
 
         match result {
             Ok(v) => Ok(v),
@@ -79,7 +82,7 @@ impl PersonCreate {
             self.person_paternal_surname,
             self.person_maternal_surname,
         )
-            .execute(&mut db)
+            .execute(db)
             .await;
 
         match result {
@@ -113,7 +116,7 @@ impl PersonLink {
             self.person_classroom_username,
             self.person_id,
         )
-        .execute(&mut db)
+        .execute(db)
         .await;
 
         match res {

backend/src/model/register.rs

@@ -83,7 +83,7 @@ impl RegisterCreate {
             self.person_id,
             self.course_id
         )
-        .execute(&mut db)
+        .execute(db)
         .await;
 
         match result {
@@ -107,7 +107,7 @@ impl RegisterCreate {
                 WHERE register_course_id IN 
                 (SELECT course_id FROM course WHERE course_name LIKE 'Matpel%')",
             )
-            .fetch_one(&mut db)
+            .fetch_one(db)
             .await;
 
             match res {
@@ -126,7 +126,7 @@ impl RegisterCreate {
                 WHERE register_course_id=?",
                 course_id
             )
-            .fetch_one(&mut db)
+            .fetch_one(db)
             .await;
 
             match res {
@@ -345,7 +345,7 @@ impl Register {
                 WHERE register_person_id = (SELECT person_id FROM person WHERE person_dni = ?)",
             dni
         )
-        .fetch_all(&mut db)
+        .fetch_all(db)
         .await;
         log::info!(
             "DB (get register by id) took: {:?} ms",
@@ -381,7 +381,7 @@ impl Register {
         let mut db = db().await?;
 
         let res = sqlx::query!("DELETE FROM register WHERE register_id = ?", register_id)
-            .execute(&mut db)
+            .execute(db)
             .await;
 
         match res {