feat: keep the connection alive

Author: invisal

src/drivers/MySQLConnection.ts

@@ -75,6 +75,9 @@ export default class MySQLConnection extends SQLLikeConnection {
   protected pool: Pool | undefined;
   protected currentConnection: PoolConnection | undefined;
   protected onStateChangedCallback: (state: string) => void;
+  protected lastActivity = 0;
+  protected isRunning = false;
+  protected keepAliveTimerId?: NodeJS.Timer;
 
   constructor(
     connectionConfig: DatabaseConnectionConfig,
@@ -94,8 +97,16 @@ export default class MySQLConnection extends SQLLikeConnection {
         connectionLimit: 1,
       });
 
+      this.lastActivity = Date.now();
       this.onStateChangedCallback('Connected');
 
+      this.keepAliveTimerId = setInterval(() => {
+        if (Date.now() - this.lastActivity > 6000 && !this.isRunning) {
+          this.lastActivity = Date.now();
+          this.ping();
+        }
+      }, 5000);
+
       this.pool.on('connection', (connection) => {
         this.currentConnection = connection;
       });
@@ -104,6 +115,10 @@ export default class MySQLConnection extends SQLLikeConnection {
     return this.pool;
   }
 
+  protected async ping() {
+    this.currentConnection?.ping();
+  }
+
   async killCurrentQuery() {
     if (this.currentConnection) {
       // Make another connection quickly to cancel the query
@@ -121,6 +136,9 @@ export default class MySQLConnection extends SQLLikeConnection {
     sql: string,
     params?: Record<string, unknown>
   ): Promise<QueryResult> {
+    this.lastActivity = Date.now();
+    this.isRunning = true;
+
     try {
       const conn = await this.getConnection();
       const result = await conn.query(sql, params);
@@ -144,13 +162,16 @@ export default class MySQLConnection extends SQLLikeConnection {
         mapHeaderType
       );
 
+      this.isRunning = false;
       return {
         headers,
         rows: result[0] as Record<string, unknown>[],
         keys: {},
         error: null,
       };
     } catch (e: unknown) {
+      this.isRunning = false;
+
       return {
         headers: [],
         rows: [],
@@ -168,5 +189,9 @@ export default class MySQLConnection extends SQLLikeConnection {
       conn.end();
       conn.destroy();
     }
+
+    if (this.keepAliveTimerId) {
+      clearTimeout(this.keepAliveTimerId);
+    }
   }
 }