feat: add lazy refresh type for postgres, sql server and mysql

Author: kgala2

cloud-sql/mysql/servlet/src/main/java/com/example/cloudsql/ConnectorConnectionPoolFactory.java

@@ -73,6 +73,12 @@ public static DataSource createConnectionPool() {
     config.addDataSourceProperty("ipTypes", "PUBLIC,PRIVATE");
     // [START cloud_sql_mysql_servlet_connect_unix]
 
+    // setting the refresh strategy to LAZY
+    // to refresh the tokens when they are needed, rather than on a regular interval
+    // this is recommended for serverless environments to 
+    // avoid background refreshes from throttling CPU.
+    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy")
+    
     // ... Specify additional connection properties here.
     // [START_EXCLUDE]
     configureConnectionPool(config);

cloud-sql/mysql/servlet/src/main/java/com/example/cloudsql/ConnectorIamAuthnConnectionPoolFactory.java

@@ -60,6 +60,12 @@ public static DataSource createConnectionPool() {
     // The Java Connector will handle SSL so it is unneccesary to enable it at the driver level.
     config.addDataSourceProperty("sslmode", "disable");
 
+    // setting the refresh strategy to LAZY
+    // to refresh the tokens when they are needed, rather than on a regular interval
+    // this is recommended for serverless environments to 
+    // avoid background refreshes from throttling CPU.
+    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy")
+
 
     // ... Specify additional connection properties here.
     // [START_EXCLUDE]

cloud-sql/postgres/servlet/src/main/java/com/example/cloudsql/ConnectorConnectionPoolFactory.java

@@ -72,6 +72,11 @@ public static DataSource createConnectionPool() {
     config.addDataSourceProperty("ipTypes", "PUBLIC,PRIVATE");
     // [START cloud_sql_postgres_servlet_connect_unix]
 
+    // setting the refresh strategy to LAZY
+    // to refresh the tokens when they are needed, rather than on a regular interval
+    // this is recommended for serverless environments to 
+    // avoid background refreshes from throttling CPU.
+    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy")
 
     // ... Specify additional connection properties here.
     // [START_EXCLUDE]

cloud-sql/postgres/servlet/src/main/java/com/example/cloudsql/ConnectorIamAuthnConnectionPoolFactory.java

@@ -61,6 +61,11 @@ public static DataSource createConnectionPool() {
     // The Java Connector will handle SSL so it is unneccesary to enable it at the driver level.
     config.addDataSourceProperty("sslmode", "disable");
 
+    // setting the refresh strategy to LAZY
+    // to refresh the tokens when they are needed, rather than on a regular interval
+    // this is recommended for serverless environments to 
+    // avoid background refreshes from throttling CPU.
+    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy")
 
     // ... Specify additional connection properties here.
     // [START_EXCLUDE]

cloud-sql/sqlserver/servlet/src/main/java/com/example/cloudsql/ConnectorConnectionPoolFactory.java

@@ -61,6 +61,12 @@ public static DataSource createConnectionPool() {
     // at the driver level.
     config.addDataSourceProperty("encrypt", "false");
 
+    // setting the refresh strategy to LAZY
+    // to refresh the tokens when they are needed, rather than on a regular interval
+    // this is recommended for serverless environments to 
+    // avoid background refreshes from throttling CPU.
+    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy")
+
     // ... Specify additional connection properties here.
     // [START_EXCLUDE]
     configureConnectionPool(config);