Deprecated functions being used in module file.

There are deprecated code used in module file which will be removed in future release.

$ drupal-check modules/perfmon/
 5/5 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ ------------------------------------------------------------------------- 
  Line   perfmon.module                                                           
 ------ ------------------------------------------------------------------------- 
  229    Call to deprecated function db_insert():                                 
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call insert() on it. For example,                                        
  247    Call to deprecated function db_truncate():                               
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call truncate() on it. For example,                                      
  254    Call to deprecated function db_select():                                 
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call select() on it. For example,                                        
  272    Call to deprecated function db_truncate():                               
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call truncate() on it. For example,                                      
  290    Call to deprecated function db_truncate():                               
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call truncate() on it. For example,                                      
  297    Call to deprecated function db_update():                                 
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call update() on it. For example,                                        
  329    Call to deprecated function db_query():                                  
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call query() on it. For example,                                         
  339    Call to deprecated function db_query():                                  
         as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Instead, get        
         a database connection injected into your service from the container and  
         call query() on it. For example,                                         
 ------ ------------------------------------------------------------------------- 

                                                                                                                        
 [ERROR] Found 8 errors