/*
    * Copyright 2020-2023 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.demo;
   
   import java.util.Objects;
   
   import com.sun.jna.platform.win32.COM.COMException;
  
  import oshi.annotation.SuppressForbidden;
  import oshi.driver.windows.wmi.Win32OperatingSystem;
  import oshi.util.platform.windows.WmiQueryHandler;
  
  /**
   * Class demonstrating WMI stat performance improvements if the user does COM initialization so OSHI doesn't have to
   */
  public class UserComInit {
  
      private static final int REPETITIONS = 300;
  
      @SuppressForbidden(reason = "Using System.out in a demo class")
      public static void main(String[] args) {
          wakeUpCom();
          System.out.println("Collecting statistics with default COM setup");
          loopWmiQueries();
          System.out.println("Collecting statistics with user-init COM setup");
          loopWmiQueriesWithUserCom();
      }
  
      private static void wakeUpCom() {
          // The first COM query can take extra long so just do one separately
          Win32OperatingSystem.queryOsVersion();
      }
  
      @SuppressForbidden(reason = "Using System.out in a demo class")
      private static void loopWmiQueries() {
          long t = System.nanoTime();
          for (int i = 0; i < REPETITIONS; i++) {
              Win32OperatingSystem.queryOsVersion();
          }
          t = System.nanoTime() - t;
          System.out.println("Average ms per rep: " + t / (1_000_000d * REPETITIONS));
      }
  
      private static void loopWmiQueriesWithUserCom() {
          // Create instance using existing WmiQueryHandler class for convenience, only to
          // be used for COM init/uninit. Not needed if user initializes COM.
          WmiQueryHandler handlerForSingleCOMinit = Objects.requireNonNull(WmiQueryHandler.createInstance());
  
          boolean singleComInit = false;
          try {
              // Initialize using the default query handler. This is unnecessary in a user
              // application if the application controls COM initialization elsewhere.
              singleComInit = handlerForSingleCOMinit.initCOM();
  
              // Change query handler class to not initialize COM
              WmiQueryHandler.setInstanceClass(WmiNoComInitQueryHandler.class);
  
              loopWmiQueries();
          } catch (COMException e) {
              // Ignore for demo. Production code should handle this!
          } finally {
              // User should ununitialize COM in their own application
              if (singleComInit) {
                  handlerForSingleCOMinit.unInitCOM();
              }
          }
      }
  }