/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.unix.aix.perfstat;
   
   import java.util.Arrays;
   
   import com.sun.jna.platform.unix.aix.Perfstat;
  import com.sun.jna.platform.unix.aix.Perfstat.perfstat_id_t;
  import com.sun.jna.platform.unix.aix.Perfstat.perfstat_process_t;
  
  import oshi.annotation.concurrent.ThreadSafe;
  
  /**
   * Utility to query performance stats for processes
   */
  @ThreadSafe
  public final class PerfstatProcess {
  
      private static final Perfstat PERF = Perfstat.INSTANCE;
  
      private PerfstatProcess() {
      }
  
      /**
       * Queries perfstat_process for per-process usage statistics
       *
       * @return an array of usage statistics
       */
      public static perfstat_process_t[] queryProcesses() {
          perfstat_process_t process = new perfstat_process_t();
          // With null, null, ..., 0, returns total # of elements
          int procCount = PERF.perfstat_process(null, null, process.size(), 0);
          if (procCount > 0) {
              perfstat_process_t[] proct = (perfstat_process_t[]) process.toArray(procCount);
              perfstat_id_t firstprocess = new perfstat_id_t(); // name is ""
              int ret = PERF.perfstat_process(firstprocess, proct, process.size(), procCount);
              if (ret > 0) {
                  return Arrays.copyOf(proct, ret);
              }
          }
          return new perfstat_process_t[0];
      }
  }