/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.unix.aix.perfstat;
   
   import com.sun.jna.platform.unix.aix.Perfstat;
   import com.sun.jna.platform.unix.aix.Perfstat.perfstat_cpu_t;
   import com.sun.jna.platform.unix.aix.Perfstat.perfstat_cpu_total_t;
  import com.sun.jna.platform.unix.aix.Perfstat.perfstat_id_t;
  
  import oshi.annotation.concurrent.ThreadSafe;
  
  /**
   * Utility to query performance stats for cpu
   */
  @ThreadSafe
  public final class PerfstatCpu {
  
      private static final Perfstat PERF = Perfstat.INSTANCE;
  
      private PerfstatCpu() {
      }
  
      /**
       * Queries perfstat_cpu_total for total CPU usage statistics
       *
       * @return usage statistics
       */
      public static perfstat_cpu_total_t queryCpuTotal() {
          perfstat_cpu_total_t cpu = new perfstat_cpu_total_t();
          int ret = PERF.perfstat_cpu_total(null, cpu, cpu.size(), 1);
          if (ret > 0) {
              return cpu;
          }
          return new perfstat_cpu_total_t();
      }
  
      /**
       * Queries perfstat_cpu for per-CPU usage statistics
       *
       * @return an array of usage statistics
       */
      public static perfstat_cpu_t[] queryCpu() {
          perfstat_cpu_t cpu = new perfstat_cpu_t();
          // With null, null, ..., 0, returns total # of elements
          int cputotal = PERF.perfstat_cpu(null, null, cpu.size(), 0);
          if (cputotal > 0) {
              perfstat_cpu_t[] statp = (perfstat_cpu_t[]) cpu.toArray(cputotal);
              perfstat_id_t firstcpu = new perfstat_id_t(); // name is ""
              int ret = PERF.perfstat_cpu(firstcpu, statp, cpu.size(), cputotal);
              if (ret > 0) {
                  return statp;
              }
          }
          return new perfstat_cpu_t[0];
      }
  
      /**
       * Returns affinity mask from the number of CPU in the OS.
       *
       * @return affinity mask
       */
      public static long queryCpuAffinityMask() {
          int cpus = queryCpuTotal().ncpus;
          if (cpus < 63) {
              return (1L << cpus) - 1;
          }
          return cpus == 63 ? Long.MAX_VALUE : -1L;
      }
  }