/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.unix.solaris.kstat;
   
   import static oshi.software.os.unix.solaris.SolarisOperatingSystem.HAS_KSTAT2;
   
   import com.sun.jna.platform.unix.solaris.LibKstat.Kstat;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.util.platform.unix.solaris.KstatUtil;
  import oshi.util.platform.unix.solaris.KstatUtil.KstatChain;
  import oshi.util.tuples.Pair;
  
  /**
   * Utility to query geom part list
   */
  @ThreadSafe
  public final class SystemPages {
  
      private SystemPages() {
      }
  
      /**
       * Queries the {@code system_pages} kstat and returns available and physical memory
       *
       * @return A pair with the available and total memory, in pages. Mutiply by page size for bytes.
       */
      public static Pair<Long, Long> queryAvailableTotal() {
          if (HAS_KSTAT2) {
              // Use Kstat2 implementation
              return queryAvailableTotal2();
          }
          long memAvailable = 0;
          long memTotal = 0;
          // Get first result
          try (KstatChain kc = KstatUtil.openChain()) {
              Kstat ksp = kc.lookup(null, -1, "system_pages");
              // Set values
              if (ksp != null && kc.read(ksp)) {
                  memAvailable = KstatUtil.dataLookupLong(ksp, "availrmem"); // not a typo
                  memTotal = KstatUtil.dataLookupLong(ksp, "physmem");
              }
          }
          return new Pair<>(memAvailable, memTotal);
      }
  
      private static Pair<Long, Long> queryAvailableTotal2() {
          Object[] results = KstatUtil.queryKstat2("kstat:/pages/unix/system_pages", "availrmem", "physmem");
          long avail = results[0] == null ? 0L : (long) results[0];
          long total = results[1] == null ? 0L : (long) results[1];
          return new Pair<>(avail, total);
      }
  }