/*
    * Copyright 2016-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.hardware.platform.unix.freebsd;
   
   import static oshi.util.Memoizer.defaultExpiration;
   import static oshi.util.Memoizer.memoize;
   
  import java.util.function.Supplier;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.hardware.VirtualMemory;
  import oshi.hardware.common.AbstractGlobalMemory;
  import oshi.util.ExecutingCommand;
  import oshi.util.ParseUtil;
  import oshi.util.platform.unix.freebsd.BsdSysctlUtil;
  
  /**
   * Memory obtained by sysctl vm.stats
   */
  @ThreadSafe
  final class FreeBsdGlobalMemory extends AbstractGlobalMemory {
  
      private final Supplier<Long> available = memoize(this::queryVmStats, defaultExpiration());
  
      private final Supplier<Long> total = memoize(FreeBsdGlobalMemory::queryPhysMem);
  
      private final Supplier<Long> pageSize = memoize(FreeBsdGlobalMemory::queryPageSize);
  
      private final Supplier<VirtualMemory> vm = memoize(this::createVirtualMemory);
  
      @Override
      public long getAvailable() {
          return available.get();
      }
  
      @Override
      public long getTotal() {
          return total.get();
      }
  
      @Override
      public long getPageSize() {
          return pageSize.get();
      }
  
      @Override
      public VirtualMemory getVirtualMemory() {
          return vm.get();
      }
  
      private long queryVmStats() {
          // cached removed in FreeBSD 12 but was always set to 0
          int inactive = BsdSysctlUtil.sysctl("vm.stats.vm.v_inactive_count", 0);
          int free = BsdSysctlUtil.sysctl("vm.stats.vm.v_free_count", 0);
          return (inactive + free) * getPageSize();
      }
  
      private static long queryPhysMem() {
          return BsdSysctlUtil.sysctl("hw.physmem", 0L);
      }
  
      private static long queryPageSize() {
          // sysctl hw.pagesize doesn't work on FreeBSD 13
          return ParseUtil.parseLongOrDefault(ExecutingCommand.getFirstAnswer("sysconf PAGESIZE"), 4096L);
      }
  
      private VirtualMemory createVirtualMemory() {
          return new FreeBsdVirtualMemory(this);
      }
  }