modules/cldc-compact/src/main/java/cc/squirreljme/jvm/mle/AtomicShelf.java

   1 // -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
   2 // ---------------------------------------------------------------------------
   3 // SquirrelJME
   4 //     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 // ---------------------------------------------------------------------------
   6 // SquirrelJME is under the GNU General Public License v3+, or later.
   7 // See license.mkd for licensing and copyright information.
   8 // ---------------------------------------------------------------------------
   9
  10 package cc.squirreljme.jvm.mle;
  11
  12 import cc.squirreljme.runtime.cldc.annotation.Api;
  13
  14 /**
  15  * This shelf provides helpers for atomic operations.
  16  *
  17  * @since 2020/05/30
  18  */
  19 @SquirrelJMEVendorApi
  20 public final class AtomicShelf
  21 {
  22         /**
  23          * Not used.
  24          *
  25          * @since 2020/05/30
  26          */
  27         private AtomicShelf()
  28         {
  29         }
  30
  31         /**
  32          * Lock for garbage collection operations.
  33          *
  34          * @return The locking key if locked, otherwise {@code 0} when busy.
  35          * @since 2020/05/30
  36          */
  37         @SquirrelJMEVendorApi
  38         public static native int gcLock();
  39
  40         /**
  41          * Unlocks the garbage collector provided that the previous locking key
  42          * matches.
  43          *
  44          * @param __key The key that was previously used to lock the garbage
  45          * collector.
  46          * @since 2020/05/30
  47          */
  48         @SquirrelJMEVendorApi
  49         public static native void gcUnlock(int __key);
  50
  51         /**
  52          * For constant lock spins, this provides a consistent means of counting
  53          * and then potentially fire-spinning or resting depending on the
  54          * situation. This may cause a thread to preempt.
  55          *
  56          * On cooperatively tasked systems, this may switch to another thread.
  57          *
  58          * @param __count The number of times the lock has spun.
  59          * @since 2020/05/30
  60          */
  61         @SquirrelJMEVendorApi
  62         public static native void spinLock(int __count);
  63
  64         /**
  65          * Returns a "unique" atomic tick value. The value returned should be
  66          * unique enough but the actual value that is returned should not be used
  67          * in any way for comparisons other than equality.
  68          *
  69          * @return The tick value, note that it should not be used for comparisons
  70          * other than equality.
  71          * @since 2020/05/03
  72          */
  73         @SquirrelJMEVendorApi
  74         public static native int tick();
  75 }