1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 #ifndef SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP
  25 #define SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP
  26 
  27 #include "runtime/atomic.hpp"
  28 #include "runtime/orderAccess.hpp"
  29 
  30 inline ZMarkTerminate::ZMarkTerminate() :
  31     _nworkers(0),
  32     _nworking_stage0(0),
  33     _nworking_stage1(0) {}
  34 
  35 inline bool ZMarkTerminate::enter_stage(volatile uint* nworking_stage) {
  36   return Atomic::sub(1u, nworking_stage) == 0;
  37 }
  38 
  39 inline void ZMarkTerminate::exit_stage(volatile uint* nworking_stage) {
  40   Atomic::add(nworking_stage, 1u);
  41 }
  42 
  43 inline bool ZMarkTerminate::try_exit_stage(volatile uint* nworking_stage) {
  44   uint nworking = Atomic::load(nworking_stage);
  45 
  46   for (;;) {
  47     if (nworking == 0) {
  48       return false;
  49     }
  50 
  51     const uint new_nworking = nworking + 1;
  52     const uint prev_nworking = Atomic::cmpxchg(new_nworking, nworking_stage, nworking);
  53     if (prev_nworking == nworking) {
  54       // Success
  55       return true;
  56     }
  57 
  58     // Retry
  59     nworking = prev_nworking;
  60   }
  61 }
  62 
  63 inline void ZMarkTerminate::reset(uint nworkers) {
  64   _nworkers = _nworking_stage0 = _nworking_stage1 = nworkers;
  65 }
  66 
  67 inline bool ZMarkTerminate::enter_stage0() {
  68   return enter_stage(&_nworking_stage0);
  69 }
  70 
  71 inline void ZMarkTerminate::exit_stage0() {
  72   exit_stage(&_nworking_stage0);
  73 }
  74 
  75 inline bool ZMarkTerminate::try_exit_stage0() {
  76   return try_exit_stage(&_nworking_stage0);
  77 }
  78 
  79 inline bool ZMarkTerminate::enter_stage1() {
  80   return enter_stage(&_nworking_stage1);
  81 }
  82 
  83 inline bool ZMarkTerminate::try_exit_stage1() {
  84   return try_exit_stage(&_nworking_stage1);
  85 }
  86 
  87 #endif // SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP