1 /*
   2  * Copyright (c) 2016, 2018, 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
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  23  */
  24 
  25 #ifndef SHARE_VM_JFR_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP
  26 #define SHARE_VM_JFR_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "jfr/utilities/jfrTypes.hpp"
  30 
  31 #define USED_BIT 1
  32 #define METHOD_USED_BIT (USED_BIT << 2)
  33 #define EPOCH_1_SHIFT 0
  34 #define EPOCH_2_SHIFT 1
  35 #define LEAKP_SHIFT 8
  36 
  37 #define USED_EPOCH_1_BIT (USED_BIT << EPOCH_1_SHIFT)
  38 #define USED_EPOCH_2_BIT (USED_BIT << EPOCH_2_SHIFT)
  39 #define LEAKP_USED_EPOCH_1_BIT (USED_EPOCH_1_BIT << LEAKP_SHIFT)
  40 #define LEAKP_USED_EPOCH_2_BIT (USED_EPOCH_2_BIT << LEAKP_SHIFT)
  41 #define METHOD_USED_EPOCH_1_BIT (METHOD_USED_BIT << EPOCH_1_SHIFT)
  42 #define METHOD_USED_EPOCH_2_BIT (METHOD_USED_BIT << EPOCH_2_SHIFT)
  43 #define METHOD_AND_CLASS_IN_USE_BITS (METHOD_USED_BIT | USED_BIT)
  44 #define METHOD_AND_CLASS_IN_USE_EPOCH_1_BITS (METHOD_AND_CLASS_IN_USE_BITS << EPOCH_1_SHIFT)
  45 #define METHOD_AND_CLASS_IN_USE_EPOCH_2_BITS (METHOD_AND_CLASS_IN_USE_BITS << EPOCH_2_SHIFT)
  46 
  47 class JfrTraceIdEpoch : AllStatic {
  48   friend class JfrCheckpointManager;
  49  private:
  50   static bool _epoch_state;
  51   static void shift_epoch();
  52 
  53  public:
  54   static u1 epoch() {
  55     return _epoch_state;
  56   }
  57 
  58   static jlong epoch_address() {
  59     return (jlong)&_epoch_state;
  60   }
  61 
  62   static u1 current() {
  63     return _epoch_state ? (u1)1 : (u1)0;
  64   }
  65 
  66   static u1 previous() {
  67     return _epoch_state ? (u1)0 : (u1)1;
  68   }
  69 
  70   static traceid in_use_this_epoch_bit() {
  71     return _epoch_state ? USED_EPOCH_2_BIT : USED_EPOCH_1_BIT;
  72   }
  73 
  74   static traceid in_use_prev_epoch_bit() {
  75     return _epoch_state ? USED_EPOCH_1_BIT : USED_EPOCH_2_BIT;
  76   }
  77 
  78   static traceid leakp_in_use_this_epoch_bit() {
  79     return _epoch_state ? LEAKP_USED_EPOCH_2_BIT : LEAKP_USED_EPOCH_1_BIT;
  80   }
  81 
  82   static traceid leakp_in_use_prev_epoch_bit() {
  83     return _epoch_state ? LEAKP_USED_EPOCH_1_BIT : LEAKP_USED_EPOCH_2_BIT;
  84   }
  85 
  86   static traceid method_in_use_this_epoch_bit() {
  87     return _epoch_state ? METHOD_USED_EPOCH_2_BIT : METHOD_USED_EPOCH_1_BIT;
  88   }
  89 
  90   static traceid method_in_use_prev_epoch_bit() {
  91     return _epoch_state ? METHOD_USED_EPOCH_1_BIT : METHOD_USED_EPOCH_2_BIT;
  92   }
  93 
  94   static traceid method_and_class_in_use_this_epoch_bits() {
  95     return _epoch_state ? METHOD_AND_CLASS_IN_USE_EPOCH_2_BITS : METHOD_AND_CLASS_IN_USE_EPOCH_1_BITS;
  96   }
  97 
  98   static traceid method_and_class_in_use_prev_epoch_bits() {
  99     return _epoch_state ? METHOD_AND_CLASS_IN_USE_EPOCH_1_BITS :  METHOD_AND_CLASS_IN_USE_EPOCH_2_BITS;
 100   }
 101 };
 102 
 103 #endif // SHARE_VM_JFR_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDEPOCH_HPP