1 /*

     2  * Copyright (c) 2012, 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

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "jfr/recorder/storage/jfrStorageControl.hpp"

    27 #include "runtime/atomic.hpp"

    28 #include "runtime/orderAccess.inline.hpp"

    29 

    30 // returns the updated value

    31 static jlong atomic_add(size_t value, size_t volatile* const dest) {

    32   size_t compare_value;

    33   size_t exchange_value;

    34   do {

    35     compare_value = OrderAccess::load_acquire(dest);

    36     exchange_value = compare_value + value;

    37   } while (Atomic::cmpxchg(exchange_value, dest, compare_value) != compare_value);

    38   return exchange_value;

    39 }

    40 

    41 static jlong atomic_dec(size_t volatile* const dest) {

    42   size_t compare_value;

    43   size_t exchange_value;

    44   do {

    45     compare_value = OrderAccess::load_acquire(dest);

    46     assert(compare_value >= 1, "invariant");

    47     exchange_value = compare_value - 1;

    48   } while (Atomic::cmpxchg(exchange_value, dest, compare_value) != compare_value);

    49   return exchange_value;

    50 }

    51 

    52 const size_t max_lease_factor = 2;

    53 JfrStorageControl::JfrStorageControl(size_t global_count_total, size_t in_memory_discard_threshold) :

    54   _global_count_total(global_count_total),

    55   _full_count(0),

    56   _global_lease_count(0),

    57   _dead_count(0),

    58   _to_disk_threshold(0),

    59   _in_memory_discard_threshold(in_memory_discard_threshold),

    60   _global_lease_threshold(global_count_total / max_lease_factor),

    61   _scavenge_threshold(0),

    62   _to_disk(false) {}

    63 

    64 bool JfrStorageControl::to_disk() const {

    65   return _to_disk;

    66 }

    67 

    68 void JfrStorageControl::set_to_disk(bool enable) {

    69   _to_disk = enable;

    70 }

    71 

    72 // concurrent with lax requirement

    73 

    74 size_t JfrStorageControl::full_count() const {

    75   return _full_count;

    76 }

    77 

    78 size_t JfrStorageControl::increment_full() {

    79   return atomic_add(1, &_full_count);

    80 }

    81 

    82 size_t JfrStorageControl::decrement_full() {

    83   return atomic_dec(&_full_count);

    84 }

    85 

    86 void JfrStorageControl::reset_full() {

    87   Atomic::store((size_t)0, &_full_count);

    88 }

    89 

    90 bool JfrStorageControl::should_post_buffer_full_message() const {

    91   return to_disk() && (full_count() > _to_disk_threshold);

    92 }

    93 

    94 bool JfrStorageControl::should_discard() const {

    95   return !to_disk() && full_count() >= _in_memory_discard_threshold;

    96 }

    97 

    98 // concurrent with accuracy requirement

    99 

   100 size_t JfrStorageControl::global_lease_count() const {

   101   return OrderAccess::load_acquire(&_global_lease_count);

   102 }

   103 

   104 size_t JfrStorageControl::increment_leased() {

   105   return atomic_add(1, &_global_lease_count);

   106 }

   107 

   108 size_t JfrStorageControl::decrement_leased() {

   109   return atomic_dec(&_global_lease_count);

   110 }

   111 

   112 bool JfrStorageControl::is_global_lease_allowed() const {

   113   return global_lease_count() <= _global_lease_threshold;

   114 }

   115 

   116 // concurrent with lax requirement

   117 

   118 size_t JfrStorageControl::dead_count() const {

   119   return _dead_count;

   120 }

   121 

   122 size_t JfrStorageControl::increment_dead() {

   123   return atomic_add(1, &_dead_count);

   124 }

   125 

   126 size_t JfrStorageControl::decrement_dead() {

   127   return atomic_dec(&_dead_count);

   128 }

   129 

   130 bool JfrStorageControl::should_scavenge() const {

   131   return dead_count() >= _scavenge_threshold;

   132 }

   133 

   134 void JfrStorageControl::set_scavenge_threshold(size_t number_of_dead_buffers) {

   135   _scavenge_threshold = number_of_dead_buffers;

   136 }

   137