342
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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 # include "incls/_precompiled.incl"
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26 # include "incls/_ptrQueue.cpp.incl"
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27
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28 PtrQueue::PtrQueue(PtrQueueSet* qset_, bool perm) :
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29 _qset(qset_), _buf(NULL), _index(0), _active(false),
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30 _perm(perm), _lock(NULL)
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31 {}
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32
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33 PtrQueue::~PtrQueue() {
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34 if (!_perm && _buf != NULL) {
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35 if (_index == _sz) {
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36 // No work to do.
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37 qset()->deallocate_buffer(_buf);
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38 } else {
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39 // We must NULL out the unused entries, then enqueue.
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40 for (size_t i = 0; i < _index; i += oopSize) {
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41 _buf[byte_index_to_index((int)i)] = NULL;
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42 }
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43 qset()->enqueue_complete_buffer(_buf);
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44 _buf = NULL;
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45 }
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46 }
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47 }
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48
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49
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50 static int byte_index_to_index(int ind) {
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51 assert((ind % oopSize) == 0, "Invariant.");
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52 return ind / oopSize;
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53 }
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54
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55 static int index_to_byte_index(int byte_ind) {
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56 return byte_ind * oopSize;
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57 }
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58
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59 void PtrQueue::enqueue_known_active(void* ptr) {
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60 assert(0 <= _index && _index <= _sz, "Invariant.");
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61 assert(_index == 0 || _buf != NULL, "invariant");
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62
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63 while (_index == 0) {
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64 handle_zero_index();
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65 }
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66 assert(_index > 0, "postcondition");
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67
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68 _index -= oopSize;
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69 _buf[byte_index_to_index((int)_index)] = ptr;
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70 assert(0 <= _index && _index <= _sz, "Invariant.");
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71 }
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72
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73 void PtrQueue::locking_enqueue_completed_buffer(void** buf) {
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74 assert(_lock->owned_by_self(), "Required.");
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75 _lock->unlock();
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76 qset()->enqueue_complete_buffer(buf);
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77 // We must relock only because the caller will unlock, for the normal
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78 // case.
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79 _lock->lock_without_safepoint_check();
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80 }
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81
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82
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83 PtrQueueSet::PtrQueueSet(bool notify_when_complete) :
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84 _max_completed_queue(0),
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85 _cbl_mon(NULL), _fl_lock(NULL),
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86 _notify_when_complete(notify_when_complete),
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87 _sz(0),
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88 _completed_buffers_head(NULL),
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89 _completed_buffers_tail(NULL),
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90 _n_completed_buffers(0),
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91 _process_completed_threshold(0), _process_completed(false),
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92 _buf_free_list(NULL), _buf_free_list_sz(0)
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93 {}
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94
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95 void** PtrQueueSet::allocate_buffer() {
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96 assert(_sz > 0, "Didn't set a buffer size.");
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97 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
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98 if (_buf_free_list != NULL) {
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99 void** res = _buf_free_list;
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100 _buf_free_list = (void**)_buf_free_list[0];
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101 _buf_free_list_sz--;
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102 // Just override the next pointer with NULL, just in case we scan this part
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103 // of the buffer.
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104 res[0] = NULL;
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105 return res;
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106 } else {
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107 return NEW_C_HEAP_ARRAY(void*, _sz);
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108 }
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109 }
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110
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111 void PtrQueueSet::deallocate_buffer(void** buf) {
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112 assert(_sz > 0, "Didn't set a buffer size.");
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113 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
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114 buf[0] = (void*)_buf_free_list;
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115 _buf_free_list = buf;
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116 _buf_free_list_sz++;
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117 }
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118
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119 void PtrQueueSet::reduce_free_list() {
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120 // For now we'll adopt the strategy of deleting half.
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121 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag);
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122 size_t n = _buf_free_list_sz / 2;
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123 while (n > 0) {
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124 assert(_buf_free_list != NULL, "_buf_free_list_sz must be wrong.");
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125 void** head = _buf_free_list;
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126 _buf_free_list = (void**)_buf_free_list[0];
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127 FREE_C_HEAP_ARRAY(void*,head);
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128 n--;
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129 }
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130 }
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131
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132 void PtrQueueSet::enqueue_complete_buffer(void** buf, size_t index, bool ignore_max_completed) {
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133 // I use explicit locking here because there's a bailout in the middle.
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134 _cbl_mon->lock_without_safepoint_check();
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135
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136 Thread* thread = Thread::current();
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137 assert( ignore_max_completed ||
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138 thread->is_Java_thread() ||
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139 SafepointSynchronize::is_at_safepoint(),
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140 "invariant" );
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141 ignore_max_completed = ignore_max_completed || !thread->is_Java_thread();
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142
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143 if (!ignore_max_completed && _max_completed_queue > 0 &&
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144 _n_completed_buffers >= (size_t) _max_completed_queue) {
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145 _cbl_mon->unlock();
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146 bool b = mut_process_buffer(buf);
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147 if (b) {
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148 deallocate_buffer(buf);
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149 return;
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150 }
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151
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152 // Otherwise, go ahead and enqueue the buffer. Must reaquire the lock.
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153 _cbl_mon->lock_without_safepoint_check();
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154 }
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155
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156 // Here we still hold the _cbl_mon.
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157 CompletedBufferNode* cbn = new CompletedBufferNode;
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158 cbn->buf = buf;
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159 cbn->next = NULL;
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160 cbn->index = index;
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161 if (_completed_buffers_tail == NULL) {
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162 assert(_completed_buffers_head == NULL, "Well-formedness");
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163 _completed_buffers_head = cbn;
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164 _completed_buffers_tail = cbn;
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165 } else {
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166 _completed_buffers_tail->next = cbn;
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167 _completed_buffers_tail = cbn;
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168 }
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169 _n_completed_buffers++;
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170
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171 if (!_process_completed &&
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172 _n_completed_buffers == _process_completed_threshold) {
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173 _process_completed = true;
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174 if (_notify_when_complete)
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175 _cbl_mon->notify_all();
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176 }
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177 debug_only(assert_completed_buffer_list_len_correct_locked());
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178 _cbl_mon->unlock();
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179 }
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180
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181 int PtrQueueSet::completed_buffers_list_length() {
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182 int n = 0;
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183 CompletedBufferNode* cbn = _completed_buffers_head;
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184 while (cbn != NULL) {
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185 n++;
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186 cbn = cbn->next;
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187 }
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188 return n;
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189 }
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190
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191 void PtrQueueSet::assert_completed_buffer_list_len_correct() {
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192 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
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193 assert_completed_buffer_list_len_correct_locked();
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194 }
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195
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196 void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() {
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197 guarantee((size_t)completed_buffers_list_length() == _n_completed_buffers,
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198 "Completed buffer length is wrong.");
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199 }
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200
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201 void PtrQueueSet::set_buffer_size(size_t sz) {
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202 assert(_sz == 0 && sz > 0, "Should be called only once.");
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203 _sz = sz * oopSize;
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204 }
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205
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206 void PtrQueueSet::set_process_completed_threshold(size_t sz) {
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207 _process_completed_threshold = sz;
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208 }
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