1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp" |
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27 #include "gc_implementation/concurrentMarkSweep/freeList.hpp" |
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28 #include "memory/sharedHeap.hpp" |
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29 #include "runtime/globals.hpp" |
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30 #include "runtime/mutex.hpp" |
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31 #include "runtime/vmThread.hpp" |
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32 |
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33 // Free list. A FreeList is used to access a linked list of chunks |
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34 // of space in the heap. The head and tail are maintained so that |
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35 // items can be (as in the current implementation) added at the |
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36 // at the tail of the list and removed from the head of the list to |
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37 // maintain a FIFO queue. |
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38 |
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39 FreeList::FreeList() : |
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40 _head(NULL), _tail(NULL) |
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41 #ifdef ASSERT |
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42 , _protecting_lock(NULL) |
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43 #endif |
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44 { |
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45 _size = 0; |
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46 _count = 0; |
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47 _hint = 0; |
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48 init_statistics(); |
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49 } |
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50 |
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51 FreeList::FreeList(FreeChunk* fc) : |
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52 _head(fc), _tail(fc) |
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53 #ifdef ASSERT |
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54 , _protecting_lock(NULL) |
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55 #endif |
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56 { |
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57 _size = fc->size(); |
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58 _count = 1; |
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59 _hint = 0; |
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60 init_statistics(); |
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61 #ifndef PRODUCT |
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62 _allocation_stats.set_returnedBytes(size() * HeapWordSize); |
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63 #endif |
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64 } |
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65 |
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66 FreeList::FreeList(HeapWord* addr, size_t size) : |
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67 _head((FreeChunk*) addr), _tail((FreeChunk*) addr) |
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68 #ifdef ASSERT |
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69 , _protecting_lock(NULL) |
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70 #endif |
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71 { |
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72 assert(size > sizeof(FreeChunk), "size is too small"); |
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73 head()->setSize(size); |
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74 _size = size; |
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75 _count = 1; |
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76 init_statistics(); |
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77 #ifndef PRODUCT |
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78 _allocation_stats.set_returnedBytes(_size * HeapWordSize); |
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79 #endif |
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80 } |
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81 |
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82 void FreeList::reset(size_t hint) { |
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83 set_count(0); |
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84 set_head(NULL); |
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85 set_tail(NULL); |
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86 set_hint(hint); |
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87 } |
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88 |
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89 void FreeList::init_statistics(bool split_birth) { |
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90 _allocation_stats.initialize(split_birth); |
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91 } |
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92 |
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93 FreeChunk* FreeList::getChunkAtHead() { |
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94 assert_proper_lock_protection(); |
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95 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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96 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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97 FreeChunk* fc = head(); |
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98 if (fc != NULL) { |
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99 FreeChunk* nextFC = fc->next(); |
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100 if (nextFC != NULL) { |
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101 // The chunk fc being removed has a "next". Set the "next" to the |
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102 // "prev" of fc. |
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103 nextFC->linkPrev(NULL); |
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104 } else { // removed tail of list |
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105 link_tail(NULL); |
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106 } |
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107 link_head(nextFC); |
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108 decrement_count(); |
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109 } |
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110 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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111 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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112 return fc; |
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113 } |
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114 |
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115 |
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116 void FreeList::getFirstNChunksFromList(size_t n, FreeList* fl) { |
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117 assert_proper_lock_protection(); |
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118 assert(fl->count() == 0, "Precondition"); |
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119 if (count() > 0) { |
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120 int k = 1; |
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121 fl->set_head(head()); n--; |
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122 FreeChunk* tl = head(); |
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123 while (tl->next() != NULL && n > 0) { |
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124 tl = tl->next(); n--; k++; |
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125 } |
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126 assert(tl != NULL, "Loop Inv."); |
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127 |
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128 // First, fix up the list we took from. |
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129 FreeChunk* new_head = tl->next(); |
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130 set_head(new_head); |
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131 set_count(count() - k); |
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132 if (new_head == NULL) { |
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133 set_tail(NULL); |
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134 } else { |
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135 new_head->linkPrev(NULL); |
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136 } |
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137 // Now we can fix up the tail. |
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138 tl->linkNext(NULL); |
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139 // And return the result. |
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140 fl->set_tail(tl); |
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141 fl->set_count(k); |
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142 } |
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143 } |
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144 |
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145 // Remove this chunk from the list |
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146 void FreeList::removeChunk(FreeChunk*fc) { |
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147 assert_proper_lock_protection(); |
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148 assert(head() != NULL, "Remove from empty list"); |
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149 assert(fc != NULL, "Remove a NULL chunk"); |
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150 assert(size() == fc->size(), "Wrong list"); |
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151 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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152 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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153 |
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154 FreeChunk* prevFC = fc->prev(); |
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155 FreeChunk* nextFC = fc->next(); |
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156 if (nextFC != NULL) { |
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157 // The chunk fc being removed has a "next". Set the "next" to the |
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158 // "prev" of fc. |
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159 nextFC->linkPrev(prevFC); |
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160 } else { // removed tail of list |
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161 link_tail(prevFC); |
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162 } |
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163 if (prevFC == NULL) { // removed head of list |
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164 link_head(nextFC); |
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165 assert(nextFC == NULL || nextFC->prev() == NULL, |
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166 "Prev of head should be NULL"); |
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167 } else { |
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168 prevFC->linkNext(nextFC); |
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169 assert(tail() != prevFC || prevFC->next() == NULL, |
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170 "Next of tail should be NULL"); |
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171 } |
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172 decrement_count(); |
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173 assert(((head() == NULL) + (tail() == NULL) + (count() == 0)) % 3 == 0, |
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174 "H/T/C Inconsistency"); |
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175 // clear next and prev fields of fc, debug only |
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176 NOT_PRODUCT( |
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177 fc->linkPrev(NULL); |
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178 fc->linkNext(NULL); |
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179 ) |
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180 assert(fc->isFree(), "Should still be a free chunk"); |
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181 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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182 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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183 assert(head() == NULL || head()->size() == size(), "wrong item on list"); |
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184 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); |
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185 } |
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186 |
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187 // Add this chunk at the head of the list. |
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188 void FreeList::returnChunkAtHead(FreeChunk* chunk, bool record_return) { |
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189 assert_proper_lock_protection(); |
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190 assert(chunk != NULL, "insert a NULL chunk"); |
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191 assert(size() == chunk->size(), "Wrong size"); |
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192 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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193 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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194 |
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195 FreeChunk* oldHead = head(); |
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196 assert(chunk != oldHead, "double insertion"); |
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197 chunk->linkAfter(oldHead); |
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198 link_head(chunk); |
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199 if (oldHead == NULL) { // only chunk in list |
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200 assert(tail() == NULL, "inconsistent FreeList"); |
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201 link_tail(chunk); |
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202 } |
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203 increment_count(); // of # of chunks in list |
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204 DEBUG_ONLY( |
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205 if (record_return) { |
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206 increment_returnedBytes_by(size()*HeapWordSize); |
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207 } |
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208 ) |
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209 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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210 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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211 assert(head() == NULL || head()->size() == size(), "wrong item on list"); |
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212 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); |
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213 } |
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214 |
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215 void FreeList::returnChunkAtHead(FreeChunk* chunk) { |
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216 assert_proper_lock_protection(); |
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217 returnChunkAtHead(chunk, true); |
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218 } |
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219 |
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220 // Add this chunk at the tail of the list. |
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221 void FreeList::returnChunkAtTail(FreeChunk* chunk, bool record_return) { |
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222 assert_proper_lock_protection(); |
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223 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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224 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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225 assert(chunk != NULL, "insert a NULL chunk"); |
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226 assert(size() == chunk->size(), "wrong size"); |
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227 |
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228 FreeChunk* oldTail = tail(); |
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229 assert(chunk != oldTail, "double insertion"); |
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230 if (oldTail != NULL) { |
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231 oldTail->linkAfter(chunk); |
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232 } else { // only chunk in list |
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233 assert(head() == NULL, "inconsistent FreeList"); |
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234 link_head(chunk); |
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235 } |
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236 link_tail(chunk); |
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237 increment_count(); // of # of chunks in list |
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238 DEBUG_ONLY( |
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239 if (record_return) { |
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240 increment_returnedBytes_by(size()*HeapWordSize); |
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241 } |
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242 ) |
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243 assert(head() == NULL || head()->prev() == NULL, "list invariant"); |
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244 assert(tail() == NULL || tail()->next() == NULL, "list invariant"); |
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245 assert(head() == NULL || head()->size() == size(), "wrong item on list"); |
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246 assert(tail() == NULL || tail()->size() == size(), "wrong item on list"); |
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247 } |
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248 |
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249 void FreeList::returnChunkAtTail(FreeChunk* chunk) { |
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250 returnChunkAtTail(chunk, true); |
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251 } |
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252 |
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253 void FreeList::prepend(FreeList* fl) { |
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254 assert_proper_lock_protection(); |
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255 if (fl->count() > 0) { |
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256 if (count() == 0) { |
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257 set_head(fl->head()); |
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258 set_tail(fl->tail()); |
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259 set_count(fl->count()); |
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260 } else { |
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261 // Both are non-empty. |
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262 FreeChunk* fl_tail = fl->tail(); |
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263 FreeChunk* this_head = head(); |
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264 assert(fl_tail->next() == NULL, "Well-formedness of fl"); |
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265 fl_tail->linkNext(this_head); |
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266 this_head->linkPrev(fl_tail); |
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267 set_head(fl->head()); |
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268 set_count(count() + fl->count()); |
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269 } |
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270 fl->set_head(NULL); |
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271 fl->set_tail(NULL); |
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272 fl->set_count(0); |
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273 } |
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274 } |
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275 |
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276 // verifyChunkInFreeLists() is used to verify that an item is in this free list. |
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277 // It is used as a debugging aid. |
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278 bool FreeList::verifyChunkInFreeLists(FreeChunk* fc) const { |
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279 // This is an internal consistency check, not part of the check that the |
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280 // chunk is in the free lists. |
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281 guarantee(fc->size() == size(), "Wrong list is being searched"); |
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282 FreeChunk* curFC = head(); |
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283 while (curFC) { |
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284 // This is an internal consistency check. |
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285 guarantee(size() == curFC->size(), "Chunk is in wrong list."); |
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286 if (fc == curFC) { |
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287 return true; |
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288 } |
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289 curFC = curFC->next(); |
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290 } |
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291 return false; |
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292 } |
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293 |
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294 #ifndef PRODUCT |
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295 void FreeList::verify_stats() const { |
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296 // The +1 of the LH comparand is to allow some "looseness" in |
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297 // checking: we usually call this interface when adding a block |
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298 // and we'll subsequently update the stats; we cannot update the |
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299 // stats beforehand because in the case of the large-block BT |
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300 // dictionary for example, this might be the first block and |
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301 // in that case there would be no place that we could record |
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302 // the stats (which are kept in the block itself). |
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303 assert((_allocation_stats.prevSweep() + _allocation_stats.splitBirths() |
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304 + _allocation_stats.coalBirths() + 1) // Total Production Stock + 1 |
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305 >= (_allocation_stats.splitDeaths() + _allocation_stats.coalDeaths() |
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306 + (ssize_t)count()), // Total Current Stock + depletion |
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307 err_msg("FreeList " PTR_FORMAT " of size " SIZE_FORMAT |
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308 " violates Conservation Principle: " |
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309 "prevSweep(" SIZE_FORMAT ")" |
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310 " + splitBirths(" SIZE_FORMAT ")" |
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311 " + coalBirths(" SIZE_FORMAT ") + 1 >= " |
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312 " splitDeaths(" SIZE_FORMAT ")" |
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313 " coalDeaths(" SIZE_FORMAT ")" |
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314 " + count(" SSIZE_FORMAT ")", |
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315 this, _size, _allocation_stats.prevSweep(), _allocation_stats.splitBirths(), |
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316 _allocation_stats.splitBirths(), _allocation_stats.splitDeaths(), |
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317 _allocation_stats.coalDeaths(), count())); |
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318 } |
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319 |
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320 void FreeList::assert_proper_lock_protection_work() const { |
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321 assert(_protecting_lock != NULL, "Don't call this directly"); |
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322 assert(ParallelGCThreads > 0, "Don't call this directly"); |
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323 Thread* thr = Thread::current(); |
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324 if (thr->is_VM_thread() || thr->is_ConcurrentGC_thread()) { |
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325 // assert that we are holding the freelist lock |
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326 } else if (thr->is_GC_task_thread()) { |
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327 assert(_protecting_lock->owned_by_self(), "FreeList RACE DETECTED"); |
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328 } else if (thr->is_Java_thread()) { |
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329 assert(!SafepointSynchronize::is_at_safepoint(), "Should not be executing"); |
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330 } else { |
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331 ShouldNotReachHere(); // unaccounted thread type? |
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332 } |
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333 } |
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334 #endif |
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335 |
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336 // Print the "label line" for free list stats. |
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337 void FreeList::print_labels_on(outputStream* st, const char* c) { |
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338 st->print("%16s\t", c); |
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339 st->print("%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" |
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340 "%14s\t" "%14s\t" "%14s\t" "%14s\t" "%14s\t" "\n", |
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341 "bfrsurp", "surplus", "desired", "prvSwep", "bfrSwep", |
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342 "count", "cBirths", "cDeaths", "sBirths", "sDeaths"); |
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343 } |
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344 |
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345 // Print the AllocationStats for the given free list. If the second argument |
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346 // to the call is a non-null string, it is printed in the first column; |
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347 // otherwise, if the argument is null (the default), then the size of the |
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348 // (free list) block is printed in the first column. |
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349 void FreeList::print_on(outputStream* st, const char* c) const { |
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350 if (c != NULL) { |
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351 st->print("%16s", c); |
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352 } else { |
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353 st->print(SIZE_FORMAT_W(16), size()); |
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354 } |
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355 st->print("\t" |
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356 SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" |
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357 SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\t" SSIZE_FORMAT_W(14) "\n", |
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358 bfrSurp(), surplus(), desired(), prevSweep(), beforeSweep(), |
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359 count(), coalBirths(), coalDeaths(), splitBirths(), splitDeaths()); |
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360 } |
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