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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/_heapRegionSeq.cpp.incl"
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27
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28 // Local to this file.
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29
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30 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
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31 if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
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32 else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
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33 else if (*hr1p == *hr2p) return 0;
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34 else {
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35 assert(false, "We should never compare distinct overlapping regions.");
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36 }
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37 return 0;
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38 }
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39
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40 HeapRegionSeq::HeapRegionSeq() :
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41 _alloc_search_start(0),
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42 // The line below is the worst bit of C++ hackery I've ever written
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43 // (Detlefs, 11/23). You should think of it as equivalent to
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44 // "_regions(100, true)": initialize the growable array and inform it
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45 // that it should allocate its elem array(s) on the C heap. The first
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46 // argument, however, is actually a comma expression (new-expr, 100).
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47 // The purpose of the new_expr is to inform the growable array that it
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48 // is *already* allocated on the C heap: it uses the placement syntax to
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49 // keep it from actually doing any allocation.
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50 _regions((ResourceObj::operator new (sizeof(GrowableArray<HeapRegion*>),
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51 (void*)&_regions,
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52 ResourceObj::C_HEAP),
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53 100),
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54 true),
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55 _next_rr_candidate(0),
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56 _seq_bottom(NULL)
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57 {}
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58
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59 // Private methods.
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60
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61 HeapWord*
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62 HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {
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63 assert(G1CollectedHeap::isHumongous(word_size),
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64 "Allocation size should be humongous");
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65 int cur = ind;
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66 int first = cur;
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67 size_t sumSizes = 0;
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68 while (cur < _regions.length() && sumSizes < word_size) {
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69 // Loop invariant:
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70 // For all i in [first, cur):
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71 // _regions.at(i)->is_empty()
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72 // && _regions.at(i) is contiguous with its predecessor, if any
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73 // && sumSizes is the sum of the sizes of the regions in the interval
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74 // [first, cur)
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75 HeapRegion* curhr = _regions.at(cur);
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76 if (curhr->is_empty()
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77 && !curhr->is_reserved()
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78 && (first == cur
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79 || (_regions.at(cur-1)->end() ==
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80 curhr->bottom()))) {
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81 sumSizes += curhr->capacity() / HeapWordSize;
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82 } else {
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83 first = cur + 1;
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84 sumSizes = 0;
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85 }
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86 cur++;
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87 }
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88 if (sumSizes >= word_size) {
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89 _alloc_search_start = cur;
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90 // Mark the allocated regions as allocated.
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91 bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();
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92 HeapRegion* first_hr = _regions.at(first);
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93 for (int i = first; i < cur; i++) {
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94 HeapRegion* hr = _regions.at(i);
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95 if (zf)
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96 hr->ensure_zero_filled();
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97 {
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98 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
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99 hr->set_zero_fill_allocated();
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100 }
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101 size_t sz = hr->capacity() / HeapWordSize;
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102 HeapWord* tmp = hr->allocate(sz);
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103 assert(tmp != NULL, "Humongous allocation failure");
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104 MemRegion mr = MemRegion(tmp, sz);
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105 SharedHeap::fill_region_with_object(mr);
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106 hr->declare_filled_region_to_BOT(mr);
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107 if (i == first) {
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108 first_hr->set_startsHumongous();
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109 } else {
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110 assert(i > first, "sanity");
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111 hr->set_continuesHumongous(first_hr);
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112 }
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113 }
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114 HeapWord* first_hr_bot = first_hr->bottom();
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115 HeapWord* obj_end = first_hr_bot + word_size;
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116 first_hr->set_top(obj_end);
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117 return first_hr_bot;
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118 } else {
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119 // If we started from the beginning, we want to know why we can't alloc.
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120 return NULL;
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121 }
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122 }
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123
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124 void HeapRegionSeq::print_empty_runs(bool reserved_are_empty) {
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125 int empty_run = 0;
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126 int n_empty = 0;
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127 bool at_least_one_reserved = false;
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128 int empty_run_start;
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129 for (int i = 0; i < _regions.length(); i++) {
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130 HeapRegion* r = _regions.at(i);
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131 if (r->continuesHumongous()) continue;
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132 if (r->is_empty() && (reserved_are_empty || !r->is_reserved())) {
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133 assert(!r->isHumongous(), "H regions should not be empty.");
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134 if (empty_run == 0) empty_run_start = i;
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135 empty_run++;
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136 n_empty++;
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137 if (r->is_reserved()) {
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138 at_least_one_reserved = true;
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139 }
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140 } else {
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141 if (empty_run > 0) {
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142 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
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143 if (reserved_are_empty && at_least_one_reserved)
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144 gclog_or_tty->print("(R)");
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145 empty_run = 0;
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146 at_least_one_reserved = false;
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147 }
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148 }
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149 }
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150 if (empty_run > 0) {
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151 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
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152 if (reserved_are_empty && at_least_one_reserved) gclog_or_tty->print("(R)");
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153 }
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154 gclog_or_tty->print_cr(" [tot = %d]", n_empty);
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155 }
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156
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157 int HeapRegionSeq::find(HeapRegion* hr) {
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158 // FIXME: optimized for adjacent regions of fixed size.
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159 int ind = hr->hrs_index();
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160 if (ind != -1) {
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161 assert(_regions.at(ind) == hr, "Mismatch");
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162 }
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163 return ind;
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164 }
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165
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166
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167 // Public methods.
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168
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169 void HeapRegionSeq::insert(HeapRegion* hr) {
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170 if (_regions.length() == 0
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171 || _regions.top()->end() <= hr->bottom()) {
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172 hr->set_hrs_index(_regions.length());
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173 _regions.append(hr);
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174 } else {
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175 _regions.append(hr);
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176 _regions.sort(orderRegions);
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177 for (int i = 0; i < _regions.length(); i++) {
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178 _regions.at(i)->set_hrs_index(i);
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179 }
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180 }
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181 char* bot = (char*)_regions.at(0)->bottom();
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182 if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
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183 }
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184
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185 size_t HeapRegionSeq::length() {
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186 return _regions.length();
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187 }
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188
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189 size_t HeapRegionSeq::free_suffix() {
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190 size_t res = 0;
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191 int first = _regions.length() - 1;
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192 int cur = first;
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193 while (cur >= 0 &&
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194 (_regions.at(cur)->is_empty()
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195 && !_regions.at(cur)->is_reserved()
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196 && (first == cur
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197 || (_regions.at(cur+1)->bottom() ==
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198 _regions.at(cur)->end())))) {
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199 res++;
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200 cur--;
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201 }
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202 return res;
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203 }
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204
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205 HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {
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206 int cur = _alloc_search_start;
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207 // Make sure "cur" is a valid index.
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208 assert(cur >= 0, "Invariant.");
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209 HeapWord* res = alloc_obj_from_region_index(cur, word_size);
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210 if (res == NULL)
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211 res = alloc_obj_from_region_index(0, word_size);
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212 return res;
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213 }
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214
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215 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
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216 iterate_from((HeapRegion*)NULL, blk);
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217 }
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218
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219 // The first argument r is the heap region at which iteration begins.
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220 // This operation runs fastest when r is NULL, or the heap region for
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221 // which a HeapRegionClosure most recently returned true, or the
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222 // heap region immediately to its right in the sequence. In all
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223 // other cases a linear search is required to find the index of r.
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224
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225 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
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226
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227 // :::: FIXME ::::
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228 // Static cache value is bad, especially when we start doing parallel
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229 // remembered set update. For now just don't cache anything (the
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230 // code in the def'd out blocks).
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231
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232 #if 0
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233 static int cached_j = 0;
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234 #endif
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235 int len = _regions.length();
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236 int j = 0;
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237 // Find the index of r.
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238 if (r != NULL) {
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239 #if 0
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240 assert(cached_j >= 0, "Invariant.");
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241 if ((cached_j < len) && (r == _regions.at(cached_j))) {
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242 j = cached_j;
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243 } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
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244 j = cached_j + 1;
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245 } else {
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246 j = find(r);
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247 #endif
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248 if (j < 0) {
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249 j = 0;
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250 }
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251 #if 0
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252 }
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253 #endif
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254 }
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255 int i;
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256 for (i = j; i < len; i += 1) {
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257 int res = blk->doHeapRegion(_regions.at(i));
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258 if (res) {
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259 #if 0
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260 cached_j = i;
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261 #endif
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262 blk->incomplete();
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263 return;
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264 }
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265 }
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266 for (i = 0; i < j; i += 1) {
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267 int res = blk->doHeapRegion(_regions.at(i));
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268 if (res) {
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269 #if 0
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270 cached_j = i;
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271 #endif
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272 blk->incomplete();
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273 return;
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274 }
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275 }
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276 }
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277
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278 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
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279 int len = _regions.length();
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280 int i;
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281 for (i = idx; i < len; i++) {
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282 if (blk->doHeapRegion(_regions.at(i))) {
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283 blk->incomplete();
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284 return;
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285 }
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286 }
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287 for (i = 0; i < idx; i++) {
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288 if (blk->doHeapRegion(_regions.at(i))) {
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289 blk->incomplete();
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290 return;
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291 }
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292 }
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293 }
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294
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295 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
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296 size_t& num_regions_deleted) {
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297 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
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298 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
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299
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300 if (_regions.length() == 0) {
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301 num_regions_deleted = 0;
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302 return MemRegion();
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303 }
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304 int j = _regions.length() - 1;
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305 HeapWord* end = _regions.at(j)->end();
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306 HeapWord* last_start = end;
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307 while (j >= 0 && shrink_bytes > 0) {
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308 HeapRegion* cur = _regions.at(j);
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309 // We have to leave humongous regions where they are,
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310 // and work around them.
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311 if (cur->isHumongous()) {
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312 return MemRegion(last_start, end);
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313 }
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314 cur->reset_zero_fill();
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315 assert(cur == _regions.top(), "Should be top");
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316 if (!cur->is_empty()) break;
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317 shrink_bytes -= cur->capacity();
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318 num_regions_deleted++;
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319 _regions.pop();
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320 last_start = cur->bottom();
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321 // We need to delete these somehow, but can't currently do so here: if
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322 // we do, the ZF thread may still access the deleted region. We'll
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323 // leave this here as a reminder that we have to do something about
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324 // this.
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325 // delete cur;
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326 j--;
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327 }
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328 return MemRegion(last_start, end);
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329 }
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330
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331
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332 class PrintHeapRegionClosure : public HeapRegionClosure {
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333 public:
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334 bool doHeapRegion(HeapRegion* r) {
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335 gclog_or_tty->print(PTR_FORMAT ":", r);
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336 r->print();
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337 return false;
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338 }
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339 };
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340
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341 void HeapRegionSeq::print() {
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342 PrintHeapRegionClosure cl;
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343 iterate(&cl);
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344 }
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