0
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1 /*
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2 * Copyright 2003-2006 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/_compactingPermGenGen.cpp.incl"
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27
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28
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29 // Recursively adjust all pointers in an object and all objects by
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30 // referenced it. Clear marks on objects in order to prevent visiting
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31 // any object twice.
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32
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33 class RecursiveAdjustSharedObjectClosure : public OopClosure {
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34 public:
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35 void do_oop(oop* o) {
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36 oop obj = *o;
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37 if (obj->is_shared_readwrite()) {
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38 if (obj->mark()->is_marked()) {
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39 obj->init_mark(); // Don't revisit this object.
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40 obj->oop_iterate(this); // Recurse - adjust objects referenced.
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41 obj->adjust_pointers(); // Adjust this object's references.
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42
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43 // Special case: if a class has a read-only constant pool,
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44 // then the read-write objects referenced by the pool must
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45 // have their marks reset.
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46
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47 if (obj->klass() == Universe::instanceKlassKlassObj()) {
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48 instanceKlass* ik = instanceKlass::cast((klassOop)obj);
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49 constantPoolOop cp = ik->constants();
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50 if (cp->is_shared_readonly()) {
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51 cp->oop_iterate(this);
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52 }
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53 }
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54 }
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55 }
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56 };
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57 };
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58
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59
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60 // We need to go through all placeholders in the system dictionary and
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61 // try to resolve them into shared classes. Other threads might be in
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62 // the process of loading a shared class and have strong roots on
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63 // their stack to the class without having added the class to the
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64 // dictionary yet. This means the class will be marked during phase 1
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65 // but will not be unmarked during the application of the
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66 // RecursiveAdjustSharedObjectClosure to the SystemDictionary. Note
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67 // that we must not call find_shared_class with non-read-only symbols
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68 // as doing so can cause hash codes to be computed, destroying
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69 // forwarding pointers.
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70 class TraversePlaceholdersClosure : public OopClosure {
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71 public:
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72 void do_oop(oop* o) {
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73 oop obj = *o;
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74 if (obj->klass() == Universe::symbolKlassObj() &&
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75 obj->is_shared_readonly()) {
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76 symbolHandle sym((symbolOop) obj);
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77 oop k = SystemDictionary::find_shared_class(sym);
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78 if (k != NULL) {
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79 RecursiveAdjustSharedObjectClosure clo;
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80 clo.do_oop(&k);
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81 }
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82 }
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83 }
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84 };
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85
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86
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87 void CompactingPermGenGen::initialize_performance_counters() {
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88
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89 const char* gen_name = "perm";
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90
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91 // Generation Counters - generation 2, 1 subspace
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92 _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);
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93
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94 _space_counters = new CSpaceCounters(gen_name, 0,
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95 _virtual_space.reserved_size(),
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96 _the_space, _gen_counters);
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97 }
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98
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99 void CompactingPermGenGen::update_counters() {
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100 if (UsePerfData) {
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101 _space_counters->update_all();
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102 _gen_counters->update_all();
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103 }
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104 }
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105
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106
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107 CompactingPermGenGen::CompactingPermGenGen(ReservedSpace rs,
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108 ReservedSpace shared_rs,
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109 size_t initial_byte_size,
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110 int level, GenRemSet* remset,
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111 ContiguousSpace* space,
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112 PermanentGenerationSpec* spec_) :
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113 OneContigSpaceCardGeneration(rs, initial_byte_size, MinPermHeapExpansion,
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114 level, remset, space) {
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115
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116 set_spec(spec_);
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117 if (!UseSharedSpaces && !DumpSharedSpaces) {
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118 spec()->disable_sharing();
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119 }
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120
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121 // Break virtual space into address ranges for all spaces.
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122
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123 if (spec()->enable_shared_spaces()) {
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124 shared_end = (HeapWord*)(shared_rs.base() + shared_rs.size());
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125 misccode_end = shared_end;
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126 misccode_bottom = misccode_end - heap_word_size(spec()->misc_code_size());
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127 miscdata_end = misccode_bottom;
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128 miscdata_bottom = miscdata_end - heap_word_size(spec()->misc_data_size());
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129 readwrite_end = miscdata_bottom;
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130 readwrite_bottom =
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131 readwrite_end - heap_word_size(spec()->read_write_size());
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132 readonly_end = readwrite_bottom;
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133 readonly_bottom =
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134 readonly_end - heap_word_size(spec()->read_only_size());
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135 shared_bottom = readonly_bottom;
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136 unshared_end = shared_bottom;
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137 assert((char*)shared_bottom == shared_rs.base(), "shared space mismatch");
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138 } else {
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139 shared_end = (HeapWord*)(rs.base() + rs.size());
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140 misccode_end = shared_end;
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141 misccode_bottom = shared_end;
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142 miscdata_end = shared_end;
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143 miscdata_bottom = shared_end;
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144 readwrite_end = shared_end;
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145 readwrite_bottom = shared_end;
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146 readonly_end = shared_end;
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147 readonly_bottom = shared_end;
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148 shared_bottom = shared_end;
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149 unshared_end = shared_bottom;
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150 }
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151 unshared_bottom = (HeapWord*) rs.base();
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152
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153 // Verify shared and unshared spaces adjacent.
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154 assert((char*)shared_bottom == rs.base()+rs.size(), "shared space mismatch");
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155 assert(unshared_end > unshared_bottom, "shared space mismatch");
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156
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157 // Split reserved memory into pieces.
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158
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159 ReservedSpace ro_rs = shared_rs.first_part(spec()->read_only_size(),
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160 UseSharedSpaces);
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161 ReservedSpace tmp_rs1 = shared_rs.last_part(spec()->read_only_size());
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162 ReservedSpace rw_rs = tmp_rs1.first_part(spec()->read_write_size(),
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163 UseSharedSpaces);
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164 ReservedSpace tmp_rs2 = tmp_rs1.last_part(spec()->read_write_size());
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165 ReservedSpace md_rs = tmp_rs2.first_part(spec()->misc_data_size(),
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166 UseSharedSpaces);
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167 ReservedSpace mc_rs = tmp_rs2.last_part(spec()->misc_data_size());
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168
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169 _shared_space_size = spec()->read_only_size()
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170 + spec()->read_write_size()
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171 + spec()->misc_data_size()
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172 + spec()->misc_code_size();
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173
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174 // Allocate the unshared (default) space.
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175 _the_space = new ContigPermSpace(_bts,
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176 MemRegion(unshared_bottom, heap_word_size(initial_byte_size)));
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177 if (_the_space == NULL)
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178 vm_exit_during_initialization("Could not allocate an unshared"
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179 " CompactingPermGen Space");
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180
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181 // Allocate shared spaces
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182 if (spec()->enable_shared_spaces()) {
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183
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184 // If mapping a shared file, the space is not committed, don't
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185 // mangle.
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186 NOT_PRODUCT(bool old_ZapUnusedHeapArea = ZapUnusedHeapArea;)
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187 NOT_PRODUCT(if (UseSharedSpaces) ZapUnusedHeapArea = false;)
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188
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189 // Commit the memory behind the shared spaces if dumping (not
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190 // mapping).
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191 if (DumpSharedSpaces) {
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192 _ro_vs.initialize(ro_rs, spec()->read_only_size());
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193 _rw_vs.initialize(rw_rs, spec()->read_write_size());
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194 _md_vs.initialize(md_rs, spec()->misc_data_size());
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195 _mc_vs.initialize(mc_rs, spec()->misc_code_size());
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196 }
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197
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198 // Allocate the shared spaces.
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199 _ro_bts = new BlockOffsetSharedArray(
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200 MemRegion(readonly_bottom,
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201 heap_word_size(spec()->read_only_size())),
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202 heap_word_size(spec()->read_only_size()));
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203 _ro_space = new OffsetTableContigSpace(_ro_bts,
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204 MemRegion(readonly_bottom, readonly_end));
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205 _rw_bts = new BlockOffsetSharedArray(
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206 MemRegion(readwrite_bottom,
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207 heap_word_size(spec()->read_write_size())),
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208 heap_word_size(spec()->read_write_size()));
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209 _rw_space = new OffsetTableContigSpace(_rw_bts,
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210 MemRegion(readwrite_bottom, readwrite_end));
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211
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212 // Restore mangling flag.
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213 NOT_PRODUCT(ZapUnusedHeapArea = old_ZapUnusedHeapArea;)
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214
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215 if (_ro_space == NULL || _rw_space == NULL)
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216 vm_exit_during_initialization("Could not allocate a shared space");
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217
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218 // Cover both shared spaces entirely with cards.
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219 _rs->resize_covered_region(MemRegion(readonly_bottom, readwrite_end));
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220
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221 if (UseSharedSpaces) {
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222
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223 // Map in the regions in the shared file.
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224 FileMapInfo* mapinfo = FileMapInfo::current_info();
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225 size_t image_alignment = mapinfo->alignment();
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226 CollectedHeap* ch = Universe::heap();
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227 if ((!mapinfo->map_space(ro, ro_rs, _ro_space)) ||
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228 (!mapinfo->map_space(rw, rw_rs, _rw_space)) ||
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229 (!mapinfo->map_space(md, md_rs, NULL)) ||
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230 (!mapinfo->map_space(mc, mc_rs, NULL)) ||
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231 // check the alignment constraints
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232 (ch == NULL || ch->kind() != CollectedHeap::GenCollectedHeap ||
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233 image_alignment !=
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234 ((GenCollectedHeap*)ch)->gen_policy()->max_alignment())) {
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235 // Base addresses didn't match; skip sharing, but continue
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236 shared_rs.release();
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237 spec()->disable_sharing();
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238 // If -Xshare:on is specified, print out the error message and exit VM,
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239 // otherwise, set UseSharedSpaces to false and continue.
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240 if (RequireSharedSpaces) {
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241 vm_exit_during_initialization("Unable to use shared archive.", NULL);
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242 } else {
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243 FLAG_SET_DEFAULT(UseSharedSpaces, false);
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244 }
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245
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246 // Note: freeing the block offset array objects does not
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247 // currently free up the underlying storage.
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248 delete _ro_bts;
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249 _ro_bts = NULL;
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250 delete _ro_space;
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251 _ro_space = NULL;
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252 delete _rw_bts;
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253 _rw_bts = NULL;
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254 delete _rw_space;
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255 _rw_space = NULL;
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256 shared_end = (HeapWord*)(rs.base() + rs.size());
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257 _rs->resize_covered_region(MemRegion(shared_bottom, shared_bottom));
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258 }
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259 }
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260
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261 // Reserved region includes shared spaces for oop.is_in_reserved().
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262 _reserved.set_end(shared_end);
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263
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264 } else {
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265 _ro_space = NULL;
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266 _rw_space = NULL;
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267 }
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268 }
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269
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270
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271 // Do a complete scan of the shared read write space to catch all
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272 // objects which contain references to any younger generation. Forward
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273 // the pointers. Avoid space_iterate, as actually visiting all the
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274 // objects in the space will page in more objects than we need.
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275 // Instead, use the system dictionary as strong roots into the read
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276 // write space.
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277
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278 void CompactingPermGenGen::pre_adjust_pointers() {
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279 if (spec()->enable_shared_spaces()) {
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280 RecursiveAdjustSharedObjectClosure blk;
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281 Universe::oops_do(&blk);
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282 StringTable::oops_do(&blk);
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283 SystemDictionary::always_strong_classes_do(&blk);
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284 TraversePlaceholdersClosure tpc;
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285 SystemDictionary::placeholders_do(&tpc);
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286 }
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287 }
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288
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289
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290 #ifdef ASSERT
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291 class VerifyMarksClearedClosure : public ObjectClosure {
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292 public:
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293 void do_object(oop obj) {
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294 assert(SharedSkipVerify || !obj->mark()->is_marked(),
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295 "Shared oop still marked?");
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296 }
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297 };
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298 #endif
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299
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300
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301 void CompactingPermGenGen::post_compact() {
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302 #ifdef ASSERT
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303 if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
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304 VerifyMarksClearedClosure blk;
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305 rw_space()->object_iterate(&blk);
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306 }
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307 #endif
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308 }
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309
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310
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311 void CompactingPermGenGen::space_iterate(SpaceClosure* blk, bool usedOnly) {
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312 OneContigSpaceCardGeneration::space_iterate(blk, usedOnly);
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313 if (spec()->enable_shared_spaces()) {
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314 #ifdef PRODUCT
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315 // Making the rw_space walkable will page in the entire space, and
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316 // is to be avoided. However, this is required for Verify options.
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317 ShouldNotReachHere();
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318 #endif
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319
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320 blk->do_space(ro_space());
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321 blk->do_space(rw_space());
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322 }
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323 }
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324
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325
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326 void CompactingPermGenGen::print_on(outputStream* st) const {
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327 OneContigSpaceCardGeneration::print_on(st);
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328 if (spec()->enable_shared_spaces()) {
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329 st->print(" ro");
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330 ro_space()->print_on(st);
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331 st->print(" rw");
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332 rw_space()->print_on(st);
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333 } else {
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334 st->print_cr("No shared spaces configured.");
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335 }
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336 }
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337
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338
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339 // References from the perm gen to the younger generation objects may
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340 // occur in static fields in Java classes or in constant pool references
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341 // to String objects.
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342
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343 void CompactingPermGenGen::younger_refs_iterate(OopsInGenClosure* blk) {
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344 OneContigSpaceCardGeneration::younger_refs_iterate(blk);
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345 if (spec()->enable_shared_spaces()) {
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346 blk->set_generation(this);
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347 // ro_space has no younger gen refs.
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348 _rs->younger_refs_in_space_iterate(rw_space(), blk);
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349 blk->reset_generation();
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350 }
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351 }
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352
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353
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354 // Shared spaces are addressed in pre_adjust_pointers.
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355 void CompactingPermGenGen::adjust_pointers() {
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356 the_space()->adjust_pointers();
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357 }
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358
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359
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360 void CompactingPermGenGen::compact() {
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361 the_space()->compact();
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362 }
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363
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364
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365 size_t CompactingPermGenGen::contiguous_available() const {
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366 // Don't include shared spaces.
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367 return OneContigSpaceCardGeneration::contiguous_available()
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368 - _shared_space_size;
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369 }
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370
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371 size_t CompactingPermGenGen::max_capacity() const {
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372 // Don't include shared spaces.
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373 assert(UseSharedSpaces || (_shared_space_size == 0),
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374 "If not used, the size of shared spaces should be 0");
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375 return OneContigSpaceCardGeneration::max_capacity()
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376 - _shared_space_size;
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377 }
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378
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379
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380
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381 bool CompactingPermGenGen::grow_by(size_t bytes) {
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382 // Don't allow _virtual_size to expand into shared spaces.
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383 size_t max_bytes = _virtual_space.uncommitted_size() - _shared_space_size;
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384 if (bytes > _shared_space_size) {
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385 bytes = _shared_space_size;
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386 }
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387 return OneContigSpaceCardGeneration::grow_by(bytes);
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388 }
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389
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390
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391 void CompactingPermGenGen::grow_to_reserved() {
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392 // Don't allow _virtual_size to expand into shared spaces.
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393 if (_virtual_space.uncommitted_size() > _shared_space_size) {
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394 size_t remaining_bytes =
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395 _virtual_space.uncommitted_size() - _shared_space_size;
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396 bool success = OneContigSpaceCardGeneration::grow_by(remaining_bytes);
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397 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
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398 }
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399 }
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400
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401
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402 // No young generation references, clear this generation's main space's
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403 // card table entries. Do NOT clear the card table entries for the
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404 // read-only space (always clear) or the read-write space (valuable
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405 // information).
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406
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407 void CompactingPermGenGen::clear_remembered_set() {
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408 _rs->clear(MemRegion(the_space()->bottom(), the_space()->end()));
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409 }
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410
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411
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412 // Objects in this generation's main space may have moved, invalidate
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413 // that space's cards. Do NOT invalidate the card table entries for the
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414 // read-only or read-write spaces, as those objects never move.
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415
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416 void CompactingPermGenGen::invalidate_remembered_set() {
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417 _rs->invalidate(used_region());
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418 }
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419
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420
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421 void CompactingPermGenGen::verify(bool allow_dirty) {
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422 the_space()->verify(allow_dirty);
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423 if (!SharedSkipVerify && spec()->enable_shared_spaces()) {
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424 ro_space()->verify(allow_dirty);
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425 rw_space()->verify(allow_dirty);
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426 }
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427 }
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428
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429
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430 HeapWord* CompactingPermGenGen::unshared_bottom;
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431 HeapWord* CompactingPermGenGen::unshared_end;
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432 HeapWord* CompactingPermGenGen::shared_bottom;
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433 HeapWord* CompactingPermGenGen::shared_end;
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434 HeapWord* CompactingPermGenGen::readonly_bottom;
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435 HeapWord* CompactingPermGenGen::readonly_end;
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436 HeapWord* CompactingPermGenGen::readwrite_bottom;
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437 HeapWord* CompactingPermGenGen::readwrite_end;
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438 HeapWord* CompactingPermGenGen::miscdata_bottom;
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439 HeapWord* CompactingPermGenGen::miscdata_end;
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440 HeapWord* CompactingPermGenGen::misccode_bottom;
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441 HeapWord* CompactingPermGenGen::misccode_end;
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442
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443 // JVM/TI RedefineClasses() support:
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444 bool CompactingPermGenGen::remap_shared_readonly_as_readwrite() {
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445 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
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446
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447 if (UseSharedSpaces) {
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448 // remap the shared readonly space to shared readwrite, private
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449 FileMapInfo* mapinfo = FileMapInfo::current_info();
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450 if (!mapinfo->remap_shared_readonly_as_readwrite()) {
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451 return false;
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452 }
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453 }
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454 return true;
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455 }
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456
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457 void** CompactingPermGenGen::_vtbl_list;
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