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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/_mutableSpace.cpp.incl"
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27
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28 void MutableSpace::initialize(MemRegion mr, bool clear_space) {
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29 HeapWord* bottom = mr.start();
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30 HeapWord* end = mr.end();
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31
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32 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
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33 "invalid space boundaries");
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34 set_bottom(bottom);
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35 set_end(end);
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36
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37 if (clear_space) clear();
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38 }
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39
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40 void MutableSpace::clear() {
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41 set_top(bottom());
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42 if (ZapUnusedHeapArea) mangle_unused_area();
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43 }
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44
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45 // This version requires locking. */
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46 HeapWord* MutableSpace::allocate(size_t size) {
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47 assert(Heap_lock->owned_by_self() ||
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48 (SafepointSynchronize::is_at_safepoint() &&
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49 Thread::current()->is_VM_thread()),
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50 "not locked");
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51 HeapWord* obj = top();
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52 if (pointer_delta(end(), obj) >= size) {
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53 HeapWord* new_top = obj + size;
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54 set_top(new_top);
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55 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
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56 "checking alignment");
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57 return obj;
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58 } else {
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59 return NULL;
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60 }
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61 }
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62
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63 // This version is lock-free.
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64 HeapWord* MutableSpace::cas_allocate(size_t size) {
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65 do {
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66 HeapWord* obj = top();
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67 if (pointer_delta(end(), obj) >= size) {
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68 HeapWord* new_top = obj + size;
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69 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
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70 // result can be one of two:
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71 // the old top value: the exchange succeeded
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72 // otherwise: the new value of the top is returned.
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73 if (result != obj) {
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74 continue; // another thread beat us to the allocation, try again
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75 }
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76 assert(is_object_aligned((intptr_t)obj) && is_object_aligned((intptr_t)new_top),
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77 "checking alignment");
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78 return obj;
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79 } else {
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80 return NULL;
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81 }
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82 } while (true);
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83 }
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84
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85 // Try to deallocate previous allocation. Returns true upon success.
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86 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) {
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87 HeapWord* expected_top = obj + size;
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88 return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top;
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89 }
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90
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91 void MutableSpace::oop_iterate(OopClosure* cl) {
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92 HeapWord* obj_addr = bottom();
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93 HeapWord* t = top();
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94 // Could call objects iterate, but this is easier.
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95 while (obj_addr < t) {
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96 obj_addr += oop(obj_addr)->oop_iterate(cl);
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97 }
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98 }
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99
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100 void MutableSpace::object_iterate(ObjectClosure* cl) {
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101 HeapWord* p = bottom();
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102 while (p < top()) {
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103 cl->do_object(oop(p));
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104 p += oop(p)->size();
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105 }
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106 }
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107
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108 void MutableSpace::print_short() const { print_short_on(tty); }
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109 void MutableSpace::print_short_on( outputStream* st) const {
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110 st->print(" space " SIZE_FORMAT "K, %d%% used", capacity_in_bytes() / K,
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111 (int) ((double) used_in_bytes() * 100 / capacity_in_bytes()));
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112 }
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113
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114 void MutableSpace::print() const { print_on(tty); }
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115 void MutableSpace::print_on(outputStream* st) const {
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116 MutableSpace::print_short_on(st);
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117 st->print_cr(" [" INTPTR_FORMAT "," INTPTR_FORMAT "," INTPTR_FORMAT ")",
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118 bottom(), top(), end());
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119 }
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120
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121 void MutableSpace::verify(bool allow_dirty) const {
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122 HeapWord* p = bottom();
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123 HeapWord* t = top();
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124 HeapWord* prev_p = NULL;
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125 while (p < t) {
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126 oop(p)->verify();
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127 prev_p = p;
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128 p += oop(p)->size();
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129 }
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130 guarantee(p == top(), "end of last object must match end of space");
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131 }
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