1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/heapRegion.hpp"
27 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
28 #include "gc_implementation/g1/heapRegionSets.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "memory/allocation.hpp"
31
32 // Private
33
34 uint HeapRegionSeq::find_contiguous_from(uint from, uint num) {
35 uint len = length();
36 assert(num > 1, "use this only for sequences of length 2 or greater");
37 assert(from <= len,
38 err_msg("from: %u should be valid and <= than %u", from, len));
39
40 uint curr = from;
41 uint first = G1_NULL_HRS_INDEX;
42 uint num_so_far = 0;
43 while (curr < len && num_so_far < num) {
44 if (at(curr)->is_empty()) {
45 if (first == G1_NULL_HRS_INDEX) {
46 first = curr;
47 num_so_far = 1;
48 } else {
49 num_so_far += 1;
50 }
51 } else {
52 first = G1_NULL_HRS_INDEX;
53 num_so_far = 0;
54 }
55 curr += 1;
56 }
57 assert(num_so_far <= num, "post-condition");
58 if (num_so_far == num) {
59 // we found enough space for the humongous object
60 assert(from <= first && first < len, "post-condition");
61 assert(first < curr && (curr - first) == num, "post-condition");
62 for (uint i = first; i < first + num; ++i) {
63 assert(at(i)->is_empty(), "post-condition");
64 }
65 return first;
66 } else {
67 // we failed to find enough space for the humongous object
68 return G1_NULL_HRS_INDEX;
69 }
70 }
71
72 // Public
73
74 void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* end,
75 uint max_length) {
76 assert((uintptr_t) bottom % HeapRegion::GrainBytes == 0,
77 "bottom should be heap region aligned");
78 assert((uintptr_t) end % HeapRegion::GrainBytes == 0,
79 "end should be heap region aligned");
80
81 _length = 0;
82 _heap_bottom = bottom;
83 _heap_end = end;
84 _region_shift = HeapRegion::LogOfHRGrainBytes;
85 _next_search_index = 0;
86 _allocated_length = 0;
87 _max_length = max_length;
88
89 _regions = NEW_C_HEAP_ARRAY(HeapRegion*, max_length, mtGC);
90 memset(_regions, 0, (size_t) max_length * sizeof(HeapRegion*));
91 _regions_biased = _regions - ((uintx) bottom >> _region_shift);
92
93 assert(&_regions[0] == &_regions_biased[addr_to_index_biased(bottom)],
94 "bottom should be included in the region with index 0");
95 }
96
97 MemRegion HeapRegionSeq::expand_by(HeapWord* old_end,
98 HeapWord* new_end,
99 FreeRegionList* list) {
100 assert(old_end < new_end, "don't call it otherwise");
101 G1CollectedHeap* g1h = G1CollectedHeap::heap();
102
103 HeapWord* next_bottom = old_end;
104 assert(_heap_bottom <= next_bottom, "invariant");
105 while (next_bottom < new_end) {
106 assert(next_bottom < _heap_end, "invariant");
107 uint index = length();
108
109 assert(index < _max_length, "otherwise we cannot expand further");
110 if (index == 0) {
111 // We have not allocated any regions so far
112 assert(next_bottom == _heap_bottom, "invariant");
113 } else {
114 // next_bottom should match the end of the last/previous region
115 assert(next_bottom == at(index - 1)->end(), "invariant");
116 }
117
118 if (index == _allocated_length) {
119 // We have to allocate a new HeapRegion.
120 HeapRegion* new_hr = g1h->new_heap_region(index, next_bottom);
121 if (new_hr == NULL) {
122 // allocation failed, we bail out and return what we have done so far
123 return MemRegion(old_end, next_bottom);
124 }
125 assert(_regions[index] == NULL, "invariant");
126 _regions[index] = new_hr;
127 increment_allocated_length();
128 }
129 // Have to increment the length first, otherwise we will get an
130 // assert failure at(index) below.
131 increment_length();
132 HeapRegion* hr = at(index);
133 list->add_as_tail(hr);
134
135 next_bottom = hr->end();
136 }
137 assert(next_bottom == new_end, "post-condition");
138 return MemRegion(old_end, next_bottom);
139 }
140
141 uint HeapRegionSeq::free_suffix() {
142 uint res = 0;
143 uint index = length();
144 while (index > 0) {
145 index -= 1;
146 if (!at(index)->is_empty()) {
147 break;
148 }
149 res += 1;
150 }
151 return res;
152 }
153
154 uint HeapRegionSeq::find_contiguous(uint num) {
155 assert(num > 1, "use this only for sequences of length 2 or greater");
156 assert(_next_search_index <= length(),
157 err_msg("_next_search_index: %u should be valid and <= than %u",
158 _next_search_index, length()));
159
160 uint start = _next_search_index;
161 uint res = find_contiguous_from(start, num);
162 if (res == G1_NULL_HRS_INDEX && start > 0) {
163 // Try starting from the beginning. If _next_search_index was 0,
164 // no point in doing this again.
165 res = find_contiguous_from(0, num);
166 }
167 if (res != G1_NULL_HRS_INDEX) {
168 assert(res < length(), err_msg("res: %u should be valid", res));
169 _next_search_index = res + num;
170 assert(_next_search_index <= length(),
171 err_msg("_next_search_index: %u should be valid and <= than %u",
172 _next_search_index, length()));
173 }
174 return res;
175 }
176
177 void HeapRegionSeq::iterate(HeapRegionClosure* blk) const {
178 iterate_from((HeapRegion*) NULL, blk);
179 }
180
181 void HeapRegionSeq::iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const {
182 uint hr_index = 0;
183 if (hr != NULL) {
184 hr_index = hr->hrs_index();
185 }
186
187 uint len = length();
188 for (uint i = hr_index; i < len; i += 1) {
189 bool res = blk->doHeapRegion(at(i));
190 if (res) {
191 blk->incomplete();
192 return;
193 }
194 }
195 for (uint i = 0; i < hr_index; i += 1) {
196 bool res = blk->doHeapRegion(at(i));
197 if (res) {
198 blk->incomplete();
199 return;
200 }
201 }
202 }
203
204 uint HeapRegionSeq::shrink_by(uint num_regions_to_remove) {
205 // Reset this in case it's currently pointing into the regions that
206 // we just removed.
207 _next_search_index = 0;
208
209 assert(length() > 0, "the region sequence should not be empty");
210 assert(length() <= _allocated_length, "invariant");
211 assert(_allocated_length > 0, "we should have at least one region committed");
212 assert(num_regions_to_remove < length(), "We should never remove all regions");
213
214 uint i = 0;
215 for (; i < num_regions_to_remove; i++) {
216 HeapRegion* cur = at(length() - 1);
217
218 if (!cur->is_empty()) {
219 // We have to give up if the region can not be moved
220 break;
221 }
222 assert(!cur->isHumongous(), "Humongous regions should not be empty");
223
224 decrement_length();
225 }
226 return i;
227 }
228
229 #ifndef PRODUCT
230 void HeapRegionSeq::verify_optional() {
231 guarantee(_length <= _allocated_length,
232 err_msg("invariant: _length: %u _allocated_length: %u",
233 _length, _allocated_length));
234 guarantee(_allocated_length <= _max_length,
235 err_msg("invariant: _allocated_length: %u _max_length: %u",
236 _allocated_length, _max_length));
237 guarantee(_next_search_index <= _length,
238 err_msg("invariant: _next_search_index: %u _length: %u",
239 _next_search_index, _length));
240
241 HeapWord* prev_end = _heap_bottom;
242 for (uint i = 0; i < _allocated_length; i += 1) {
243 HeapRegion* hr = _regions[i];
244 guarantee(hr != NULL, err_msg("invariant: i: %u", i));
245 guarantee(hr->bottom() == prev_end,
246 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
247 i, HR_FORMAT_PARAMS(hr), prev_end));
248 guarantee(hr->hrs_index() == i,
249 err_msg("invariant: i: %u hrs_index(): %u", i, hr->hrs_index()));
250 if (i < _length) {
251 // Asserts will fire if i is >= _length
252 HeapWord* addr = hr->bottom();
253 guarantee(addr_to_region(addr) == hr, "sanity");
254 guarantee(addr_to_region_unsafe(addr) == hr, "sanity");
255 } else {
256 guarantee(hr->is_empty(), "sanity");
257 guarantee(!hr->isHumongous(), "sanity");
258 // using assert instead of guarantee here since containing_set()
259 // is only available in non-product builds.
260 assert(hr->containing_set() == NULL, "sanity");
261 }
262 if (hr->startsHumongous()) {
263 prev_end = hr->orig_end();
264 } else {
265 prev_end = hr->end();
266 }
267 }
268 for (uint i = _allocated_length; i < _max_length; i += 1) {
269 guarantee(_regions[i] == NULL, err_msg("invariant i: %u", i));
270 }
271 }
272 #endif // PRODUCT