1 /*
2 * Copyright (c) 2001, 2009, 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 "incls/_precompiled.incl"
26 #include "incls/_heapRegionSeq.cpp.incl"
27
28 // Local to this file.
29
30 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
31 if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
32 else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
33 else if (*hr1p == *hr2p) return 0;
34 else {
35 assert(false, "We should never compare distinct overlapping regions.");
36 }
37 return 0;
38 }
39
40 HeapRegionSeq::HeapRegionSeq(const size_t max_size) :
41 _alloc_search_start(0),
42 // The line below is the worst bit of C++ hackery I've ever written
43 // (Detlefs, 11/23). You should think of it as equivalent to
44 // "_regions(100, true)": initialize the growable array and inform it
45 // that it should allocate its elem array(s) on the C heap.
46 //
47 // The first argument, however, is actually a comma expression
48 // (set_allocation_type(this, C_HEAP), 100). The purpose of the
49 // set_allocation_type() call is to replace the default allocation
50 // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
51 // allow to pass the assert in GenericGrowableArray() which checks
52 // that a growable array object must be on C heap if elements are.
53 //
54 // Note: containing object is allocated on C heap since it is CHeapObj.
55 //
56 _regions((ResourceObj::set_allocation_type((address)&_regions,
57 ResourceObj::C_HEAP),
58 (int)max_size),
59 true),
60 _next_rr_candidate(0),
61 _seq_bottom(NULL)
62 {}
63
64 // Private methods.
65
66 HeapWord*
67 HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {
68 assert(G1CollectedHeap::isHumongous(word_size),
69 "Allocation size should be humongous");
70 int cur = ind;
71 int first = cur;
72 size_t sumSizes = 0;
73 while (cur < _regions.length() && sumSizes < word_size) {
74 // Loop invariant:
75 // For all i in [first, cur):
76 // _regions.at(i)->is_empty()
77 // && _regions.at(i) is contiguous with its predecessor, if any
78 // && sumSizes is the sum of the sizes of the regions in the interval
79 // [first, cur)
80 HeapRegion* curhr = _regions.at(cur);
81 if (curhr->is_empty()
82 && (first == cur
83 || (_regions.at(cur-1)->end() ==
84 curhr->bottom()))) {
85 sumSizes += curhr->capacity() / HeapWordSize;
86 } else {
87 first = cur + 1;
88 sumSizes = 0;
89 }
90 cur++;
91 }
92 if (sumSizes >= word_size) {
93 _alloc_search_start = cur;
94 // Mark the allocated regions as allocated.
95 bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();
96 HeapRegion* first_hr = _regions.at(first);
97 for (int i = first; i < cur; i++) {
98 HeapRegion* hr = _regions.at(i);
99 if (zf)
100 hr->ensure_zero_filled();
101 {
102 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
103 hr->set_zero_fill_allocated();
104 }
105 size_t sz = hr->capacity() / HeapWordSize;
106 HeapWord* tmp = hr->allocate(sz);
107 assert(tmp != NULL, "Humongous allocation failure");
108 MemRegion mr = MemRegion(tmp, sz);
109 CollectedHeap::fill_with_object(mr);
110 hr->declare_filled_region_to_BOT(mr);
111 if (i == first) {
112 first_hr->set_startsHumongous();
113 } else {
114 assert(i > first, "sanity");
115 hr->set_continuesHumongous(first_hr);
116 }
117 }
118 HeapWord* first_hr_bot = first_hr->bottom();
119 HeapWord* obj_end = first_hr_bot + word_size;
120 first_hr->set_top(obj_end);
121 return first_hr_bot;
122 } else {
123 // If we started from the beginning, we want to know why we can't alloc.
124 return NULL;
125 }
126 }
127
128 void HeapRegionSeq::print_empty_runs() {
129 int empty_run = 0;
130 int n_empty = 0;
131 int empty_run_start;
132 for (int i = 0; i < _regions.length(); i++) {
133 HeapRegion* r = _regions.at(i);
134 if (r->continuesHumongous()) continue;
135 if (r->is_empty()) {
136 assert(!r->isHumongous(), "H regions should not be empty.");
137 if (empty_run == 0) empty_run_start = i;
138 empty_run++;
139 n_empty++;
140 } else {
141 if (empty_run > 0) {
142 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
143 empty_run = 0;
144 }
145 }
146 }
147 if (empty_run > 0) {
148 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
149 }
150 gclog_or_tty->print_cr(" [tot = %d]", n_empty);
151 }
152
153 int HeapRegionSeq::find(HeapRegion* hr) {
154 // FIXME: optimized for adjacent regions of fixed size.
155 int ind = hr->hrs_index();
156 if (ind != -1) {
157 assert(_regions.at(ind) == hr, "Mismatch");
158 }
159 return ind;
160 }
161
162
163 // Public methods.
164
165 void HeapRegionSeq::insert(HeapRegion* hr) {
166 assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");
167 if (_regions.length() == 0
168 || _regions.top()->end() <= hr->bottom()) {
169 hr->set_hrs_index(_regions.length());
170 _regions.append(hr);
171 } else {
172 _regions.append(hr);
173 _regions.sort(orderRegions);
174 for (int i = 0; i < _regions.length(); i++) {
175 _regions.at(i)->set_hrs_index(i);
176 }
177 }
178 char* bot = (char*)_regions.at(0)->bottom();
179 if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
180 }
181
182 size_t HeapRegionSeq::length() {
183 return _regions.length();
184 }
185
186 size_t HeapRegionSeq::free_suffix() {
187 size_t res = 0;
188 int first = _regions.length() - 1;
189 int cur = first;
190 while (cur >= 0 &&
191 (_regions.at(cur)->is_empty()
192 && (first == cur
193 || (_regions.at(cur+1)->bottom() ==
194 _regions.at(cur)->end())))) {
195 res++;
196 cur--;
197 }
198 return res;
199 }
200
201 HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {
202 int cur = _alloc_search_start;
203 // Make sure "cur" is a valid index.
204 assert(cur >= 0, "Invariant.");
205 HeapWord* res = alloc_obj_from_region_index(cur, word_size);
206 if (res == NULL)
207 res = alloc_obj_from_region_index(0, word_size);
208 return res;
209 }
210
211 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
212 iterate_from((HeapRegion*)NULL, blk);
213 }
214
215 // The first argument r is the heap region at which iteration begins.
216 // This operation runs fastest when r is NULL, or the heap region for
217 // which a HeapRegionClosure most recently returned true, or the
218 // heap region immediately to its right in the sequence. In all
219 // other cases a linear search is required to find the index of r.
220
221 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
222
223 // :::: FIXME ::::
224 // Static cache value is bad, especially when we start doing parallel
225 // remembered set update. For now just don't cache anything (the
226 // code in the def'd out blocks).
227
228 #if 0
229 static int cached_j = 0;
230 #endif
231 int len = _regions.length();
232 int j = 0;
233 // Find the index of r.
234 if (r != NULL) {
235 #if 0
236 assert(cached_j >= 0, "Invariant.");
237 if ((cached_j < len) && (r == _regions.at(cached_j))) {
238 j = cached_j;
239 } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
240 j = cached_j + 1;
241 } else {
242 j = find(r);
243 #endif
244 if (j < 0) {
245 j = 0;
246 }
247 #if 0
248 }
249 #endif
250 }
251 int i;
252 for (i = j; i < len; i += 1) {
253 int res = blk->doHeapRegion(_regions.at(i));
254 if (res) {
255 #if 0
256 cached_j = i;
257 #endif
258 blk->incomplete();
259 return;
260 }
261 }
262 for (i = 0; i < j; i += 1) {
263 int res = blk->doHeapRegion(_regions.at(i));
264 if (res) {
265 #if 0
266 cached_j = i;
267 #endif
268 blk->incomplete();
269 return;
270 }
271 }
272 }
273
274 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
275 int len = _regions.length();
276 int i;
277 for (i = idx; i < len; i++) {
278 if (blk->doHeapRegion(_regions.at(i))) {
279 blk->incomplete();
280 return;
281 }
282 }
283 for (i = 0; i < idx; i++) {
284 if (blk->doHeapRegion(_regions.at(i))) {
285 blk->incomplete();
286 return;
287 }
288 }
289 }
290
291 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
292 size_t& num_regions_deleted) {
293 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
294 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
295
296 if (_regions.length() == 0) {
297 num_regions_deleted = 0;
298 return MemRegion();
299 }
300 int j = _regions.length() - 1;
301 HeapWord* end = _regions.at(j)->end();
302 HeapWord* last_start = end;
303 while (j >= 0 && shrink_bytes > 0) {
304 HeapRegion* cur = _regions.at(j);
305 // We have to leave humongous regions where they are,
306 // and work around them.
307 if (cur->isHumongous()) {
308 return MemRegion(last_start, end);
309 }
310 assert(cur == _regions.top(), "Should be top");
311 if (!cur->is_empty()) break;
312 cur->reset_zero_fill();
313 shrink_bytes -= cur->capacity();
314 num_regions_deleted++;
315 _regions.pop();
316 last_start = cur->bottom();
317 // We need to delete these somehow, but can't currently do so here: if
318 // we do, the ZF thread may still access the deleted region. We'll
319 // leave this here as a reminder that we have to do something about
320 // this.
321 // delete cur;
322 j--;
323 }
324 return MemRegion(last_start, end);
325 }
326
327
328 class PrintHeapRegionClosure : public HeapRegionClosure {
329 public:
330 bool doHeapRegion(HeapRegion* r) {
331 gclog_or_tty->print(PTR_FORMAT ":", r);
332 r->print();
333 return false;
334 }
335 };
336
337 void HeapRegionSeq::print() {
338 PrintHeapRegionClosure cl;
339 iterate(&cl);
340 }