Fri, 04 Mar 2011 17:13:19 -0500
7014923: G1: code cleanup
Summary: Some G1 code cleanup.
Reviewed-by: johnc, jcoomes, jwilhelm
1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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.
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
27 #include "gc_implementation/g1/heapRegionSeq.hpp"
28 #include "memory/allocation.hpp"
30 // Local to this file.
32 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
33 if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
34 else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
35 else if (*hr1p == *hr2p) return 0;
36 else {
37 assert(false, "We should never compare distinct overlapping regions.");
38 }
39 return 0;
40 }
42 HeapRegionSeq::HeapRegionSeq(const size_t max_size) :
43 _alloc_search_start(0),
44 // The line below is the worst bit of C++ hackery I've ever written
45 // (Detlefs, 11/23). You should think of it as equivalent to
46 // "_regions(100, true)": initialize the growable array and inform it
47 // that it should allocate its elem array(s) on the C heap.
48 //
49 // The first argument, however, is actually a comma expression
50 // (set_allocation_type(this, C_HEAP), 100). The purpose of the
51 // set_allocation_type() call is to replace the default allocation
52 // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
53 // allow to pass the assert in GenericGrowableArray() which checks
54 // that a growable array object must be on C heap if elements are.
55 //
56 // Note: containing object is allocated on C heap since it is CHeapObj.
57 //
58 _regions((ResourceObj::set_allocation_type((address)&_regions,
59 ResourceObj::C_HEAP),
60 (int)max_size),
61 true),
62 _next_rr_candidate(0),
63 _seq_bottom(NULL)
64 {}
66 // Private methods.
68 void HeapRegionSeq::print_empty_runs() {
69 int empty_run = 0;
70 int n_empty = 0;
71 int empty_run_start;
72 for (int i = 0; i < _regions.length(); i++) {
73 HeapRegion* r = _regions.at(i);
74 if (r->continuesHumongous()) continue;
75 if (r->is_empty()) {
76 assert(!r->isHumongous(), "H regions should not be empty.");
77 if (empty_run == 0) empty_run_start = i;
78 empty_run++;
79 n_empty++;
80 } else {
81 if (empty_run > 0) {
82 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
83 empty_run = 0;
84 }
85 }
86 }
87 if (empty_run > 0) {
88 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
89 }
90 gclog_or_tty->print_cr(" [tot = %d]", n_empty);
91 }
93 int HeapRegionSeq::find(HeapRegion* hr) {
94 // FIXME: optimized for adjacent regions of fixed size.
95 int ind = hr->hrs_index();
96 if (ind != -1) {
97 assert(_regions.at(ind) == hr, "Mismatch");
98 }
99 return ind;
100 }
103 // Public methods.
105 void HeapRegionSeq::insert(HeapRegion* hr) {
106 assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");
107 if (_regions.length() == 0
108 || _regions.top()->end() <= hr->bottom()) {
109 hr->set_hrs_index(_regions.length());
110 _regions.append(hr);
111 } else {
112 _regions.append(hr);
113 _regions.sort(orderRegions);
114 for (int i = 0; i < _regions.length(); i++) {
115 _regions.at(i)->set_hrs_index(i);
116 }
117 }
118 char* bot = (char*)_regions.at(0)->bottom();
119 if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
120 }
122 size_t HeapRegionSeq::length() {
123 return _regions.length();
124 }
126 size_t HeapRegionSeq::free_suffix() {
127 size_t res = 0;
128 int first = _regions.length() - 1;
129 int cur = first;
130 while (cur >= 0 &&
131 (_regions.at(cur)->is_empty()
132 && (first == cur
133 || (_regions.at(cur+1)->bottom() ==
134 _regions.at(cur)->end())))) {
135 res++;
136 cur--;
137 }
138 return res;
139 }
141 int HeapRegionSeq::find_contiguous_from(int from, size_t num) {
142 assert(num > 1, "pre-condition");
143 assert(0 <= from && from <= _regions.length(),
144 err_msg("from: %d should be valid and <= than %d",
145 from, _regions.length()));
147 int curr = from;
148 int first = -1;
149 size_t num_so_far = 0;
150 while (curr < _regions.length() && num_so_far < num) {
151 HeapRegion* curr_hr = _regions.at(curr);
152 if (curr_hr->is_empty()) {
153 if (first == -1) {
154 first = curr;
155 num_so_far = 1;
156 } else {
157 num_so_far += 1;
158 }
159 } else {
160 first = -1;
161 num_so_far = 0;
162 }
163 curr += 1;
164 }
166 assert(num_so_far <= num, "post-condition");
167 if (num_so_far == num) {
168 // we found enough space for the humongous object
169 assert(from <= first && first < _regions.length(), "post-condition");
170 assert(first < curr && (curr - first) == (int) num, "post-condition");
171 for (int i = first; i < first + (int) num; ++i) {
172 assert(_regions.at(i)->is_empty(), "post-condition");
173 }
174 return first;
175 } else {
176 // we failed to find enough space for the humongous object
177 return -1;
178 }
179 }
181 int HeapRegionSeq::find_contiguous(size_t num) {
182 assert(num > 1, "otherwise we should not be calling this");
183 assert(0 <= _alloc_search_start && _alloc_search_start <= _regions.length(),
184 err_msg("_alloc_search_start: %d should be valid and <= than %d",
185 _alloc_search_start, _regions.length()));
187 int start = _alloc_search_start;
188 int res = find_contiguous_from(start, num);
189 if (res == -1 && start != 0) {
190 // Try starting from the beginning. If _alloc_search_start was 0,
191 // no point in doing this again.
192 res = find_contiguous_from(0, num);
193 }
194 if (res != -1) {
195 assert(0 <= res && res < _regions.length(),
196 err_msg("res: %d should be valid", res));
197 _alloc_search_start = res + (int) num;
198 assert(0 < _alloc_search_start && _alloc_search_start <= _regions.length(),
199 err_msg("_alloc_search_start: %d should be valid",
200 _alloc_search_start));
201 }
202 return res;
203 }
205 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
206 iterate_from((HeapRegion*)NULL, blk);
207 }
209 // The first argument r is the heap region at which iteration begins.
210 // This operation runs fastest when r is NULL, or the heap region for
211 // which a HeapRegionClosure most recently returned true, or the
212 // heap region immediately to its right in the sequence. In all
213 // other cases a linear search is required to find the index of r.
215 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
217 // :::: FIXME ::::
218 // Static cache value is bad, especially when we start doing parallel
219 // remembered set update. For now just don't cache anything (the
220 // code in the def'd out blocks).
222 #if 0
223 static int cached_j = 0;
224 #endif
225 int len = _regions.length();
226 int j = 0;
227 // Find the index of r.
228 if (r != NULL) {
229 #if 0
230 assert(cached_j >= 0, "Invariant.");
231 if ((cached_j < len) && (r == _regions.at(cached_j))) {
232 j = cached_j;
233 } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
234 j = cached_j + 1;
235 } else {
236 j = find(r);
237 #endif
238 if (j < 0) {
239 j = 0;
240 }
241 #if 0
242 }
243 #endif
244 }
245 int i;
246 for (i = j; i < len; i += 1) {
247 int res = blk->doHeapRegion(_regions.at(i));
248 if (res) {
249 #if 0
250 cached_j = i;
251 #endif
252 blk->incomplete();
253 return;
254 }
255 }
256 for (i = 0; i < j; i += 1) {
257 int res = blk->doHeapRegion(_regions.at(i));
258 if (res) {
259 #if 0
260 cached_j = i;
261 #endif
262 blk->incomplete();
263 return;
264 }
265 }
266 }
268 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
269 int len = _regions.length();
270 int i;
271 for (i = idx; i < len; i++) {
272 if (blk->doHeapRegion(_regions.at(i))) {
273 blk->incomplete();
274 return;
275 }
276 }
277 for (i = 0; i < idx; i++) {
278 if (blk->doHeapRegion(_regions.at(i))) {
279 blk->incomplete();
280 return;
281 }
282 }
283 }
285 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
286 size_t& num_regions_deleted) {
287 // Reset this in case it's currently pointing into the regions that
288 // we just removed.
289 _alloc_search_start = 0;
291 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
292 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
294 if (_regions.length() == 0) {
295 num_regions_deleted = 0;
296 return MemRegion();
297 }
298 int j = _regions.length() - 1;
299 HeapWord* end = _regions.at(j)->end();
300 HeapWord* last_start = end;
301 while (j >= 0 && shrink_bytes > 0) {
302 HeapRegion* cur = _regions.at(j);
303 // We have to leave humongous regions where they are,
304 // and work around them.
305 if (cur->isHumongous()) {
306 return MemRegion(last_start, end);
307 }
308 assert(cur == _regions.top(), "Should be top");
309 if (!cur->is_empty()) break;
310 shrink_bytes -= cur->capacity();
311 num_regions_deleted++;
312 _regions.pop();
313 last_start = cur->bottom();
314 // We need to delete these somehow, but can't currently do so here: if
315 // we do, the ZF thread may still access the deleted region. We'll
316 // leave this here as a reminder that we have to do something about
317 // this.
318 // delete cur;
319 j--;
320 }
321 return MemRegion(last_start, end);
322 }
324 class PrintHeapRegionClosure : public HeapRegionClosure {
325 public:
326 bool doHeapRegion(HeapRegion* r) {
327 gclog_or_tty->print(PTR_FORMAT ":", r);
328 r->print();
329 return false;
330 }
331 };
333 void HeapRegionSeq::print() {
334 PrintHeapRegionClosure cl;
335 iterate(&cl);
336 }