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annotate src/share/vm/gc_implementation/g1/heapRegionSeq.hpp @ 3766:c3f1170908be
7045330: G1: Simplify/fix the HeapRegionSeq class
7042285: G1: native memory leak during humongous object allocation
6804436: G1: heap region indices should be size_t
Summary: A series of fixes and improvements to the HeapRegionSeq class: a) replace the _regions growable array with a standard C array, b) avoid de-allocating / re-allocating HeapRegion instances when the heap shrinks / grows (fix for 7042285), c) introduce fast method to map address to HeapRegion via a "biased" array pointer, d) embed the _hrs object in G1CollectedHeap, instead of pointing to it via an indirection, e) assume that all the regions added to the HeapRegionSeq instance are contiguous, f) replace int's with size_t's for indexes (and expand that to HeapRegion as part of 6804436), g) remove unnecessary / unused methods, h) rename a couple of fields (_alloc_search_start and _seq_bottom), i) fix iterate_from() not to always start from index 0 irrespective of the region passed to it, j) add a verification method to check the HeapRegionSeq assumptions, k) always call the wrappers for _hrs.iterate(), _hrs_length(), and _hrs.at() from G1CollectedHeap, not those methods directly, and l) unify the code that expands the sequence (by either re-using or creating a new HeapRegion) and make it robust wrt to a HeapRegion allocation failing.
Reviewed-by: stefank, johnc, brutisso
author | tonyp |
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date | Fri, 10 Jun 2011 13:16:40 -0400 |
parents | 1216415d8e35 |
children | 4f93f0d00802 |
rev | line source |
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342 | 1 /* |
2149 | 2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. |
342 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
342 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP |
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP | |
27 | |
342 | 28 class HeapRegion; |
29 class HeapRegionClosure; | |
3766 | 30 class FreeRegionList; |
31 | |
32 #define G1_NULL_HRS_INDEX ((size_t) -1) | |
33 | |
34 // This class keeps track of the region metadata (i.e., HeapRegion | |
35 // instances). They are kept in the _regions array in address | |
36 // order. A region's index in the array corresponds to its index in | |
37 // the heap (i.e., 0 is the region at the bottom of the heap, 1 is | |
38 // the one after it, etc.). Two regions that are consecutive in the | |
39 // array should also be adjacent in the address space (i.e., | |
40 // region(i).end() == region(i+1).bottom(). | |
41 // | |
42 // We create a HeapRegion when we commit the region's address space | |
43 // for the first time. When we uncommit the address space of a | |
44 // region we retain the HeapRegion to be able to re-use it in the | |
45 // future (in case we recommit it). | |
46 // | |
47 // We keep track of three lengths: | |
48 // | |
49 // * _length (returned by length()) is the number of currently | |
50 // committed regions. | |
51 // * _allocated_length (not exposed outside this class) is the | |
52 // number of regions for which we have HeapRegions. | |
53 // * _max_length (returned by max_length()) is the maximum number of | |
54 // regions the heap can have. | |
55 // | |
56 // and maintain that: _length <= _allocated_length <= _max_length | |
342 | 57 |
58 class HeapRegionSeq: public CHeapObj { | |
59 | |
3766 | 60 // The array that holds the HeapRegions. |
61 HeapRegion** _regions; | |
62 | |
63 // Version of _regions biased to address 0 | |
64 HeapRegion** _regions_biased; | |
65 | |
66 // The number of regions committed in the heap. | |
67 size_t _length; | |
342 | 68 |
3766 | 69 // The address of the first reserved word in the heap. |
70 HeapWord* _heap_bottom; | |
71 | |
72 // The address of the last reserved word in the heap - 1. | |
73 HeapWord* _heap_end; | |
74 | |
75 // The log of the region byte size. | |
76 size_t _region_shift; | |
77 | |
78 // A hint for which index to start searching from for humongous | |
79 // allocations. | |
80 size_t _next_search_index; | |
342 | 81 |
3766 | 82 // The number of regions for which we have allocated HeapRegions for. |
83 size_t _allocated_length; | |
84 | |
85 // The maximum number of regions in the heap. | |
86 size_t _max_length; | |
87 | |
88 // Find a contiguous set of empty regions of length num, starting | |
89 // from the given index. | |
90 size_t find_contiguous_from(size_t from, size_t num); | |
342 | 91 |
3766 | 92 // Map a heap address to a biased region index. Assume that the |
93 // address is valid. | |
94 inline size_t addr_to_index_biased(HeapWord* addr) const; | |
342 | 95 |
3766 | 96 void increment_length(size_t* length) { |
97 assert(*length < _max_length, "pre-condition"); | |
98 *length += 1; | |
99 } | |
100 | |
101 void decrement_length(size_t* length) { | |
102 assert(*length > 0, "pre-condition"); | |
103 *length -= 1; | |
104 } | |
342 | 105 |
106 public: | |
3766 | 107 // Empty contructor, we'll initialize it with the initialize() method. |
108 HeapRegionSeq() { } | |
109 | |
110 void initialize(HeapWord* bottom, HeapWord* end, size_t max_length); | |
342 | 111 |
3766 | 112 // Return the HeapRegion at the given index. Assume that the index |
113 // is valid. | |
114 inline HeapRegion* at(size_t index) const; | |
115 | |
116 // If addr is within the committed space return its corresponding | |
117 // HeapRegion, otherwise return NULL. | |
118 inline HeapRegion* addr_to_region(HeapWord* addr) const; | |
119 | |
120 // Return the HeapRegion that corresponds to the given | |
121 // address. Assume the address is valid. | |
122 inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const; | |
342 | 123 |
3766 | 124 // Return the number of regions that have been committed in the heap. |
125 size_t length() const { return _length; } | |
126 | |
127 // Return the maximum number of regions in the heap. | |
128 size_t max_length() const { return _max_length; } | |
342 | 129 |
3766 | 130 // Expand the sequence to reflect that the heap has grown from |
131 // old_end to new_end. Either create new HeapRegions, or re-use | |
132 // existing ones, and return them in the given list. Returns the | |
133 // memory region that covers the newly-created regions. If a | |
134 // HeapRegion allocation fails, the result memory region might be | |
135 // smaller than the desired one. | |
136 MemRegion expand_by(HeapWord* old_end, HeapWord* new_end, | |
137 FreeRegionList* list); | |
342 | 138 |
3766 | 139 // Return the number of contiguous regions at the end of the sequence |
342 | 140 // that are available for allocation. |
141 size_t free_suffix(); | |
142 | |
2361 | 143 // Find a contiguous set of empty regions of length num and return |
3766 | 144 // the index of the first region or G1_NULL_HRS_INDEX if the |
145 // search was unsuccessful. | |
146 size_t find_contiguous(size_t num); | |
342 | 147 |
3766 | 148 // Apply blk->doHeapRegion() on all committed regions in address order, |
149 // terminating the iteration early if doHeapRegion() returns true. | |
150 void iterate(HeapRegionClosure* blk) const; | |
342 | 151 |
3766 | 152 // As above, but start the iteration from hr and loop around. If hr |
153 // is NULL, we start from the first region in the heap. | |
154 void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const; | |
342 | 155 |
3766 | 156 // Tag as uncommitted as many regions that are completely free as |
157 // possible, up to shrink_bytes, from the suffix of the committed | |
158 // sequence. Return a MemRegion that corresponds to the address | |
159 // range of the uncommitted regions. Assume shrink_bytes is page and | |
160 // heap region aligned. | |
161 MemRegion shrink_by(size_t shrink_bytes, size_t* num_regions_deleted); | |
342 | 162 |
3766 | 163 // Do some sanity checking. |
164 void verify_optional() PRODUCT_RETURN; | |
342 | 165 }; |
1972 | 166 |
167 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP |