Sat, 06 Oct 2012 01:17:44 -0700
7127708: G1: change task num types from int to uint in concurrent mark
Summary: Change the type of various task num fields, parameters etc to unsigned and rename them to be more consistent with the other collectors. Code changes were also reviewed by Vitaly Davidovich.
Reviewed-by: johnc
Contributed-by: Kaushik Srenevasan <kaushik@twitter.com>
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
28 class HeapRegion;
29 class HeapRegionClosure;
30 class FreeRegionList;
32 // This class keeps track of the region metadata (i.e., HeapRegion
33 // instances). They are kept in the _regions array in address
34 // order. A region's index in the array corresponds to its index in
35 // the heap (i.e., 0 is the region at the bottom of the heap, 1 is
36 // the one after it, etc.). Two regions that are consecutive in the
37 // array should also be adjacent in the address space (i.e.,
38 // region(i).end() == region(i+1).bottom().
39 //
40 // We create a HeapRegion when we commit the region's address space
41 // for the first time. When we uncommit the address space of a
42 // region we retain the HeapRegion to be able to re-use it in the
43 // future (in case we recommit it).
44 //
45 // We keep track of three lengths:
46 //
47 // * _length (returned by length()) is the number of currently
48 // committed regions.
49 // * _allocated_length (not exposed outside this class) is the
50 // number of regions for which we have HeapRegions.
51 // * _max_length (returned by max_length()) is the maximum number of
52 // regions the heap can have.
53 //
54 // and maintain that: _length <= _allocated_length <= _max_length
56 class HeapRegionSeq: public CHeapObj<mtGC> {
57 friend class VMStructs;
59 // The array that holds the HeapRegions.
60 HeapRegion** _regions;
62 // Version of _regions biased to address 0
63 HeapRegion** _regions_biased;
65 // The number of regions committed in the heap.
66 uint _length;
68 // The address of the first reserved word in the heap.
69 HeapWord* _heap_bottom;
71 // The address of the last reserved word in the heap - 1.
72 HeapWord* _heap_end;
74 // The log of the region byte size.
75 uint _region_shift;
77 // A hint for which index to start searching from for humongous
78 // allocations.
79 uint _next_search_index;
81 // The number of regions for which we have allocated HeapRegions for.
82 uint _allocated_length;
84 // The maximum number of regions in the heap.
85 uint _max_length;
87 // Find a contiguous set of empty regions of length num, starting
88 // from the given index.
89 uint find_contiguous_from(uint from, uint num);
91 // Map a heap address to a biased region index. Assume that the
92 // address is valid.
93 inline uintx addr_to_index_biased(HeapWord* addr) const;
95 void increment_length(uint* length) {
96 assert(*length < _max_length, "pre-condition");
97 *length += 1;
98 }
100 void decrement_length(uint* length) {
101 assert(*length > 0, "pre-condition");
102 *length -= 1;
103 }
105 public:
106 // Empty contructor, we'll initialize it with the initialize() method.
107 HeapRegionSeq() { }
109 void initialize(HeapWord* bottom, HeapWord* end, uint max_length);
111 // Return the HeapRegion at the given index. Assume that the index
112 // is valid.
113 inline HeapRegion* at(uint index) const;
115 // If addr is within the committed space return its corresponding
116 // HeapRegion, otherwise return NULL.
117 inline HeapRegion* addr_to_region(HeapWord* addr) const;
119 // Return the HeapRegion that corresponds to the given
120 // address. Assume the address is valid.
121 inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const;
123 // Return the number of regions that have been committed in the heap.
124 uint length() const { return _length; }
126 // Return the maximum number of regions in the heap.
127 uint max_length() const { return _max_length; }
129 // Expand the sequence to reflect that the heap has grown from
130 // old_end to new_end. Either create new HeapRegions, or re-use
131 // existing ones, and return them in the given list. Returns the
132 // memory region that covers the newly-created regions. If a
133 // HeapRegion allocation fails, the result memory region might be
134 // smaller than the desired one.
135 MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
136 FreeRegionList* list);
138 // Return the number of contiguous regions at the end of the sequence
139 // that are available for allocation.
140 uint free_suffix();
142 // Find a contiguous set of empty regions of length num and return
143 // the index of the first region or G1_NULL_HRS_INDEX if the
144 // search was unsuccessful.
145 uint find_contiguous(uint num);
147 // Apply blk->doHeapRegion() on all committed regions in address order,
148 // terminating the iteration early if doHeapRegion() returns true.
149 void iterate(HeapRegionClosure* blk) const;
151 // As above, but start the iteration from hr and loop around. If hr
152 // is NULL, we start from the first region in the heap.
153 void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
155 // Tag as uncommitted as many regions that are completely free as
156 // possible, up to shrink_bytes, from the suffix of the committed
157 // sequence. Return a MemRegion that corresponds to the address
158 // range of the uncommitted regions. Assume shrink_bytes is page and
159 // heap region aligned.
160 MemRegion shrink_by(size_t shrink_bytes, uint* num_regions_deleted);
162 // Do some sanity checking.
163 void verify_optional() PRODUCT_RETURN;
164 };
166 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP