Fri, 09 Sep 2011 05:20:58 -0400
7087717: G1: make the G1PrintRegionLivenessInfo parameter diagnostic
Reviewed-by: brutisso, ysr
1 /*
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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 #define G1_NULL_HRS_INDEX ((size_t) -1)
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
58 class HeapRegionSeq: public CHeapObj {
60 // The array that holds the HeapRegions.
61 HeapRegion** _regions;
63 // Version of _regions biased to address 0
64 HeapRegion** _regions_biased;
66 // The number of regions committed in the heap.
67 size_t _length;
69 // The address of the first reserved word in the heap.
70 HeapWord* _heap_bottom;
72 // The address of the last reserved word in the heap - 1.
73 HeapWord* _heap_end;
75 // The log of the region byte size.
76 size_t _region_shift;
78 // A hint for which index to start searching from for humongous
79 // allocations.
80 size_t _next_search_index;
82 // The number of regions for which we have allocated HeapRegions for.
83 size_t _allocated_length;
85 // The maximum number of regions in the heap.
86 size_t _max_length;
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);
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;
96 void increment_length(size_t* length) {
97 assert(*length < _max_length, "pre-condition");
98 *length += 1;
99 }
101 void decrement_length(size_t* length) {
102 assert(*length > 0, "pre-condition");
103 *length -= 1;
104 }
106 public:
107 // Empty contructor, we'll initialize it with the initialize() method.
108 HeapRegionSeq() { }
110 void initialize(HeapWord* bottom, HeapWord* end, size_t max_length);
112 // Return the HeapRegion at the given index. Assume that the index
113 // is valid.
114 inline HeapRegion* at(size_t index) const;
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;
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;
124 // Return the number of regions that have been committed in the heap.
125 size_t length() const { return _length; }
127 // Return the maximum number of regions in the heap.
128 size_t max_length() const { return _max_length; }
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);
139 // Return the number of contiguous regions at the end of the sequence
140 // that are available for allocation.
141 size_t free_suffix();
143 // Find a contiguous set of empty regions of length num and return
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);
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;
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;
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);
163 // Do some sanity checking.
164 void verify_optional() PRODUCT_RETURN;
165 };
167 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP