--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp Wed Jun 08 21:48:38 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp Fri Jun 10 13:16:40 2011 -0400
@@ -25,92 +25,143 @@
#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
-#include "gc_implementation/g1/heapRegion.hpp"
-#include "utilities/growableArray.hpp"
-
class HeapRegion;
class HeapRegionClosure;
+class FreeRegionList;
+
+#define G1_NULL_HRS_INDEX ((size_t) -1)
+
+// This class keeps track of the region metadata (i.e., HeapRegion
+// instances). They are kept in the _regions array in address
+// order. A region's index in the array corresponds to its index in
+// the heap (i.e., 0 is the region at the bottom of the heap, 1 is
+// the one after it, etc.). Two regions that are consecutive in the
+// array should also be adjacent in the address space (i.e.,
+// region(i).end() == region(i+1).bottom().
+//
+// We create a HeapRegion when we commit the region's address space
+// for the first time. When we uncommit the address space of a
+// region we retain the HeapRegion to be able to re-use it in the
+// future (in case we recommit it).
+//
+// We keep track of three lengths:
+//
+// * _length (returned by length()) is the number of currently
+// committed regions.
+// * _allocated_length (not exposed outside this class) is the
+// number of regions for which we have HeapRegions.
+// * _max_length (returned by max_length()) is the maximum number of
+// regions the heap can have.
+//
+// and maintain that: _length <= _allocated_length <= _max_length
class HeapRegionSeq: public CHeapObj {
- // _regions is kept sorted by start address order, and no two regions are
- // overlapping.
- GrowableArray<HeapRegion*> _regions;
+ // The array that holds the HeapRegions.
+ HeapRegion** _regions;
+
+ // Version of _regions biased to address 0
+ HeapRegion** _regions_biased;
+
+ // The number of regions committed in the heap.
+ size_t _length;
- // The index in "_regions" at which to start the next allocation search.
- // (For efficiency only; private to obj_allocate after initialization.)
- int _alloc_search_start;
+ // The address of the first reserved word in the heap.
+ HeapWord* _heap_bottom;
+
+ // The address of the last reserved word in the heap - 1.
+ HeapWord* _heap_end;
+
+ // The log of the region byte size.
+ size_t _region_shift;
+
+ // A hint for which index to start searching from for humongous
+ // allocations.
+ size_t _next_search_index;
- // Finds a contiguous set of empty regions of length num, starting
- // from a given index.
- int find_contiguous_from(int from, size_t num);
+ // The number of regions for which we have allocated HeapRegions for.
+ size_t _allocated_length;
+
+ // The maximum number of regions in the heap.
+ size_t _max_length;
+
+ // Find a contiguous set of empty regions of length num, starting
+ // from the given index.
+ size_t find_contiguous_from(size_t from, size_t num);
- // Currently, we're choosing collection sets in a round-robin fashion,
- // starting here.
- int _next_rr_candidate;
+ // Map a heap address to a biased region index. Assume that the
+ // address is valid.
+ inline size_t addr_to_index_biased(HeapWord* addr) const;
- // The bottom address of the bottom-most region, or else NULL if there
- // are no regions in the sequence.
- char* _seq_bottom;
+ void increment_length(size_t* length) {
+ assert(*length < _max_length, "pre-condition");
+ *length += 1;
+ }
+
+ void decrement_length(size_t* length) {
+ assert(*length > 0, "pre-condition");
+ *length -= 1;
+ }
public:
- // Initializes "this" to the empty sequence of regions.
- HeapRegionSeq(const size_t max_size);
+ // Empty contructor, we'll initialize it with the initialize() method.
+ HeapRegionSeq() { }
+
+ void initialize(HeapWord* bottom, HeapWord* end, size_t max_length);
- // Adds "hr" to "this" sequence. Requires "hr" not to overlap with
- // any region already in "this". (Will perform better if regions are
- // inserted in ascending address order.)
- void insert(HeapRegion* hr);
+ // Return the HeapRegion at the given index. Assume that the index
+ // is valid.
+ inline HeapRegion* at(size_t index) const;
+
+ // If addr is within the committed space return its corresponding
+ // HeapRegion, otherwise return NULL.
+ inline HeapRegion* addr_to_region(HeapWord* addr) const;
+
+ // Return the HeapRegion that corresponds to the given
+ // address. Assume the address is valid.
+ inline HeapRegion* addr_to_region_unsafe(HeapWord* addr) const;
- // Given a HeapRegion*, returns its index within _regions,
- // or returns -1 if not found.
- int find(HeapRegion* hr);
+ // Return the number of regions that have been committed in the heap.
+ size_t length() const { return _length; }
+
+ // Return the maximum number of regions in the heap.
+ size_t max_length() const { return _max_length; }
- // Requires the index to be valid, and return the region at the index.
- HeapRegion* at(size_t i) { return _regions.at((int)i); }
+ // Expand the sequence to reflect that the heap has grown from
+ // old_end to new_end. Either create new HeapRegions, or re-use
+ // existing ones, and return them in the given list. Returns the
+ // memory region that covers the newly-created regions. If a
+ // HeapRegion allocation fails, the result memory region might be
+ // smaller than the desired one.
+ MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
+ FreeRegionList* list);
- // Return the number of regions in the sequence.
- size_t length();
-
- // Returns the number of contiguous regions at the end of the sequence
+ // Return the number of contiguous regions at the end of the sequence
// that are available for allocation.
size_t free_suffix();
// Find a contiguous set of empty regions of length num and return
- // the index of the first region or -1 if the search was unsuccessful.
- int find_contiguous(size_t num);
+ // the index of the first region or G1_NULL_HRS_INDEX if the
+ // search was unsuccessful.
+ size_t find_contiguous(size_t num);
- // Apply the "doHeapRegion" method of "blk" to all regions in "this",
- // in address order, terminating the iteration early
- // if the "doHeapRegion" method returns "true".
- void iterate(HeapRegionClosure* blk);
-
- // Apply the "doHeapRegion" method of "blk" to all regions in "this",
- // starting at "r" (or first region, if "r" is NULL), in a circular
- // manner, terminating the iteration early if the "doHeapRegion" method
- // returns "true".
- void iterate_from(HeapRegion* r, HeapRegionClosure* blk);
+ // Apply blk->doHeapRegion() on all committed regions in address order,
+ // terminating the iteration early if doHeapRegion() returns true.
+ void iterate(HeapRegionClosure* blk) const;
- // As above, but start from a given index in the sequence
- // instead of a given heap region.
- void iterate_from(int idx, HeapRegionClosure* blk);
+ // As above, but start the iteration from hr and loop around. If hr
+ // is NULL, we start from the first region in the heap.
+ void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
- // Requires "shrink_bytes" to be a multiple of the page size and heap
- // region granularity. Deletes as many "rightmost" completely free heap
- // regions from the sequence as comprise shrink_bytes bytes. Returns the
- // MemRegion indicating the region those regions comprised, and sets
- // "num_regions_deleted" to the number of regions deleted.
- MemRegion shrink_by(size_t shrink_bytes, size_t& num_regions_deleted);
+ // Tag as uncommitted as many regions that are completely free as
+ // possible, up to shrink_bytes, from the suffix of the committed
+ // sequence. Return a MemRegion that corresponds to the address
+ // range of the uncommitted regions. Assume shrink_bytes is page and
+ // heap region aligned.
+ MemRegion shrink_by(size_t shrink_bytes, size_t* num_regions_deleted);
- // If "addr" falls within a region in the sequence, return that region,
- // or else NULL.
- inline HeapRegion* addr_to_region(const void* addr);
-
- void print();
-
- // Prints out runs of empty regions.
- void print_empty_runs();
-
+ // Do some sanity checking.
+ void verify_optional() PRODUCT_RETURN;
};
#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP