src/share/vm/gc_implementation/g1/heapRegionSeq.cpp
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rev 4204 : 7163191: G1: introduce a "heap spanning table" abstraction
Summary: Add a heap spanning table and employ it for the heap region sequence table.
Reviewed-by:
rev 4205 : imported patch bengt-and-thomas-comments
@@ -69,85 +69,65 @@
}
}
// Public
-void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* end,
- uint max_length) {
- assert((uintptr_t) bottom % HeapRegion::GrainBytes == 0,
- "bottom should be heap region aligned");
- assert((uintptr_t) end % HeapRegion::GrainBytes == 0,
- "end should be heap region aligned");
-
- _length = 0;
- _heap_bottom = bottom;
- _heap_end = end;
- _region_shift = HeapRegion::LogOfHRGrainBytes;
- _next_search_index = 0;
- _allocated_length = 0;
- _max_length = max_length;
-
- _regions = NEW_C_HEAP_ARRAY(HeapRegion*, max_length, mtGC);
- memset(_regions, 0, (size_t) max_length * sizeof(HeapRegion*));
- _regions_biased = _regions - ((uintx) bottom >> _region_shift);
-
- assert(&_regions[0] == &_regions_biased[addr_to_index_biased(bottom)],
- "bottom should be included in the region with index 0");
-}
-
-MemRegion HeapRegionSeq::expand_by(HeapWord* old_end,
- HeapWord* new_end,
- FreeRegionList* list) {
- assert(old_end < new_end, "don't call it otherwise");
+MemRegion HeapRegionSeq::expand_to(HeapWord* new_end, FreeRegionList* list) {
+ assert(_heap_end < new_end && new_end <= _max_heap_end,
+ err_msg("new_end: "PTR_FORMAT" heap end: "PTR_FORMAT" "
+ "max heap end: "PTR_FORMAT, new_end, _heap_end, _max_heap_end));
G1CollectedHeap* g1h = G1CollectedHeap::heap();
- HeapWord* next_bottom = old_end;
- assert(_heap_bottom <= next_bottom, "invariant");
- while (next_bottom < new_end) {
- assert(next_bottom < _heap_end, "invariant");
+ uint new_length = length_for(new_end);
uint index = length();
+ HeapWord* next_hr_bottom = _heap_end;
+ while (index < new_length) {
+ assert(length_for(next_hr_bottom) == index,
+ err_msg("invariant, length_for: "PTR_FORMAT" %u index: %u",
+ next_hr_bottom, length_for(next_hr_bottom), index));
- assert(index < _max_length, "otherwise we cannot expand further");
if (index == 0) {
- // We have not allocated any regions so far
- assert(next_bottom == _heap_bottom, "invariant");
+ // We have not allocated any regions so far.
+ assert(next_hr_bottom == _heap_bottom, "invariant");
} else {
- // next_bottom should match the end of the last/previous region
- assert(next_bottom == at(index - 1)->end(), "invariant");
+ // The previous region should exist.
+ assert(_regions[index - 1] != NULL, "invariant");
+ // next_hr_bottom should match the end of the previous region.
+ assert(next_hr_bottom == _regions[index - 1]->end(), "invariant");
}
- if (index == _allocated_length) {
- // We have to allocate a new HeapRegion.
- HeapRegion* new_hr = g1h->new_heap_region(index, next_bottom);
- if (new_hr == NULL) {
- // allocation failed, we bail out and return what we have done so far
- return MemRegion(old_end, next_bottom);
- }
- assert(_regions[index] == NULL, "invariant");
- _regions[index] = new_hr;
- increment_length(&_allocated_length);
- }
- // Have to increment the length first, otherwise we will get an
- // assert failure at(index) below.
- increment_length(&_length);
- HeapRegion* hr = at(index);
+ HeapRegion* hr;
+ if (index < _length_high_watermark) {
+ // This region should have been previously allocated.
+ assert(_regions[index] != NULL, err_msg("invariant, index: %u", index));
+
+ hr = _regions[index];
+ } else {
+ // We have to allocate a new region.
+ assert(_regions[index] == NULL, err_msg("invariant, index: %u", index));
+
+ hr = g1h->new_heap_region(index, next_hr_bottom);
+ // If allocation fails, bail out and return what we have done so far.
+ if (hr == NULL) break;
+ _regions[index] = hr;
+ }
list->add_as_tail(hr);
- next_bottom = hr->end();
+ index += 1;
+ next_hr_bottom = hr->end();
}
- assert(next_bottom == new_end, "post-condition");
- return MemRegion(old_end, next_bottom);
+
+ HeapWord* prev_heap_end = update_heap_end(next_hr_bottom);
+ return MemRegion(prev_heap_end, next_hr_bottom);
}
uint HeapRegionSeq::free_suffix() {
uint res = 0;
uint index = length();
while (index > 0) {
index -= 1;
- if (!at(index)->is_empty()) {
- break;
- }
+ if (!at(index)->is_empty()) break;
res += 1;
}
return res;
}
@@ -199,77 +179,72 @@
return;
}
}
}
-MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
+MemRegion HeapRegionSeq::shrink_to(HeapWord* new_end,
uint* num_regions_deleted) {
+ assert(_heap_bottom < new_end && new_end <= _heap_end,
+ err_msg("new_end: "PTR_FORMAT" heap bottom: "PTR_FORMAT" "
+ "heap end: "PTR_FORMAT, new_end, _heap_bottom, _heap_end));
+
// Reset this in case it's currently pointing into the regions that
// we just removed.
_next_search_index = 0;
- assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
- assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
- assert(length() > 0, "the region sequence should not be empty");
- assert(length() <= _allocated_length, "invariant");
- assert(_allocated_length > 0, "we should have at least one region committed");
-
- // around the loop, i will be the next region to be removed
- uint i = length() - 1;
- assert(i > 0, "we should never remove all regions");
- // [last_start, end) is the MemRegion that covers the regions we will remove.
- HeapWord* end = at(i)->end();
- HeapWord* last_start = end;
- *num_regions_deleted = 0;
- while (shrink_bytes > 0) {
- HeapRegion* cur = at(i);
+ uint new_length = length_for(new_end);
+ uint index = length();
+ HeapWord* last_hr_bottom = _heap_end;
+ while (index > new_length) {
+ assert(length_for(last_hr_bottom) == index,
+ err_msg("invariant, length_for: "PTR_FORMAT" %u index: %u",
+ last_hr_bottom, length_for(last_hr_bottom), index));
+
+ HeapRegion* hr = at(index - 1);
// We should leave the humongous regions where they are.
- if (cur->isHumongous()) break;
+ if (hr->isHumongous()) break;
// We should stop shrinking if we come across a non-empty region.
- if (!cur->is_empty()) break;
+ if (!hr->is_empty()) break;
+
+ index -= 1;
+ last_hr_bottom = hr->bottom();
+ }
+
+ *num_regions_deleted = length() - index;
- i -= 1;
- *num_regions_deleted += 1;
- shrink_bytes -= cur->capacity();
- last_start = cur->bottom();
- decrement_length(&_length);
- // We will reclaim the HeapRegion. _allocated_length should be
- // covering this index. So, even though we removed the region from
- // the active set by decreasing _length, we still have it
- // available in the future if we need to re-use it.
- assert(i > 0, "we should never remove all regions");
- assert(length() > 0, "we should never remove all regions");
+ if (new_end == _heap_end) {
+ assert(*num_regions_deleted == 0, "invariant");
+ } else {
+ assert(*num_regions_deleted > 0, "invariant");
}
- return MemRegion(last_start, end);
+
+ HeapWord* prev_heap_end = update_heap_end(last_hr_bottom);
+ return MemRegion(last_hr_bottom, prev_heap_end);
}
#ifndef PRODUCT
void HeapRegionSeq::verify_optional() {
- guarantee(_length <= _allocated_length,
- err_msg("invariant: _length: %u _allocated_length: %u",
- _length, _allocated_length));
- guarantee(_allocated_length <= _max_length,
- err_msg("invariant: _allocated_length: %u _max_length: %u",
- _allocated_length, _max_length));
+ G1HeapSpanningTable<HeapRegion*>::verify_optional();
+
guarantee(_next_search_index <= _length,
err_msg("invariant: _next_search_index: %u _length: %u",
_next_search_index, _length));
HeapWord* prev_end = _heap_bottom;
- for (uint i = 0; i < _allocated_length; i += 1) {
+ for (uint i = 0; i < _length_high_watermark; i += 1) {
HeapRegion* hr = _regions[i];
guarantee(hr != NULL, err_msg("invariant: i: %u", i));
guarantee(hr->bottom() == prev_end,
err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
i, HR_FORMAT_PARAMS(hr), prev_end));
guarantee(hr->hrs_index() == i,
err_msg("invariant: i: %u hrs_index(): %u", i, hr->hrs_index()));
if (i < _length) {
// Asserts will fire if i is >= _length
HeapWord* addr = hr->bottom();
- guarantee(addr_to_region(addr) == hr, "sanity");
- guarantee(addr_to_region_unsafe(addr) == hr, "sanity");
+ guarantee(at(addr) == hr, "sanity");
+ guarantee(at_unsafe(addr) == hr, "sanity");
} else {
guarantee(hr->is_empty(), "sanity");
guarantee(!hr->isHumongous(), "sanity");
// using assert instead of guarantee here since containing_set()
// is only available in non-product builds.
@@ -279,10 +254,17 @@
prev_end = hr->orig_end();
} else {
prev_end = hr->end();
}
}
- for (uint i = _allocated_length; i < _max_length; i += 1) {
+ for (uint i = _length_high_watermark; i < _max_length; i += 1) {
guarantee(_regions[i] == NULL, err_msg("invariant i: %u", i));
}
}
#endif // PRODUCT
+
+void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* max_end) {
+ initialize_base(bottom, max_end, HeapRegion::LogOfHRGrainBytes);
+ _next_search_index = 0;
+ _regions = create_new_array();
+ _regions_biased = get_biased_array(_regions);
+}