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psPromotionLAB.hpp
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/
psPromotionLAB.hpp
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/*
* Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP
#define SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP
#include "gc/parallel/objectStartArray.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "memory/allocation.hpp"
//
// PSPromotionLAB is a parallel scavenge promotion lab. This class acts very
// much like a MutableSpace. We couldn't embed a MutableSpace, though, as
// it has a considerable number of asserts and invariants that are violated.
//
class ObjectStartArray;
class PSPromotionLAB : public CHeapObj<mtGC> {
protected:
static size_t filler_header_size;
enum LabState {
needs_flush,
flushed,
zero_size
};
HeapWord* _top;
HeapWord* _bottom;
HeapWord* _end;
LabState _state;
void set_top(HeapWord* value) { _top = value; }
void set_bottom(HeapWord* value) { _bottom = value; }
void set_end(HeapWord* value) { _end = value; }
// The shared initialize code invokes this.
debug_only(virtual bool lab_is_valid(MemRegion lab) { return false; });
PSPromotionLAB() : _top(NULL), _bottom(NULL), _end(NULL), _state(zero_size) { }
public:
// Filling and flushing.
void initialize(MemRegion lab);
virtual void flush();
// Accessors
HeapWord* bottom() const { return _bottom; }
HeapWord* end() const { return _end; }
HeapWord* top() const { return _top; }
bool is_flushed() { return _state == flushed; }
bool unallocate_object(HeapWord* obj, size_t obj_size);
// Returns a subregion containing all objects in this space.
MemRegion used_region() { return MemRegion(bottom(), top()); }
// Boolean queries.
bool is_empty() const { return used() == 0; }
bool not_empty() const { return used() > 0; }
bool contains(const void* p) const { return _bottom <= p && p < _end; }
// Size computations. Sizes are in bytes.
size_t capacity() const { return byte_size(bottom(), end()); }
size_t used() const { return byte_size(bottom(), top()); }
size_t free() const { return byte_size(top(), end()); }
};
class PSYoungPromotionLAB : public PSPromotionLAB {
public:
PSYoungPromotionLAB() { }
// Not MT safe
inline HeapWord* allocate(size_t size);
debug_only(virtual bool lab_is_valid(MemRegion lab);)
};
class PSOldPromotionLAB : public PSPromotionLAB {
private:
ObjectStartArray* _start_array;
public:
PSOldPromotionLAB() : _start_array(NULL) { }
PSOldPromotionLAB(ObjectStartArray* start_array) : _start_array(start_array) { }
void set_start_array(ObjectStartArray* start_array) { _start_array = start_array; }
void flush();
// Not MT safe
HeapWord* allocate(size_t size) {
// Cannot test for this now that we're doing promotion failures
// assert(_state != flushed, "Sanity");
assert(_start_array != NULL, "Sanity");
HeapWord* obj = top();
// Pointer overflow check is needed here.
if (end() >= obj && size <= (size_t) (end() - obj)) {
HeapWord* new_top = obj + size;
set_top(new_top);
assert(is_object_aligned(obj) && is_object_aligned(new_top),
"checking alignment");
_start_array->allocate_block(obj);
return obj;
}
return NULL;
}
debug_only(virtual bool lab_is_valid(MemRegion lab));
};
#endif // SHARE_GC_PARALLEL_PSPROMOTIONLAB_HPP