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/*
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* Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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// A MutableSpace is a subtype of ImmutableSpace that supports the
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// concept of allocation. This includes the concepts that a space may
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// be only partially full, and the querry methods that go with such
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// an assumption.
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//
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// Invariant: (ImmutableSpace +) bottom() <= top() <= end()
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// top() is inclusive and end() is exclusive.
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class MutableSpace: public ImmutableSpace {
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friend class VMStructs;
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protected:
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HeapWord* _top;
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public:
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virtual ~MutableSpace() {}
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MutableSpace() { _top = NULL; }
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// Accessors
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HeapWord* top() const { return _top; }
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virtual void set_top(HeapWord* value) { _top = value; }
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HeapWord** top_addr() { return &_top; }
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HeapWord** end_addr() { return &_end; }
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virtual void set_bottom(HeapWord* value) { _bottom = value; }
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virtual void set_end(HeapWord* value) { _end = value; }
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// Returns a subregion containing all objects in this space.
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MemRegion used_region() { return MemRegion(bottom(), top()); }
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// Initialization
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virtual void initialize(MemRegion mr, bool clear_space);
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virtual void clear();
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virtual void update() { }
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virtual void accumulate_statistics() { }
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// Overwrites the unused portion of this space. Note that some collectors
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// may use this "scratch" space during collections.
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virtual void mangle_unused_area() {
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mangle_region(MemRegion(_top, _end));
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}
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virtual void ensure_parsability() { }
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void mangle_region(MemRegion mr) {
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debug_only(Copy::fill_to_words(mr.start(), mr.word_size(), badHeapWord));
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}
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// Boolean querries.
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bool is_empty() const { return used_in_words() == 0; }
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bool not_empty() const { return used_in_words() > 0; }
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bool contains(const void* p) const { return _bottom <= p && p < _end; }
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// Size computations. Sizes are in bytes.
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size_t used_in_bytes() const { return used_in_words() * HeapWordSize; }
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size_t free_in_bytes() const { return free_in_words() * HeapWordSize; }
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// Size computations. Sizes are in heapwords.
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virtual size_t used_in_words() const { return pointer_delta(top(), bottom()); }
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virtual size_t free_in_words() const { return pointer_delta(end(), top()); }
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virtual size_t tlab_capacity(Thread* thr) const { return capacity_in_bytes(); }
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virtual size_t unsafe_max_tlab_alloc(Thread* thr) const { return free_in_bytes(); }
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// Allocation (return NULL if full)
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virtual HeapWord* allocate(size_t word_size);
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virtual HeapWord* cas_allocate(size_t word_size);
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// Optional deallocation. Used in NUMA-allocator.
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bool cas_deallocate(HeapWord *obj, size_t size);
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// Iteration.
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void oop_iterate(OopClosure* cl);
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void object_iterate(ObjectClosure* cl);
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// Debugging
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virtual void print() const;
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virtual void print_on(outputStream* st) const;
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virtual void print_short() const;
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virtual void print_short_on(outputStream* st) const;
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virtual void verify(bool allow_dirty) const;
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};
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