jmasa@698: /*
mikael@4153:  * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
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jmasa@698:  * This code is free software; you can redistribute it and/or modify it
jmasa@698:  * under the terms of the GNU General Public License version 2 only, as
jmasa@698:  * published by the Free Software Foundation.
jmasa@698:  *
jmasa@698:  * This code is distributed in the hope that it will be useful, but WITHOUT
jmasa@698:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jmasa@698:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jmasa@698:  * version 2 for more details (a copy is included in the LICENSE file that
jmasa@698:  * accompanied this code).
jmasa@698:  *
jmasa@698:  * You should have received a copy of the GNU General Public License version
jmasa@698:  * 2 along with this work; if not, write to the Free Software Foundation,
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jmasa@698:  */
jmasa@698: 
stefank@2314: #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_SPACEDECORATOR_HPP
stefank@2314: #define SHARE_VM_GC_IMPLEMENTATION_SHARED_SPACEDECORATOR_HPP
stefank@2314: 
stefank@2314: #include "gc_implementation/shared/mutableSpace.hpp"
stefank@2314: #include "memory/space.hpp"
stefank@2314: #include "utilities/globalDefinitions.hpp"
stefank@2314: 
jmasa@698: class SpaceDecorator: public AllStatic {
jmasa@698:  public:
jmasa@698:   // Initialization flags.
jmasa@698:   static const bool Clear               = true;
jmasa@698:   static const bool DontClear           = false;
jmasa@698:   static const bool Mangle              = true;
jmasa@698:   static const bool DontMangle          = false;
jmasa@698: };
jmasa@698: 
jmasa@698: // Functionality for use with class Space and class MutableSpace.
jmasa@698: //   The approach taken with the mangling is to mangle all
jmasa@698: // the space initially and then to mangle areas that have
jmasa@698: // been allocated since the last collection.  Mangling is
jmasa@698: // done in the context of a generation and in the context
jmasa@698: // of a space.
jmasa@698: //   The space in a generation is mangled when it is first
jmasa@698: // initialized and when the generation grows.  The spaces
jmasa@698: // are not necessarily up-to-date when this mangling occurs
jmasa@698: // and the method mangle_region() is used.
jmasa@698: //   After allocations have been done in a space, the space generally
jmasa@698: // need to be remangled.  Remangling is only done on the
jmasa@698: // recently allocated regions in the space.  Typically, that is
jmasa@698: // the region between the new top and the top just before a
jmasa@698: // garbage collection.
jmasa@698: //   An exception to the usual mangling in a space is done when the
jmasa@698: // space is used for an extraordinary purpose.  Specifically, when
jmasa@698: // to-space is used as scratch space for a mark-sweep-compact
jmasa@698: // collection.
jmasa@698: //   Spaces are mangled after a collection.  If the generation
jmasa@698: // grows after a collection, the added space is mangled as part of
jmasa@698: // the growth of the generation.  No additional mangling is needed when the
jmasa@698: // spaces are resized after an expansion.
jmasa@698: //   The class SpaceMangler keeps a pointer to the top of the allocated
jmasa@698: // area and provides the methods for doing the piece meal mangling.
jmasa@698: // Methods for doing sparces and full checking of the mangling are
jmasa@698: // included.  The full checking is done if DEBUG_MANGLING is defined.
jmasa@698: //   GenSpaceMangler is used with the GenCollectedHeap collectors and
jmasa@698: // MutableSpaceMangler is used with the ParallelScavengeHeap collectors.
jmasa@698: // These subclasses abstract the differences in the types of spaces used
jmasa@698: // by each heap.
jmasa@698: 
zgu@3900: class SpaceMangler: public CHeapObj<mtGC> {
jmasa@698:   friend class VMStructs;
jmasa@698: 
jmasa@698:   // High water mark for allocations.  Typically, the space above
jmasa@698:   // this point have been mangle previously and don't need to be
jmasa@698:   // touched again.  Space belows this point has been allocated
jmasa@698:   // and remangling is needed between the current top and this
jmasa@698:   // high water mark.
jmasa@698:   HeapWord* _top_for_allocations;
jmasa@698:   HeapWord* top_for_allocations() { return _top_for_allocations; }
jmasa@698: 
jmasa@698:  public:
jmasa@698: 
jmasa@698:   // Setting _top_for_allocations to NULL at initialization
jmasa@698:   // makes it always below top so that mangling done as part
jmasa@698:   // of the initialize() call of a space does nothing (as it
jmasa@698:   // should since the mangling is done as part of the constructor
jmasa@698:   // for the space.
jmasa@698:   SpaceMangler() : _top_for_allocations(NULL) {}
jmasa@698: 
jmasa@698:   // Methods for top and end that delegate to the specific
jmasa@698:   // space type.
jmasa@698:   virtual HeapWord* top() const = 0;
jmasa@698:   virtual HeapWord* end() const = 0;
jmasa@698: 
jmasa@698:   // Return true if q matches the mangled pattern.
jmasa@698:   static bool is_mangled(HeapWord* q) PRODUCT_RETURN0;
jmasa@698: 
jmasa@698:   // Used to save the an address in a space for later use during mangling.
jmasa@698:   void set_top_for_allocations(HeapWord* v);
jmasa@698: 
jmasa@698:   // Overwrites the unused portion of this space.
jmasa@698:   // Mangle only the region not previously mangled [top, top_previously_mangled)
jmasa@698:   void mangle_unused_area();
jmasa@698:   // Mangle all the unused region [top, end)
jmasa@698:   void mangle_unused_area_complete();
jmasa@698:   // Do some sparse checking on the area that should have been mangled.
jmasa@698:   void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
jmasa@698:   // Do a complete check of the area that should be mangled.
jmasa@698:   void check_mangled_unused_area_complete() PRODUCT_RETURN;
jmasa@698: 
jmasa@698:   // Mangle the MemRegion.  This is a non-space specific mangler.  It
jmasa@698:   // is used during the initial mangling of a space before the space
jmasa@698:   // is fully constructed.  Also is used when a generation is expanded
jmasa@698:   // and possibly before the spaces have been reshaped to to the new
jmasa@698:   // size of the generation.
jcoomes@1902:   static void mangle_region(MemRegion mr) PRODUCT_RETURN;
jmasa@698: };
jmasa@698: 
jmasa@698: class ContiguousSpace;
jmasa@698: 
jmasa@698: // For use with GenCollectedHeap's
jmasa@698: class GenSpaceMangler: public SpaceMangler {
jmasa@698:   ContiguousSpace* _sp;
jmasa@698: 
jmasa@698:   ContiguousSpace* sp() { return _sp; }
jmasa@698: 
jmasa@698:   HeapWord* top() const { return _sp->top(); }
jmasa@698:   HeapWord* end() const { return _sp->end(); }
jmasa@698: 
jmasa@698:  public:
jmasa@698:   GenSpaceMangler(ContiguousSpace* sp) : SpaceMangler(), _sp(sp) {}
jmasa@698: };
jmasa@698: 
jmasa@698: // For use with ParallelScavengeHeap's.
jmasa@698: class MutableSpaceMangler: public SpaceMangler {
jmasa@698:   MutableSpace* _sp;
jmasa@698: 
jmasa@698:   MutableSpace* sp() { return _sp; }
jmasa@698: 
jmasa@698:   HeapWord* top() const { return _sp->top(); }
jmasa@698:   HeapWord* end() const { return _sp->end(); }
jmasa@698: 
jmasa@698:  public:
jmasa@698:   MutableSpaceMangler(MutableSpace* sp) : SpaceMangler(), _sp(sp) {}
jmasa@698: };
stefank@2314: 
stefank@2314: #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_SPACEDECORATOR_HPP