| /* |
| * Copyright 1997-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| // A space is an abstraction for the "storage units" backing |
| // up the generation abstraction. It includes specific |
| // implementations for keeping track of free and used space, |
| // for iterating over objects and free blocks, etc. |
| |
| // Here's the Space hierarchy: |
| // |
| // - Space -- an asbtract base class describing a heap area |
| // - CompactibleSpace -- a space supporting compaction |
| // - CompactibleFreeListSpace -- (used for CMS generation) |
| // - ContiguousSpace -- a compactible space in which all free space |
| // is contiguous |
| // - EdenSpace -- contiguous space used as nursery |
| // - ConcEdenSpace -- contiguous space with a 'soft end safe' allocation |
| // - OffsetTableContigSpace -- contiguous space with a block offset array |
| // that allows "fast" block_start calls |
| // - TenuredSpace -- (used for TenuredGeneration) |
| // - ContigPermSpace -- an offset table contiguous space for perm gen |
| |
| // Forward decls. |
| class Space; |
| class BlockOffsetArray; |
| class BlockOffsetArrayContigSpace; |
| class Generation; |
| class CompactibleSpace; |
| class BlockOffsetTable; |
| class GenRemSet; |
| class CardTableRS; |
| class DirtyCardToOopClosure; |
| |
| |
| // An oop closure that is circumscribed by a filtering memory region. |
| class SpaceMemRegionOopsIterClosure: public virtual OopClosure { |
| OopClosure* cl; |
| MemRegion mr; |
| public: |
| void do_oop(oop* p) { |
| if (mr.contains(p)) { |
| cl->do_oop(p); |
| } |
| } |
| SpaceMemRegionOopsIterClosure(OopClosure* _cl, MemRegion _mr): cl(_cl), mr(_mr) {} |
| }; |
| |
| |
| // A Space describes a heap area. Class Space is an abstract |
| // base class. |
| // |
| // Space supports allocation, size computation and GC support is provided. |
| // |
| // Invariant: bottom() and end() are on page_size boundaries and |
| // bottom() <= top() <= end() |
| // top() is inclusive and end() is exclusive. |
| |
| class Space: public CHeapObj { |
| friend class VMStructs; |
| protected: |
| HeapWord* _bottom; |
| HeapWord* _end; |
| |
| // Used in support of save_marks() |
| HeapWord* _saved_mark_word; |
| |
| MemRegionClosure* _preconsumptionDirtyCardClosure; |
| |
| // A sequential tasks done structure. This supports |
| // parallel GC, where we have threads dynamically |
| // claiming sub-tasks from a larger parallel task. |
| SequentialSubTasksDone _par_seq_tasks; |
| |
| Space(): |
| _bottom(NULL), _end(NULL), _preconsumptionDirtyCardClosure(NULL) { } |
| |
| public: |
| // Accessors |
| HeapWord* bottom() const { return _bottom; } |
| HeapWord* end() const { return _end; } |
| virtual void set_bottom(HeapWord* value) { _bottom = value; } |
| virtual void set_end(HeapWord* value) { _end = value; } |
| |
| HeapWord* saved_mark_word() const { return _saved_mark_word; } |
| void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; } |
| |
| MemRegionClosure* preconsumptionDirtyCardClosure() const { |
| return _preconsumptionDirtyCardClosure; |
| } |
| void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) { |
| _preconsumptionDirtyCardClosure = cl; |
| } |
| |
| // Returns a subregion of the space containing all the objects in |
| // the space. |
| virtual MemRegion used_region() const { return MemRegion(bottom(), end()); } |
| |
| // Returns a region that is guaranteed to contain (at least) all objects |
| // allocated at the time of the last call to "save_marks". If the space |
| // initializes its DirtyCardToOopClosure's specifying the "contig" option |
| // (that is, if the space is contiguous), then this region must contain only |
| // such objects: the memregion will be from the bottom of the region to the |
| // saved mark. Otherwise, the "obj_allocated_since_save_marks" method of |
| // the space must distiguish between objects in the region allocated before |
| // and after the call to save marks. |
| virtual MemRegion used_region_at_save_marks() const { |
| return MemRegion(bottom(), saved_mark_word()); |
| } |
| |
| // Initialization |
| virtual void initialize(MemRegion mr, bool clear_space); |
| virtual void clear(); |
| |
| // For detecting GC bugs. Should only be called at GC boundaries, since |
| // some unused space may be used as scratch space during GC's. |
| // Default implementation does nothing. We also call this when expanding |
| // a space to satisfy an allocation request. See bug #4668531 |
| virtual void mangle_unused_area() {} |
| virtual void mangle_region(MemRegion mr) {} |
| |
| // Testers |
| bool is_empty() const { return used() == 0; } |
| bool not_empty() const { return used() > 0; } |
| |
| // Returns true iff the given the space contains the |
| // given address as part of an allocated object. For |
| // ceratin kinds of spaces, this might be a potentially |
| // expensive operation. To prevent performance problems |
| // on account of its inadvertent use in product jvm's, |
| // we restrict its use to assertion checks only. |
| virtual bool is_in(const void* p) const; |
| |
| // Returns true iff the given reserved memory of the space contains the |
| // given address. |
| bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; } |
| |
| // Returns true iff the given block is not allocated. |
| virtual bool is_free_block(const HeapWord* p) const = 0; |
| |
| // Test whether p is double-aligned |
| static bool is_aligned(void* p) { |
| return ((intptr_t)p & (sizeof(double)-1)) == 0; |
| } |
| |
| // Size computations. Sizes are in bytes. |
| size_t capacity() const { return byte_size(bottom(), end()); } |
| virtual size_t used() const = 0; |
| virtual size_t free() const = 0; |
| |
| // Iterate over all the ref-containing fields of all objects in the |
| // space, calling "cl.do_oop" on each. Fields in objects allocated by |
| // applications of the closure are not included in the iteration. |
| virtual void oop_iterate(OopClosure* cl); |
| |
| // Same as above, restricted to the intersection of a memory region and |
| // the space. Fields in objects allocated by applications of the closure |
| // are not included in the iteration. |
| virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0; |
| |
| // Iterate over all objects in the space, calling "cl.do_object" on |
| // each. Objects allocated by applications of the closure are not |
| // included in the iteration. |
| virtual void object_iterate(ObjectClosure* blk) = 0; |
| |
| // Iterate over all objects that intersect with mr, calling "cl->do_object" |
| // on each. There is an exception to this: if this closure has already |
| // been invoked on an object, it may skip such objects in some cases. This is |
| // Most likely to happen in an "upwards" (ascending address) iteration of |
| // MemRegions. |
| virtual void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
| |
| // Iterate over as many initialized objects in the space as possible, |
| // calling "cl.do_object_careful" on each. Return NULL if all objects |
| // in the space (at the start of the iteration) were iterated over. |
| // Return an address indicating the extent of the iteration in the |
| // event that the iteration had to return because of finding an |
| // uninitialized object in the space, or if the closure "cl" |
| // signalled early termination. |
| virtual HeapWord* object_iterate_careful(ObjectClosureCareful* cl); |
| virtual HeapWord* object_iterate_careful_m(MemRegion mr, |
| ObjectClosureCareful* cl); |
| |
| // Create and return a new dirty card to oop closure. Can be |
| // overriden to return the appropriate type of closure |
| // depending on the type of space in which the closure will |
| // operate. ResourceArea allocated. |
| virtual DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary = NULL); |
| |
| // If "p" is in the space, returns the address of the start of the |
| // "block" that contains "p". We say "block" instead of "object" since |
| // some heaps may not pack objects densely; a chunk may either be an |
| // object or a non-object. If "p" is not in the space, return NULL. |
| virtual HeapWord* block_start(const void* p) const = 0; |
| |
| // Requires "addr" to be the start of a chunk, and returns its size. |
| // "addr + size" is required to be the start of a new chunk, or the end |
| // of the active area of the heap. |
| virtual size_t block_size(const HeapWord* addr) const = 0; |
| |
| // Requires "addr" to be the start of a block, and returns "TRUE" iff |
| // the block is an object. |
| virtual bool block_is_obj(const HeapWord* addr) const = 0; |
| |
| // Requires "addr" to be the start of a block, and returns "TRUE" iff |
| // the block is an object and the object is alive. |
| virtual bool obj_is_alive(const HeapWord* addr) const; |
| |
| // Allocation (return NULL if full). Assumes the caller has established |
| // mutually exclusive access to the space. |
| virtual HeapWord* allocate(size_t word_size) = 0; |
| |
| // Allocation (return NULL if full). Enforces mutual exclusion internally. |
| virtual HeapWord* par_allocate(size_t word_size) = 0; |
| |
| // Returns true if this object has been allocated since a |
| // generation's "save_marks" call. |
| virtual bool obj_allocated_since_save_marks(const oop obj) const = 0; |
| |
| // Mark-sweep-compact support: all spaces can update pointers to objects |
| // moving as a part of compaction. |
| virtual void adjust_pointers(); |
| |
| // PrintHeapAtGC support |
| virtual void print() const; |
| virtual void print_on(outputStream* st) const; |
| virtual void print_short() const; |
| virtual void print_short_on(outputStream* st) const; |
| |
| |
| // Accessor for parallel sequential tasks. |
| SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; } |
| |
| // IF "this" is a ContiguousSpace, return it, else return NULL. |
| virtual ContiguousSpace* toContiguousSpace() { |
| return NULL; |
| } |
| |
| // Debugging |
| virtual void verify(bool allow_dirty) const = 0; |
| }; |
| |
| // A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an |
| // OopClosure to (the addresses of) all the ref-containing fields that could |
| // be modified by virtue of the given MemRegion being dirty. (Note that |
| // because of the imprecise nature of the write barrier, this may iterate |
| // over oops beyond the region.) |
| // This base type for dirty card to oop closures handles memory regions |
| // in non-contiguous spaces with no boundaries, and should be sub-classed |
| // to support other space types. See ContiguousDCTOC for a sub-class |
| // that works with ContiguousSpaces. |
| |
| class DirtyCardToOopClosure: public MemRegionClosureRO { |
| protected: |
| OopClosure* _cl; |
| Space* _sp; |
| CardTableModRefBS::PrecisionStyle _precision; |
| HeapWord* _boundary; // If non-NULL, process only non-NULL oops |
| // pointing below boundary. |
| HeapWord* _min_done; // ObjHeadPreciseArray precision requires |
| // a downwards traversal; this is the |
| // lowest location already done (or, |
| // alternatively, the lowest address that |
| // shouldn't be done again. NULL means infinity.) |
| NOT_PRODUCT(HeapWord* _last_bottom;) |
| |
| // Get the actual top of the area on which the closure will |
| // operate, given where the top is assumed to be (the end of the |
| // memory region passed to do_MemRegion) and where the object |
| // at the top is assumed to start. For example, an object may |
| // start at the top but actually extend past the assumed top, |
| // in which case the top becomes the end of the object. |
| virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj); |
| |
| // Walk the given memory region from bottom to (actual) top |
| // looking for objects and applying the oop closure (_cl) to |
| // them. The base implementation of this treats the area as |
| // blocks, where a block may or may not be an object. Sub- |
| // classes should override this to provide more accurate |
| // or possibly more efficient walking. |
| virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top); |
| |
| public: |
| DirtyCardToOopClosure(Space* sp, OopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary) : |
| _sp(sp), _cl(cl), _precision(precision), _boundary(boundary), |
| _min_done(NULL) { |
| NOT_PRODUCT(_last_bottom = NULL;) |
| } |
| |
| void do_MemRegion(MemRegion mr); |
| |
| void set_min_done(HeapWord* min_done) { |
| _min_done = min_done; |
| } |
| #ifndef PRODUCT |
| void set_last_bottom(HeapWord* last_bottom) { |
| _last_bottom = last_bottom; |
| } |
| #endif |
| }; |
| |
| // A structure to represent a point at which objects are being copied |
| // during compaction. |
| class CompactPoint : public StackObj { |
| public: |
| Generation* gen; |
| CompactibleSpace* space; |
| HeapWord* threshold; |
| CompactPoint(Generation* _gen, CompactibleSpace* _space, |
| HeapWord* _threshold) : |
| gen(_gen), space(_space), threshold(_threshold) {} |
| }; |
| |
| |
| // A space that supports compaction operations. This is usually, but not |
| // necessarily, a space that is normally contiguous. But, for example, a |
| // free-list-based space whose normal collection is a mark-sweep without |
| // compaction could still support compaction in full GC's. |
| |
| class CompactibleSpace: public Space { |
| friend class VMStructs; |
| friend class CompactibleFreeListSpace; |
| friend class CompactingPermGenGen; |
| friend class CMSPermGenGen; |
| private: |
| HeapWord* _compaction_top; |
| CompactibleSpace* _next_compaction_space; |
| |
| public: |
| virtual void initialize(MemRegion mr, bool clear_space); |
| |
| // Used temporarily during a compaction phase to hold the value |
| // top should have when compaction is complete. |
| HeapWord* compaction_top() const { return _compaction_top; } |
| |
| void set_compaction_top(HeapWord* value) { |
| assert(value == NULL || (value >= bottom() && value <= end()), |
| "should point inside space"); |
| _compaction_top = value; |
| } |
| |
| // Perform operations on the space needed after a compaction |
| // has been performed. |
| virtual void reset_after_compaction() {} |
| |
| // Returns the next space (in the current generation) to be compacted in |
| // the global compaction order. Also is used to select the next |
| // space into which to compact. |
| |
| virtual CompactibleSpace* next_compaction_space() const { |
| return _next_compaction_space; |
| } |
| |
| void set_next_compaction_space(CompactibleSpace* csp) { |
| _next_compaction_space = csp; |
| } |
| |
| // MarkSweep support phase2 |
| |
| // Start the process of compaction of the current space: compute |
| // post-compaction addresses, and insert forwarding pointers. The fields |
| // "cp->gen" and "cp->compaction_space" are the generation and space into |
| // which we are currently compacting. This call updates "cp" as necessary, |
| // and leaves the "compaction_top" of the final value of |
| // "cp->compaction_space" up-to-date. Offset tables may be updated in |
| // this phase as if the final copy had occurred; if so, "cp->threshold" |
| // indicates when the next such action should be taken. |
| virtual void prepare_for_compaction(CompactPoint* cp); |
| // MarkSweep support phase3 |
| virtual void adjust_pointers(); |
| // MarkSweep support phase4 |
| virtual void compact(); |
| |
| // The maximum percentage of objects that can be dead in the compacted |
| // live part of a compacted space ("deadwood" support.) |
| virtual int allowed_dead_ratio() const { return 0; }; |
| |
| // Some contiguous spaces may maintain some data structures that should |
| // be updated whenever an allocation crosses a boundary. This function |
| // returns the first such boundary. |
| // (The default implementation returns the end of the space, so the |
| // boundary is never crossed.) |
| virtual HeapWord* initialize_threshold() { return end(); } |
| |
| // "q" is an object of the given "size" that should be forwarded; |
| // "cp" names the generation ("gen") and containing "this" (which must |
| // also equal "cp->space"). "compact_top" is where in "this" the |
| // next object should be forwarded to. If there is room in "this" for |
| // the object, insert an appropriate forwarding pointer in "q". |
| // If not, go to the next compaction space (there must |
| // be one, since compaction must succeed -- we go to the first space of |
| // the previous generation if necessary, updating "cp"), reset compact_top |
| // and then forward. In either case, returns the new value of "compact_top". |
| // If the forwarding crosses "cp->threshold", invokes the "cross_threhold" |
| // function of the then-current compaction space, and updates "cp->threshold |
| // accordingly". |
| virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp, |
| HeapWord* compact_top); |
| |
| // Return a size with adjusments as required of the space. |
| virtual size_t adjust_object_size_v(size_t size) const { return size; } |
| |
| protected: |
| // Used during compaction. |
| HeapWord* _first_dead; |
| HeapWord* _end_of_live; |
| |
| // Minimum size of a free block. |
| virtual size_t minimum_free_block_size() const = 0; |
| |
| // This the function is invoked when an allocation of an object covering |
| // "start" to "end occurs crosses the threshold; returns the next |
| // threshold. (The default implementation does nothing.) |
| virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) { |
| return end(); |
| } |
| |
| // Requires "allowed_deadspace_words > 0", that "q" is the start of a |
| // free block of the given "word_len", and that "q", were it an object, |
| // would not move if forwared. If the size allows, fill the free |
| // block with an object, to prevent excessive compaction. Returns "true" |
| // iff the free region was made deadspace, and modifies |
| // "allowed_deadspace_words" to reflect the number of available deadspace |
| // words remaining after this operation. |
| bool insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q, |
| size_t word_len); |
| }; |
| |
| #define SCAN_AND_FORWARD(cp,scan_limit,block_is_obj,block_size) { \ |
| /* Compute the new addresses for the live objects and store it in the mark \ |
| * Used by universe::mark_sweep_phase2() \ |
| */ \ |
| HeapWord* compact_top; /* This is where we are currently compacting to. */ \ |
| \ |
| /* We're sure to be here before any objects are compacted into this \ |
| * space, so this is a good time to initialize this: \ |
| */ \ |
| set_compaction_top(bottom()); \ |
| \ |
| if (cp->space == NULL) { \ |
| assert(cp->gen != NULL, "need a generation"); \ |
| assert(cp->threshold == NULL, "just checking"); \ |
| assert(cp->gen->first_compaction_space() == this, "just checking"); \ |
| cp->space = cp->gen->first_compaction_space(); \ |
| compact_top = cp->space->bottom(); \ |
| cp->space->set_compaction_top(compact_top); \ |
| cp->threshold = cp->space->initialize_threshold(); \ |
| } else { \ |
| compact_top = cp->space->compaction_top(); \ |
| } \ |
| \ |
| /* We allow some amount of garbage towards the bottom of the space, so \ |
| * we don't start compacting before there is a significant gain to be made.\ |
| * Occasionally, we want to ensure a full compaction, which is determined \ |
| * by the MarkSweepAlwaysCompactCount parameter. \ |
| */ \ |
| int invocations = SharedHeap::heap()->perm_gen()->stat_record()->invocations;\ |
| bool skip_dead = ((invocations % MarkSweepAlwaysCompactCount) != 0); \ |
| \ |
| size_t allowed_deadspace = 0; \ |
| if (skip_dead) { \ |
| int ratio = allowed_dead_ratio(); \ |
| allowed_deadspace = (capacity() * ratio / 100) / HeapWordSize; \ |
| } \ |
| \ |
| HeapWord* q = bottom(); \ |
| HeapWord* t = scan_limit(); \ |
| \ |
| HeapWord* end_of_live= q; /* One byte beyond the last byte of the last \ |
| live object. */ \ |
| HeapWord* first_dead = end();/* The first dead object. */ \ |
| LiveRange* liveRange = NULL; /* The current live range, recorded in the \ |
| first header of preceding free area. */ \ |
| _first_dead = first_dead; \ |
| \ |
| const intx interval = PrefetchScanIntervalInBytes; \ |
| \ |
| while (q < t) { \ |
| assert(!block_is_obj(q) || \ |
| oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() || \ |
| oop(q)->mark()->has_bias_pattern(), \ |
| "these are the only valid states during a mark sweep"); \ |
| if (block_is_obj(q) && oop(q)->is_gc_marked()) { \ |
| /* prefetch beyond q */ \ |
| Prefetch::write(q, interval); \ |
| /* size_t size = oop(q)->size(); changing this for cms for perm gen */\ |
| size_t size = block_size(q); \ |
| compact_top = cp->space->forward(oop(q), size, cp, compact_top); \ |
| q += size; \ |
| end_of_live = q; \ |
| } else { \ |
| /* run over all the contiguous dead objects */ \ |
| HeapWord* end = q; \ |
| do { \ |
| /* prefetch beyond end */ \ |
| Prefetch::write(end, interval); \ |
| end += block_size(end); \ |
| } while (end < t && (!block_is_obj(end) || !oop(end)->is_gc_marked()));\ |
| \ |
| /* see if we might want to pretend this object is alive so that \ |
| * we don't have to compact quite as often. \ |
| */ \ |
| if (allowed_deadspace > 0 && q == compact_top) { \ |
| size_t sz = pointer_delta(end, q); \ |
| if (insert_deadspace(allowed_deadspace, q, sz)) { \ |
| compact_top = cp->space->forward(oop(q), sz, cp, compact_top); \ |
| q = end; \ |
| end_of_live = end; \ |
| continue; \ |
| } \ |
| } \ |
| \ |
| /* otherwise, it really is a free region. */ \ |
| \ |
| /* for the previous LiveRange, record the end of the live objects. */ \ |
| if (liveRange) { \ |
| liveRange->set_end(q); \ |
| } \ |
| \ |
| /* record the current LiveRange object. \ |
| * liveRange->start() is overlaid on the mark word. \ |
| */ \ |
| liveRange = (LiveRange*)q; \ |
| liveRange->set_start(end); \ |
| liveRange->set_end(end); \ |
| \ |
| /* see if this is the first dead region. */ \ |
| if (q < first_dead) { \ |
| first_dead = q; \ |
| } \ |
| \ |
| /* move on to the next object */ \ |
| q = end; \ |
| } \ |
| } \ |
| \ |
| assert(q == t, "just checking"); \ |
| if (liveRange != NULL) { \ |
| liveRange->set_end(q); \ |
| } \ |
| _end_of_live = end_of_live; \ |
| if (end_of_live < first_dead) { \ |
| first_dead = end_of_live; \ |
| } \ |
| _first_dead = first_dead; \ |
| \ |
| /* save the compaction_top of the compaction space. */ \ |
| cp->space->set_compaction_top(compact_top); \ |
| } |
| |
| #define SCAN_AND_ADJUST_POINTERS(adjust_obj_size) { \ |
| /* adjust all the interior pointers to point at the new locations of objects \ |
| * Used by MarkSweep::mark_sweep_phase3() */ \ |
| \ |
| HeapWord* q = bottom(); \ |
| HeapWord* t = _end_of_live; /* Established by "prepare_for_compaction". */ \ |
| \ |
| assert(_first_dead <= _end_of_live, "Stands to reason, no?"); \ |
| \ |
| if (q < t && _first_dead > q && \ |
| !oop(q)->is_gc_marked()) { \ |
| /* we have a chunk of the space which hasn't moved and we've \ |
| * reinitialized the mark word during the previous pass, so we can't \ |
| * use is_gc_marked for the traversal. */ \ |
| HeapWord* end = _first_dead; \ |
| \ |
| while (q < end) { \ |
| /* I originally tried to conjoin "block_start(q) == q" to the \ |
| * assertion below, but that doesn't work, because you can't \ |
| * accurately traverse previous objects to get to the current one \ |
| * after their pointers (including pointers into permGen) have been \ |
| * updated, until the actual compaction is done. dld, 4/00 */ \ |
| assert(block_is_obj(q), \ |
| "should be at block boundaries, and should be looking at objs"); \ |
| \ |
| debug_only(MarkSweep::track_interior_pointers(oop(q))); \ |
| \ |
| /* point all the oops to the new location */ \ |
| size_t size = oop(q)->adjust_pointers(); \ |
| size = adjust_obj_size(size); \ |
| \ |
| debug_only(MarkSweep::check_interior_pointers()); \ |
| \ |
| debug_only(MarkSweep::validate_live_oop(oop(q), size)); \ |
| \ |
| q += size; \ |
| } \ |
| \ |
| if (_first_dead == t) { \ |
| q = t; \ |
| } else { \ |
| /* $$$ This is funky. Using this to read the previously written \ |
| * LiveRange. See also use below. */ \ |
| q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer(); \ |
| } \ |
| } \ |
| \ |
| const intx interval = PrefetchScanIntervalInBytes; \ |
| \ |
| debug_only(HeapWord* prev_q = NULL); \ |
| while (q < t) { \ |
| /* prefetch beyond q */ \ |
| Prefetch::write(q, interval); \ |
| if (oop(q)->is_gc_marked()) { \ |
| /* q is alive */ \ |
| debug_only(MarkSweep::track_interior_pointers(oop(q))); \ |
| /* point all the oops to the new location */ \ |
| size_t size = oop(q)->adjust_pointers(); \ |
| size = adjust_obj_size(size); \ |
| debug_only(MarkSweep::check_interior_pointers()); \ |
| debug_only(MarkSweep::validate_live_oop(oop(q), size)); \ |
| debug_only(prev_q = q); \ |
| q += size; \ |
| } else { \ |
| /* q is not a live object, so its mark should point at the next \ |
| * live object */ \ |
| debug_only(prev_q = q); \ |
| q = (HeapWord*) oop(q)->mark()->decode_pointer(); \ |
| assert(q > prev_q, "we should be moving forward through memory"); \ |
| } \ |
| } \ |
| \ |
| assert(q == t, "just checking"); \ |
| } |
| |
| #define SCAN_AND_COMPACT(obj_size) { \ |
| /* Copy all live objects to their new location \ |
| * Used by MarkSweep::mark_sweep_phase4() */ \ |
| \ |
| HeapWord* q = bottom(); \ |
| HeapWord* const t = _end_of_live; \ |
| debug_only(HeapWord* prev_q = NULL); \ |
| \ |
| if (q < t && _first_dead > q && \ |
| !oop(q)->is_gc_marked()) { \ |
| debug_only( \ |
| /* we have a chunk of the space which hasn't moved and we've reinitialized the \ |
| * mark word during the previous pass, so we can't use is_gc_marked for the \ |
| * traversal. */ \ |
| HeapWord* const end = _first_dead; \ |
| \ |
| while (q < end) { \ |
| size_t size = obj_size(q); \ |
| assert(!oop(q)->is_gc_marked(), "should be unmarked (special dense prefix handling)"); \ |
| debug_only(MarkSweep::live_oop_moved_to(q, size, q)); \ |
| debug_only(prev_q = q); \ |
| q += size; \ |
| } \ |
| ) /* debug_only */ \ |
| \ |
| if (_first_dead == t) { \ |
| q = t; \ |
| } else { \ |
| /* $$$ Funky */ \ |
| q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer(); \ |
| } \ |
| } \ |
| \ |
| const intx scan_interval = PrefetchScanIntervalInBytes; \ |
| const intx copy_interval = PrefetchCopyIntervalInBytes; \ |
| while (q < t) { \ |
| if (!oop(q)->is_gc_marked()) { \ |
| /* mark is pointer to next marked oop */ \ |
| debug_only(prev_q = q); \ |
| q = (HeapWord*) oop(q)->mark()->decode_pointer(); \ |
| assert(q > prev_q, "we should be moving forward through memory"); \ |
| } else { \ |
| /* prefetch beyond q */ \ |
| Prefetch::read(q, scan_interval); \ |
| \ |
| /* size and destination */ \ |
| size_t size = obj_size(q); \ |
| HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); \ |
| \ |
| /* prefetch beyond compaction_top */ \ |
| Prefetch::write(compaction_top, copy_interval); \ |
| \ |
| /* copy object and reinit its mark */ \ |
| debug_only(MarkSweep::live_oop_moved_to(q, size, compaction_top)); \ |
| assert(q != compaction_top, "everything in this pass should be moving"); \ |
| Copy::aligned_conjoint_words(q, compaction_top, size); \ |
| oop(compaction_top)->init_mark(); \ |
| assert(oop(compaction_top)->klass() != NULL, "should have a class"); \ |
| \ |
| debug_only(prev_q = q); \ |
| q += size; \ |
| } \ |
| } \ |
| \ |
| /* Reset space after compaction is complete */ \ |
| reset_after_compaction(); \ |
| /* We do this clear, below, since it has overloaded meanings for some */ \ |
| /* space subtypes. For example, OffsetTableContigSpace's that were */ \ |
| /* compacted into will have had their offset table thresholds updated */ \ |
| /* continuously, but those that weren't need to have their thresholds */ \ |
| /* re-initialized. Also mangles unused area for debugging. */ \ |
| if (is_empty()) { \ |
| clear(); \ |
| } else { \ |
| if (ZapUnusedHeapArea) mangle_unused_area(); \ |
| } \ |
| } |
| |
| // A space in which the free area is contiguous. It therefore supports |
| // faster allocation, and compaction. |
| class ContiguousSpace: public CompactibleSpace { |
| friend class OneContigSpaceCardGeneration; |
| friend class VMStructs; |
| protected: |
| HeapWord* _top; |
| HeapWord* _concurrent_iteration_safe_limit; |
| |
| // Allocation helpers (return NULL if full). |
| inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value); |
| inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value); |
| |
| public: |
| virtual void initialize(MemRegion mr, bool clear_space); |
| |
| // Accessors |
| HeapWord* top() const { return _top; } |
| void set_top(HeapWord* value) { _top = value; } |
| |
| void set_saved_mark() { _saved_mark_word = top(); } |
| void reset_saved_mark() { _saved_mark_word = bottom(); } |
| |
| virtual void clear(); |
| |
| WaterMark bottom_mark() { return WaterMark(this, bottom()); } |
| WaterMark top_mark() { return WaterMark(this, top()); } |
| WaterMark saved_mark() { return WaterMark(this, saved_mark_word()); } |
| bool saved_mark_at_top() const { return saved_mark_word() == top(); } |
| |
| void mangle_unused_area(); |
| void mangle_region(MemRegion mr); |
| |
| // Size computations: sizes 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()); } |
| |
| // Override from space. |
| bool is_in(const void* p) const; |
| |
| virtual bool is_free_block(const HeapWord* p) const; |
| |
| // In a contiguous space we have a more obvious bound on what parts |
| // contain objects. |
| MemRegion used_region() const { return MemRegion(bottom(), top()); } |
| |
| MemRegion used_region_at_save_marks() const { |
| return MemRegion(bottom(), saved_mark_word()); |
| } |
| |
| // Allocation (return NULL if full) |
| virtual HeapWord* allocate(size_t word_size); |
| virtual HeapWord* par_allocate(size_t word_size); |
| |
| virtual bool obj_allocated_since_save_marks(const oop obj) const { |
| return (HeapWord*)obj >= saved_mark_word(); |
| } |
| |
| // Iteration |
| void oop_iterate(OopClosure* cl); |
| void oop_iterate(MemRegion mr, OopClosure* cl); |
| void object_iterate(ObjectClosure* blk); |
| void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl); |
| // iterates on objects up to the safe limit |
| HeapWord* object_iterate_careful(ObjectClosureCareful* cl); |
| inline HeapWord* concurrent_iteration_safe_limit(); |
| // changes the safe limit, all objects from bottom() to the new |
| // limit should be properly initialized |
| inline void set_concurrent_iteration_safe_limit(HeapWord* new_limit); |
| |
| #ifndef SERIALGC |
| // In support of parallel oop_iterate. |
| #define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \ |
| void par_oop_iterate(MemRegion mr, OopClosureType* blk); |
| |
| ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL) |
| #undef ContigSpace_PAR_OOP_ITERATE_DECL |
| #endif // SERIALGC |
| |
| // Compaction support |
| virtual void reset_after_compaction() { |
| assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space"); |
| set_top(compaction_top()); |
| // set new iteration safe limit |
| set_concurrent_iteration_safe_limit(compaction_top()); |
| } |
| virtual size_t minimum_free_block_size() const { return 0; } |
| |
| // Override. |
| DirtyCardToOopClosure* new_dcto_cl(OopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary = NULL); |
| |
| // Apply "blk->do_oop" to the addresses of all reference fields in objects |
| // starting with the _saved_mark_word, which was noted during a generation's |
| // save_marks and is required to denote the head of an object. |
| // Fields in objects allocated by applications of the closure |
| // *are* included in the iteration. |
| // Updates _saved_mark_word to point to just after the last object |
| // iterated over. |
| #define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ |
| void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); |
| |
| ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL) |
| #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL |
| |
| // Same as object_iterate, but starting from "mark", which is required |
| // to denote the start of an object. Objects allocated by |
| // applications of the closure *are* included in the iteration. |
| virtual void object_iterate_from(WaterMark mark, ObjectClosure* blk); |
| |
| // Very inefficient implementation. |
| virtual HeapWord* block_start(const void* p) const; |
| size_t block_size(const HeapWord* p) const; |
| // If a block is in the allocated area, it is an object. |
| bool block_is_obj(const HeapWord* p) const { return p < top(); } |
| |
| // Addresses for inlined allocation |
| HeapWord** top_addr() { return &_top; } |
| HeapWord** end_addr() { return &_end; } |
| |
| // Overrides for more efficient compaction support. |
| void prepare_for_compaction(CompactPoint* cp); |
| |
| // PrintHeapAtGC support. |
| virtual void print_on(outputStream* st) const; |
| |
| // Checked dynamic downcasts. |
| virtual ContiguousSpace* toContiguousSpace() { |
| return this; |
| } |
| |
| // Debugging |
| virtual void verify(bool allow_dirty) const; |
| |
| // Used to increase collection frequency. "factor" of 0 means entire |
| // space. |
| void allocate_temporary_filler(int factor); |
| |
| }; |
| |
| |
| // A dirty card to oop closure that does filtering. |
| // It knows how to filter out objects that are outside of the _boundary. |
| class Filtering_DCTOC : public DirtyCardToOopClosure { |
| protected: |
| // Override. |
| void walk_mem_region(MemRegion mr, |
| HeapWord* bottom, HeapWord* top); |
| |
| // Walk the given memory region, from bottom to top, applying |
| // the given oop closure to (possibly) all objects found. The |
| // given oop closure may or may not be the same as the oop |
| // closure with which this closure was created, as it may |
| // be a filtering closure which makes use of the _boundary. |
| // We offer two signatures, so the FilteringClosure static type is |
| // apparent. |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| OopClosure* cl) = 0; |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| FilteringClosure* cl) = 0; |
| |
| public: |
| Filtering_DCTOC(Space* sp, OopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary) : |
| DirtyCardToOopClosure(sp, cl, precision, boundary) {} |
| }; |
| |
| // A dirty card to oop closure for contiguous spaces |
| // (ContiguousSpace and sub-classes). |
| // It is a FilteringClosure, as defined above, and it knows: |
| // |
| // 1. That the actual top of any area in a memory region |
| // contained by the space is bounded by the end of the contiguous |
| // region of the space. |
| // 2. That the space is really made up of objects and not just |
| // blocks. |
| |
| class ContiguousSpaceDCTOC : public Filtering_DCTOC { |
| protected: |
| // Overrides. |
| HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj); |
| |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| OopClosure* cl); |
| virtual void walk_mem_region_with_cl(MemRegion mr, |
| HeapWord* bottom, HeapWord* top, |
| FilteringClosure* cl); |
| |
| public: |
| ContiguousSpaceDCTOC(ContiguousSpace* sp, OopClosure* cl, |
| CardTableModRefBS::PrecisionStyle precision, |
| HeapWord* boundary) : |
| Filtering_DCTOC(sp, cl, precision, boundary) |
| {} |
| }; |
| |
| |
| // Class EdenSpace describes eden-space in new generation. |
| |
| class DefNewGeneration; |
| |
| class EdenSpace : public ContiguousSpace { |
| friend class VMStructs; |
| private: |
| DefNewGeneration* _gen; |
| |
| // _soft_end is used as a soft limit on allocation. As soft limits are |
| // reached, the slow-path allocation code can invoke other actions and then |
| // adjust _soft_end up to a new soft limit or to end(). |
| HeapWord* _soft_end; |
| |
| public: |
| EdenSpace(DefNewGeneration* gen) : _gen(gen) { _soft_end = NULL; } |
| |
| // Get/set just the 'soft' limit. |
| HeapWord* soft_end() { return _soft_end; } |
| HeapWord** soft_end_addr() { return &_soft_end; } |
| void set_soft_end(HeapWord* value) { _soft_end = value; } |
| |
| // Override. |
| void clear(); |
| |
| // Set both the 'hard' and 'soft' limits (_end and _soft_end). |
| void set_end(HeapWord* value) { |
| set_soft_end(value); |
| ContiguousSpace::set_end(value); |
| } |
| |
| // Allocation (return NULL if full) |
| HeapWord* allocate(size_t word_size); |
| HeapWord* par_allocate(size_t word_size); |
| }; |
| |
| // Class ConcEdenSpace extends EdenSpace for the sake of safe |
| // allocation while soft-end is being modified concurrently |
| |
| class ConcEdenSpace : public EdenSpace { |
| public: |
| ConcEdenSpace(DefNewGeneration* gen) : EdenSpace(gen) { } |
| |
| // Allocation (return NULL if full) |
| HeapWord* par_allocate(size_t word_size); |
| }; |
| |
| |
| // A ContigSpace that Supports an efficient "block_start" operation via |
| // a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with |
| // other spaces.) This is the abstract base class for old generation |
| // (tenured, perm) spaces. |
| |
| class OffsetTableContigSpace: public ContiguousSpace { |
| friend class VMStructs; |
| protected: |
| BlockOffsetArrayContigSpace _offsets; |
| Mutex _par_alloc_lock; |
| |
| public: |
| // Constructor |
| OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, |
| MemRegion mr); |
| |
| void set_bottom(HeapWord* value); |
| void set_end(HeapWord* value); |
| |
| void clear(); |
| |
| inline HeapWord* block_start(const void* p) const; |
| |
| // Add offset table update. |
| virtual inline HeapWord* allocate(size_t word_size); |
| inline HeapWord* par_allocate(size_t word_size); |
| |
| // MarkSweep support phase3 |
| virtual HeapWord* initialize_threshold(); |
| virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end); |
| |
| virtual void print_on(outputStream* st) const; |
| |
| // Debugging |
| void verify(bool allow_dirty) const; |
| |
| // Shared space support |
| void serialize_block_offset_array_offsets(SerializeOopClosure* soc); |
| }; |
| |
| |
| // Class TenuredSpace is used by TenuredGeneration |
| |
| class TenuredSpace: public OffsetTableContigSpace { |
| friend class VMStructs; |
| protected: |
| // Mark sweep support |
| int allowed_dead_ratio() const; |
| public: |
| // Constructor |
| TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray, |
| MemRegion mr) : |
| OffsetTableContigSpace(sharedOffsetArray, mr) {} |
| }; |
| |
| |
| // Class ContigPermSpace is used by CompactingPermGen |
| |
| class ContigPermSpace: public OffsetTableContigSpace { |
| friend class VMStructs; |
| protected: |
| // Mark sweep support |
| int allowed_dead_ratio() const; |
| public: |
| // Constructor |
| ContigPermSpace(BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr) : |
| OffsetTableContigSpace(sharedOffsetArray, mr) {} |
| }; |
