6672698: mangle_unused_area() should not remangle the entire heap at each collection.
Summary: Maintain a high water mark for the allocations in a space and mangle only up to that high water mark.
Reviewed-by: ysr, apetrusenko
/*
* Copyright 2005-2007 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.
*
*/
class ParallelScavengeHeap;
class PSAdaptiveSizePolicy;
class PSYoungGen;
class PSOldGen;
class PSPermGen;
class ParCompactionManager;
class ParallelTaskTerminator;
class PSParallelCompact;
class GCTaskManager;
class GCTaskQueue;
class PreGCValues;
class MoveAndUpdateClosure;
class RefProcTaskExecutor;
class SpaceInfo
{
public:
MutableSpace* space() const { return _space; }
// Where the free space will start after the collection. Valid only after the
// summary phase completes.
HeapWord* new_top() const { return _new_top; }
// Allows new_top to be set.
HeapWord** new_top_addr() { return &_new_top; }
// Where the smallest allowable dense prefix ends (used only for perm gen).
HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
// Where the dense prefix ends, or the compacted region begins.
HeapWord* dense_prefix() const { return _dense_prefix; }
// The start array for the (generation containing the) space, or NULL if there
// is no start array.
ObjectStartArray* start_array() const { return _start_array; }
void set_space(MutableSpace* s) { _space = s; }
void set_new_top(HeapWord* addr) { _new_top = addr; }
void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; }
void set_start_array(ObjectStartArray* s) { _start_array = s; }
private:
MutableSpace* _space;
HeapWord* _new_top;
HeapWord* _min_dense_prefix;
HeapWord* _dense_prefix;
ObjectStartArray* _start_array;
};
class ParallelCompactData
{
public:
// Sizes are in HeapWords, unless indicated otherwise.
static const size_t Log2ChunkSize;
static const size_t ChunkSize;
static const size_t ChunkSizeBytes;
// Mask for the bits in a size_t to get an offset within a chunk.
static const size_t ChunkSizeOffsetMask;
// Mask for the bits in a pointer to get an offset within a chunk.
static const size_t ChunkAddrOffsetMask;
// Mask for the bits in a pointer to get the address of the start of a chunk.
static const size_t ChunkAddrMask;
static const size_t Log2BlockSize;
static const size_t BlockSize;
static const size_t BlockOffsetMask;
static const size_t BlockMask;
static const size_t BlocksPerChunk;
class ChunkData
{
public:
// Destination address of the chunk.
HeapWord* destination() const { return _destination; }
// The first chunk containing data destined for this chunk.
size_t source_chunk() const { return _source_chunk; }
// The object (if any) starting in this chunk and ending in a different
// chunk that could not be updated during the main (parallel) compaction
// phase. This is different from _partial_obj_addr, which is an object that
// extends onto a source chunk. However, the two uses do not overlap in
// time, so the same field is used to save space.
HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
// The starting address of the partial object extending onto the chunk.
HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
// Size of the partial object extending onto the chunk (words).
size_t partial_obj_size() const { return _partial_obj_size; }
// Size of live data that lies within this chunk due to objects that start
// in this chunk (words). This does not include the partial object
// extending onto the chunk (if any), or the part of an object that extends
// onto the next chunk (if any).
size_t live_obj_size() const { return _dc_and_los & los_mask; }
// Total live data that lies within the chunk (words).
size_t data_size() const { return partial_obj_size() + live_obj_size(); }
// The destination_count is the number of other chunks to which data from
// this chunk will be copied. At the end of the summary phase, the valid
// values of destination_count are
//
// 0 - data from the chunk will be compacted completely into itself, or the
// chunk is empty. The chunk can be claimed and then filled.
// 1 - data from the chunk will be compacted into 1 other chunk; some
// data from the chunk may also be compacted into the chunk itself.
// 2 - data from the chunk will be copied to 2 other chunks.
//
// During compaction as chunks are emptied, the destination_count is
// decremented (atomically) and when it reaches 0, it can be claimed and
// then filled.
//
// A chunk is claimed for processing by atomically changing the
// destination_count to the claimed value (dc_claimed). After a chunk has
// been filled, the destination_count should be set to the completed value
// (dc_completed).
inline uint destination_count() const;
inline uint destination_count_raw() const;
// The location of the java heap data that corresponds to this chunk.
inline HeapWord* data_location() const;
// The highest address referenced by objects in this chunk.
inline HeapWord* highest_ref() const;
// Whether this chunk is available to be claimed, has been claimed, or has
// been completed.
//
// Minor subtlety: claimed() returns true if the chunk is marked
// completed(), which is desirable since a chunk must be claimed before it
// can be completed.
bool available() const { return _dc_and_los < dc_one; }
bool claimed() const { return _dc_and_los >= dc_claimed; }
bool completed() const { return _dc_and_los >= dc_completed; }
// These are not atomic.
void set_destination(HeapWord* addr) { _destination = addr; }
void set_source_chunk(size_t chunk) { _source_chunk = chunk; }
void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
void set_partial_obj_size(size_t words) {
_partial_obj_size = (chunk_sz_t) words;
}
inline void set_destination_count(uint count);
inline void set_live_obj_size(size_t words);
inline void set_data_location(HeapWord* addr);
inline void set_completed();
inline bool claim_unsafe();
// These are atomic.
inline void add_live_obj(size_t words);
inline void set_highest_ref(HeapWord* addr);
inline void decrement_destination_count();
inline bool claim();
private:
// The type used to represent object sizes within a chunk.
typedef uint chunk_sz_t;
// Constants for manipulating the _dc_and_los field, which holds both the
// destination count and live obj size. The live obj size lives at the
// least significant end so no masking is necessary when adding.
static const chunk_sz_t dc_shift; // Shift amount.
static const chunk_sz_t dc_mask; // Mask for destination count.
static const chunk_sz_t dc_one; // 1, shifted appropriately.
static const chunk_sz_t dc_claimed; // Chunk has been claimed.
static const chunk_sz_t dc_completed; // Chunk has been completed.
static const chunk_sz_t los_mask; // Mask for live obj size.
HeapWord* _destination;
size_t _source_chunk;
HeapWord* _partial_obj_addr;
chunk_sz_t _partial_obj_size;
chunk_sz_t volatile _dc_and_los;
#ifdef ASSERT
// These enable optimizations that are only partially implemented. Use
// debug builds to prevent the code fragments from breaking.
HeapWord* _data_location;
HeapWord* _highest_ref;
#endif // #ifdef ASSERT
#ifdef ASSERT
public:
uint _pushed; // 0 until chunk is pushed onto a worker's stack
private:
#endif
};
// 'Blocks' allow shorter sections of the bitmap to be searched. Each Block
// holds an offset, which is the amount of live data in the Chunk to the left
// of the first live object in the Block. This amount of live data will
// include any object extending into the block. The first block in
// a chunk does not include any partial object extending into the
// the chunk.
//
// The offset also encodes the
// 'parity' of the first 1 bit in the Block: a positive offset means the
// first 1 bit marks the start of an object, a negative offset means the first
// 1 bit marks the end of an object.
class BlockData
{
public:
typedef short int blk_ofs_t;
blk_ofs_t offset() const { return _offset >= 0 ? _offset : -_offset; }
blk_ofs_t raw_offset() const { return _offset; }
void set_first_is_start_bit(bool v) { _first_is_start_bit = v; }
#if 0
// The need for this method was anticipated but it is
// never actually used. Do not include it for now. If
// it is needed, consider the problem of what is passed
// as "v". To avoid warning errors the method set_start_bit_offset()
// was changed to take a size_t as the parameter and to do the
// check for the possible overflow. Doing the cast in these
// methods better limits the potential problems because of
// the size of the field to this class.
void set_raw_offset(blk_ofs_t v) { _offset = v; }
#endif
void set_start_bit_offset(size_t val) {
assert(val >= 0, "sanity");
_offset = (blk_ofs_t) val;
assert(val == (size_t) _offset, "Value is too large");
_first_is_start_bit = true;
}
void set_end_bit_offset(size_t val) {
assert(val >= 0, "sanity");
_offset = (blk_ofs_t) val;
assert(val == (size_t) _offset, "Value is too large");
_offset = - _offset;
_first_is_start_bit = false;
}
bool first_is_start_bit() {
assert(_set_phase > 0, "Not initialized");
return _first_is_start_bit;
}
bool first_is_end_bit() {
assert(_set_phase > 0, "Not initialized");
return !_first_is_start_bit;
}
private:
blk_ofs_t _offset;
// This is temporary until the mark_bitmap is separated into
// a start bit array and an end bit array.
bool _first_is_start_bit;
#ifdef ASSERT
short _set_phase;
static short _cur_phase;
public:
static void set_cur_phase(short v) { _cur_phase = v; }
#endif
};
public:
ParallelCompactData();
bool initialize(MemRegion covered_region);
size_t chunk_count() const { return _chunk_count; }
// Convert chunk indices to/from ChunkData pointers.
inline ChunkData* chunk(size_t chunk_idx) const;
inline size_t chunk(const ChunkData* const chunk_ptr) const;
// Returns true if the given address is contained within the chunk
bool chunk_contains(size_t chunk_index, HeapWord* addr);
size_t block_count() const { return _block_count; }
inline BlockData* block(size_t n) const;
// Returns true if the given block is in the given chunk.
static bool chunk_contains_block(size_t chunk_index, size_t block_index);
void add_obj(HeapWord* addr, size_t len);
void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
// Fill in the chunks covering [beg, end) so that no data moves; i.e., the
// destination of chunk n is simply the start of chunk n. The argument beg
// must be chunk-aligned; end need not be.
void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
bool summarize(HeapWord* target_beg, HeapWord* target_end,
HeapWord* source_beg, HeapWord* source_end,
HeapWord** target_next, HeapWord** source_next = 0);
void clear();
void clear_range(size_t beg_chunk, size_t end_chunk);
void clear_range(HeapWord* beg, HeapWord* end) {
clear_range(addr_to_chunk_idx(beg), addr_to_chunk_idx(end));
}
// Return the number of words between addr and the start of the chunk
// containing addr.
inline size_t chunk_offset(const HeapWord* addr) const;
// Convert addresses to/from a chunk index or chunk pointer.
inline size_t addr_to_chunk_idx(const HeapWord* addr) const;
inline ChunkData* addr_to_chunk_ptr(const HeapWord* addr) const;
inline HeapWord* chunk_to_addr(size_t chunk) const;
inline HeapWord* chunk_to_addr(size_t chunk, size_t offset) const;
inline HeapWord* chunk_to_addr(const ChunkData* chunk) const;
inline HeapWord* chunk_align_down(HeapWord* addr) const;
inline HeapWord* chunk_align_up(HeapWord* addr) const;
inline bool is_chunk_aligned(HeapWord* addr) const;
// Analogous to chunk_offset() for blocks.
size_t block_offset(const HeapWord* addr) const;
size_t addr_to_block_idx(const HeapWord* addr) const;
size_t addr_to_block_idx(const oop obj) const {
return addr_to_block_idx((HeapWord*) obj);
}
inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
inline HeapWord* block_to_addr(size_t block) const;
// Return the address one past the end of the partial object.
HeapWord* partial_obj_end(size_t chunk_idx) const;
// Return the new location of the object p after the
// the compaction.
HeapWord* calc_new_pointer(HeapWord* addr);
// Same as calc_new_pointer() using blocks.
HeapWord* block_calc_new_pointer(HeapWord* addr);
// Same as calc_new_pointer() using chunks.
HeapWord* chunk_calc_new_pointer(HeapWord* addr);
HeapWord* calc_new_pointer(oop p) {
return calc_new_pointer((HeapWord*) p);
}
// Return the updated address for the given klass
klassOop calc_new_klass(klassOop);
// Given a block returns true if the partial object for the
// corresponding chunk ends in the block. Returns false, otherwise
// If there is no partial object, returns false.
bool partial_obj_ends_in_block(size_t block_index);
// Returns the block index for the block
static size_t block_idx(BlockData* block);
#ifdef ASSERT
void verify_clear(const PSVirtualSpace* vspace);
void verify_clear();
#endif // #ifdef ASSERT
private:
bool initialize_block_data(size_t region_size);
bool initialize_chunk_data(size_t region_size);
PSVirtualSpace* create_vspace(size_t count, size_t element_size);
private:
HeapWord* _region_start;
#ifdef ASSERT
HeapWord* _region_end;
#endif // #ifdef ASSERT
PSVirtualSpace* _chunk_vspace;
ChunkData* _chunk_data;
size_t _chunk_count;
PSVirtualSpace* _block_vspace;
BlockData* _block_data;
size_t _block_count;
};
inline uint
ParallelCompactData::ChunkData::destination_count_raw() const
{
return _dc_and_los & dc_mask;
}
inline uint
ParallelCompactData::ChunkData::destination_count() const
{
return destination_count_raw() >> dc_shift;
}
inline void
ParallelCompactData::ChunkData::set_destination_count(uint count)
{
assert(count <= (dc_completed >> dc_shift), "count too large");
const chunk_sz_t live_sz = (chunk_sz_t) live_obj_size();
_dc_and_los = (count << dc_shift) | live_sz;
}
inline void ParallelCompactData::ChunkData::set_live_obj_size(size_t words)
{
assert(words <= los_mask, "would overflow");
_dc_and_los = destination_count_raw() | (chunk_sz_t)words;
}
inline void ParallelCompactData::ChunkData::decrement_destination_count()
{
assert(_dc_and_los < dc_claimed, "already claimed");
assert(_dc_and_los >= dc_one, "count would go negative");
Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
}
inline HeapWord* ParallelCompactData::ChunkData::data_location() const
{
DEBUG_ONLY(return _data_location;)
NOT_DEBUG(return NULL;)
}
inline HeapWord* ParallelCompactData::ChunkData::highest_ref() const
{
DEBUG_ONLY(return _highest_ref;)
NOT_DEBUG(return NULL;)
}
inline void ParallelCompactData::ChunkData::set_data_location(HeapWord* addr)
{
DEBUG_ONLY(_data_location = addr;)
}
inline void ParallelCompactData::ChunkData::set_completed()
{
assert(claimed(), "must be claimed first");
_dc_and_los = dc_completed | (chunk_sz_t) live_obj_size();
}
// MT-unsafe claiming of a chunk. Should only be used during single threaded
// execution.
inline bool ParallelCompactData::ChunkData::claim_unsafe()
{
if (available()) {
_dc_and_los |= dc_claimed;
return true;
}
return false;
}
inline void ParallelCompactData::ChunkData::add_live_obj(size_t words)
{
assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
Atomic::add((int) words, (volatile int*) &_dc_and_los);
}
inline void ParallelCompactData::ChunkData::set_highest_ref(HeapWord* addr)
{
#ifdef ASSERT
HeapWord* tmp = _highest_ref;
while (addr > tmp) {
tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
}
#endif // #ifdef ASSERT
}
inline bool ParallelCompactData::ChunkData::claim()
{
const int los = (int) live_obj_size();
const int old = Atomic::cmpxchg(dc_claimed | los,
(volatile int*) &_dc_and_los, los);
return old == los;
}
inline ParallelCompactData::ChunkData*
ParallelCompactData::chunk(size_t chunk_idx) const
{
assert(chunk_idx <= chunk_count(), "bad arg");
return _chunk_data + chunk_idx;
}
inline size_t
ParallelCompactData::chunk(const ChunkData* const chunk_ptr) const
{
assert(chunk_ptr >= _chunk_data, "bad arg");
assert(chunk_ptr <= _chunk_data + chunk_count(), "bad arg");
return pointer_delta(chunk_ptr, _chunk_data, sizeof(ChunkData));
}
inline ParallelCompactData::BlockData*
ParallelCompactData::block(size_t n) const {
assert(n < block_count(), "bad arg");
return _block_data + n;
}
inline size_t
ParallelCompactData::chunk_offset(const HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr <= _region_end, "bad addr");
return (size_t(addr) & ChunkAddrOffsetMask) >> LogHeapWordSize;
}
inline size_t
ParallelCompactData::addr_to_chunk_idx(const HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr <= _region_end, "bad addr");
return pointer_delta(addr, _region_start) >> Log2ChunkSize;
}
inline ParallelCompactData::ChunkData*
ParallelCompactData::addr_to_chunk_ptr(const HeapWord* addr) const
{
return chunk(addr_to_chunk_idx(addr));
}
inline HeapWord*
ParallelCompactData::chunk_to_addr(size_t chunk) const
{
assert(chunk <= _chunk_count, "chunk out of range");
return _region_start + (chunk << Log2ChunkSize);
}
inline HeapWord*
ParallelCompactData::chunk_to_addr(const ChunkData* chunk) const
{
return chunk_to_addr(pointer_delta(chunk, _chunk_data, sizeof(ChunkData)));
}
inline HeapWord*
ParallelCompactData::chunk_to_addr(size_t chunk, size_t offset) const
{
assert(chunk <= _chunk_count, "chunk out of range");
assert(offset < ChunkSize, "offset too big"); // This may be too strict.
return chunk_to_addr(chunk) + offset;
}
inline HeapWord*
ParallelCompactData::chunk_align_down(HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr < _region_end + ChunkSize, "bad addr");
return (HeapWord*)(size_t(addr) & ChunkAddrMask);
}
inline HeapWord*
ParallelCompactData::chunk_align_up(HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr <= _region_end, "bad addr");
return chunk_align_down(addr + ChunkSizeOffsetMask);
}
inline bool
ParallelCompactData::is_chunk_aligned(HeapWord* addr) const
{
return chunk_offset(addr) == 0;
}
inline size_t
ParallelCompactData::block_offset(const HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr <= _region_end, "bad addr");
return pointer_delta(addr, _region_start) & BlockOffsetMask;
}
inline size_t
ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
{
assert(addr >= _region_start, "bad addr");
assert(addr <= _region_end, "bad addr");
return pointer_delta(addr, _region_start) >> Log2BlockSize;
}
inline ParallelCompactData::BlockData*
ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
{
return block(addr_to_block_idx(addr));
}
inline HeapWord*
ParallelCompactData::block_to_addr(size_t block) const
{
assert(block < _block_count, "block out of range");
return _region_start + (block << Log2BlockSize);
}
// Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
// do_addr() method.
//
// The closure is initialized with the number of heap words to process
// (words_remaining()), and becomes 'full' when it reaches 0. The do_addr()
// methods in subclasses should update the total as words are processed. Since
// only one subclass actually uses this mechanism to terminate iteration, the
// default initial value is > 0. The implementation is here and not in the
// single subclass that uses it to avoid making is_full() virtual, and thus
// adding a virtual call per live object.
class ParMarkBitMapClosure: public StackObj {
public:
typedef ParMarkBitMap::idx_t idx_t;
typedef ParMarkBitMap::IterationStatus IterationStatus;
public:
inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
size_t words = max_uintx);
inline ParCompactionManager* compaction_manager() const;
inline ParMarkBitMap* bitmap() const;
inline size_t words_remaining() const;
inline bool is_full() const;
inline HeapWord* source() const;
inline void set_source(HeapWord* addr);
virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
protected:
inline void decrement_words_remaining(size_t words);
private:
ParMarkBitMap* const _bitmap;
ParCompactionManager* const _compaction_manager;
DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger.
size_t _words_remaining; // Words left to copy.
protected:
HeapWord* _source; // Next addr that would be read.
};
inline
ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
ParCompactionManager* cm,
size_t words):
_bitmap(bitmap), _compaction_manager(cm)
#ifdef ASSERT
, _initial_words_remaining(words)
#endif
{
_words_remaining = words;
_source = NULL;
}
inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
return _compaction_manager;
}
inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
return _bitmap;
}
inline size_t ParMarkBitMapClosure::words_remaining() const {
return _words_remaining;
}
inline bool ParMarkBitMapClosure::is_full() const {
return words_remaining() == 0;
}
inline HeapWord* ParMarkBitMapClosure::source() const {
return _source;
}
inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
_source = addr;
}
inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
assert(_words_remaining >= words, "processed too many words");
_words_remaining -= words;
}
// Closure for updating the block data during the summary phase.
class BitBlockUpdateClosure: public ParMarkBitMapClosure {
// ParallelCompactData::BlockData::blk_ofs_t _live_data_left;
size_t _live_data_left;
size_t _cur_block;
HeapWord* _chunk_start;
HeapWord* _chunk_end;
size_t _chunk_index;
public:
BitBlockUpdateClosure(ParMarkBitMap* mbm,
ParCompactionManager* cm,
size_t chunk_index);
size_t cur_block() { return _cur_block; }
size_t chunk_index() { return _chunk_index; }
size_t live_data_left() { return _live_data_left; }
// Returns true the first bit in the current block (cur_block) is
// a start bit.
// Returns true if the current block is within the chunk for the closure;
bool chunk_contains_cur_block();
// Set the chunk index and related chunk values for
// a new chunk.
void reset_chunk(size_t chunk_index);
virtual IterationStatus do_addr(HeapWord* addr, size_t words);
};
// The UseParallelOldGC collector is a stop-the-world garbage
// collector that does parts of the collection using parallel threads.
// The collection includes the tenured generation and the young
// generation. The permanent generation is collected at the same
// time as the other two generations but the permanent generation
// is collect by a single GC thread. The permanent generation is
// collected serially because of the requirement that during the
// processing of a klass AAA, any objects reference by AAA must
// already have been processed. This requirement is enforced by
// a left (lower address) to right (higher address) sliding compaction.
//
// There are four phases of the collection.
//
// - marking phase
// - summary phase
// - compacting phase
// - clean up phase
//
// Roughly speaking these phases correspond, respectively, to
// - mark all the live objects
// - calculate the destination of each object at the end of the collection
// - move the objects to their destination
// - update some references and reinitialize some variables
//
// These three phases are invoked in PSParallelCompact::invoke_no_policy().
// The marking phase is implemented in PSParallelCompact::marking_phase()
// and does a complete marking of the heap.
// The summary phase is implemented in PSParallelCompact::summary_phase().
// The move and update phase is implemented in PSParallelCompact::compact().
//
// A space that is being collected is divided into chunks and with
// each chunk is associated an object of type ParallelCompactData.
// Each chunk is of a fixed size and typically will contain more than
// 1 object and may have parts of objects at the front and back of the
// chunk.
//
// chunk -----+---------------------+----------
// objects covered [ AAA )[ BBB )[ CCC )[ DDD )
//
// The marking phase does a complete marking of all live objects in the
// heap. The marking also compiles the size of the data for
// all live objects covered by the chunk. This size includes the
// part of any live object spanning onto the chunk (part of AAA
// if it is live) from the front, all live objects contained in the chunk
// (BBB and/or CCC if they are live), and the part of any live objects
// covered by the chunk that extends off the chunk (part of DDD if it is
// live). The marking phase uses multiple GC threads and marking is
// done in a bit array of type ParMarkBitMap. The marking of the
// bit map is done atomically as is the accumulation of the size of the
// live objects covered by a chunk.
//
// The summary phase calculates the total live data to the left of
// each chunk XXX. Based on that total and the bottom of the space,
// it can calculate the starting location of the live data in XXX.
// The summary phase calculates for each chunk XXX quantites such as
//
// - the amount of live data at the beginning of a chunk from an object
// entering the chunk.
// - the location of the first live data on the chunk
// - a count of the number of chunks receiving live data from XXX.
//
// See ParallelCompactData for precise details. The summary phase also
// calculates the dense prefix for the compaction. The dense prefix
// is a portion at the beginning of the space that is not moved. The
// objects in the dense prefix do need to have their object references
// updated. See method summarize_dense_prefix().
//
// The summary phase is done using 1 GC thread.
//
// The compaction phase moves objects to their new location and updates
// all references in the object.
//
// A current exception is that objects that cross a chunk boundary
// are moved but do not have their references updated. References are
// not updated because it cannot easily be determined if the klass
// pointer KKK for the object AAA has been updated. KKK likely resides
// in a chunk to the left of the chunk containing AAA. These AAA's
// have there references updated at the end in a clean up phase.
// See the method PSParallelCompact::update_deferred_objects(). An
// alternate strategy is being investigated for this deferral of updating.
//
// Compaction is done on a chunk basis. A chunk that is ready to be
// filled is put on a ready list and GC threads take chunk off the list
// and fill them. A chunk is ready to be filled if it
// empty of live objects. Such a chunk may have been initially
// empty (only contained
// dead objects) or may have had all its live objects copied out already.
// A chunk that compacts into itself is also ready for filling. The
// ready list is initially filled with empty chunks and chunks compacting
// into themselves. There is always at least 1 chunk that can be put on
// the ready list. The chunks are atomically added and removed from
// the ready list.
//
class PSParallelCompact : AllStatic {
public:
// Convenient access to type names.
typedef ParMarkBitMap::idx_t idx_t;
typedef ParallelCompactData::ChunkData ChunkData;
typedef ParallelCompactData::BlockData BlockData;
typedef enum {
perm_space_id, old_space_id, eden_space_id,
from_space_id, to_space_id, last_space_id
} SpaceId;
public:
// Inline closure decls
//
class IsAliveClosure: public BoolObjectClosure {
public:
virtual void do_object(oop p);
virtual bool do_object_b(oop p);
};
class KeepAliveClosure: public OopClosure {
private:
ParCompactionManager* _compaction_manager;
protected:
template <class T> inline void do_oop_work(T* p);
public:
KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
virtual void do_oop(oop* p);
virtual void do_oop(narrowOop* p);
};
// Current unused
class FollowRootClosure: public OopsInGenClosure {
private:
ParCompactionManager* _compaction_manager;
public:
FollowRootClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
virtual void do_oop(oop* p);
virtual void do_oop(narrowOop* p);
virtual const bool do_nmethods() const { return true; }
};
class FollowStackClosure: public VoidClosure {
private:
ParCompactionManager* _compaction_manager;
public:
FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
virtual void do_void();
};
class AdjustPointerClosure: public OopsInGenClosure {
private:
bool _is_root;
public:
AdjustPointerClosure(bool is_root) : _is_root(is_root) { }
virtual void do_oop(oop* p);
virtual void do_oop(narrowOop* p);
};
// Closure for verifying update of pointers. Does not
// have any side effects.
class VerifyUpdateClosure: public ParMarkBitMapClosure {
const MutableSpace* _space; // Is this ever used?
public:
VerifyUpdateClosure(ParCompactionManager* cm, const MutableSpace* sp) :
ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), _space(sp)
{ }
virtual IterationStatus do_addr(HeapWord* addr, size_t words);
const MutableSpace* space() { return _space; }
};
// Closure for updating objects altered for debug checking
class ResetObjectsClosure: public ParMarkBitMapClosure {
public:
ResetObjectsClosure(ParCompactionManager* cm):
ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm)
{ }
virtual IterationStatus do_addr(HeapWord* addr, size_t words);
};
friend class KeepAliveClosure;
friend class FollowStackClosure;
friend class AdjustPointerClosure;
friend class FollowRootClosure;
friend class instanceKlassKlass;
friend class RefProcTaskProxy;
private:
static elapsedTimer _accumulated_time;
static unsigned int _total_invocations;
static unsigned int _maximum_compaction_gc_num;
static jlong _time_of_last_gc; // ms
static CollectorCounters* _counters;
static ParMarkBitMap _mark_bitmap;
static ParallelCompactData _summary_data;
static IsAliveClosure _is_alive_closure;
static SpaceInfo _space_info[last_space_id];
static bool _print_phases;
static AdjustPointerClosure _adjust_root_pointer_closure;
static AdjustPointerClosure _adjust_pointer_closure;
// Reference processing (used in ...follow_contents)
static ReferenceProcessor* _ref_processor;
// Updated location of intArrayKlassObj.
static klassOop _updated_int_array_klass_obj;
// Values computed at initialization and used by dead_wood_limiter().
static double _dwl_mean;
static double _dwl_std_dev;
static double _dwl_first_term;
static double _dwl_adjustment;
#ifdef ASSERT
static bool _dwl_initialized;
#endif // #ifdef ASSERT
private:
// Closure accessors
static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; }
static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; }
static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; }
static void initialize_space_info();
// Return true if details about individual phases should be printed.
static inline bool print_phases();
// Clear the marking bitmap and summary data that cover the specified space.
static void clear_data_covering_space(SpaceId id);
static void pre_compact(PreGCValues* pre_gc_values);
static void post_compact();
// Mark live objects
static void marking_phase(ParCompactionManager* cm,
bool maximum_heap_compaction);
static void follow_stack(ParCompactionManager* cm);
static void follow_weak_klass_links(ParCompactionManager* cm);
template <class T> static inline void adjust_pointer(T* p, bool is_root);
static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
template <class T>
static inline void follow_root(ParCompactionManager* cm, T* p);
// Compute the dense prefix for the designated space. This is an experimental
// implementation currently not used in production.
static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
bool maximum_compaction);
// Methods used to compute the dense prefix.
// Compute the value of the normal distribution at x = density. The mean and
// standard deviation are values saved by initialize_dead_wood_limiter().
static inline double normal_distribution(double density);
// Initialize the static vars used by dead_wood_limiter().
static void initialize_dead_wood_limiter();
// Return the percentage of space that can be treated as "dead wood" (i.e.,
// not reclaimed).
static double dead_wood_limiter(double density, size_t min_percent);
// Find the first (left-most) chunk in the range [beg, end) that has at least
// dead_words of dead space to the left. The argument beg must be the first
// chunk in the space that is not completely live.
static ChunkData* dead_wood_limit_chunk(const ChunkData* beg,
const ChunkData* end,
size_t dead_words);
// Return a pointer to the first chunk in the range [beg, end) that is not
// completely full.
static ChunkData* first_dead_space_chunk(const ChunkData* beg,
const ChunkData* end);
// Return a value indicating the benefit or 'yield' if the compacted region
// were to start (or equivalently if the dense prefix were to end) at the
// candidate chunk. Higher values are better.
//
// The value is based on the amount of space reclaimed vs. the costs of (a)
// updating references in the dense prefix plus (b) copying objects and
// updating references in the compacted region.
static inline double reclaimed_ratio(const ChunkData* const candidate,
HeapWord* const bottom,
HeapWord* const top,
HeapWord* const new_top);
// Compute the dense prefix for the designated space.
static HeapWord* compute_dense_prefix(const SpaceId id,
bool maximum_compaction);
// Return true if dead space crosses onto the specified Chunk; bit must be the
// bit index corresponding to the first word of the Chunk.
static inline bool dead_space_crosses_boundary(const ChunkData* chunk,
idx_t bit);
// Summary phase utility routine to fill dead space (if any) at the dense
// prefix boundary. Should only be called if the the dense prefix is
// non-empty.
static void fill_dense_prefix_end(SpaceId id);
static void summarize_spaces_quick();
static void summarize_space(SpaceId id, bool maximum_compaction);
static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
static bool block_first_offset(size_t block_index, idx_t* block_offset_ptr);
// Fill in the BlockData
static void summarize_blocks(ParCompactionManager* cm,
SpaceId first_compaction_space_id);
// The space that is compacted after space_id.
static SpaceId next_compaction_space_id(SpaceId space_id);
// Adjust addresses in roots. Does not adjust addresses in heap.
static void adjust_roots();
// Serial code executed in preparation for the compaction phase.
static void compact_prologue();
// Move objects to new locations.
static void compact_perm(ParCompactionManager* cm);
static void compact();
// Add available chunks to the stack and draining tasks to the task queue.
static void enqueue_chunk_draining_tasks(GCTaskQueue* q,
uint parallel_gc_threads);
// Add dense prefix update tasks to the task queue.
static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
uint parallel_gc_threads);
// Add chunk stealing tasks to the task queue.
static void enqueue_chunk_stealing_tasks(
GCTaskQueue* q,
ParallelTaskTerminator* terminator_ptr,
uint parallel_gc_threads);
// For debugging only - compacts the old gen serially
static void compact_serial(ParCompactionManager* cm);
// If objects are left in eden after a collection, try to move the boundary
// and absorb them into the old gen. Returns true if eden was emptied.
static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
PSYoungGen* young_gen,
PSOldGen* old_gen);
// Reset time since last full gc
static void reset_millis_since_last_gc();
protected:
#ifdef VALIDATE_MARK_SWEEP
static GrowableArray<void*>* _root_refs_stack;
static GrowableArray<oop> * _live_oops;
static GrowableArray<oop> * _live_oops_moved_to;
static GrowableArray<size_t>* _live_oops_size;
static size_t _live_oops_index;
static size_t _live_oops_index_at_perm;
static GrowableArray<void*>* _other_refs_stack;
static GrowableArray<void*>* _adjusted_pointers;
static bool _pointer_tracking;
static bool _root_tracking;
// The following arrays are saved since the time of the last GC and
// assist in tracking down problems where someone has done an errant
// store into the heap, usually to an oop that wasn't properly
// handleized across a GC. If we crash or otherwise fail before the
// next GC, we can query these arrays to find out the object we had
// intended to do the store to (assuming it is still alive) and the
// offset within that object. Covered under RecordMarkSweepCompaction.
static GrowableArray<HeapWord*> * _cur_gc_live_oops;
static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to;
static GrowableArray<size_t>* _cur_gc_live_oops_size;
static GrowableArray<HeapWord*> * _last_gc_live_oops;
static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to;
static GrowableArray<size_t>* _last_gc_live_oops_size;
#endif
public:
class MarkAndPushClosure: public OopClosure {
private:
ParCompactionManager* _compaction_manager;
public:
MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
virtual void do_oop(oop* p);
virtual void do_oop(narrowOop* p);
virtual const bool do_nmethods() const { return true; }
};
PSParallelCompact();
// Convenient accessor for Universe::heap().
static ParallelScavengeHeap* gc_heap() {
return (ParallelScavengeHeap*)Universe::heap();
}
static void invoke(bool maximum_heap_compaction);
static void invoke_no_policy(bool maximum_heap_compaction);
static void post_initialize();
// Perform initialization for PSParallelCompact that requires
// allocations. This should be called during the VM initialization
// at a pointer where it would be appropriate to return a JNI_ENOMEM
// in the event of a failure.
static bool initialize();
// Public accessors
static elapsedTimer* accumulated_time() { return &_accumulated_time; }
static unsigned int total_invocations() { return _total_invocations; }
static CollectorCounters* counters() { return _counters; }
// Used to add tasks
static GCTaskManager* const gc_task_manager();
static klassOop updated_int_array_klass_obj() {
return _updated_int_array_klass_obj;
}
// Marking support
static inline bool mark_obj(oop obj);
// Check mark and maybe push on marking stack
template <class T> static inline void mark_and_push(ParCompactionManager* cm,
T* p);
// Compaction support.
// Return true if p is in the range [beg_addr, end_addr).
static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
// Convenience wrappers for per-space data kept in _space_info.
static inline MutableSpace* space(SpaceId space_id);
static inline HeapWord* new_top(SpaceId space_id);
static inline HeapWord* dense_prefix(SpaceId space_id);
static inline ObjectStartArray* start_array(SpaceId space_id);
// Return true if the klass should be updated.
static inline bool should_update_klass(klassOop k);
// Move and update the live objects in the specified space.
static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
// Process the end of the given chunk range in the dense prefix.
// This includes saving any object not updated.
static void dense_prefix_chunks_epilogue(ParCompactionManager* cm,
size_t chunk_start_index,
size_t chunk_end_index,
idx_t exiting_object_offset,
idx_t chunk_offset_start,
idx_t chunk_offset_end);
// Update a chunk in the dense prefix. For each live object
// in the chunk, update it's interior references. For each
// dead object, fill it with deadwood. Dead space at the end
// of a chunk range will be filled to the start of the next
// live object regardless of the chunk_index_end. None of the
// objects in the dense prefix move and dead space is dead
// (holds only dead objects that don't need any processing), so
// dead space can be filled in any order.
static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
SpaceId space_id,
size_t chunk_index_start,
size_t chunk_index_end);
// Return the address of the count + 1st live word in the range [beg, end).
static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
// Return the address of the word to be copied to dest_addr, which must be
// aligned to a chunk boundary.
static HeapWord* first_src_addr(HeapWord* const dest_addr,
size_t src_chunk_idx);
// Determine the next source chunk, set closure.source() to the start of the
// new chunk return the chunk index. Parameter end_addr is the address one
// beyond the end of source range just processed. If necessary, switch to a
// new source space and set src_space_id (in-out parameter) and src_space_top
// (out parameter) accordingly.
static size_t next_src_chunk(MoveAndUpdateClosure& closure,
SpaceId& src_space_id,
HeapWord*& src_space_top,
HeapWord* end_addr);
// Decrement the destination count for each non-empty source chunk in the
// range [beg_chunk, chunk(chunk_align_up(end_addr))).
static void decrement_destination_counts(ParCompactionManager* cm,
size_t beg_chunk,
HeapWord* end_addr);
// Fill a chunk, copying objects from one or more source chunks.
static void fill_chunk(ParCompactionManager* cm, size_t chunk_idx);
static void fill_and_update_chunk(ParCompactionManager* cm, size_t chunk) {
fill_chunk(cm, chunk);
}
// Update the deferred objects in the space.
static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
// Mark pointer and follow contents.
template <class T>
static inline void mark_and_follow(ParCompactionManager* cm, T* p);
static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
static ParallelCompactData& summary_data() { return _summary_data; }
static inline void adjust_pointer(oop* p) { adjust_pointer(p, false); }
static inline void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
template <class T>
static inline void adjust_pointer(T* p,
HeapWord* beg_addr,
HeapWord* end_addr);
// Reference Processing
static ReferenceProcessor* const ref_processor() { return _ref_processor; }
// Return the SpaceId for the given address.
static SpaceId space_id(HeapWord* addr);
// Time since last full gc (in milliseconds).
static jlong millis_since_last_gc();
#ifdef VALIDATE_MARK_SWEEP
static void track_adjusted_pointer(void* p, bool isroot);
static void check_adjust_pointer(void* p);
static void track_interior_pointers(oop obj);
static void check_interior_pointers();
static void reset_live_oop_tracking(bool at_perm);
static void register_live_oop(oop p, size_t size);
static void validate_live_oop(oop p, size_t size);
static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
static void compaction_complete();
// Querying operation of RecordMarkSweepCompaction results.
// Finds and prints the current base oop and offset for a word
// within an oop that was live during the last GC. Helpful for
// tracking down heap stomps.
static void print_new_location_of_heap_address(HeapWord* q);
#endif // #ifdef VALIDATE_MARK_SWEEP
// Call backs for class unloading
// Update subklass/sibling/implementor links at end of marking.
static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);
#ifndef PRODUCT
// Debugging support.
static const char* space_names[last_space_id];
static void print_chunk_ranges();
static void print_dense_prefix_stats(const char* const algorithm,
const SpaceId id,
const bool maximum_compaction,
HeapWord* const addr);
#endif // #ifndef PRODUCT
#ifdef ASSERT
// Verify that all the chunks have been emptied.
static void verify_complete(SpaceId space_id);
#endif // #ifdef ASSERT
};
inline bool PSParallelCompact::mark_obj(oop obj) {
const int obj_size = obj->size();
if (mark_bitmap()->mark_obj(obj, obj_size)) {
_summary_data.add_obj(obj, obj_size);
return true;
} else {
return false;
}
}
template <class T>
inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) {
assert(!Universe::heap()->is_in_reserved(p),
"roots shouldn't be things within the heap");
#ifdef VALIDATE_MARK_SWEEP
if (ValidateMarkSweep) {
guarantee(!_root_refs_stack->contains(p), "should only be in here once");
_root_refs_stack->push(p);
}
#endif
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
if (mark_bitmap()->is_unmarked(obj)) {
if (mark_obj(obj)) {
obj->follow_contents(cm);
}
}
}
follow_stack(cm);
}
template <class T>
inline void PSParallelCompact::mark_and_follow(ParCompactionManager* cm,
T* p) {
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
if (mark_bitmap()->is_unmarked(obj)) {
if (mark_obj(obj)) {
obj->follow_contents(cm);
}
}
}
}
template <class T>
inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) {
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
if (mark_bitmap()->is_unmarked(obj)) {
if (mark_obj(obj)) {
// This thread marked the object and owns the subsequent processing of it.
cm->save_for_scanning(obj);
}
}
}
}
template <class T>
inline void PSParallelCompact::adjust_pointer(T* p, bool isroot) {
T heap_oop = oopDesc::load_heap_oop(p);
if (!oopDesc::is_null(heap_oop)) {
oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
oop new_obj = (oop)summary_data().calc_new_pointer(obj);
assert(new_obj != NULL || // is forwarding ptr?
obj->is_shared(), // never forwarded?
"should be forwarded");
// Just always do the update unconditionally?
if (new_obj != NULL) {
assert(Universe::heap()->is_in_reserved(new_obj),
"should be in object space");
oopDesc::encode_store_heap_oop_not_null(p, new_obj);
}
}
VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot));
}
template <class T>
inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
#ifdef VALIDATE_MARK_SWEEP
if (ValidateMarkSweep) {
if (!Universe::heap()->is_in_reserved(p)) {
_root_refs_stack->push(p);
} else {
_other_refs_stack->push(p);
}
}
#endif
mark_and_push(_compaction_manager, p);
}
inline bool PSParallelCompact::print_phases() {
return _print_phases;
}
inline double PSParallelCompact::normal_distribution(double density) {
assert(_dwl_initialized, "uninitialized");
const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
}
inline bool
PSParallelCompact::dead_space_crosses_boundary(const ChunkData* chunk,
idx_t bit)
{
assert(bit > 0, "cannot call this for the first bit/chunk");
assert(_summary_data.chunk_to_addr(chunk) == _mark_bitmap.bit_to_addr(bit),
"sanity check");
// Dead space crosses the boundary if (1) a partial object does not extend
// onto the chunk, (2) an object does not start at the beginning of the chunk,
// and (3) an object does not end at the end of the prior chunk.
return chunk->partial_obj_size() == 0 &&
!_mark_bitmap.is_obj_beg(bit) &&
!_mark_bitmap.is_obj_end(bit - 1);
}
inline bool
PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
return p >= beg_addr && p < end_addr;
}
inline bool
PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
return is_in((HeapWord*)p, beg_addr, end_addr);
}
inline MutableSpace* PSParallelCompact::space(SpaceId id) {
assert(id < last_space_id, "id out of range");
return _space_info[id].space();
}
inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
assert(id < last_space_id, "id out of range");
return _space_info[id].new_top();
}
inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
assert(id < last_space_id, "id out of range");
return _space_info[id].dense_prefix();
}
inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
assert(id < last_space_id, "id out of range");
return _space_info[id].start_array();
}
inline bool PSParallelCompact::should_update_klass(klassOop k) {
return ((HeapWord*) k) >= dense_prefix(perm_space_id);
}
template <class T>
inline void PSParallelCompact::adjust_pointer(T* p,
HeapWord* beg_addr,
HeapWord* end_addr) {
if (is_in((HeapWord*)p, beg_addr, end_addr)) {
adjust_pointer(p);
}
}
class MoveAndUpdateClosure: public ParMarkBitMapClosure {
public:
inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
ObjectStartArray* start_array,
HeapWord* destination, size_t words);
// Accessors.
HeapWord* destination() const { return _destination; }
// If the object will fit (size <= words_remaining()), copy it to the current
// destination, update the interior oops and the start array and return either
// full (if the closure is full) or incomplete. If the object will not fit,
// return would_overflow.
virtual IterationStatus do_addr(HeapWord* addr, size_t size);
// Copy enough words to fill this closure, starting at source(). Interior
// oops and the start array are not updated. Return full.
IterationStatus copy_until_full();
// Copy enough words to fill this closure or to the end of an object,
// whichever is smaller, starting at source(). Interior oops and the start
// array are not updated.
void copy_partial_obj();
protected:
// Update variables to indicate that word_count words were processed.
inline void update_state(size_t word_count);
protected:
ObjectStartArray* const _start_array;
HeapWord* _destination; // Next addr to be written.
};
inline
MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
ParCompactionManager* cm,
ObjectStartArray* start_array,
HeapWord* destination,
size_t words) :
ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
{
_destination = destination;
}
inline void MoveAndUpdateClosure::update_state(size_t words)
{
decrement_words_remaining(words);
_source += words;
_destination += words;
}
class UpdateOnlyClosure: public ParMarkBitMapClosure {
private:
const PSParallelCompact::SpaceId _space_id;
ObjectStartArray* const _start_array;
public:
UpdateOnlyClosure(ParMarkBitMap* mbm,
ParCompactionManager* cm,
PSParallelCompact::SpaceId space_id);
// Update the object.
virtual IterationStatus do_addr(HeapWord* addr, size_t words);
inline void do_addr(HeapWord* addr);
};
inline void UpdateOnlyClosure::do_addr(HeapWord* addr)
{
_start_array->allocate_block(addr);
oop(addr)->update_contents(compaction_manager());
}
class FillClosure: public ParMarkBitMapClosure {
public:
FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
_space_id(space_id),
_start_array(PSParallelCompact::start_array(space_id)) {
assert(_space_id == PSParallelCompact::perm_space_id ||
_space_id == PSParallelCompact::old_space_id,
"cannot use FillClosure in the young gen");
assert(bitmap() != NULL, "need a bitmap");
assert(_start_array != NULL, "need a start array");
}
void fill_region(HeapWord* addr, size_t size) {
MemRegion region(addr, size);
SharedHeap::fill_region_with_object(region);
_start_array->allocate_block(addr);
}
virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
fill_region(addr, size);
return ParMarkBitMap::incomplete;
}
private:
const PSParallelCompact::SpaceId _space_id;
ObjectStartArray* const _start_array;
};