Initial changes for new metaspace. Only tested for Linux x64.
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#ifndef SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
#define SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
#include <memory/metaspace/settings.hpp>
#include "memory/allocation.hpp"
#include "memory/metaspace/counter.hpp"
#include "memory/metaspace/commitMask.hpp"
#include "memory/metaspace/rootChunkArea.hpp"
#include "memory/virtualspace.hpp"
#include "memory/memRegion.hpp"
#include "utilities/debug.hpp"
#include "utilities/bitMap.hpp"
#include "utilities/globalDefinitions.hpp"
class outputStream;
namespace metaspace {
class CommitLimiter;
class MetachunkListCluster;
// VirtualSpaceNode manage a single address range of the Metaspace.
//
// That address range may contain interleaved committed and uncommitted
// regions. It keeps track of which regions have committed and offers
// functions to commit and uncommit regions.
//
// It allocates and hands out memory ranges, starting at the bottom.
//
// Address range must be aligned to root chunk size.
//
class VirtualSpaceNode : public CHeapObj<mtClass> {
// Link to next VirtualSpaceNode
VirtualSpaceNode* _next;
ReservedSpace _rs;
// Start pointer of the area.
MetaWord* const _base;
// Size, in words, of the whole node
const size_t _word_size;
// Size, in words, of the range of this node which has been handed out in
// the form of chunks.
size_t _used_words;
// The bitmap describing the commit state of the region:
// Each bit covers a region of 64K (see constants::commit_granule_size).
CommitMask _commit_mask;
// An array/LUT of RootChunkArea objects. Each one describes
// fragmentation inside a root chunk.
RootChunkAreaLUT _root_chunk_area_lut;
// Limiter object to ask before expanding the committed size of this node.
CommitLimiter* const _commit_limiter;
// Points to outside size counters which we are to increase/decrease when we commit/uncommit
// space from this node.
SizeCounter* const _total_reserved_words_counter;
SizeCounter* const _total_committed_words_counter;
// For debug and tracing purposes
const int _node_id;
/// committing, uncommitting ///
// Given a pointer into this node, calculate the start of the commit granule
// the pointer points into.
MetaWord* calc_start_of_granule(MetaWord* p) const {
DEBUG_ONLY(check_pointer(p));
return align_down(p, Settings::commit_granule_bytes());
}
// Given an address range, ensure it is committed.
//
// The range has to be aligned to granule size.
//
// Function will:
// - check how many granules in that region are uncommitted; If all are committed, it
// returns true immediately.
// - check if committing those uncommitted granules would bring us over the commit limit
// (GC threshold, MaxMetaspaceSize). If true, it returns false.
// - commit the memory.
// - mark the range as committed in the commit mask
//
// Returns true if success, false if it did hit a commit limit.
bool commit_range(MetaWord* p, size_t word_size);
//// creation ////
// Create a new empty node spanning the given reserved space.
VirtualSpaceNode(int node_id,
ReservedSpace rs,
CommitLimiter* limiter,
SizeCounter* reserve_counter,
SizeCounter* commit_counter);
MetaWord* base() const { return _base; }
public:
// Create a node of a given size
static VirtualSpaceNode* create_node(int node_id,
size_t word_size,
CommitLimiter* limiter,
SizeCounter* reserve_words_counter,
SizeCounter* commit_words_counter);
// Create a node over an existing space
static VirtualSpaceNode* create_node(int node_id,
ReservedSpace rs,
CommitLimiter* limiter,
SizeCounter* reserve_words_counter,
SizeCounter* commit_words_counter);
~VirtualSpaceNode();
// Reserved size of the whole node.
size_t word_size() const { return _word_size; }
//// Chunk allocation, splitting, merging /////
// Allocate a root chunk from this node. Will fail and return NULL
// if the node is full.
// Note: this just returns a chunk whose memory is reserved; no memory is committed yet.
// Hence, before using this chunk, it must be committed.
// Also, no limits are checked, since no committing takes place.
Metachunk* allocate_root_chunk();
// Given a chunk c, split it recursively until you get a chunk of the given target_level.
//
// The original chunk must not be part of a freelist.
//
// Returns pointer to the result chunk; the splitted-off chunks are added as
// free chunks to the freelists.
//
// Returns NULL if chunk cannot be split at least once.
Metachunk* split(chklvl_t target_level, Metachunk* c, MetachunkListCluster* freelists);
// Given a chunk, attempt to merge it recursively with its neighboring chunks.
//
// If successful (merged at least once), returns address of
// the merged chunk; NULL otherwise.
//
// The merged chunks are removed from the freelists.
//
// !!! Please note that if this method returns a non-NULL value, the
// original chunk will be invalid and should not be accessed anymore! !!!
Metachunk* merge(Metachunk* c, MetachunkListCluster* freelists);
// Given a chunk c, which must be "in use" and must not be a root chunk, attempt to
// enlarge it in place by claiming its trailing buddy.
//
// This will only work if c is the leader of the buddy pair and the trailing buddy is free.
//
// If successful, the follower chunk will be removed from the freelists, the leader chunk c will
// double in size (level decreased by one).
//
// On success, true is returned, false otherwise.
bool attempt_enlarge_chunk(Metachunk* c, MetachunkListCluster* freelists);
// Attempts to purge the node:
//
// If all chunks living in this node are free, they will all be removed from their freelists
// and deletes the node.
//
// Returns true if the node has been deleted, false if not.
// !! If this returns true, do not access the node from this point on. !!
bool attempt_purge(MetachunkListCluster* freelists);
// Attempts to uncommit free areas according to the rules set in settings.
// Returns number of words uncommitted.
size_t uncommit_free_areas();
/// misc /////
// Returns size, in words, of the used space in this node alone.
// (Notes:
// - This is the space handed out to the ChunkManager, so it is "used" from the viewpoint of this node,
// but not necessarily used for Metadata.
// - This may or may not be committed memory.
size_t used_words() const { return _used_words; }
// Returns size, in words, of how much space is left in this node alone.
size_t free_words() const { return _word_size - _used_words; }
// Returns size, in words, of committed space in this node alone.
// Note: iterates over commit mask and hence may be a tad expensive on large nodes.
size_t committed_words() const;
//// Committing/uncommitting memory /////
// Given an address range, ensure it is committed.
//
// The range does not have to be aligned to granule size. However, the function will always commit
// whole granules.
//
// Function will:
// - check how many granules in that region are uncommitted; If all are committed, it
// returns true immediately.
// - check if committing those uncommitted granules would bring us over the commit limit
// (GC threshold, MaxMetaspaceSize). If true, it returns false.
// - commit the memory.
// - mark the range as committed in the commit mask
//
// Returns true if success, false if it did hit a commit limit.
bool ensure_range_is_committed(MetaWord* p, size_t word_size);
// Given an address range (which has to be aligned to commit granule size):
// - uncommit it
// - mark it as uncommitted in the commit mask
void uncommit_range(MetaWord* p, size_t word_size);
//// List stuff ////
VirtualSpaceNode* next() const { return _next; }
void set_next(VirtualSpaceNode* vsn) { _next = vsn; }
/// Debug stuff ////
// Print a description about this node.
void print_on(outputStream* st) const;
// Verify counters and basic structure. Slow mode: verify all chunks in depth
bool contains(const MetaWord* p) const {
return p >= _base && p < _base + _used_words;
}
#ifdef ASSERT
void check_pointer(const MetaWord* p) const {
assert(contains(p), "invalid pointer");
}
void verify(bool slow) const;
#endif
};
} // namespace metaspace
#endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP