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/*
* Copyright (c) 1997, 2022, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_MEMORY_HEAP_HPP
#define SHARE_MEMORY_HEAP_HPP
#include "code/codeBlob.hpp"
#include "memory/allocation.hpp"
#include "memory/virtualspace.hpp"
#include "runtime/atomic.hpp"
#include "utilities/macros.hpp"
// Blocks
class HeapBlock {
friend class VMStructs;
public:
struct Header {
size_t _length; // the length in segments
bool _used; // Used bit
};
protected:
union {
Header _header;
int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
// pad to 0 mod 8
};
public:
// Initialization
void initialize(size_t length) { _header._length = length; set_used(); }
// Merging/splitting
void set_length(size_t length) { _header._length = length; }
// Accessors
void* allocated_space() const { return (void*)(this + 1); }
size_t length() const { return _header._length; }
// Used/free
void set_used() { _header._used = true; }
void set_free() { _header._used = false; }
bool free() { return !_header._used; }
};
class FreeBlock: public HeapBlock {
friend class VMStructs;
protected:
FreeBlock* _link;
public:
// Initialization
void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; }
// Accessors
FreeBlock* link() const { return _link; }
void set_link(FreeBlock* link) { _link = link; }
};
class CodeHeap : public CHeapObj<mtCode> {
friend class VMStructs;
protected:
VirtualSpace _memory; // the memory holding the blocks
VirtualSpace _segmap; // the memory holding the segment map
size_t _number_of_committed_segments;
size_t _number_of_reserved_segments;
size_t _segment_size;
int _log2_segment_size;
size_t _next_segment;
FreeBlock* _freelist;
FreeBlock* _last_insert_point; // last insert point in add_to_freelist
size_t _freelist_segments; // No. of segments in freelist
int _freelist_length;
size_t _max_allocated_capacity; // Peak capacity that was allocated during lifetime of the heap
const char* _name; // Name of the CodeHeap
const CodeBlobType _code_blob_type; // CodeBlobType it contains
int _blob_count; // Number of CodeBlobs
int _nmethod_count; // Number of nmethods
int _adapter_count; // Number of adapters
int _full_count; // Number of times the code heap was full
int _fragmentation_count; // #FreeBlock joins without fully initializing segment map elements.
enum { free_sentinel = 0xFF };
static const int fragmentation_limit = 10000; // defragment after that many potential fragmentations.
static const int freelist_limit = 100; // improve insert point search if list is longer than this limit.
static char segmap_template[free_sentinel+1];
// Helper functions
size_t size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
size_t segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; }
bool is_segment_unused(int val) const { return val == free_sentinel; }
void* address_for(size_t i) const { return (void*)(_memory.low() + segments_to_size(i)); }
void* find_block_for(void* p) const;
HeapBlock* block_at(size_t i) const { return (HeapBlock*)address_for(i); }
// These methods take segment map indices as range boundaries
void mark_segmap_as_free(size_t beg, size_t end);
void mark_segmap_as_used(size_t beg, size_t end, bool is_FreeBlock_join);
void invalidate(size_t beg, size_t end, size_t header_bytes);
void clear(size_t beg, size_t end);
void clear(); // clears all heap contents
static void init_segmap_template();
// Freelist management helpers
FreeBlock* following_block(FreeBlock* b);
void insert_after(FreeBlock* a, FreeBlock* b);
bool merge_right (FreeBlock* a);
// Toplevel freelist management
void add_to_freelist(HeapBlock* b);
HeapBlock* search_freelist(size_t length);
// Iteration helpers
void* next_used(HeapBlock* b) const;
HeapBlock* block_start(void* p) const;
// to perform additional actions on creation of executable code
void on_code_mapping(char* base, size_t size);
public:
CodeHeap(const char* name, const CodeBlobType code_blob_type);
// Heap extents
bool reserve(ReservedSpace rs, size_t committed_size, size_t segment_size);
bool expand_by(size_t size); // expands committed memory by size
// Memory allocation
void* allocate (size_t size); // Allocate 'size' bytes in the code cache or return NULL
void deallocate(void* p); // Deallocate memory
// Free the tail of segments allocated by the last call to 'allocate()' which exceed 'used_size'.
// ATTENTION: this is only safe to use if there was no other call to 'allocate()' after
// 'p' was allocated. Only intended for freeing memory which would be otherwise
// wasted after the interpreter generation because we don't know the interpreter size
// beforehand and we also can't easily relocate the interpreter to a new location.
void deallocate_tail(void* p, size_t used_size);
// Boundaries of committed space.
char* low() const { return _memory.low(); }
char* high() const { return _memory.high(); }
// Boundaries of reserved space.
char* low_boundary() const { return _memory.low_boundary(); }
char* high_boundary() const { return _memory.high_boundary(); }
// Containment means "contained in committed space".
bool contains(const void* p) const { return low() <= p && p < high(); }
bool contains_blob(const CodeBlob* blob) const {
return contains((void*)blob);
}
virtual void* find_start(void* p) const; // returns the block containing p or NULL
virtual CodeBlob* find_blob(void* start) const;
size_t alignment_unit() const; // alignment of any block
size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit
static size_t header_size() { return sizeof(HeapBlock); } // returns the header size for each heap block
size_t segment_size() const { return _segment_size; } // for CodeHeapState
HeapBlock* first_block() const; // for CodeHeapState
HeapBlock* next_block(HeapBlock* b) const; // for CodeHeapState
HeapBlock* split_block(HeapBlock* b, size_t split_seg); // split one block into two
FreeBlock* freelist() const { return _freelist; } // for CodeHeapState
size_t allocated_in_freelist() const { return _freelist_segments * CodeCacheSegmentSize; }
int freelist_length() const { return _freelist_length; } // number of elements in the freelist
// returns the first block or NULL
virtual void* first() const { return next_used(first_block()); }
// returns the next block given a block p or NULL
virtual void* next(void* p) const { return next_used(next_block(block_start(p))); }
// Statistics
size_t capacity() const;
size_t max_capacity() const;
int allocated_segments() const;
size_t allocated_capacity() const;
size_t max_allocated_capacity() const { return _max_allocated_capacity; }
size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); }
// Returns true if the CodeHeap contains CodeBlobs of the given type
bool accepts(CodeBlobType code_blob_type) const{ return (_code_blob_type == CodeBlobType::All) ||
(_code_blob_type == code_blob_type); }
CodeBlobType code_blob_type() const { return _code_blob_type; }
// Debugging / Profiling
const char* name() const { return _name; }
int blob_count() { return _blob_count; }
int nmethod_count() { return _nmethod_count; }
void set_nmethod_count(int count) { _nmethod_count = count; }
int adapter_count() { return _adapter_count; }
void set_adapter_count(int count) { _adapter_count = count; }
int full_count() { return _full_count; }
int report_full() { return Atomic::add(&_full_count, 1); }
private:
size_t heap_unallocated_capacity() const;
int defrag_segmap(bool do_defrag);
int segmap_hops(size_t beg, size_t end);
public:
// Debugging
void verify() PRODUCT_RETURN;
void print() PRODUCT_RETURN;
};
#endif // SHARE_MEMORY_HEAP_HPP
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