1/*
2 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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24
25#ifndef SHARE_MEMORY_METASPACE_BLOCKFREELIST_HPP
26#define SHARE_MEMORY_METASPACE_BLOCKFREELIST_HPP
27
28#include "memory/allocation.hpp"
29#include "memory/binaryTreeDictionary.hpp"
30#include "memory/freeList.hpp"
31#include "memory/metaspace/smallBlocks.hpp"
32#include "memory/metaspace/metablock.hpp"
33#include "utilities/globalDefinitions.hpp"
34
35namespace metaspace {
36
37typedef BinaryTreeDictionary<Metablock, FreeList<Metablock> > BlockTreeDictionary;
38
39// Used to manage the free list of Metablocks (a block corresponds
40// to the allocation of a quantum of metadata).
41class BlockFreelist : public CHeapObj<mtClass> {
42
43 BlockTreeDictionary* const _dictionary;
44 SmallBlocks* _small_blocks;
45
46 // Only allocate and split from freelist if the size of the allocation
47 // is at least 1/4th the size of the available block.
48 const static int WasteMultiplier = 4;
49
50 // Accessors
51 BlockTreeDictionary* dictionary() const { return _dictionary; }
52 SmallBlocks* small_blocks() {
53 if (_small_blocks == NULL) {
54 _small_blocks = new SmallBlocks();
55 }
56 return _small_blocks;
57 }
58
59 public:
60
61 BlockFreelist();
62 ~BlockFreelist();
63
64 // Get and return a block to the free list
65 MetaWord* get_block(size_t word_size);
66 void return_block(MetaWord* p, size_t word_size);
67
68 // Returns the total size, in words, of all blocks kept in this structure.
69 size_t total_size() const {
70 size_t result = dictionary()->total_size();
71 if (_small_blocks != NULL) {
72 result = result + _small_blocks->total_size();
73 }
74 return result;
75 }
76
77 // Returns the number of all blocks kept in this structure.
78 uintx num_blocks() const {
79 uintx result = dictionary()->total_free_blocks();
80 if (_small_blocks != NULL) {
81 result = result + _small_blocks->total_num_blocks();
82 }
83 return result;
84 }
85
86 static size_t min_dictionary_size() { return TreeChunk<Metablock, FreeList<Metablock> >::min_size(); }
87 void print_on(outputStream* st) const;
88};
89
90} // namespace metaspace
91
92#endif // SHARE_MEMORY_METASPACE_BLOCKFREELIST_HPP
93