Wed, 26 Jun 2013 16:58:37 +0200
8013590: NPG: Add a memory pool MXBean for Metaspace
Reviewed-by: jmasa, mgerdin
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #ifndef SHARE_VM_MEMORY_FREELIST_HPP
26 #define SHARE_VM_MEMORY_FREELIST_HPP
28 #include "gc_implementation/shared/allocationStats.hpp"
30 class CompactibleFreeListSpace;
32 // A class for maintaining a free list of Chunk's. The FreeList
33 // maintains a the structure of the list (head, tail, etc.) plus
34 // statistics for allocations from the list. The links between items
35 // are not part of FreeList. The statistics are
36 // used to make decisions about coalescing Chunk's when they
37 // are swept during collection.
38 //
39 // See the corresponding .cpp file for a description of the specifics
40 // for that implementation.
42 class Mutex;
44 template <class Chunk_t>
45 class FreeList VALUE_OBJ_CLASS_SPEC {
46 friend class CompactibleFreeListSpace;
47 friend class VMStructs;
49 private:
50 Chunk_t* _head; // Head of list of free chunks
51 Chunk_t* _tail; // Tail of list of free chunks
52 size_t _size; // Size in Heap words of each chunk
53 ssize_t _count; // Number of entries in list
55 protected:
57 #ifdef ASSERT
58 Mutex* _protecting_lock;
59 #endif
61 // Asserts false if the protecting lock (if any) is not held.
62 void assert_proper_lock_protection_work() const PRODUCT_RETURN;
63 void assert_proper_lock_protection() const {
64 #ifdef ASSERT
65 if (_protecting_lock != NULL)
66 assert_proper_lock_protection_work();
67 #endif
68 }
70 void increment_count() {
71 _count++;
72 }
74 void decrement_count() {
75 _count--;
76 assert(_count >= 0, "Count should not be negative");
77 }
79 public:
80 // Constructor
81 // Construct a list without any entries.
82 FreeList();
84 // Do initialization
85 void initialize();
87 // Reset the head, tail, and count of a free list.
88 void reset();
90 // Declare the current free list to be protected by the given lock.
91 #ifdef ASSERT
92 Mutex* protecting_lock() const { return _protecting_lock; }
93 void set_protecting_lock(Mutex* v) {
94 _protecting_lock = v;
95 }
96 #endif
98 // Accessors.
99 Chunk_t* head() const {
100 assert_proper_lock_protection();
101 return _head;
102 }
103 void set_head(Chunk_t* v) {
104 assert_proper_lock_protection();
105 _head = v;
106 assert(!_head || _head->size() == _size, "bad chunk size");
107 }
108 // Set the head of the list and set the prev field of non-null
109 // values to NULL.
110 void link_head(Chunk_t* v);
112 Chunk_t* tail() const {
113 assert_proper_lock_protection();
114 return _tail;
115 }
116 void set_tail(Chunk_t* v) {
117 assert_proper_lock_protection();
118 _tail = v;
119 assert(!_tail || _tail->size() == _size, "bad chunk size");
120 }
121 // Set the tail of the list and set the next field of non-null
122 // values to NULL.
123 void link_tail(Chunk_t* v) {
124 assert_proper_lock_protection();
125 set_tail(v);
126 if (v != NULL) {
127 v->clear_next();
128 }
129 }
131 // No locking checks in read-accessors: lock-free reads (only) are benign.
132 // Readers are expected to have the lock if they are doing work that
133 // requires atomicity guarantees in sections of code.
134 size_t size() const {
135 return _size;
136 }
137 void set_size(size_t v) {
138 assert_proper_lock_protection();
139 _size = v;
140 }
141 ssize_t count() const { return _count; }
142 void set_count(ssize_t v) { _count = v;}
144 size_t get_better_size() { return size(); }
146 size_t returned_bytes() const { ShouldNotReachHere(); return 0; }
147 void set_returned_bytes(size_t v) {}
148 void increment_returned_bytes_by(size_t v) {}
150 // Unlink head of list and return it. Returns NULL if
151 // the list is empty.
152 Chunk_t* get_chunk_at_head();
154 // Remove the first "n" or "count", whichever is smaller, chunks from the
155 // list, setting "fl", which is required to be empty, to point to them.
156 void getFirstNChunksFromList(size_t n, FreeList<Chunk_t>* fl);
158 // Unlink this chunk from it's free list
159 void remove_chunk(Chunk_t* fc);
161 // Add this chunk to this free list.
162 void return_chunk_at_head(Chunk_t* fc);
163 void return_chunk_at_tail(Chunk_t* fc);
165 // Similar to returnChunk* but also records some diagnostic
166 // information.
167 void return_chunk_at_head(Chunk_t* fc, bool record_return);
168 void return_chunk_at_tail(Chunk_t* fc, bool record_return);
170 // Prepend "fl" (whose size is required to be the same as that of "this")
171 // to the front of "this" list.
172 void prepend(FreeList<Chunk_t>* fl);
174 // Verify that the chunk is in the list.
175 // found. Return NULL if "fc" is not found.
176 bool verify_chunk_in_free_list(Chunk_t* fc) const;
178 // Printing support
179 static void print_labels_on(outputStream* st, const char* c);
180 void print_on(outputStream* st, const char* c = NULL) const;
181 };
183 #endif // SHARE_VM_MEMORY_FREELIST_HPP