1 /*
 2  * Copyright (c) 2023 Red Hat, Inc. All rights reserved.
 3  * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
 4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 5  *
 6  * This code is free software; you can redistribute it and/or modify it
 7  * under the terms of the GNU General Public License version 2 only, as
 8  * published by the Free Software Foundation.
 9  *
10  * This code is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * version 2 for more details (a copy is included in the LICENSE file that
14  * accompanied this code).
15  *
16  * You should have received a copy of the GNU General Public License version
17  * 2 along with this work; if not, write to the Free Software Foundation,
18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19  *
20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21  * or visit www.oracle.com if you need additional information or have any
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24  */
25 
26 #ifndef SHARE_MEMORY_METASPACE_METABLOCK_HPP
27 #define SHARE_MEMORY_METASPACE_METABLOCK_HPP
28 
29 #include "utilities/globalDefinitions.hpp"
30 
31 class outputStream;
32 
33 namespace metaspace {
34 
35 // Tiny structure to be passed by value
36 class MetaBlock {
37 
38   MetaWord* _base;
39   size_t _word_size;
40 
41 public:
42 
43   MetaBlock(MetaWord* p, size_t word_size) :
44     _base(word_size == 0 ? nullptr : p), _word_size(word_size) {}
45   MetaBlock() : MetaBlock(nullptr, 0) {}
46 
47   MetaWord* base() const { return _base; }
48   const MetaWord* end() const { return _base + _word_size; }
49   size_t word_size() const { return _word_size; }
50   bool is_empty() const { return _base == nullptr; }
51   bool is_nonempty() const { return _base != nullptr; }
52   void reset() { _base = nullptr; _word_size = 0; }
53 
54   bool operator==(const MetaBlock& rhs) const {
55     return base() == rhs.base() &&
56            word_size() == rhs.word_size();
57   }
58 
59   // Split off tail block.
60   inline MetaBlock split_off_tail(size_t tailsize);
61 
62   DEBUG_ONLY(inline void verify() const;)
63 
64   // Convenience functions
65   inline bool is_aligned_base(size_t alignment_words) const;
66   inline bool is_aligned_size(size_t alignment_words) const;
67 
68   void print_on(outputStream* st) const;
69 };
70 
71 #define METABLOCKFORMAT                 "block (@" PTR_FORMAT " word size " SIZE_FORMAT ")"
72 #define METABLOCKFORMATARGS(__block__)  p2i((__block__).base()), (__block__).word_size()
73 
74 } // namespace metaspace
75 
76 #endif // SHARE_MEMORY_METASPACE_METABLOCK_HPP