1 /*
2 * Copyright (c) 2018, 2023, 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
6 * under the terms of the GNU General Public License version 2 only, as
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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_SHARED_MEMALLOCATOR_HPP
26 #define SHARE_GC_SHARED_MEMALLOCATOR_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "oops/oopsHierarchy.hpp"
30 #include "runtime/javaThread.hpp"
31 #include "utilities/exceptions.hpp"
32 #include "utilities/globalDefinitions.hpp"
33 #include "utilities/macros.hpp"
34
35 // These fascilities are used for allocating, and initializing newly allocated objects.
36
37 class MemAllocator: StackObj {
38 protected:
39 class Allocation;
40
41 Thread* const _thread;
42 Klass* const _klass;
43 const size_t _word_size;
44
45 // Allocate from the current thread's TLAB, without taking a new TLAB (no safepoint).
46 HeapWord* mem_allocate_inside_tlab_fast() const;
47
48 private:
49 // Allocate in a TLAB. Could allocate a new TLAB, and therefore potentially safepoint.
50 HeapWord* mem_allocate_inside_tlab(Allocation& allocation) const;
51 HeapWord* mem_allocate_inside_tlab_slow(Allocation& allocation) const;
52
53 // Allocate outside a TLAB. Could safepoint.
54 HeapWord* mem_allocate_outside_tlab(Allocation& allocation) const;
55
56 // Fast-path TLAB allocation failed. Takes a slow-path and potentially safepoint.
57 HeapWord* mem_allocate_slow(Allocation& allocation) const;
58
59 protected:
60 MemAllocator(Klass* klass, size_t word_size, Thread* thread)
61 : _thread(thread),
62 _klass(klass),
63 _word_size(word_size)
64 {
65 assert(_thread == Thread::current(), "must be");
66 }
67
68 // Initialization provided by subclasses.
69 virtual oop initialize(HeapWord* mem) const = 0;
70
71 // This function clears the memory of the object.
72 void mem_clear(HeapWord* mem) const;
73
74 // This finish constructing an oop by installing the mark word and the Klass* pointer
75 // last. At the point when the Klass pointer is initialized, this is a constructed object
76 // that must be parseable as an oop by concurrent collectors.
77 oop finish(HeapWord* mem) const;
78
79 // Raw memory allocation. This will try to do a TLAB allocation, and otherwise fall
80 // back to calling CollectedHeap::mem_allocate().
81 HeapWord* mem_allocate(Allocation& allocation) const;
82
83 public:
84 // Allocate and fully construct the object, and perform various instrumentation. Could safepoint.
85 oop allocate() const;
86 };
87
88 class ObjAllocator: public MemAllocator {
89 public:
90 ObjAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
91 : MemAllocator(klass, word_size, thread) {}
92
93 virtual oop initialize(HeapWord* mem) const;
94 };
95
96 class ObjBufferAllocator: public MemAllocator {
97 public:
98 ObjBufferAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
99 : MemAllocator(klass, word_size, thread) {}
100 virtual oop initialize(HeapWord* mem) const;
101 };
102
103
104 class ObjArrayAllocator: public MemAllocator {
105 protected:
106 const int _length;
107 const bool _do_zero;
108
109 public:
110 ObjArrayAllocator(Klass* klass, size_t word_size, int length, bool do_zero,
111 Thread* thread = Thread::current())
112 : MemAllocator(klass, word_size, thread),
113 _length(length),
114 _do_zero(do_zero) {}
115
116 virtual oop initialize(HeapWord* mem) const;
117 };
118
119 class ClassAllocator: public MemAllocator {
120 public:
121 ClassAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
122 : MemAllocator(klass, word_size, thread) {}
123
124 virtual oop initialize(HeapWord* mem) const;
125 };
126
127 #endif // SHARE_GC_SHARED_MEMALLOCATOR_HPP