1 /*
2 * Copyright (c) 2018, 2024, 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_slow(Allocation& allocation) const;
51
52 // Allocate outside a TLAB. Could safepoint.
53 HeapWord* mem_allocate_outside_tlab(Allocation& allocation) const;
54
55 protected:
56 MemAllocator(Klass* klass, size_t word_size, Thread* thread)
57 : _thread(thread),
58 _klass(klass),
59 _word_size(word_size)
60 {
61 assert(_thread == Thread::current(), "must be");
62 }
63
64 // Initialization provided by subclasses.
65 virtual oop initialize(HeapWord* mem) const = 0;
66
67 // This function clears the memory of the object.
68 void mem_clear(HeapWord* mem) const;
69
70 // This finish constructing an oop by installing the mark word and the Klass* pointer
71 // last. At the point when the Klass pointer is initialized, this is a constructed object
72 // that must be parseable as an oop by concurrent collectors.
73 oop finish(HeapWord* mem) const;
74
75 // Raw memory allocation. This will try to do a TLAB allocation, and otherwise fall
76 // back to calling CollectedHeap::mem_allocate().
77 HeapWord* mem_allocate(Allocation& allocation) const;
78
79 public:
80 // Allocate and fully construct the object, and perform various instrumentation. Could safepoint.
81 oop allocate() const;
82 };
83
84 class ObjAllocator: public MemAllocator {
85 public:
86 ObjAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
87 : MemAllocator(klass, word_size, thread) {}
88
89 virtual oop initialize(HeapWord* mem) const;
90 };
91
92 class ObjArrayAllocator: public MemAllocator {
93 protected:
94 const int _length;
95 const bool _do_zero;
96
97 void mem_zap_start_padding(HeapWord* mem) const PRODUCT_RETURN;
98 void mem_zap_end_padding(HeapWord* mem) const PRODUCT_RETURN;
99
100 public:
101 ObjArrayAllocator(Klass* klass, size_t word_size, int length, bool do_zero,
102 Thread* thread = Thread::current())
103 : MemAllocator(klass, word_size, thread),
104 _length(length),
105 _do_zero(do_zero) {}
106
107 virtual oop initialize(HeapWord* mem) const;
108 };
109
110 class ClassAllocator: public MemAllocator {
111 public:
112 ClassAllocator(Klass* klass, size_t word_size, Thread* thread = Thread::current())
113 : MemAllocator(klass, word_size, thread) {}
114
115 virtual oop initialize(HeapWord* mem) const;
116 };
117
118 // Manages a scope where a failed heap allocation results in
119 // suppression of JVMTI "resource exhausted" events and
120 // throwing a shared, backtrace-less OOME instance.
121 // Used for OOMEs that will not be propagated to user code.
122 class InternalOOMEMark: public StackObj {
123 private:
124 bool _outer;
125 JavaThread* _thread;
126
127 public:
128 explicit InternalOOMEMark(JavaThread* thread) {
129 assert(thread != nullptr, "nullptr is not supported");
130 _outer = thread->is_in_internal_oome_mark();
131 thread->set_is_in_internal_oome_mark(true);
132 _thread = thread;
133 }
134
135 ~InternalOOMEMark() {
136 // Check that only InternalOOMEMark sets
137 // JavaThread::_is_in_internal_oome_mark
138 assert(_thread->is_in_internal_oome_mark(), "must be");
139 _thread->set_is_in_internal_oome_mark(_outer);
140 }
141
142 JavaThread* thread() const { return _thread; }
143 };
144
145 #endif // SHARE_GC_SHARED_MEMALLOCATOR_HPP