1 /*
2 * Copyright (c) 2001, 2019, 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.
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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
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23 */
24
25 #ifndef SHARE_GC_SHARED_SATBMARKQUEUE_HPP
26 #define SHARE_GC_SHARED_SATBMARKQUEUE_HPP
27
28 #include "gc/shared/ptrQueue.hpp"
29 #include "memory/allocation.hpp"
30
31 class Thread;
32 class Monitor;
33 class SATBMarkQueueSet;
34
35 // Base class for processing the contents of a SATB buffer.
36 class SATBBufferClosure : public StackObj {
37 protected:
38 ~SATBBufferClosure() { }
39
40 public:
41 // Process the SATB entries in the designated buffer range.
42 virtual void do_buffer(void** buffer, size_t size) = 0;
43 };
44
45 // A PtrQueue whose elements are (possibly stale) pointers to object heads.
46 class SATBMarkQueue: public PtrQueue {
47 friend class SATBMarkQueueSet;
48
49 private:
50 // Filter out unwanted entries from the buffer.
51 inline void filter();
52
53 // Removes entries from the buffer that are no longer needed.
54 template<typename Filter>
55 inline void apply_filter(Filter filter_out);
56
57 public:
58 SATBMarkQueue(SATBMarkQueueSet* qset);
59
60 // Process queue entries and free resources.
61 void flush();
62
63 // Apply cl to the active part of the buffer.
64 // Prerequisite: Must be at a safepoint.
65 void apply_closure_and_empty(SATBBufferClosure* cl);
66
67 // Overrides PtrQueue::should_enqueue_buffer(). See the method's
68 // definition for more information.
69 virtual bool should_enqueue_buffer();
70
71 #ifndef PRODUCT
72 // Helpful for debugging
73 void print(const char* name);
74 #endif // PRODUCT
75
76 // Compiler support.
77 static ByteSize byte_offset_of_index() {
78 return PtrQueue::byte_offset_of_index<SATBMarkQueue>();
79 }
80 using PtrQueue::byte_width_of_index;
81
82 static ByteSize byte_offset_of_buf() {
83 return PtrQueue::byte_offset_of_buf<SATBMarkQueue>();
84 }
85 using PtrQueue::byte_width_of_buf;
86
87 static ByteSize byte_offset_of_active() {
88 return PtrQueue::byte_offset_of_active<SATBMarkQueue>();
89 }
90 using PtrQueue::byte_width_of_active;
91
92 };
93
94 class SATBMarkQueueSet: public PtrQueueSet {
95 size_t _buffer_enqueue_threshold;
96
97 #ifdef ASSERT
98 void dump_active_states(bool expected_active);
99 void verify_active_states(bool expected_active);
100 #endif // ASSERT
101
102 protected:
103 SATBMarkQueueSet();
104 ~SATBMarkQueueSet() {}
105
106 template<typename Filter>
107 void apply_filter(Filter filter, SATBMarkQueue* queue) {
108 queue->apply_filter(filter);
109 }
110
111 void initialize(Monitor* cbl_mon,
112 BufferNode::Allocator* allocator,
113 size_t process_completed_buffers_threshold,
114 uint buffer_enqueue_threshold_percentage);
115
116 public:
117 virtual SATBMarkQueue& satb_queue_for_thread(Thread* const t) const = 0;
118
119 // Apply "set_active(active)" to all SATB queues in the set. It should be
120 // called only with the world stopped. The method will assert that the
121 // SATB queues of all threads it visits, as well as the SATB queue
122 // set itself, has an active value same as expected_active.
123 void set_active_all_threads(bool active, bool expected_active);
124
125 size_t buffer_enqueue_threshold() const { return _buffer_enqueue_threshold; }
126 virtual void filter(SATBMarkQueue* queue) = 0;
127
128 // Filter all the currently-active SATB buffers.
129 void filter_thread_buffers();
130
131 // If there exists some completed buffer, pop and process it, and
132 // return true. Otherwise return false. Processing a buffer
133 // consists of applying the closure to the active range of the
134 // buffer; the leading entries may be excluded due to filtering.
135 bool apply_closure_to_completed_buffer(SATBBufferClosure* cl);
136
137 #ifndef PRODUCT
138 // Helpful for debugging
139 void print_all(const char* msg);
140 #endif // PRODUCT
141
142 // If a marking is being abandoned, reset any unprocessed log buffers.
143 void abandon_partial_marking();
144 };
145
146 inline void SATBMarkQueue::filter() {
147 static_cast<SATBMarkQueueSet*>(qset())->filter(this);
148 }
149
150 // Removes entries from the buffer that are no longer needed, as
151 // determined by filter. If e is a void* entry in the buffer,
152 // filter_out(e) must be a valid expression whose value is convertible
153 // to bool. Entries are removed (filtered out) if the result is true,
154 // retained if false.
155 template<typename Filter>
156 inline void SATBMarkQueue::apply_filter(Filter filter_out) {
157 void** buf = this->_buf;
158
159 if (buf == NULL) {
160 // nothing to do
161 return;
162 }
163
164 // Two-fingered compaction toward the end.
165 void** src = &buf[this->index()];
166 void** dst = &buf[this->capacity()];
167 assert(src <= dst, "invariant");
168 for ( ; src < dst; ++src) {
169 // Search low to high for an entry to keep.
170 void* entry = *src;
171 if (!filter_out(entry)) {
172 // Found keeper. Search high to low for an entry to discard.
173 while (src < --dst) {
174 if (filter_out(*dst)) {
175 *dst = entry; // Replace discard with keeper.
176 break;
177 }
178 }
179 // If discard search failed (src == dst), the outer loop will also end.
180 }
181 }
182 // dst points to the lowest retained entry, or the end of the buffer
183 // if all the entries were filtered out.
184 this->set_index(dst - buf);
185 }
186
187 #endif // SHARE_GC_SHARED_SATBMARKQUEUE_HPP