1 /*
2 * Copyright (c) 2001, 2018, 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 JavaThread;
32 class SATBMarkQueueSet;
33
34 // Base class for processing the contents of a SATB buffer.
35 class SATBBufferClosure : public StackObj {
36 protected:
37 ~SATBBufferClosure() { }
38
39 public:
40 // Process the SATB entries in the designated buffer range.
41 virtual void do_buffer(void** buffer, size_t size) = 0;
42 };
43
44 // A PtrQueue whose elements are (possibly stale) pointers to object heads.
45 class SATBMarkQueue: public PtrQueue {
46 friend class SATBMarkQueueSet;
47
48 private:
49 // Filter out unwanted entries from the buffer.
50 inline void filter();
51
52 // Removes entries from the buffer that are no longer needed.
53 template<typename Filter>
54 inline void apply_filter(Filter filter_out);
55
56 public:
57 SATBMarkQueue(SATBMarkQueueSet* qset, bool permanent = false);
58
59 // Process queue entries and free resources.
60 void flush();
61
62 // Apply cl to the active part of the buffer.
63 // Prerequisite: Must be at a safepoint.
64 void apply_closure_and_empty(SATBBufferClosure* cl);
65
66 // Overrides PtrQueue::should_enqueue_buffer(). See the method's
67 // definition for more information.
68 virtual bool should_enqueue_buffer();
69
70 #ifndef PRODUCT
71 // Helpful for debugging
72 void print(const char* name);
73 #endif // PRODUCT
74
75 // Compiler support.
76 static ByteSize byte_offset_of_index() {
77 return PtrQueue::byte_offset_of_index<SATBMarkQueue>();
78 }
79 using PtrQueue::byte_width_of_index;
80
81 static ByteSize byte_offset_of_buf() {
82 return PtrQueue::byte_offset_of_buf<SATBMarkQueue>();
83 }
84 using PtrQueue::byte_width_of_buf;
85
86 static ByteSize byte_offset_of_active() {
87 return PtrQueue::byte_offset_of_active<SATBMarkQueue>();
88 }
89 using PtrQueue::byte_width_of_active;
90
91 };
92
93 class SATBMarkQueueSet: public PtrQueueSet {
94 SATBMarkQueue _shared_satb_queue;
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, Mutex* fl_lock,
112 int process_completed_threshold,
113 uint buffer_enqueue_threshold_percentage,
114 Mutex* lock);
115
116 public:
117 virtual SATBMarkQueue& satb_queue_for_thread(JavaThread* 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 SATBMarkQueue* shared_satb_queue() { return &_shared_satb_queue; }
143
144 // If a marking is being abandoned, reset any unprocessed log buffers.
145 void abandon_partial_marking();
146 };
147
148 inline void SATBMarkQueue::filter() {
149 static_cast<SATBMarkQueueSet*>(qset())->filter(this);
150 }
151
152 // Removes entries from the buffer that are no longer needed, as
153 // determined by filter. If e is a void* entry in the buffer,
154 // filter_out(e) must be a valid expression whose value is convertible
155 // to bool. Entries are removed (filtered out) if the result is true,
156 // retained if false.
157 template<typename Filter>
158 inline void SATBMarkQueue::apply_filter(Filter filter_out) {
159 void** buf = this->_buf;
160
161 if (buf == NULL) {
162 // nothing to do
163 return;
164 }
165
166 // Two-fingered compaction toward the end.
167 void** src = &buf[this->index()];
168 void** dst = &buf[this->capacity()];
169 assert(src <= dst, "invariant");
170 for ( ; src < dst; ++src) {
171 // Search low to high for an entry to keep.
172 void* entry = *src;
173 if (!filter_out(entry)) {
174 // Found keeper. Search high to low for an entry to discard.
175 while (src < --dst) {
176 if (filter_out(*dst)) {
177 *dst = entry; // Replace discard with keeper.
178 break;
179 }
180 }
181 // If discard search failed (src == dst), the outer loop will also end.
182 }
183 }
184 // dst points to the lowest retained entry, or the end of the buffer
185 // if all the entries were filtered out.
186 this->set_index(dst - buf);
187 }
188
189 #endif // SHARE_GC_SHARED_SATBMARKQUEUE_HPP