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comparison src/share/vm/gc_implementation/g1/ptrQueue.hpp @ 342:37f87013dfd8

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6711316: Open source the Garbage-First garbage collector Summary: First mercurial integration of the code for the Garbage-First garbage collector. Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author ysr
date Thu, 05 Jun 2008 15:57:56 -0700
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children da9cb4e97a5f
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189:0b27f3512f9e 342:37f87013dfd8
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // There are various techniques that require threads to be able to log
26 // addresses. For example, a generational write barrier might log
27 // the addresses of modified old-generation objects. This type supports
28 // this operation.
29
30 class PtrQueueSet;
31
32 class PtrQueue: public CHeapObj {
33
34 protected:
35 // The ptr queue set to which this queue belongs.
36 PtrQueueSet* _qset;
37
38 // Whether updates should be logged.
39 bool _active;
40
41 // The buffer.
42 void** _buf;
43 // The index at which an object was last enqueued. Starts at "_sz"
44 // (indicating an empty buffer) and goes towards zero.
45 size_t _index;
46
47 // The size of the buffer.
48 size_t _sz;
49
50 // If true, the queue is permanent, and doesn't need to deallocate
51 // its buffer in the destructor (since that obtains a lock which may not
52 // be legally locked by then.
53 bool _perm;
54
55 // If there is a lock associated with this buffer, this is that lock.
56 Mutex* _lock;
57
58 PtrQueueSet* qset() { return _qset; }
59
60 public:
61 // Initialize this queue to contain a null buffer, and be part of the
62 // given PtrQueueSet.
63 PtrQueue(PtrQueueSet*, bool perm = false);
64 // Release any contained resources.
65 ~PtrQueue();
66
67 // Associate a lock with a ptr queue.
68 void set_lock(Mutex* lock) { _lock = lock; }
69
70 void reset() { if (_buf != NULL) _index = _sz; }
71
72 // Enqueues the given "obj".
73 void enqueue(void* ptr) {
74 if (!_active) return;
75 else enqueue_known_active(ptr);
76 }
77
78 inline void handle_zero_index();
79 void locking_enqueue_completed_buffer(void** buf);
80
81 void enqueue_known_active(void* ptr);
82
83 size_t size() {
84 assert(_sz >= _index, "Invariant.");
85 return _buf == NULL ? 0 : _sz - _index;
86 }
87
88 // Set the "active" property of the queue to "b". An enqueue to an
89 // inactive thread is a no-op. Setting a queue to inactive resets its
90 // log to the empty state.
91 void set_active(bool b) {
92 _active = b;
93 if (!b && _buf != NULL) {
94 _index = _sz;
95 } else if (b && _buf != NULL) {
96 assert(_index == _sz, "invariant: queues are empty when activated.");
97 }
98 }
99
100 static int byte_index_to_index(int ind) {
101 assert((ind % oopSize) == 0, "Invariant.");
102 return ind / oopSize;
103 }
104
105 static int index_to_byte_index(int byte_ind) {
106 return byte_ind * oopSize;
107 }
108
109 // To support compiler.
110 static ByteSize byte_offset_of_index() {
111 return byte_offset_of(PtrQueue, _index);
112 }
113 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
114
115 static ByteSize byte_offset_of_buf() {
116 return byte_offset_of(PtrQueue, _buf);
117 }
118 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
119
120 static ByteSize byte_offset_of_active() {
121 return byte_offset_of(PtrQueue, _active);
122 }
123 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
124
125 };
126
127 // A PtrQueueSet represents resources common to a set of pointer queues.
128 // In particular, the individual queues allocate buffers from this shared
129 // set, and return completed buffers to the set.
130 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
131 class PtrQueueSet: public CHeapObj {
132
133 protected:
134
135 class CompletedBufferNode: public CHeapObj {
136 public:
137 void** buf;
138 size_t index;
139 CompletedBufferNode* next;
140 CompletedBufferNode() : buf(NULL),
141 index(0), next(NULL){ }
142 };
143
144 Monitor* _cbl_mon; // Protects the fields below.
145 CompletedBufferNode* _completed_buffers_head;
146 CompletedBufferNode* _completed_buffers_tail;
147 size_t _n_completed_buffers;
148 size_t _process_completed_threshold;
149 volatile bool _process_completed;
150
151 // This (and the interpretation of the first element as a "next"
152 // pointer) are protected by the TLOQ_FL_lock.
153 Mutex* _fl_lock;
154 void** _buf_free_list;
155 size_t _buf_free_list_sz;
156
157 // The size of all buffers in the set.
158 size_t _sz;
159
160 bool _all_active;
161
162 // If true, notify_all on _cbl_mon when the threshold is reached.
163 bool _notify_when_complete;
164
165 // Maximum number of elements allowed on completed queue: after that,
166 // enqueuer does the work itself. Zero indicates no maximum.
167 int _max_completed_queue;
168
169 int completed_buffers_list_length();
170 void assert_completed_buffer_list_len_correct_locked();
171 void assert_completed_buffer_list_len_correct();
172
173 protected:
174 // A mutator thread does the the work of processing a buffer.
175 // Returns "true" iff the work is complete (and the buffer may be
176 // deallocated).
177 virtual bool mut_process_buffer(void** buf) {
178 ShouldNotReachHere();
179 return false;
180 }
181
182 public:
183 // Create an empty ptr queue set.
184 PtrQueueSet(bool notify_when_complete = false);
185
186 // Because of init-order concerns, we can't pass these as constructor
187 // arguments.
188 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
189 int max_completed_queue = 0) {
190 _max_completed_queue = max_completed_queue;
191 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
192 _cbl_mon = cbl_mon; _fl_lock = fl_lock;
193 }
194
195 // Return an empty oop array of size _sz (required to be non-zero).
196 void** allocate_buffer();
197
198 // Return an empty buffer to the free list. The "buf" argument is
199 // required to be a pointer to the head of an array of length "_sz".
200 void deallocate_buffer(void** buf);
201
202 // Declares that "buf" is a complete buffer.
203 void enqueue_complete_buffer(void** buf, size_t index = 0,
204 bool ignore_max_completed = false);
205
206 bool completed_buffers_exist_dirty() {
207 return _n_completed_buffers > 0;
208 }
209
210 bool process_completed_buffers() { return _process_completed; }
211
212 bool active() { return _all_active; }
213
214 // Set the buffer size. Should be called before any "enqueue" operation
215 // can be called. And should only be called once.
216 void set_buffer_size(size_t sz);
217
218 // Get the buffer size.
219 size_t buffer_size() { return _sz; }
220
221 // Set the number of completed buffers that triggers log processing.
222 void set_process_completed_threshold(size_t sz);
223
224 // Must only be called at a safe point. Indicates that the buffer free
225 // list size may be reduced, if that is deemed desirable.
226 void reduce_free_list();
227
228 size_t completed_buffers_num() { return _n_completed_buffers; }
229 };