1 /*
2 * Copyright (c) 2001, 2009, 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 // 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 // The definition of placement operator new(size_t, void*) in the <new>.
31 #include <new>
32
33 class PtrQueueSet;
34 class PtrQueue VALUE_OBJ_CLASS_SPEC {
35
36 protected:
37 // The ptr queue set to which this queue belongs.
38 PtrQueueSet* _qset;
39
40 // Whether updates should be logged.
41 bool _active;
42
43 // The buffer.
44 void** _buf;
45 // The index at which an object was last enqueued. Starts at "_sz"
46 // (indicating an empty buffer) and goes towards zero.
47 size_t _index;
48
49 // The size of the buffer.
50 size_t _sz;
51
52 // If true, the queue is permanent, and doesn't need to deallocate
53 // its buffer in the destructor (since that obtains a lock which may not
54 // be legally locked by then.
55 bool _perm;
56
57 // If there is a lock associated with this buffer, this is that lock.
58 Mutex* _lock;
59
60 PtrQueueSet* qset() { return _qset; }
61
62 public:
63 // Initialize this queue to contain a null buffer, and be part of the
64 // given PtrQueueSet.
65 PtrQueue(PtrQueueSet*, bool perm = false, bool active = false);
66 // Release any contained resources.
67 void flush();
68 // Calls flush() when destroyed.
69 ~PtrQueue() { flush(); }
70
71 // Associate a lock with a ptr queue.
72 void set_lock(Mutex* lock) { _lock = lock; }
73
74 void reset() { if (_buf != NULL) _index = _sz; }
75
76 // Enqueues the given "obj".
77 void enqueue(void* ptr) {
78 if (!_active) return;
79 else enqueue_known_active(ptr);
80 }
81
82 void handle_zero_index();
83 void locking_enqueue_completed_buffer(void** buf);
84
85 void enqueue_known_active(void* ptr);
86
87 size_t size() {
88 assert(_sz >= _index, "Invariant.");
89 return _buf == NULL ? 0 : _sz - _index;
90 }
91
92 bool is_empty() {
93 return _buf == NULL || _sz == _index;
94 }
95
96 // Set the "active" property of the queue to "b". An enqueue to an
97 // inactive thread is a no-op. Setting a queue to inactive resets its
98 // log to the empty state.
99 void set_active(bool b) {
100 _active = b;
101 if (!b && _buf != NULL) {
102 _index = _sz;
103 } else if (b && _buf != NULL) {
104 assert(_index == _sz, "invariant: queues are empty when activated.");
105 }
106 }
107
108 bool is_active() { return _active; }
109
110 static int byte_index_to_index(int ind) {
111 assert((ind % oopSize) == 0, "Invariant.");
112 return ind / oopSize;
113 }
114
115 static int index_to_byte_index(int byte_ind) {
116 return byte_ind * oopSize;
117 }
118
119 // To support compiler.
120 static ByteSize byte_offset_of_index() {
121 return byte_offset_of(PtrQueue, _index);
122 }
123 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
124
125 static ByteSize byte_offset_of_buf() {
126 return byte_offset_of(PtrQueue, _buf);
127 }
128 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
129
130 static ByteSize byte_offset_of_active() {
131 return byte_offset_of(PtrQueue, _active);
132 }
133 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
134
135 };
136
137 class BufferNode {
138 size_t _index;
139 BufferNode* _next;
140 public:
141 BufferNode() : _index(0), _next(NULL) { }
142 BufferNode* next() const { return _next; }
143 void set_next(BufferNode* n) { _next = n; }
144 size_t index() const { return _index; }
145 void set_index(size_t i) { _index = i; }
146
147 // Align the size of the structure to the size of the pointer
148 static size_t aligned_size() {
149 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*));
150 return alignment;
151 }
152
153 // BufferNode is allocated before the buffer.
154 // The chunk of memory that holds both of them is a block.
155
156 // Produce a new BufferNode given a buffer.
157 static BufferNode* new_from_buffer(void** buf) {
158 return new (make_block_from_buffer(buf)) BufferNode;
159 }
160
161 // The following are the required conversion routines:
162 static BufferNode* make_node_from_buffer(void** buf) {
163 return (BufferNode*)make_block_from_buffer(buf);
164 }
165 static void** make_buffer_from_node(BufferNode *node) {
166 return make_buffer_from_block(node);
167 }
168 static void* make_block_from_node(BufferNode *node) {
169 return (void*)node;
170 }
171 static void** make_buffer_from_block(void* p) {
172 return (void**)((char*)p + aligned_size());
173 }
174 static void* make_block_from_buffer(void** p) {
175 return (void*)((char*)p - aligned_size());
176 }
177 };
178
179 // A PtrQueueSet represents resources common to a set of pointer queues.
180 // In particular, the individual queues allocate buffers from this shared
181 // set, and return completed buffers to the set.
182 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
183 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {
184 protected:
185 Monitor* _cbl_mon; // Protects the fields below.
186 BufferNode* _completed_buffers_head;
187 BufferNode* _completed_buffers_tail;
188 int _n_completed_buffers;
189 int _process_completed_threshold;
190 volatile bool _process_completed;
191
192 // This (and the interpretation of the first element as a "next"
193 // pointer) are protected by the TLOQ_FL_lock.
194 Mutex* _fl_lock;
195 BufferNode* _buf_free_list;
196 size_t _buf_free_list_sz;
197 // Queue set can share a freelist. The _fl_owner variable
198 // specifies the owner. It is set to "this" by default.
199 PtrQueueSet* _fl_owner;
200
201 // The size of all buffers in the set.
202 size_t _sz;
203
204 bool _all_active;
205
206 // If true, notify_all on _cbl_mon when the threshold is reached.
207 bool _notify_when_complete;
208
209 // Maximum number of elements allowed on completed queue: after that,
210 // enqueuer does the work itself. Zero indicates no maximum.
211 int _max_completed_queue;
212 int _completed_queue_padding;
213
214 int completed_buffers_list_length();
215 void assert_completed_buffer_list_len_correct_locked();
216 void assert_completed_buffer_list_len_correct();
217
218 protected:
219 // A mutator thread does the the work of processing a buffer.
220 // Returns "true" iff the work is complete (and the buffer may be
221 // deallocated).
222 virtual bool mut_process_buffer(void** buf) {
223 ShouldNotReachHere();
224 return false;
225 }
226
227 public:
228 // Create an empty ptr queue set.
229 PtrQueueSet(bool notify_when_complete = false);
230
231 // Because of init-order concerns, we can't pass these as constructor
232 // arguments.
233 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
234 int process_completed_threshold,
235 int max_completed_queue,
236 PtrQueueSet *fl_owner = NULL) {
237 _max_completed_queue = max_completed_queue;
238 _process_completed_threshold = process_completed_threshold;
239 _completed_queue_padding = 0;
240 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
241 _cbl_mon = cbl_mon;
242 _fl_lock = fl_lock;
243 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
244 }
245
246 // Return an empty oop array of size _sz (required to be non-zero).
247 void** allocate_buffer();
248
249 // Return an empty buffer to the free list. The "buf" argument is
250 // required to be a pointer to the head of an array of length "_sz".
251 void deallocate_buffer(void** buf);
252
253 // Declares that "buf" is a complete buffer.
254 void enqueue_complete_buffer(void** buf, size_t index = 0);
255
256 // To be invoked by the mutator.
257 bool process_or_enqueue_complete_buffer(void** buf);
258
259 bool completed_buffers_exist_dirty() {
260 return _n_completed_buffers > 0;
261 }
262
263 bool process_completed_buffers() { return _process_completed; }
264 void set_process_completed(bool x) { _process_completed = x; }
265
266 bool is_active() { return _all_active; }
267
268 // Set the buffer size. Should be called before any "enqueue" operation
269 // can be called. And should only be called once.
270 void set_buffer_size(size_t sz);
271
272 // Get the buffer size.
273 size_t buffer_size() { return _sz; }
274
275 // Get/Set the number of completed buffers that triggers log processing.
276 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; }
277 int process_completed_threshold() const { return _process_completed_threshold; }
278
279 // Must only be called at a safe point. Indicates that the buffer free
280 // list size may be reduced, if that is deemed desirable.
281 void reduce_free_list();
282
283 int completed_buffers_num() { return _n_completed_buffers; }
284
285 void merge_bufferlists(PtrQueueSet* src);
286
287 void set_max_completed_queue(int m) { _max_completed_queue = m; }
288 int max_completed_queue() { return _max_completed_queue; }
289
290 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; }
291 int completed_queue_padding() { return _completed_queue_padding; }
292
293 // Notify the consumer if the number of buffers crossed the threshold
294 void notify_if_necessary();
295 };