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 // Set the "active" property of the queue to "b". An enqueue to an
93 // inactive thread is a no-op. Setting a queue to inactive resets its
94 // log to the empty state.
95 void set_active(bool b) {
96 _active = b;
97 if (!b && _buf != NULL) {
98 _index = _sz;
99 } else if (b && _buf != NULL) {
100 assert(_index == _sz, "invariant: queues are empty when activated.");
101 }
102 }
103
104 bool is_active() { return _active; }
105
106 static int byte_index_to_index(int ind) {
107 assert((ind % oopSize) == 0, "Invariant.");
108 return ind / oopSize;
109 }
110
111 static int index_to_byte_index(int byte_ind) {
112 return byte_ind * oopSize;
113 }
114
115 // To support compiler.
116 static ByteSize byte_offset_of_index() {
117 return byte_offset_of(PtrQueue, _index);
118 }
119 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
120
121 static ByteSize byte_offset_of_buf() {
122 return byte_offset_of(PtrQueue, _buf);
123 }
124 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
125
126 static ByteSize byte_offset_of_active() {
127 return byte_offset_of(PtrQueue, _active);
128 }
129 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
130
131 };
132
133 class BufferNode {
134 size_t _index;
135 BufferNode* _next;
136 public:
137 BufferNode() : _index(0), _next(NULL) { }
138 BufferNode* next() const { return _next; }
139 void set_next(BufferNode* n) { _next = n; }
140 size_t index() const { return _index; }
141 void set_index(size_t i) { _index = i; }
142
143 // Align the size of the structure to the size of the pointer
144 static size_t aligned_size() {
145 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*));
146 return alignment;
147 }
148
149 // BufferNode is allocated before the buffer.
150 // The chunk of memory that holds both of them is a block.
151
152 // Produce a new BufferNode given a buffer.
153 static BufferNode* new_from_buffer(void** buf) {
154 return new (make_block_from_buffer(buf)) BufferNode;
155 }
156
157 // The following are the required conversion routines:
158 static BufferNode* make_node_from_buffer(void** buf) {
159 return (BufferNode*)make_block_from_buffer(buf);
160 }
161 static void** make_buffer_from_node(BufferNode *node) {
162 return make_buffer_from_block(node);
163 }
164 static void* make_block_from_node(BufferNode *node) {
165 return (void*)node;
166 }
167 static void** make_buffer_from_block(void* p) {
168 return (void**)((char*)p + aligned_size());
169 }
170 static void* make_block_from_buffer(void** p) {
171 return (void*)((char*)p - aligned_size());
172 }
173 };
174
175 // A PtrQueueSet represents resources common to a set of pointer queues.
176 // In particular, the individual queues allocate buffers from this shared
177 // set, and return completed buffers to the set.
178 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
179 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {
180 protected:
181 Monitor* _cbl_mon; // Protects the fields below.
182 BufferNode* _completed_buffers_head;
183 BufferNode* _completed_buffers_tail;
184 int _n_completed_buffers;
185 int _process_completed_threshold;
186 volatile bool _process_completed;
187
188 // This (and the interpretation of the first element as a "next"
189 // pointer) are protected by the TLOQ_FL_lock.
190 Mutex* _fl_lock;
191 BufferNode* _buf_free_list;
192 size_t _buf_free_list_sz;
193 // Queue set can share a freelist. The _fl_owner variable
194 // specifies the owner. It is set to "this" by default.
195 PtrQueueSet* _fl_owner;
196
197 // The size of all buffers in the set.
198 size_t _sz;
199
200 bool _all_active;
201
202 // If true, notify_all on _cbl_mon when the threshold is reached.
203 bool _notify_when_complete;
204
205 // Maximum number of elements allowed on completed queue: after that,
206 // enqueuer does the work itself. Zero indicates no maximum.
207 int _max_completed_queue;
208 int _completed_queue_padding;
209
210 int completed_buffers_list_length();
211 void assert_completed_buffer_list_len_correct_locked();
212 void assert_completed_buffer_list_len_correct();
213
214 protected:
215 // A mutator thread does the the work of processing a buffer.
216 // Returns "true" iff the work is complete (and the buffer may be
217 // deallocated).
218 virtual bool mut_process_buffer(void** buf) {
219 ShouldNotReachHere();
220 return false;
221 }
222
223 public:
224 // Create an empty ptr queue set.
225 PtrQueueSet(bool notify_when_complete = false);
226
227 // Because of init-order concerns, we can't pass these as constructor
228 // arguments.
229 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
230 int process_completed_threshold,
231 int max_completed_queue,
232 PtrQueueSet *fl_owner = NULL) {
233 _max_completed_queue = max_completed_queue;
234 _process_completed_threshold = process_completed_threshold;
235 _completed_queue_padding = 0;
236 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
237 _cbl_mon = cbl_mon;
238 _fl_lock = fl_lock;
239 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
240 }
241
242 // Return an empty oop array of size _sz (required to be non-zero).
243 void** allocate_buffer();
244
245 // Return an empty buffer to the free list. The "buf" argument is
246 // required to be a pointer to the head of an array of length "_sz".
247 void deallocate_buffer(void** buf);
248
249 // Declares that "buf" is a complete buffer.
250 void enqueue_complete_buffer(void** buf, size_t index = 0);
251
252 // To be invoked by the mutator.
253 bool process_or_enqueue_complete_buffer(void** buf);
254
255 bool completed_buffers_exist_dirty() {
256 return _n_completed_buffers > 0;
257 }
258
259 bool process_completed_buffers() { return _process_completed; }
260 void set_process_completed(bool x) { _process_completed = x; }
261
262 bool is_active() { return _all_active; }
263
264 // Set the buffer size. Should be called before any "enqueue" operation
265 // can be called. And should only be called once.
266 void set_buffer_size(size_t sz);
267
268 // Get the buffer size.
269 size_t buffer_size() { return _sz; }
270
271 // Get/Set the number of completed buffers that triggers log processing.
272 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; }
273 int process_completed_threshold() const { return _process_completed_threshold; }
274
275 // Must only be called at a safe point. Indicates that the buffer free
276 // list size may be reduced, if that is deemed desirable.
277 void reduce_free_list();
278
279 int completed_buffers_num() { return _n_completed_buffers; }
280
281 void merge_bufferlists(PtrQueueSet* src);
282
283 void set_max_completed_queue(int m) { _max_completed_queue = m; }
284 int max_completed_queue() { return _max_completed_queue; }
285
286 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; }
287 int completed_queue_padding() { return _completed_queue_padding; }
288
289 // Notify the consumer if the number of buffers crossed the threshold
290 void notify_if_necessary();
291 };