1 /*
2 * Copyright (c) 2001, 2013, 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_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "utilities/sizes.hpp"
30
31 // There are various techniques that require threads to be able to log
32 // addresses. For example, a generational write barrier might log
33 // the addresses of modified old-generation objects. This type supports
34 // this operation.
35
36 // The definition of placement operator new(size_t, void*) in the <new>.
37 #include <new>
38
39 class PtrQueueSet;
40 class PtrQueue VALUE_OBJ_CLASS_SPEC {
41 friend class VMStructs;
42
43 protected:
44 // The ptr queue set to which this queue belongs.
45 PtrQueueSet* _qset;
46
47 // Whether updates should be logged.
48 bool _active;
49
50 // The buffer.
51 void** _buf;
52 // The index at which an object was last enqueued. Starts at "_sz"
53 // (indicating an empty buffer) and goes towards zero.
54 size_t _index;
55
56 // The size of the buffer.
57 size_t _sz;
58
59 // If true, the queue is permanent, and doesn't need to deallocate
60 // its buffer in the destructor (since that obtains a lock which may not
61 // be legally locked by then.
62 bool _perm;
63
64 // If there is a lock associated with this buffer, this is that lock.
65 Mutex* _lock;
66
67 PtrQueueSet* qset() { return _qset; }
68
69 public:
70 // Initialize this queue to contain a null buffer, and be part of the
71 // given PtrQueueSet.
72 PtrQueue(PtrQueueSet* qset, bool perm = false, bool active = false);
73 // Release any contained resources.
74 virtual void flush();
75 // Calls flush() when destroyed.
76 ~PtrQueue() { flush(); }
77
78 // Associate a lock with a ptr queue.
79 void set_lock(Mutex* lock) { _lock = lock; }
80
81 void reset() { if (_buf != NULL) _index = _sz; }
82
83 void enqueue(volatile void* ptr) {
84 enqueue((void*)(ptr));
85 }
86
87 // Enqueues the given "obj".
88 void enqueue(void* ptr) {
89 if (!_active) return;
90 else enqueue_known_active(ptr);
91 }
92
93 // This method is called when we're doing the zero index handling
94 // and gives a chance to the queues to do any pre-enqueueing
95 // processing they might want to do on the buffer. It should return
96 // true if the buffer should be enqueued, or false if enough
97 // entries were cleared from it so that it can be re-used. It should
98 // not return false if the buffer is still full (otherwise we can
99 // get into an infinite loop).
100 virtual bool should_enqueue_buffer() { return true; }
101 void handle_zero_index();
102 void locking_enqueue_completed_buffer(void** buf);
103
104 void enqueue_known_active(void* ptr);
105
106 size_t size() {
107 assert(_sz >= _index, "Invariant.");
108 return _buf == NULL ? 0 : _sz - _index;
109 }
110
111 bool is_empty() {
112 return _buf == NULL || _sz == _index;
113 }
114
115 // Set the "active" property of the queue to "b". An enqueue to an
116 // inactive thread is a no-op. Setting a queue to inactive resets its
117 // log to the empty state.
118 void set_active(bool b) {
119 _active = b;
120 if (!b && _buf != NULL) {
121 _index = _sz;
122 } else if (b && _buf != NULL) {
123 assert(_index == _sz, "invariant: queues are empty when activated.");
124 }
125 }
126
127 bool is_active() { return _active; }
128
129 static int byte_index_to_index(int ind) {
130 assert((ind % oopSize) == 0, "Invariant.");
131 return ind / oopSize;
132 }
133
134 static int index_to_byte_index(int byte_ind) {
135 return byte_ind * oopSize;
136 }
137
138 // To support compiler.
139 static ByteSize byte_offset_of_index() {
140 return byte_offset_of(PtrQueue, _index);
141 }
142 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
143
144 static ByteSize byte_offset_of_buf() {
145 return byte_offset_of(PtrQueue, _buf);
146 }
147 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
148
149 static ByteSize byte_offset_of_active() {
150 return byte_offset_of(PtrQueue, _active);
151 }
152 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
153
154 };
155
156 class BufferNode {
157 size_t _index;
158 BufferNode* _next;
159 public:
160 BufferNode() : _index(0), _next(NULL) { }
161 BufferNode* next() const { return _next; }
162 void set_next(BufferNode* n) { _next = n; }
163 size_t index() const { return _index; }
164 void set_index(size_t i) { _index = i; }
165
166 // Align the size of the structure to the size of the pointer
167 static size_t aligned_size() {
168 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*));
169 return alignment;
170 }
171
172 // BufferNode is allocated before the buffer.
173 // The chunk of memory that holds both of them is a block.
174
175 // Produce a new BufferNode given a buffer.
176 static BufferNode* new_from_buffer(void** buf) {
177 return new (make_block_from_buffer(buf)) BufferNode;
178 }
179
180 // The following are the required conversion routines:
181 static BufferNode* make_node_from_buffer(void** buf) {
182 return (BufferNode*)make_block_from_buffer(buf);
183 }
184 static void** make_buffer_from_node(BufferNode *node) {
185 return make_buffer_from_block(node);
186 }
187 static void* make_block_from_node(BufferNode *node) {
188 return (void*)node;
189 }
190 static void** make_buffer_from_block(void* p) {
191 return (void**)((char*)p + aligned_size());
192 }
193 static void* make_block_from_buffer(void** p) {
194 return (void*)((char*)p - aligned_size());
195 }
196 };
197
198 // A PtrQueueSet represents resources common to a set of pointer queues.
199 // In particular, the individual queues allocate buffers from this shared
200 // set, and return completed buffers to the set.
201 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
202 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {
203 protected:
204 Monitor* _cbl_mon; // Protects the fields below.
205 BufferNode* _completed_buffers_head;
206 BufferNode* _completed_buffers_tail;
207 int _n_completed_buffers;
208 int _process_completed_threshold;
209 volatile bool _process_completed;
210
211 // This (and the interpretation of the first element as a "next"
212 // pointer) are protected by the TLOQ_FL_lock.
213 Mutex* _fl_lock;
214 BufferNode* _buf_free_list;
215 size_t _buf_free_list_sz;
216 // Queue set can share a freelist. The _fl_owner variable
217 // specifies the owner. It is set to "this" by default.
218 PtrQueueSet* _fl_owner;
219
220 // The size of all buffers in the set.
221 size_t _sz;
222
223 bool _all_active;
224
225 // If true, notify_all on _cbl_mon when the threshold is reached.
226 bool _notify_when_complete;
227
228 // Maximum number of elements allowed on completed queue: after that,
229 // enqueuer does the work itself. Zero indicates no maximum.
230 int _max_completed_queue;
231 int _completed_queue_padding;
232
233 int completed_buffers_list_length();
234 void assert_completed_buffer_list_len_correct_locked();
235 void assert_completed_buffer_list_len_correct();
236
237 protected:
238 // A mutator thread does the the work of processing a buffer.
239 // Returns "true" iff the work is complete (and the buffer may be
240 // deallocated).
241 virtual bool mut_process_buffer(void** buf) {
242 ShouldNotReachHere();
243 return false;
244 }
245
246 public:
247 // Create an empty ptr queue set.
248 PtrQueueSet(bool notify_when_complete = false);
249
250 // Because of init-order concerns, we can't pass these as constructor
251 // arguments.
252 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
253 int process_completed_threshold,
254 int max_completed_queue,
255 PtrQueueSet *fl_owner = NULL) {
256 _max_completed_queue = max_completed_queue;
257 _process_completed_threshold = process_completed_threshold;
258 _completed_queue_padding = 0;
259 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
260 _cbl_mon = cbl_mon;
261 _fl_lock = fl_lock;
262 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
263 }
264
265 // Return an empty oop array of size _sz (required to be non-zero).
266 void** allocate_buffer();
267
268 // Return an empty buffer to the free list. The "buf" argument is
269 // required to be a pointer to the head of an array of length "_sz".
270 void deallocate_buffer(void** buf);
271
272 // Declares that "buf" is a complete buffer.
273 void enqueue_complete_buffer(void** buf, size_t index = 0);
274
275 // To be invoked by the mutator.
276 bool process_or_enqueue_complete_buffer(void** buf);
277
278 bool completed_buffers_exist_dirty() {
279 return _n_completed_buffers > 0;
280 }
281
282 bool process_completed_buffers() { return _process_completed; }
283 void set_process_completed(bool x) { _process_completed = x; }
284
285 bool is_active() { return _all_active; }
286
287 // Set the buffer size. Should be called before any "enqueue" operation
288 // can be called. And should only be called once.
289 void set_buffer_size(size_t sz);
290
291 // Get the buffer size.
292 size_t buffer_size() { return _sz; }
293
294 // Get/Set the number of completed buffers that triggers log processing.
295 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; }
296 int process_completed_threshold() const { return _process_completed_threshold; }
297
298 // Must only be called at a safe point. Indicates that the buffer free
299 // list size may be reduced, if that is deemed desirable.
300 void reduce_free_list();
301
302 int completed_buffers_num() { return _n_completed_buffers; }
303
304 void merge_bufferlists(PtrQueueSet* src);
305
306 void set_max_completed_queue(int m) { _max_completed_queue = m; }
307 int max_completed_queue() { return _max_completed_queue; }
308
309 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; }
310 int completed_queue_padding() { return _completed_queue_padding; }
311
312 // Notify the consumer if the number of buffers crossed the threshold
313 void notify_if_necessary();
314 };
315
316 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP