1 /*
2 * Copyright (c) 2001, 2012, 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
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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
42 protected:
43 // The ptr queue set to which this queue belongs.
44 PtrQueueSet* _qset;
45
46 // Whether updates should be logged.
47 bool _active;
48
49 // The buffer.
50 void** _buf;
51 // The index at which an object was last enqueued. Starts at "_sz"
52 // (indicating an empty buffer) and goes towards zero.
53 size_t _index;
54
55 // The size of the buffer.
56 size_t _sz;
57
58 // If true, the queue is permanent, and doesn't need to deallocate
59 // its buffer in the destructor (since that obtains a lock which may not
60 // be legally locked by then.
61 bool _perm;
62
63 // If there is a lock associated with this buffer, this is that lock.
64 Mutex* _lock;
65
66 PtrQueueSet* qset() { return _qset; }
67
68 public:
69 // Initialize this queue to contain a null buffer, and be part of the
70 // given PtrQueueSet.
71 PtrQueue(PtrQueueSet* qset, bool perm = false, bool active = false);
72 // Release any contained resources.
73 virtual void flush();
74 // Calls flush() when destroyed.
75 ~PtrQueue() { flush(); }
76
77 // Associate a lock with a ptr queue.
78 void set_lock(Mutex* lock) { _lock = lock; }
79
80 void reset() { if (_buf != NULL) _index = _sz; }
81
82 // Enqueues the given "obj".
83 void enqueue(void* ptr) {
84 if (!_active) return;
85 else enqueue_known_active(ptr);
86 }
87
88 // This method is called when we're doing the zero index handling
89 // and gives a chance to the queues to do any pre-enqueueing
90 // processing they might want to do on the buffer. It should return
91 // true if the buffer should be enqueued, or false if enough
92 // entries were cleared from it so that it can be re-used. It should
93 // not return false if the buffer is still full (otherwise we can
94 // get into an infinite loop).
95 virtual bool should_enqueue_buffer() { return true; }
96 void handle_zero_index();
97 void locking_enqueue_completed_buffer(void** buf);
98
99 void enqueue_known_active(void* ptr);
100
101 size_t size() {
102 assert(_sz >= _index, "Invariant.");
103 return _buf == NULL ? 0 : _sz - _index;
104 }
105
106 bool is_empty() {
107 return _buf == NULL || _sz == _index;
108 }
109
110 // Set the "active" property of the queue to "b". An enqueue to an
111 // inactive thread is a no-op. Setting a queue to inactive resets its
112 // log to the empty state.
113 void set_active(bool b) {
114 _active = b;
115 if (!b && _buf != NULL) {
116 _index = _sz;
117 } else if (b && _buf != NULL) {
118 assert(_index == _sz, "invariant: queues are empty when activated.");
119 }
120 }
121
122 bool is_active() { return _active; }
123
124 static int byte_index_to_index(int ind) {
125 assert((ind % oopSize) == 0, "Invariant.");
126 return ind / oopSize;
127 }
128
129 static int index_to_byte_index(int byte_ind) {
130 return byte_ind * oopSize;
131 }
132
133 // To support compiler.
134 static ByteSize byte_offset_of_index() {
135 return byte_offset_of(PtrQueue, _index);
136 }
137 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
138
139 static ByteSize byte_offset_of_buf() {
140 return byte_offset_of(PtrQueue, _buf);
141 }
142 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
143
144 static ByteSize byte_offset_of_active() {
145 return byte_offset_of(PtrQueue, _active);
146 }
147 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
148
149 };
150
151 class BufferNode {
152 size_t _index;
153 BufferNode* _next;
154 public:
155 BufferNode() : _index(0), _next(NULL) { }
156 BufferNode* next() const { return _next; }
157 void set_next(BufferNode* n) { _next = n; }
158 size_t index() const { return _index; }
159 void set_index(size_t i) { _index = i; }
160
161 // Align the size of the structure to the size of the pointer
162 static size_t aligned_size() {
163 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*));
164 return alignment;
165 }
166
167 // BufferNode is allocated before the buffer.
168 // The chunk of memory that holds both of them is a block.
169
170 // Produce a new BufferNode given a buffer.
171 static BufferNode* new_from_buffer(void** buf) {
172 return new (make_block_from_buffer(buf)) BufferNode;
173 }
174
175 // The following are the required conversion routines:
176 static BufferNode* make_node_from_buffer(void** buf) {
177 return (BufferNode*)make_block_from_buffer(buf);
178 }
179 static void** make_buffer_from_node(BufferNode *node) {
180 return make_buffer_from_block(node);
181 }
182 static void* make_block_from_node(BufferNode *node) {
183 return (void*)node;
184 }
185 static void** make_buffer_from_block(void* p) {
186 return (void**)((char*)p + aligned_size());
187 }
188 static void* make_block_from_buffer(void** p) {
189 return (void*)((char*)p - aligned_size());
190 }
191 };
192
193 // A PtrQueueSet represents resources common to a set of pointer queues.
194 // In particular, the individual queues allocate buffers from this shared
195 // set, and return completed buffers to the set.
196 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
197 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {
198 protected:
199 Monitor* _cbl_mon; // Protects the fields below.
200 BufferNode* _completed_buffers_head;
201 BufferNode* _completed_buffers_tail;
202 int _n_completed_buffers;
203 int _process_completed_threshold;
204 volatile bool _process_completed;
205
206 // This (and the interpretation of the first element as a "next"
207 // pointer) are protected by the TLOQ_FL_lock.
208 Mutex* _fl_lock;
209 BufferNode* _buf_free_list;
210 size_t _buf_free_list_sz;
211 // Queue set can share a freelist. The _fl_owner variable
212 // specifies the owner. It is set to "this" by default.
213 PtrQueueSet* _fl_owner;
214
215 // The size of all buffers in the set.
216 size_t _sz;
217
218 bool _all_active;
219
220 // If true, notify_all on _cbl_mon when the threshold is reached.
221 bool _notify_when_complete;
222
223 // Maximum number of elements allowed on completed queue: after that,
224 // enqueuer does the work itself. Zero indicates no maximum.
225 int _max_completed_queue;
226 int _completed_queue_padding;
227
228 int completed_buffers_list_length();
229 void assert_completed_buffer_list_len_correct_locked();
230 void assert_completed_buffer_list_len_correct();
231
232 protected:
233 // A mutator thread does the the work of processing a buffer.
234 // Returns "true" iff the work is complete (and the buffer may be
235 // deallocated).
236 virtual bool mut_process_buffer(void** buf) {
237 ShouldNotReachHere();
238 return false;
239 }
240
241 public:
242 // Create an empty ptr queue set.
243 PtrQueueSet(bool notify_when_complete = false);
244
245 // Because of init-order concerns, we can't pass these as constructor
246 // arguments.
247 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
248 int process_completed_threshold,
249 int max_completed_queue,
250 PtrQueueSet *fl_owner = NULL) {
251 _max_completed_queue = max_completed_queue;
252 _process_completed_threshold = process_completed_threshold;
253 _completed_queue_padding = 0;
254 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
255 _cbl_mon = cbl_mon;
256 _fl_lock = fl_lock;
257 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
258 }
259
260 // Return an empty oop array of size _sz (required to be non-zero).
261 void** allocate_buffer();
262
263 // Return an empty buffer to the free list. The "buf" argument is
264 // required to be a pointer to the head of an array of length "_sz".
265 void deallocate_buffer(void** buf);
266
267 // Declares that "buf" is a complete buffer.
268 void enqueue_complete_buffer(void** buf, size_t index = 0);
269
270 // To be invoked by the mutator.
271 bool process_or_enqueue_complete_buffer(void** buf);
272
273 bool completed_buffers_exist_dirty() {
274 return _n_completed_buffers > 0;
275 }
276
277 bool process_completed_buffers() { return _process_completed; }
278 void set_process_completed(bool x) { _process_completed = x; }
279
280 bool is_active() { return _all_active; }
281
282 // Set the buffer size. Should be called before any "enqueue" operation
283 // can be called. And should only be called once.
284 void set_buffer_size(size_t sz);
285
286 // Get the buffer size.
287 size_t buffer_size() { return _sz; }
288
289 // Get/Set the number of completed buffers that triggers log processing.
290 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; }
291 int process_completed_threshold() const { return _process_completed_threshold; }
292
293 // Must only be called at a safe point. Indicates that the buffer free
294 // list size may be reduced, if that is deemed desirable.
295 void reduce_free_list();
296
297 int completed_buffers_num() { return _n_completed_buffers; }
298
299 void merge_bufferlists(PtrQueueSet* src);
300
301 void set_max_completed_queue(int m) { _max_completed_queue = m; }
302 int max_completed_queue() { return _max_completed_queue; }
303
304 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; }
305 int completed_queue_padding() { return _completed_queue_padding; }
306
307 // Notify the consumer if the number of buffers crossed the threshold
308 void notify_if_necessary();
309 };
310
311 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP