Mon, 08 Dec 2014 18:57:33 +0100
8067655: Clean up G1 remembered set oop iteration
Summary: Pass on the static type G1ParPushHeapRSClosure to allow oop_iterate devirtualization
Reviewed-by: jmasa, kbarrett
1 /*
2 * Copyright (c) 2001, 2014, 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 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP
28 #include "memory/allocation.hpp"
29 #include "utilities/sizes.hpp"
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.
36 // The definition of placement operator new(size_t, void*) in the <new>.
37 #include <new>
39 class PtrQueueSet;
40 class PtrQueue VALUE_OBJ_CLASS_SPEC {
41 friend class VMStructs;
43 protected:
44 // The ptr queue set to which this queue belongs.
45 PtrQueueSet* _qset;
47 // Whether updates should be logged.
48 bool _active;
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;
56 // The size of the buffer.
57 size_t _sz;
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;
64 // If there is a lock associated with this buffer, this is that lock.
65 Mutex* _lock;
67 PtrQueueSet* qset() { return _qset; }
68 bool is_permanent() const { return _perm; }
70 // Process queue entries and release resources, if not permanent.
71 void flush_impl();
73 public:
74 // Initialize this queue to contain a null buffer, and be part of the
75 // given PtrQueueSet.
76 PtrQueue(PtrQueueSet* qset, bool perm = false, bool active = false);
78 // Requires queue flushed or permanent.
79 ~PtrQueue();
81 // Associate a lock with a ptr queue.
82 void set_lock(Mutex* lock) { _lock = lock; }
84 void reset() { if (_buf != NULL) _index = _sz; }
86 void enqueue(volatile void* ptr) {
87 enqueue((void*)(ptr));
88 }
90 // Enqueues the given "obj".
91 void enqueue(void* ptr) {
92 if (!_active) return;
93 else enqueue_known_active(ptr);
94 }
96 // This method is called when we're doing the zero index handling
97 // and gives a chance to the queues to do any pre-enqueueing
98 // processing they might want to do on the buffer. It should return
99 // true if the buffer should be enqueued, or false if enough
100 // entries were cleared from it so that it can be re-used. It should
101 // not return false if the buffer is still full (otherwise we can
102 // get into an infinite loop).
103 virtual bool should_enqueue_buffer() { return true; }
104 void handle_zero_index();
105 void locking_enqueue_completed_buffer(void** buf);
107 void enqueue_known_active(void* ptr);
109 size_t size() {
110 assert(_sz >= _index, "Invariant.");
111 return _buf == NULL ? 0 : _sz - _index;
112 }
114 bool is_empty() {
115 return _buf == NULL || _sz == _index;
116 }
118 // Set the "active" property of the queue to "b". An enqueue to an
119 // inactive thread is a no-op. Setting a queue to inactive resets its
120 // log to the empty state.
121 void set_active(bool b) {
122 _active = b;
123 if (!b && _buf != NULL) {
124 _index = _sz;
125 } else if (b && _buf != NULL) {
126 assert(_index == _sz, "invariant: queues are empty when activated.");
127 }
128 }
130 bool is_active() { return _active; }
132 static int byte_index_to_index(int ind) {
133 assert((ind % oopSize) == 0, "Invariant.");
134 return ind / oopSize;
135 }
137 static int index_to_byte_index(int byte_ind) {
138 return byte_ind * oopSize;
139 }
141 // To support compiler.
142 static ByteSize byte_offset_of_index() {
143 return byte_offset_of(PtrQueue, _index);
144 }
145 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }
147 static ByteSize byte_offset_of_buf() {
148 return byte_offset_of(PtrQueue, _buf);
149 }
150 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }
152 static ByteSize byte_offset_of_active() {
153 return byte_offset_of(PtrQueue, _active);
154 }
155 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }
157 };
159 class BufferNode {
160 size_t _index;
161 BufferNode* _next;
162 public:
163 BufferNode() : _index(0), _next(NULL) { }
164 BufferNode* next() const { return _next; }
165 void set_next(BufferNode* n) { _next = n; }
166 size_t index() const { return _index; }
167 void set_index(size_t i) { _index = i; }
169 // Align the size of the structure to the size of the pointer
170 static size_t aligned_size() {
171 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*));
172 return alignment;
173 }
175 // BufferNode is allocated before the buffer.
176 // The chunk of memory that holds both of them is a block.
178 // Produce a new BufferNode given a buffer.
179 static BufferNode* new_from_buffer(void** buf) {
180 return new (make_block_from_buffer(buf)) BufferNode;
181 }
183 // The following are the required conversion routines:
184 static BufferNode* make_node_from_buffer(void** buf) {
185 return (BufferNode*)make_block_from_buffer(buf);
186 }
187 static void** make_buffer_from_node(BufferNode *node) {
188 return make_buffer_from_block(node);
189 }
190 static void* make_block_from_node(BufferNode *node) {
191 return (void*)node;
192 }
193 static void** make_buffer_from_block(void* p) {
194 return (void**)((char*)p + aligned_size());
195 }
196 static void* make_block_from_buffer(void** p) {
197 return (void*)((char*)p - aligned_size());
198 }
199 };
201 // A PtrQueueSet represents resources common to a set of pointer queues.
202 // In particular, the individual queues allocate buffers from this shared
203 // set, and return completed buffers to the set.
204 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???
205 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {
206 protected:
207 Monitor* _cbl_mon; // Protects the fields below.
208 BufferNode* _completed_buffers_head;
209 BufferNode* _completed_buffers_tail;
210 int _n_completed_buffers;
211 int _process_completed_threshold;
212 volatile bool _process_completed;
214 // This (and the interpretation of the first element as a "next"
215 // pointer) are protected by the TLOQ_FL_lock.
216 Mutex* _fl_lock;
217 BufferNode* _buf_free_list;
218 size_t _buf_free_list_sz;
219 // Queue set can share a freelist. The _fl_owner variable
220 // specifies the owner. It is set to "this" by default.
221 PtrQueueSet* _fl_owner;
223 // The size of all buffers in the set.
224 size_t _sz;
226 bool _all_active;
228 // If true, notify_all on _cbl_mon when the threshold is reached.
229 bool _notify_when_complete;
231 // Maximum number of elements allowed on completed queue: after that,
232 // enqueuer does the work itself. Zero indicates no maximum.
233 int _max_completed_queue;
234 int _completed_queue_padding;
236 int completed_buffers_list_length();
237 void assert_completed_buffer_list_len_correct_locked();
238 void assert_completed_buffer_list_len_correct();
240 protected:
241 // A mutator thread does the the work of processing a buffer.
242 // Returns "true" iff the work is complete (and the buffer may be
243 // deallocated).
244 virtual bool mut_process_buffer(void** buf) {
245 ShouldNotReachHere();
246 return false;
247 }
249 public:
250 // Create an empty ptr queue set.
251 PtrQueueSet(bool notify_when_complete = false);
253 // Because of init-order concerns, we can't pass these as constructor
254 // arguments.
255 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
256 int process_completed_threshold,
257 int max_completed_queue,
258 PtrQueueSet *fl_owner = NULL) {
259 _max_completed_queue = max_completed_queue;
260 _process_completed_threshold = process_completed_threshold;
261 _completed_queue_padding = 0;
262 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");
263 _cbl_mon = cbl_mon;
264 _fl_lock = fl_lock;
265 _fl_owner = (fl_owner != NULL) ? fl_owner : this;
266 }
268 // Return an empty oop array of size _sz (required to be non-zero).
269 void** allocate_buffer();
271 // Return an empty buffer to the free list. The "buf" argument is
272 // required to be a pointer to the head of an array of length "_sz".
273 void deallocate_buffer(void** buf);
275 // Declares that "buf" is a complete buffer.
276 void enqueue_complete_buffer(void** buf, size_t index = 0);
278 // To be invoked by the mutator.
279 bool process_or_enqueue_complete_buffer(void** buf);
281 bool completed_buffers_exist_dirty() {
282 return _n_completed_buffers > 0;
283 }
285 bool process_completed_buffers() { return _process_completed; }
286 void set_process_completed(bool x) { _process_completed = x; }
288 bool is_active() { return _all_active; }
290 // Set the buffer size. Should be called before any "enqueue" operation
291 // can be called. And should only be called once.
292 void set_buffer_size(size_t sz);
294 // Get the buffer size.
295 size_t buffer_size() { return _sz; }
297 // Get/Set the number of completed buffers that triggers log processing.
298 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; }
299 int process_completed_threshold() const { return _process_completed_threshold; }
301 // Must only be called at a safe point. Indicates that the buffer free
302 // list size may be reduced, if that is deemed desirable.
303 void reduce_free_list();
305 int completed_buffers_num() { return _n_completed_buffers; }
307 void merge_bufferlists(PtrQueueSet* src);
309 void set_max_completed_queue(int m) { _max_completed_queue = m; }
310 int max_completed_queue() { return _max_completed_queue; }
312 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; }
313 int completed_queue_padding() { return _completed_queue_padding; }
315 // Notify the consumer if the number of buffers crossed the threshold
316 void notify_if_necessary();
317 };
319 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP