1 /* 2 * Copyright (c) 2001, 2015, 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 #ifndef SHARE_VM_GC_G1_PTRQUEUE_HPP 26 #define SHARE_VM_GC_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 // Noncopyable - not defined. 44 PtrQueue(const PtrQueue&); 45 PtrQueue& operator=(const PtrQueue&); 46 47 // The ptr queue set to which this queue belongs. 48 PtrQueueSet* const _qset; 49 50 // Whether updates should be logged. 51 bool _active; 52 53 // If true, the queue is permanent, and doesn't need to deallocate 54 // its buffer in the destructor (since that obtains a lock which may not 55 // be legally locked by then. 56 const bool _permanent; 57 58 protected: 59 // The buffer. 60 void** _buf; 61 // The (byte) index at which an object was last enqueued. Starts at "_sz" 62 // (indicating an empty buffer) and goes towards zero. 63 size_t _index; 64 65 // The (byte) size of the buffer. 66 size_t _sz; 67 68 // If there is a lock associated with this buffer, this is that lock. 69 Mutex* _lock; 70 71 PtrQueueSet* qset() { return _qset; } 72 bool is_permanent() const { return _permanent; } 73 74 // Process queue entries and release resources, if not permanent. 75 void flush_impl(); 76 77 // Initialize this queue to contain a null buffer, and be part of the 78 // given PtrQueueSet. 79 PtrQueue(PtrQueueSet* qset, bool permanent = false, bool active = false); 80 81 // Requires queue flushed or permanent. 82 ~PtrQueue(); 83 84 public: 85 86 // Associate a lock with a ptr queue. 87 void set_lock(Mutex* lock) { _lock = lock; } 88 89 void reset() { if (_buf != NULL) _index = _sz; } 90 91 void enqueue(volatile void* ptr) { 92 enqueue((void*)(ptr)); 93 } 94 95 // Enqueues the given "obj". 96 void enqueue(void* ptr) { 97 if (!_active) return; 98 else enqueue_known_active(ptr); 99 } 100 101 // This method is called when we're doing the zero index handling 102 // and gives a chance to the queues to do any pre-enqueueing 103 // processing they might want to do on the buffer. It should return 104 // true if the buffer should be enqueued, or false if enough 105 // entries were cleared from it so that it can be re-used. It should 106 // not return false if the buffer is still full (otherwise we can 107 // get into an infinite loop). 108 virtual bool should_enqueue_buffer() { return true; } 109 void handle_zero_index(); 110 void locking_enqueue_completed_buffer(void** buf); 111 112 void enqueue_known_active(void* ptr); 113 114 size_t size() { 115 assert(_sz >= _index, "Invariant."); 116 return _buf == NULL ? 0 : _sz - _index; 117 } 118 119 bool is_empty() { 120 return _buf == NULL || _sz == _index; 121 } 122 123 // Set the "active" property of the queue to "b". An enqueue to an 124 // inactive thread is a no-op. Setting a queue to inactive resets its 125 // log to the empty state. 126 void set_active(bool b) { 127 _active = b; 128 if (!b && _buf != NULL) { 129 _index = _sz; 130 } else if (b && _buf != NULL) { 131 assert(_index == _sz, "invariant: queues are empty when activated."); 132 } 133 } 134 135 bool is_active() { return _active; } 136 137 static size_t byte_index_to_index(size_t ind) { 138 assert((ind % sizeof(void*)) == 0, "Invariant."); 139 return ind / sizeof(void*); 140 } 141 142 // To support compiler. 143 static ByteSize byte_offset_of_index() { 144 return byte_offset_of(PtrQueue, _index); 145 } 146 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); } 147 148 static ByteSize byte_offset_of_buf() { 149 return byte_offset_of(PtrQueue, _buf); 150 } 151 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); } 152 153 static ByteSize byte_offset_of_active() { 154 return byte_offset_of(PtrQueue, _active); 155 } 156 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); } 157 158 }; 159 160 class BufferNode { 161 size_t _index; 162 BufferNode* _next; 163 public: 164 BufferNode() : _index(0), _next(NULL) { } 165 BufferNode* next() const { return _next; } 166 void set_next(BufferNode* n) { _next = n; } 167 size_t index() const { return _index; } 168 void set_index(size_t i) { _index = i; } 169 170 // Align the size of the structure to the size of the pointer 171 static size_t aligned_size() { 172 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*)); 173 return alignment; 174 } 175 176 // BufferNode is allocated before the buffer. 177 // The chunk of memory that holds both of them is a block. 178 179 // Produce a new BufferNode given a buffer. 180 static BufferNode* new_from_buffer(void** buf) { 181 return new (make_block_from_buffer(buf)) BufferNode; 182 } 183 184 // The following are the required conversion routines: 185 static BufferNode* make_node_from_buffer(void** buf) { 186 return (BufferNode*)make_block_from_buffer(buf); 187 } 188 static void** make_buffer_from_node(BufferNode *node) { 189 return make_buffer_from_block(node); 190 } 191 static void* make_block_from_node(BufferNode *node) { 192 return (void*)node; 193 } 194 static void** make_buffer_from_block(void* p) { 195 return (void**)((char*)p + aligned_size()); 196 } 197 static void* make_block_from_buffer(void** p) { 198 return (void*)((char*)p - aligned_size()); 199 } 200 }; 201 202 // A PtrQueueSet represents resources common to a set of pointer queues. 203 // In particular, the individual queues allocate buffers from this shared 204 // set, and return completed buffers to the set. 205 // All these variables are are protected by the TLOQ_CBL_mon. XXX ??? 206 class PtrQueueSet VALUE_OBJ_CLASS_SPEC { 207 protected: 208 Monitor* _cbl_mon; // Protects the fields below. 209 BufferNode* _completed_buffers_head; 210 BufferNode* _completed_buffers_tail; 211 int _n_completed_buffers; 212 int _process_completed_threshold; 213 volatile bool _process_completed; 214 215 // This (and the interpretation of the first element as a "next" 216 // pointer) are protected by the TLOQ_FL_lock. 217 Mutex* _fl_lock; 218 BufferNode* _buf_free_list; 219 size_t _buf_free_list_sz; 220 // Queue set can share a freelist. The _fl_owner variable 221 // specifies the owner. It is set to "this" by default. 222 PtrQueueSet* _fl_owner; 223 224 // The size of all buffers in the set. 225 size_t _sz; 226 227 bool _all_active; 228 229 // If true, notify_all on _cbl_mon when the threshold is reached. 230 bool _notify_when_complete; 231 232 // Maximum number of elements allowed on completed queue: after that, 233 // enqueuer does the work itself. Zero indicates no maximum. 234 int _max_completed_queue; 235 int _completed_queue_padding; 236 237 int completed_buffers_list_length(); 238 void assert_completed_buffer_list_len_correct_locked(); 239 void assert_completed_buffer_list_len_correct(); 240 241 protected: 242 // A mutator thread does the the work of processing a buffer. 243 // Returns "true" iff the work is complete (and the buffer may be 244 // deallocated). 245 virtual bool mut_process_buffer(void** buf) { 246 ShouldNotReachHere(); 247 return false; 248 } 249 250 // Create an empty ptr queue set. 251 PtrQueueSet(bool notify_when_complete = false); 252 ~PtrQueueSet(); 253 254 // Because of init-order concerns, we can't pass these as constructor 255 // arguments. 256 void initialize(Monitor* cbl_mon, 257 Mutex* fl_lock, 258 int process_completed_threshold, 259 int max_completed_queue, 260 PtrQueueSet *fl_owner = NULL); 261 262 public: 263 264 // Return an empty array of size _sz (required to be non-zero). 265 void** allocate_buffer(); 266 267 // Return an empty buffer to the free list. The "buf" argument is 268 // required to be a pointer to the head of an array of length "_sz". 269 void deallocate_buffer(void** buf); 270 271 // Declares that "buf" is a complete buffer. 272 void enqueue_complete_buffer(void** buf, size_t index = 0); 273 274 // To be invoked by the mutator. 275 bool process_or_enqueue_complete_buffer(void** buf); 276 277 bool completed_buffers_exist_dirty() { 278 return _n_completed_buffers > 0; 279 } 280 281 bool process_completed_buffers() { return _process_completed; } 282 void set_process_completed(bool x) { _process_completed = x; } 283 284 bool is_active() { return _all_active; } 285 286 // Set the buffer size. Should be called before any "enqueue" operation 287 // can be called. And should only be called once. 288 void set_buffer_size(size_t sz); 289 290 // Get the buffer size. 291 size_t buffer_size() { return _sz; } 292 293 // Get/Set the number of completed buffers that triggers log processing. 294 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; } 295 int process_completed_threshold() const { return _process_completed_threshold; } 296 297 // Must only be called at a safe point. Indicates that the buffer free 298 // list size may be reduced, if that is deemed desirable. 299 void reduce_free_list(); 300 301 int completed_buffers_num() { return _n_completed_buffers; } 302 303 void merge_bufferlists(PtrQueueSet* src); 304 305 void set_max_completed_queue(int m) { _max_completed_queue = m; } 306 int max_completed_queue() { return _max_completed_queue; } 307 308 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; } 309 int completed_queue_padding() { return _completed_queue_padding; } 310 311 // Notify the consumer if the number of buffers crossed the threshold 312 void notify_if_necessary(); 313 }; 314 315 #endif // SHARE_VM_GC_G1_PTRQUEUE_HPP