1 /* 2 * Copyright (c) 2001, 2016, 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 class PtrQueueSet; 37 class PtrQueue VALUE_OBJ_CLASS_SPEC { 38 friend class VMStructs; 39 40 // Noncopyable - not defined. 41 PtrQueue(const PtrQueue&); 42 PtrQueue& operator=(const PtrQueue&); 43 44 // The ptr queue set to which this queue belongs. 45 PtrQueueSet* const _qset; 46 47 // Whether updates should be logged. 48 bool _active; 49 50 // If true, the queue is permanent, and doesn't need to deallocate 51 // its buffer in the destructor (since that obtains a lock which may not 52 // be legally locked by then. 53 const bool _permanent; 54 55 protected: 56 // The buffer. 57 void** _buf; 58 // The (byte) index at which an object was last enqueued. Starts at "_sz" 59 // (indicating an empty buffer) and goes towards zero. 60 size_t _index; 61 62 // The (byte) size of the buffer. 63 size_t _sz; 64 65 // If there is a lock associated with this buffer, this is that lock. 66 Mutex* _lock; 67 68 PtrQueueSet* qset() { return _qset; } 69 bool is_permanent() const { return _permanent; } 70 71 // Process queue entries and release resources, if not permanent. 72 void flush_impl(); 73 74 // Initialize this queue to contain a null buffer, and be part of the 75 // given PtrQueueSet. 76 PtrQueue(PtrQueueSet* qset, bool permanent = false, bool active = false); 77 78 // Requires queue flushed or permanent. 79 ~PtrQueue(); 80 81 public: 82 83 // Associate a lock with a ptr queue. 84 void set_lock(Mutex* lock) { _lock = lock; } 85 86 void reset() { if (_buf != NULL) _index = _sz; } 87 88 void enqueue(volatile void* ptr) { 89 enqueue((void*)(ptr)); 90 } 91 92 // Enqueues the given "obj". 93 void enqueue(void* ptr) { 94 if (!_active) return; 95 else enqueue_known_active(ptr); 96 } 97 98 // This method is called when we're doing the zero index handling 99 // and gives a chance to the queues to do any pre-enqueueing 100 // processing they might want to do on the buffer. It should return 101 // true if the buffer should be enqueued, or false if enough 102 // entries were cleared from it so that it can be re-used. It should 103 // not return false if the buffer is still full (otherwise we can 104 // get into an infinite loop). 105 virtual bool should_enqueue_buffer() { return true; } 106 void handle_zero_index(); 107 void locking_enqueue_completed_buffer(void** buf); 108 109 void enqueue_known_active(void* ptr); 110 111 size_t size() { 112 assert(_sz >= _index, "Invariant."); 113 return _buf == NULL ? 0 : _sz - _index; 114 } 115 116 bool is_empty() { 117 return _buf == NULL || _sz == _index; 118 } 119 120 // Set the "active" property of the queue to "b". An enqueue to an 121 // inactive thread is a no-op. Setting a queue to inactive resets its 122 // log to the empty state. 123 void set_active(bool b) { 124 _active = b; 125 if (!b && _buf != NULL) { 126 _index = _sz; 127 } else if (b && _buf != NULL) { 128 assert(_index == _sz, "invariant: queues are empty when activated."); 129 } 130 } 131 132 bool is_active() { return _active; } 133 134 static size_t byte_index_to_index(size_t ind) { 135 assert((ind % sizeof(void*)) == 0, "Invariant."); 136 return ind / sizeof(void*); 137 } 138 139 // To support compiler. 140 141 protected: 142 template<typename Derived> 143 static ByteSize byte_offset_of_index() { 144 return byte_offset_of(Derived, _index); 145 } 146 147 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); } 148 149 template<typename Derived> 150 static ByteSize byte_offset_of_buf() { 151 return byte_offset_of(Derived, _buf); 152 } 153 154 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); } 155 156 template<typename Derived> 157 static ByteSize byte_offset_of_active() { 158 return byte_offset_of(Derived, _active); 159 } 160 161 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); } 162 163 }; 164 165 class BufferNode { 166 size_t _index; 167 BufferNode* _next; 168 void* _buffer[1]; // Pseudo flexible array member. 169 170 BufferNode() : _index(0), _next(NULL) { } 171 ~BufferNode() { } 172 173 static size_t buffer_offset() { 174 return offset_of(BufferNode, _buffer); 175 } 176 177 public: 178 BufferNode* next() const { return _next; } 179 void set_next(BufferNode* n) { _next = n; } 180 size_t index() const { return _index; } 181 void set_index(size_t i) { _index = i; } 182 183 // Allocate a new BufferNode with the "buffer" having size bytes. 184 static BufferNode* allocate(size_t byte_size); 185 186 // Free a BufferNode. 187 static void deallocate(BufferNode* node); 188 189 // Return the BufferNode containing the buffer. 190 static BufferNode* make_node_from_buffer(void** buffer) { 191 return reinterpret_cast<BufferNode*>( 192 reinterpret_cast<char*>(buffer) - buffer_offset()); 193 } 194 195 // Return the buffer for node. 196 static void** make_buffer_from_node(BufferNode *node) { 197 // &_buffer[0] might lead to index out of bounds warnings. 198 return reinterpret_cast<void**>( 199 reinterpret_cast<char*>(node) + buffer_offset()); 200 } 201 }; 202 203 // A PtrQueueSet represents resources common to a set of pointer queues. 204 // In particular, the individual queues allocate buffers from this shared 205 // set, and return completed buffers to the set. 206 // All these variables are are protected by the TLOQ_CBL_mon. XXX ??? 207 class PtrQueueSet VALUE_OBJ_CLASS_SPEC { 208 protected: 209 Monitor* _cbl_mon; // Protects the fields below. 210 BufferNode* _completed_buffers_head; 211 BufferNode* _completed_buffers_tail; 212 int _n_completed_buffers; 213 int _process_completed_threshold; 214 volatile bool _process_completed; 215 216 // This (and the interpretation of the first element as a "next" 217 // pointer) are protected by the TLOQ_FL_lock. 218 Mutex* _fl_lock; 219 BufferNode* _buf_free_list; 220 size_t _buf_free_list_sz; 221 // Queue set can share a freelist. The _fl_owner variable 222 // specifies the owner. It is set to "this" by default. 223 PtrQueueSet* _fl_owner; 224 225 // The size of all buffers in the set. 226 size_t _sz; 227 228 bool _all_active; 229 230 // If true, notify_all on _cbl_mon when the threshold is reached. 231 bool _notify_when_complete; 232 233 // Maximum number of elements allowed on completed queue: after that, 234 // enqueuer does the work itself. Zero indicates no maximum. 235 int _max_completed_queue; 236 int _completed_queue_padding; 237 238 int completed_buffers_list_length(); 239 void assert_completed_buffer_list_len_correct_locked(); 240 void assert_completed_buffer_list_len_correct(); 241 242 protected: 243 // A mutator thread does the the work of processing a buffer. 244 // Returns "true" iff the work is complete (and the buffer may be 245 // deallocated). 246 virtual bool mut_process_buffer(void** buf) { 247 ShouldNotReachHere(); 248 return false; 249 } 250 251 // Create an empty ptr queue set. 252 PtrQueueSet(bool notify_when_complete = false); 253 ~PtrQueueSet(); 254 255 // Because of init-order concerns, we can't pass these as constructor 256 // arguments. 257 void initialize(Monitor* cbl_mon, 258 Mutex* fl_lock, 259 int process_completed_threshold, 260 int max_completed_queue, 261 PtrQueueSet *fl_owner = NULL); 262 263 public: 264 265 // Return an empty 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_G1_PTRQUEUE_HPP