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 21 * questions. 22 * 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) { assert(n != this, "no loops"); _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