1 /* 2 * Copyright (c) 2001, 2010, 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*, bool perm = false, bool active = false); 72 // Release any contained resources. 73 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 void handle_zero_index(); 89 void locking_enqueue_completed_buffer(void** buf); 90 91 void enqueue_known_active(void* ptr); 92 93 size_t size() { 94 assert(_sz >= _index, "Invariant."); 95 return _buf == NULL ? 0 : _sz - _index; 96 } 97 98 bool is_empty() { 99 return _buf == NULL || _sz == _index; 100 } 101 102 // Set the "active" property of the queue to "b". An enqueue to an 103 // inactive thread is a no-op. Setting a queue to inactive resets its 104 // log to the empty state. 105 void set_active(bool b) { 106 _active = b; 107 if (!b && _buf != NULL) { 108 _index = _sz; 109 } else if (b && _buf != NULL) { 110 assert(_index == _sz, "invariant: queues are empty when activated."); 111 } 112 } 113 114 bool is_active() { return _active; } 115 116 static int byte_index_to_index(int ind) { 117 assert((ind % oopSize) == 0, "Invariant."); 118 return ind / oopSize; 119 } 120 121 static int index_to_byte_index(int byte_ind) { 122 return byte_ind * oopSize; 123 } 124 125 // To support compiler. 126 static ByteSize byte_offset_of_index() { 127 return byte_offset_of(PtrQueue, _index); 128 } 129 static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); } 130 131 static ByteSize byte_offset_of_buf() { 132 return byte_offset_of(PtrQueue, _buf); 133 } 134 static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); } 135 136 static ByteSize byte_offset_of_active() { 137 return byte_offset_of(PtrQueue, _active); 138 } 139 static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); } 140 141 }; 142 143 class BufferNode { 144 size_t _index; 145 BufferNode* _next; 146 public: 147 BufferNode() : _index(0), _next(NULL) { } 148 BufferNode* next() const { return _next; } 149 void set_next(BufferNode* n) { _next = n; } 150 size_t index() const { return _index; } 151 void set_index(size_t i) { _index = i; } 152 153 // Align the size of the structure to the size of the pointer 154 static size_t aligned_size() { 155 static const size_t alignment = round_to(sizeof(BufferNode), sizeof(void*)); 156 return alignment; 157 } 158 159 // BufferNode is allocated before the buffer. 160 // The chunk of memory that holds both of them is a block. 161 162 // Produce a new BufferNode given a buffer. 163 static BufferNode* new_from_buffer(void** buf) { 164 return new (make_block_from_buffer(buf)) BufferNode; 165 } 166 167 // The following are the required conversion routines: 168 static BufferNode* make_node_from_buffer(void** buf) { 169 return (BufferNode*)make_block_from_buffer(buf); 170 } 171 static void** make_buffer_from_node(BufferNode *node) { 172 return make_buffer_from_block(node); 173 } 174 static void* make_block_from_node(BufferNode *node) { 175 return (void*)node; 176 } 177 static void** make_buffer_from_block(void* p) { 178 return (void**)((char*)p + aligned_size()); 179 } 180 static void* make_block_from_buffer(void** p) { 181 return (void*)((char*)p - aligned_size()); 182 } 183 }; 184 185 // A PtrQueueSet represents resources common to a set of pointer queues. 186 // In particular, the individual queues allocate buffers from this shared 187 // set, and return completed buffers to the set. 188 // All these variables are are protected by the TLOQ_CBL_mon. XXX ??? 189 class PtrQueueSet VALUE_OBJ_CLASS_SPEC { 190 protected: 191 Monitor* _cbl_mon; // Protects the fields below. 192 BufferNode* _completed_buffers_head; 193 BufferNode* _completed_buffers_tail; 194 int _n_completed_buffers; 195 int _process_completed_threshold; 196 volatile bool _process_completed; 197 198 // This (and the interpretation of the first element as a "next" 199 // pointer) are protected by the TLOQ_FL_lock. 200 Mutex* _fl_lock; 201 BufferNode* _buf_free_list; 202 size_t _buf_free_list_sz; 203 // Queue set can share a freelist. The _fl_owner variable 204 // specifies the owner. It is set to "this" by default. 205 PtrQueueSet* _fl_owner; 206 207 // The size of all buffers in the set. 208 size_t _sz; 209 210 bool _all_active; 211 212 // If true, notify_all on _cbl_mon when the threshold is reached. 213 bool _notify_when_complete; 214 215 // Maximum number of elements allowed on completed queue: after that, 216 // enqueuer does the work itself. Zero indicates no maximum. 217 int _max_completed_queue; 218 int _completed_queue_padding; 219 220 int completed_buffers_list_length(); 221 void assert_completed_buffer_list_len_correct_locked(); 222 void assert_completed_buffer_list_len_correct(); 223 224 protected: 225 // A mutator thread does the the work of processing a buffer. 226 // Returns "true" iff the work is complete (and the buffer may be 227 // deallocated). 228 virtual bool mut_process_buffer(void** buf) { 229 ShouldNotReachHere(); 230 return false; 231 } 232 233 public: 234 // Create an empty ptr queue set. 235 PtrQueueSet(bool notify_when_complete = false); 236 237 // Because of init-order concerns, we can't pass these as constructor 238 // arguments. 239 void initialize(Monitor* cbl_mon, Mutex* fl_lock, 240 int process_completed_threshold, 241 int max_completed_queue, 242 PtrQueueSet *fl_owner = NULL) { 243 _max_completed_queue = max_completed_queue; 244 _process_completed_threshold = process_completed_threshold; 245 _completed_queue_padding = 0; 246 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?"); 247 _cbl_mon = cbl_mon; 248 _fl_lock = fl_lock; 249 _fl_owner = (fl_owner != NULL) ? fl_owner : this; 250 } 251 252 // Return an empty oop array of size _sz (required to be non-zero). 253 void** allocate_buffer(); 254 255 // Return an empty buffer to the free list. The "buf" argument is 256 // required to be a pointer to the head of an array of length "_sz". 257 void deallocate_buffer(void** buf); 258 259 // Declares that "buf" is a complete buffer. 260 void enqueue_complete_buffer(void** buf, size_t index = 0); 261 262 // To be invoked by the mutator. 263 bool process_or_enqueue_complete_buffer(void** buf); 264 265 bool completed_buffers_exist_dirty() { 266 return _n_completed_buffers > 0; 267 } 268 269 bool process_completed_buffers() { return _process_completed; } 270 void set_process_completed(bool x) { _process_completed = x; } 271 272 bool is_active() { return _all_active; } 273 274 // Set the buffer size. Should be called before any "enqueue" operation 275 // can be called. And should only be called once. 276 void set_buffer_size(size_t sz); 277 278 // Get the buffer size. 279 size_t buffer_size() { return _sz; } 280 281 // Get/Set the number of completed buffers that triggers log processing. 282 void set_process_completed_threshold(int sz) { _process_completed_threshold = sz; } 283 int process_completed_threshold() const { return _process_completed_threshold; } 284 285 // Must only be called at a safe point. Indicates that the buffer free 286 // list size may be reduced, if that is deemed desirable. 287 void reduce_free_list(); 288 289 int completed_buffers_num() { return _n_completed_buffers; } 290 291 void merge_bufferlists(PtrQueueSet* src); 292 293 void set_max_completed_queue(int m) { _max_completed_queue = m; } 294 int max_completed_queue() { return _max_completed_queue; } 295 296 void set_completed_queue_padding(int padding) { _completed_queue_padding = padding; } 297 int completed_queue_padding() { return _completed_queue_padding; } 298 299 // Notify the consumer if the number of buffers crossed the threshold 300 void notify_if_necessary(); 301 }; 302 303 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_PTRQUEUE_HPP