1 /* 2 * Copyright (c) 2001, 2018, 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 #include "precompiled.hpp" 26 #include "gc/shared/ptrQueue.hpp" 27 #include "memory/allocation.hpp" 28 #include "memory/allocation.inline.hpp" 29 #include "runtime/mutex.hpp" 30 #include "runtime/mutexLocker.hpp" 31 #include "runtime/thread.inline.hpp" 32 33 #include <new> 34 35 PtrQueue::PtrQueue(PtrQueueSet* qset, bool permanent, bool active) : 36 _qset(qset), 37 _active(active), 38 _permanent(permanent), 39 _index(0), 40 _capacity_in_bytes(0), 41 _buf(NULL), 42 _lock(NULL) 43 {} 44 45 PtrQueue::~PtrQueue() { 46 assert(_permanent || (_buf == NULL), "queue must be flushed before delete"); 47 } 48 49 void PtrQueue::flush_impl() { 50 if (_buf != NULL) { 51 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index()); 52 if (is_empty()) { 53 // No work to do. 54 qset()->deallocate_buffer(node); 55 } else { 56 qset()->enqueue_complete_buffer(node); 57 } 58 _buf = NULL; 59 set_index(0); 60 } 61 } 62 63 64 void PtrQueue::enqueue_known_active(void* ptr) { 65 while (_index == 0) { 66 handle_zero_index(); 67 } 68 69 assert(_buf != NULL, "postcondition"); 70 assert(index() > 0, "postcondition"); 71 assert(index() <= capacity(), "invariant"); 72 _index -= _element_size; 73 _buf[index()] = ptr; 74 } 75 76 void PtrQueue::locking_enqueue_completed_buffer(BufferNode* node) { 77 assert(_lock->owned_by_self(), "Required."); 78 qset()->enqueue_complete_buffer(node); 79 } 80 81 82 BufferNode* BufferNode::allocate(size_t size) { 83 size_t byte_size = size * sizeof(void*); 84 void* data = NEW_C_HEAP_ARRAY(char, buffer_offset() + byte_size, mtGC); 85 return new (data) BufferNode; 86 } 87 88 void BufferNode::deallocate(BufferNode* node) { 89 node->~BufferNode(); 90 FREE_C_HEAP_ARRAY(char, node); 91 } 92 93 PtrQueueSet::PtrQueueSet(bool notify_when_complete) : 94 _buffer_size(0), 95 _cbl_mon(NULL), 96 _completed_buffers_head(NULL), 97 _completed_buffers_tail(NULL), 98 _n_completed_buffers(0), 99 _process_completed_threshold(0), 100 _process_completed(false), 101 _fl_lock(NULL), 102 _buf_free_list(NULL), 103 _buf_free_list_sz(0), 104 _fl_owner(NULL), 105 _all_active(false), 106 _notify_when_complete(notify_when_complete), 107 _max_completed_queue(0), 108 _completed_queue_padding(0) 109 { 110 _fl_owner = this; 111 } 112 113 PtrQueueSet::~PtrQueueSet() { 114 // There are presently only a couple (derived) instances ever 115 // created, and they are permanent, so no harm currently done by 116 // doing nothing here. 117 } 118 119 void PtrQueueSet::initialize(Monitor* cbl_mon, 120 Mutex* fl_lock, 121 int process_completed_threshold, 122 int max_completed_queue, 123 PtrQueueSet *fl_owner) { 124 _max_completed_queue = max_completed_queue; 125 _process_completed_threshold = process_completed_threshold; 126 _completed_queue_padding = 0; 127 assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?"); 128 _cbl_mon = cbl_mon; 129 _fl_lock = fl_lock; 130 _fl_owner = (fl_owner != NULL) ? fl_owner : this; 131 } 132 133 void** PtrQueueSet::allocate_buffer() { 134 BufferNode* node = NULL; 135 { 136 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag); 137 node = _fl_owner->_buf_free_list; 138 if (node != NULL) { 139 _fl_owner->_buf_free_list = node->next(); 140 _fl_owner->_buf_free_list_sz--; 141 } 142 } 143 if (node == NULL) { 144 node = BufferNode::allocate(buffer_size()); 145 } else { 146 // Reinitialize buffer obtained from free list. 147 node->set_index(0); 148 node->set_next(NULL); 149 } 150 return BufferNode::make_buffer_from_node(node); 151 } 152 153 void PtrQueueSet::deallocate_buffer(BufferNode* node) { 154 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag); 155 node->set_next(_fl_owner->_buf_free_list); 156 _fl_owner->_buf_free_list = node; 157 _fl_owner->_buf_free_list_sz++; 158 } 159 160 void PtrQueueSet::reduce_free_list() { 161 assert(_fl_owner == this, "Free list reduction is allowed only for the owner"); 162 // For now we'll adopt the strategy of deleting half. 163 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag); 164 size_t n = _buf_free_list_sz / 2; 165 for (size_t i = 0; i < n; ++i) { 166 assert(_buf_free_list != NULL, 167 "_buf_free_list_sz is wrong: " SIZE_FORMAT, _buf_free_list_sz); 168 BufferNode* node = _buf_free_list; 169 _buf_free_list = node->next(); 170 _buf_free_list_sz--; 171 BufferNode::deallocate(node); 172 } 173 } 174 175 void PtrQueue::handle_zero_index() { 176 assert(index() == 0, "precondition"); 177 178 // This thread records the full buffer and allocates a new one (while 179 // holding the lock if there is one). 180 if (_buf != NULL) { 181 if (!should_enqueue_buffer()) { 182 assert(index() > 0, "the buffer can only be re-used if it's not full"); 183 return; 184 } 185 186 if (_lock) { 187 assert(_lock->owned_by_self(), "Required."); 188 189 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index()); 190 _buf = NULL; // clear shared _buf field 191 192 locking_enqueue_completed_buffer(node); // enqueue completed buffer 193 assert(_buf == NULL, "multiple enqueuers appear to be racing"); 194 } else { 195 BufferNode* node = BufferNode::make_node_from_buffer(_buf, index()); 196 if (qset()->process_or_enqueue_complete_buffer(node)) { 197 // Recycle the buffer. No allocation. 198 assert(_buf == BufferNode::make_buffer_from_node(node), "invariant"); 199 assert(capacity() == qset()->buffer_size(), "invariant"); 200 reset(); 201 return; 202 } 203 } 204 } 205 // Set capacity in case this is the first allocation. 206 set_capacity(qset()->buffer_size()); 207 // Allocate a new buffer. 208 _buf = qset()->allocate_buffer(); 209 reset(); 210 } 211 212 bool PtrQueueSet::process_or_enqueue_complete_buffer(BufferNode* node) { 213 if (Thread::current()->is_Java_thread()) { 214 // We don't lock. It is fine to be epsilon-precise here. 215 if (_max_completed_queue == 0 || 216 (_max_completed_queue > 0 && 217 _n_completed_buffers >= _max_completed_queue + _completed_queue_padding)) { 218 bool b = mut_process_buffer(node); 219 if (b) { 220 // True here means that the buffer hasn't been deallocated and the caller may reuse it. 221 return true; 222 } 223 } 224 } 225 // The buffer will be enqueued. The caller will have to get a new one. 226 enqueue_complete_buffer(node); 227 return false; 228 } 229 230 void PtrQueueSet::enqueue_complete_buffer(BufferNode* cbn) { 231 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 232 cbn->set_next(NULL); 233 if (_completed_buffers_tail == NULL) { 234 assert(_completed_buffers_head == NULL, "Well-formedness"); 235 _completed_buffers_head = cbn; 236 _completed_buffers_tail = cbn; 237 } else { 238 _completed_buffers_tail->set_next(cbn); 239 _completed_buffers_tail = cbn; 240 } 241 _n_completed_buffers++; 242 243 if (!_process_completed && _process_completed_threshold >= 0 && 244 _n_completed_buffers >= (size_t)_process_completed_threshold) { 245 _process_completed = true; 246 if (_notify_when_complete) { 247 _cbl_mon->notify(); 248 } 249 } 250 DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked()); 251 } 252 253 size_t PtrQueueSet::completed_buffers_list_length() { 254 size_t n = 0; 255 BufferNode* cbn = _completed_buffers_head; 256 while (cbn != NULL) { 257 n++; 258 cbn = cbn->next(); 259 } 260 return n; 261 } 262 263 void PtrQueueSet::assert_completed_buffer_list_len_correct() { 264 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 265 assert_completed_buffer_list_len_correct_locked(); 266 } 267 268 void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() { 269 guarantee(completed_buffers_list_length() == _n_completed_buffers, 270 "Completed buffer length is wrong."); 271 } 272 273 void PtrQueueSet::set_buffer_size(size_t sz) { 274 assert(_buffer_size == 0 && sz > 0, "Should be called only once."); 275 _buffer_size = sz; 276 } 277 278 // Merge lists of buffers. Notify the processing threads. 279 // The source queue is emptied as a result. The queues 280 // must share the monitor. 281 void PtrQueueSet::merge_bufferlists(PtrQueueSet *src) { 282 assert(_cbl_mon == src->_cbl_mon, "Should share the same lock"); 283 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 284 if (_completed_buffers_tail == NULL) { 285 assert(_completed_buffers_head == NULL, "Well-formedness"); 286 _completed_buffers_head = src->_completed_buffers_head; 287 _completed_buffers_tail = src->_completed_buffers_tail; 288 } else { 289 assert(_completed_buffers_head != NULL, "Well formedness"); 290 if (src->_completed_buffers_head != NULL) { 291 _completed_buffers_tail->set_next(src->_completed_buffers_head); 292 _completed_buffers_tail = src->_completed_buffers_tail; 293 } 294 } 295 _n_completed_buffers += src->_n_completed_buffers; 296 297 src->_n_completed_buffers = 0; 298 src->_completed_buffers_head = NULL; 299 src->_completed_buffers_tail = NULL; 300 301 assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL || 302 _completed_buffers_head != NULL && _completed_buffers_tail != NULL, 303 "Sanity"); 304 } 305 306 void PtrQueueSet::notify_if_necessary() { 307 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 308 assert(_process_completed_threshold >= 0, "_process_completed is negative"); 309 if (_n_completed_buffers >= (size_t)_process_completed_threshold || _max_completed_queue == 0) { 310 _process_completed = true; 311 if (_notify_when_complete) 312 _cbl_mon->notify(); 313 } 314 }