1 /* 2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25 # include "incls/_precompiled.incl" 26 # include "incls/_ptrQueue.cpp.incl" 27 28 PtrQueue::PtrQueue(PtrQueueSet* qset_, bool perm) : 29 _qset(qset_), _buf(NULL), _index(0), _active(false), 30 _perm(perm), _lock(NULL) 31 {} 32 33 void PtrQueue::flush() { 34 if (!_perm && _buf != NULL) { 35 if (_index == _sz) { 36 // No work to do. 37 qset()->deallocate_buffer(_buf); 38 } else { 39 // We must NULL out the unused entries, then enqueue. 40 for (size_t i = 0; i < _index; i += oopSize) { 41 _buf[byte_index_to_index((int)i)] = NULL; 42 } 43 qset()->enqueue_complete_buffer(_buf); 44 } 45 _buf = NULL; 46 _index = 0; 47 } 48 } 49 50 51 static int byte_index_to_index(int ind) { 52 assert((ind % oopSize) == 0, "Invariant."); 53 return ind / oopSize; 54 } 55 56 static int index_to_byte_index(int byte_ind) { 57 return byte_ind * oopSize; 58 } 59 60 void PtrQueue::enqueue_known_active(void* ptr) { 61 assert(0 <= _index && _index <= _sz, "Invariant."); 62 assert(_index == 0 || _buf != NULL, "invariant"); 63 64 while (_index == 0) { 65 handle_zero_index(); 66 } 67 assert(_index > 0, "postcondition"); 68 69 _index -= oopSize; 70 _buf[byte_index_to_index((int)_index)] = ptr; 71 assert(0 <= _index && _index <= _sz, "Invariant."); 72 } 73 74 void PtrQueue::locking_enqueue_completed_buffer(void** buf) { 75 assert(_lock->owned_by_self(), "Required."); 76 _lock->unlock(); 77 qset()->enqueue_complete_buffer(buf); 78 // We must relock only because the caller will unlock, for the normal 79 // case. 80 _lock->lock_without_safepoint_check(); 81 } 82 83 84 PtrQueueSet::PtrQueueSet(bool notify_when_complete) : 85 _max_completed_queue(0), 86 _cbl_mon(NULL), _fl_lock(NULL), 87 _notify_when_complete(notify_when_complete), 88 _sz(0), 89 _completed_buffers_head(NULL), 90 _completed_buffers_tail(NULL), 91 _n_completed_buffers(0), 92 _process_completed_threshold(0), _process_completed(false), 93 _buf_free_list(NULL), _buf_free_list_sz(0) 94 { 95 _fl_owner = this; 96 } 97 98 void** PtrQueueSet::allocate_buffer() { 99 assert(_sz > 0, "Didn't set a buffer size."); 100 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag); 101 if (_fl_owner->_buf_free_list != NULL) { 102 void** res = _fl_owner->_buf_free_list; 103 _fl_owner->_buf_free_list = (void**)_fl_owner->_buf_free_list[0]; 104 _fl_owner->_buf_free_list_sz--; 105 // Just override the next pointer with NULL, just in case we scan this part 106 // of the buffer. 107 res[0] = NULL; 108 return res; 109 } else { 110 return NEW_C_HEAP_ARRAY(void*, _sz); 111 } 112 } 113 114 void PtrQueueSet::deallocate_buffer(void** buf) { 115 assert(_sz > 0, "Didn't set a buffer size."); 116 MutexLockerEx x(_fl_owner->_fl_lock, Mutex::_no_safepoint_check_flag); 117 buf[0] = (void*)_fl_owner->_buf_free_list; 118 _fl_owner->_buf_free_list = buf; 119 _fl_owner->_buf_free_list_sz++; 120 } 121 122 void PtrQueueSet::reduce_free_list() { 123 // For now we'll adopt the strategy of deleting half. 124 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag); 125 size_t n = _buf_free_list_sz / 2; 126 while (n > 0) { 127 assert(_buf_free_list != NULL, "_buf_free_list_sz must be wrong."); 128 void** head = _buf_free_list; 129 _buf_free_list = (void**)_buf_free_list[0]; 130 FREE_C_HEAP_ARRAY(void*,head); 131 n--; 132 } 133 } 134 135 void PtrQueueSet::enqueue_complete_buffer(void** buf, size_t index, bool ignore_max_completed) { 136 // I use explicit locking here because there's a bailout in the middle. 137 _cbl_mon->lock_without_safepoint_check(); 138 139 Thread* thread = Thread::current(); 140 assert( ignore_max_completed || 141 thread->is_Java_thread() || 142 SafepointSynchronize::is_at_safepoint(), 143 "invariant" ); 144 ignore_max_completed = ignore_max_completed || !thread->is_Java_thread(); 145 146 if (!ignore_max_completed && _max_completed_queue > 0 && 147 _n_completed_buffers >= (size_t) _max_completed_queue) { 148 _cbl_mon->unlock(); 149 bool b = mut_process_buffer(buf); 150 if (b) { 151 deallocate_buffer(buf); 152 return; 153 } 154 155 // Otherwise, go ahead and enqueue the buffer. Must reaquire the lock. 156 _cbl_mon->lock_without_safepoint_check(); 157 } 158 159 // Here we still hold the _cbl_mon. 160 CompletedBufferNode* cbn = new CompletedBufferNode; 161 cbn->buf = buf; 162 cbn->next = NULL; 163 cbn->index = index; 164 if (_completed_buffers_tail == NULL) { 165 assert(_completed_buffers_head == NULL, "Well-formedness"); 166 _completed_buffers_head = cbn; 167 _completed_buffers_tail = cbn; 168 } else { 169 _completed_buffers_tail->next = cbn; 170 _completed_buffers_tail = cbn; 171 } 172 _n_completed_buffers++; 173 174 if (!_process_completed && 175 _n_completed_buffers >= _process_completed_threshold) { 176 _process_completed = true; 177 if (_notify_when_complete) 178 _cbl_mon->notify_all(); 179 } 180 debug_only(assert_completed_buffer_list_len_correct_locked()); 181 _cbl_mon->unlock(); 182 } 183 184 int PtrQueueSet::completed_buffers_list_length() { 185 int n = 0; 186 CompletedBufferNode* cbn = _completed_buffers_head; 187 while (cbn != NULL) { 188 n++; 189 cbn = cbn->next; 190 } 191 return n; 192 } 193 194 void PtrQueueSet::assert_completed_buffer_list_len_correct() { 195 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 196 assert_completed_buffer_list_len_correct_locked(); 197 } 198 199 void PtrQueueSet::assert_completed_buffer_list_len_correct_locked() { 200 guarantee((size_t)completed_buffers_list_length() == _n_completed_buffers, 201 "Completed buffer length is wrong."); 202 } 203 204 void PtrQueueSet::set_buffer_size(size_t sz) { 205 assert(_sz == 0 && sz > 0, "Should be called only once."); 206 _sz = sz * oopSize; 207 } 208 209 void PtrQueueSet::set_process_completed_threshold(size_t sz) { 210 _process_completed_threshold = sz; 211 } 212 213 // Merge lists of buffers. Notify waiting threads if the length of the list 214 // exceeds threshold. The source queue is emptied as a result. The queues 215 // must share the monitor. 216 void PtrQueueSet::merge_bufferlists(PtrQueueSet *src) { 217 assert(_cbl_mon == src->_cbl_mon, "Should share the same lock"); 218 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag); 219 if (_completed_buffers_tail == NULL) { 220 assert(_completed_buffers_head == NULL, "Well-formedness"); 221 _completed_buffers_head = src->_completed_buffers_head; 222 _completed_buffers_tail = src->_completed_buffers_tail; 223 } else { 224 assert(_completed_buffers_head != NULL, "Well formedness"); 225 if (src->_completed_buffers_head != NULL) { 226 _completed_buffers_tail->next = src->_completed_buffers_head; 227 _completed_buffers_tail = src->_completed_buffers_tail; 228 } 229 } 230 _n_completed_buffers += src->_n_completed_buffers; 231 232 src->_n_completed_buffers = 0; 233 src->_completed_buffers_head = NULL; 234 src->_completed_buffers_tail = NULL; 235 236 assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL || 237 _completed_buffers_head != NULL && _completed_buffers_tail != NULL, 238 "Sanity"); 239 240 if (!_process_completed && 241 _n_completed_buffers >= _process_completed_threshold) { 242 _process_completed = true; 243 if (_notify_when_complete) 244 _cbl_mon->notify_all(); 245 } 246 } 247 248 // Merge free lists of the two queues. The free list of the source 249 // queue is emptied as a result. The queues must share the same 250 // mutex that guards free lists. 251 void PtrQueueSet::merge_freelists(PtrQueueSet* src) { 252 assert(_fl_lock == src->_fl_lock, "Should share the same lock"); 253 MutexLockerEx x(_fl_lock, Mutex::_no_safepoint_check_flag); 254 if (_buf_free_list != NULL) { 255 void **p = _buf_free_list; 256 while (*p != NULL) { 257 p = (void**)*p; 258 } 259 *p = src->_buf_free_list; 260 } else { 261 _buf_free_list = src->_buf_free_list; 262 } 263 _buf_free_list_sz += src->_buf_free_list_sz; 264 src->_buf_free_list = NULL; 265 src->_buf_free_list_sz = 0; 266 }