177 Thread::current()->is_VM_thread()), 178 "not locked"); 179 HeapWord* obj = top(); 180 if (pointer_delta(end(), obj) >= size) { 181 HeapWord* new_top = obj + size; 182 set_top(new_top); 183 assert(is_object_aligned(obj) && is_object_aligned(new_top), 184 "checking alignment"); 185 return obj; 186 } else { 187 return NULL; 188 } 189 } 190 191 // This version is lock-free. 192 HeapWord* MutableSpace::cas_allocate(size_t size) { 193 do { 194 HeapWord* obj = top(); 195 if (pointer_delta(end(), obj) >= size) { 196 HeapWord* new_top = obj + size; 197 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj); 198 // result can be one of two: 199 // the old top value: the exchange succeeded 200 // otherwise: the new value of the top is returned. 201 if (result != obj) { 202 continue; // another thread beat us to the allocation, try again 203 } 204 assert(is_object_aligned(obj) && is_object_aligned(new_top), 205 "checking alignment"); 206 return obj; 207 } else { 208 return NULL; 209 } 210 } while (true); 211 } 212 213 // Try to deallocate previous allocation. Returns true upon success. 214 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) { 215 HeapWord* expected_top = obj + size; 216 return Atomic::cmpxchg(obj, top_addr(), expected_top) == expected_top; 217 } 218 219 void MutableSpace::oop_iterate(OopIterateClosure* cl) { 220 HeapWord* obj_addr = bottom(); 221 HeapWord* t = top(); 222 // Could call objects iterate, but this is easier. 223 while (obj_addr < t) { 224 obj_addr += oop(obj_addr)->oop_iterate_size(cl); 225 } 226 } 227 228 void MutableSpace::object_iterate(ObjectClosure* cl) { 229 HeapWord* p = bottom(); 230 while (p < top()) { 231 cl->do_object(oop(p)); 232 p += oop(p)->size(); 233 } 234 } 235 236 void MutableSpace::print_short() const { print_short_on(tty); } | 177 Thread::current()->is_VM_thread()), 178 "not locked"); 179 HeapWord* obj = top(); 180 if (pointer_delta(end(), obj) >= size) { 181 HeapWord* new_top = obj + size; 182 set_top(new_top); 183 assert(is_object_aligned(obj) && is_object_aligned(new_top), 184 "checking alignment"); 185 return obj; 186 } else { 187 return NULL; 188 } 189 } 190 191 // This version is lock-free. 192 HeapWord* MutableSpace::cas_allocate(size_t size) { 193 do { 194 HeapWord* obj = top(); 195 if (pointer_delta(end(), obj) >= size) { 196 HeapWord* new_top = obj + size; 197 HeapWord* result = Atomic::cmpxchg(top_addr(), obj, new_top); 198 // result can be one of two: 199 // the old top value: the exchange succeeded 200 // otherwise: the new value of the top is returned. 201 if (result != obj) { 202 continue; // another thread beat us to the allocation, try again 203 } 204 assert(is_object_aligned(obj) && is_object_aligned(new_top), 205 "checking alignment"); 206 return obj; 207 } else { 208 return NULL; 209 } 210 } while (true); 211 } 212 213 // Try to deallocate previous allocation. Returns true upon success. 214 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) { 215 HeapWord* expected_top = obj + size; 216 return Atomic::cmpxchg(top_addr(), expected_top, obj) == expected_top; 217 } 218 219 void MutableSpace::oop_iterate(OopIterateClosure* cl) { 220 HeapWord* obj_addr = bottom(); 221 HeapWord* t = top(); 222 // Could call objects iterate, but this is easier. 223 while (obj_addr < t) { 224 obj_addr += oop(obj_addr)->oop_iterate_size(cl); 225 } 226 } 227 228 void MutableSpace::object_iterate(ObjectClosure* cl) { 229 HeapWord* p = bottom(); 230 while (p < top()) { 231 cl->do_object(oop(p)); 232 p += oop(p)->size(); 233 } 234 } 235 236 void MutableSpace::print_short() const { print_short_on(tty); } |