175 Thread::current()->is_VM_thread()), 176 "not locked"); 177 HeapWord* obj = top(); 178 if (pointer_delta(end(), obj) >= size) { 179 HeapWord* new_top = obj + size; 180 set_top(new_top); 181 assert(is_object_aligned(obj) && is_object_aligned(new_top), 182 "checking alignment"); 183 return obj; 184 } else { 185 return NULL; 186 } 187 } 188 189 // This version is lock-free. 190 HeapWord* MutableSpace::cas_allocate(size_t size) { 191 do { 192 HeapWord* obj = top(); 193 if (pointer_delta(end(), obj) >= size) { 194 HeapWord* new_top = obj + size; 195 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 196 // result can be one of two: 197 // the old top value: the exchange succeeded 198 // otherwise: the new value of the top is returned. 199 if (result != obj) { 200 continue; // another thread beat us to the allocation, try again 201 } 202 assert(is_object_aligned(obj) && is_object_aligned(new_top), 203 "checking alignment"); 204 return obj; 205 } else { 206 return NULL; 207 } 208 } while (true); 209 } 210 211 // Try to deallocate previous allocation. Returns true upon success. 212 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) { 213 HeapWord* expected_top = obj + size; 214 return (HeapWord*)Atomic::cmpxchg_ptr(obj, top_addr(), expected_top) == expected_top; 215 } 216 217 void MutableSpace::oop_iterate_no_header(OopClosure* cl) { 218 HeapWord* obj_addr = bottom(); 219 HeapWord* t = top(); 220 // Could call objects iterate, but this is easier. 221 while (obj_addr < t) { 222 obj_addr += oop(obj_addr)->oop_iterate_no_header(cl); 223 } 224 } 225 226 void MutableSpace::object_iterate(ObjectClosure* cl) { 227 HeapWord* p = bottom(); 228 while (p < top()) { 229 cl->do_object(oop(p)); 230 p += oop(p)->size(); 231 } 232 } 233 234 void MutableSpace::print_short() const { print_short_on(tty); } | 175 Thread::current()->is_VM_thread()), 176 "not locked"); 177 HeapWord* obj = top(); 178 if (pointer_delta(end(), obj) >= size) { 179 HeapWord* new_top = obj + size; 180 set_top(new_top); 181 assert(is_object_aligned(obj) && is_object_aligned(new_top), 182 "checking alignment"); 183 return obj; 184 } else { 185 return NULL; 186 } 187 } 188 189 // This version is lock-free. 190 HeapWord* MutableSpace::cas_allocate(size_t size) { 191 do { 192 HeapWord* obj = top(); 193 if (pointer_delta(end(), obj) >= size) { 194 HeapWord* new_top = obj + size; 195 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj); 196 // result can be one of two: 197 // the old top value: the exchange succeeded 198 // otherwise: the new value of the top is returned. 199 if (result != obj) { 200 continue; // another thread beat us to the allocation, try again 201 } 202 assert(is_object_aligned(obj) && is_object_aligned(new_top), 203 "checking alignment"); 204 return obj; 205 } else { 206 return NULL; 207 } 208 } while (true); 209 } 210 211 // Try to deallocate previous allocation. Returns true upon success. 212 bool MutableSpace::cas_deallocate(HeapWord *obj, size_t size) { 213 HeapWord* expected_top = obj + size; 214 return Atomic::cmpxchg(obj, top_addr(), expected_top) == expected_top; 215 } 216 217 void MutableSpace::oop_iterate_no_header(OopClosure* cl) { 218 HeapWord* obj_addr = bottom(); 219 HeapWord* t = top(); 220 // Could call objects iterate, but this is easier. 221 while (obj_addr < t) { 222 obj_addr += oop(obj_addr)->oop_iterate_no_header(cl); 223 } 224 } 225 226 void MutableSpace::object_iterate(ObjectClosure* cl) { 227 HeapWord* p = bottom(); 228 while (p < top()) { 229 cl->do_object(oop(p)); 230 p += oop(p)->size(); 231 } 232 } 233 234 void MutableSpace::print_short() const { print_short_on(tty); } |