1 /* 2 * Copyright (c) 2001, 2014, 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_BUFFERINGOOPCLOSURE_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP 27 28 #include "memory/iterator.hpp" 29 #include "runtime/os.hpp" 30 #include "utilities/debug.hpp" 31 32 // A BufferingOops closure tries to separate out the cost of finding roots 33 // from the cost of applying closures to them. It maintains an array of 34 // ref-containing locations. Until the array is full, applying the closure 35 // to an oop* merely records that location in the array. Since this 36 // closure app cost is small, an elapsed timer can approximately attribute 37 // all of this cost to the cost of finding the roots. When the array fills 38 // up, the wrapped closure is applied to all elements, keeping track of 39 // this elapsed time of this process, and leaving the array empty. 40 // The caller must be sure to call "done" to process any unprocessed 41 // buffered entries. 42 43 class BufferingOopClosure: public OopClosure { 44 friend class TestBufferingOopClosure; 45 protected: 46 static const size_t BufferLength = 1024; 47 48 // The full-sized oops are filled in from the bottom, 49 // while the narrowOops are filled in from the top. 50 void* _buffer[BufferLength]; 51 void** _oop_top; 52 void** _narrowOop_bottom; 53 54 OopClosure* _oc; 55 double _closure_app_seconds; 56 57 58 bool is_buffer_empty() { 59 return _oop_top == _buffer && _narrowOop_bottom == (_buffer + BufferLength - 1); 60 } 61 62 bool is_buffer_full() { 63 return _narrowOop_bottom < _oop_top; 64 } 65 66 // Process addresses containing full-sized oops. 67 void process_oops() { 68 for (void** curr = _buffer; curr < _oop_top; ++curr) { 69 _oc->do_oop((oop*)(*curr)); 70 } 71 _oop_top = _buffer; 72 } 73 74 // Process addresses containing narrow oops. 75 void process_narrowOops() { 76 for (void** curr = _buffer + BufferLength - 1; curr > _narrowOop_bottom; --curr) { 77 _oc->do_oop((narrowOop*)(*curr)); 78 } 79 _narrowOop_bottom = _buffer + BufferLength - 1; 80 } 81 82 // Apply the closure to all oops and clear the buffer. 83 // Accumulate the time it took. 84 void process_buffer() { 85 double start = os::elapsedTime(); 86 87 process_oops(); 88 process_narrowOops(); 89 90 _closure_app_seconds += (os::elapsedTime() - start); 91 } 92 93 void process_buffer_if_full() { 94 if (is_buffer_full()) { 95 process_buffer(); 96 } 97 } 98 99 void add_narrowOop(narrowOop* p) { 100 assert(!is_buffer_full(), "Buffer should not be full"); 101 *_narrowOop_bottom = (void*)p; 102 _narrowOop_bottom--; 103 } 104 105 void add_oop(oop* p) { 106 assert(!is_buffer_full(), "Buffer should not be full"); 107 *_oop_top = (void*)p; 108 _oop_top++; 109 } 110 111 public: 112 virtual void do_oop(narrowOop* p) { 113 process_buffer_if_full(); 114 add_narrowOop(p); 115 } 116 117 virtual void do_oop(oop* p) { 118 process_buffer_if_full(); 119 add_oop(p); 120 } 121 122 void done() { 123 if (!is_buffer_empty()) { 124 process_buffer(); 125 } 126 } 127 128 double closure_app_seconds() { 129 return _closure_app_seconds; 130 } 131 132 BufferingOopClosure(OopClosure *oc) : 133 _oc(oc), 134 _oop_top(_buffer), 135 _narrowOop_bottom(_buffer + BufferLength - 1), 136 _closure_app_seconds(0.0) { } 137 }; 138 139 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP