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 "oops/oopsHierarchy.hpp" 30 #include "runtime/os.hpp" 31 #include "utilities/debug.hpp" 32 33 // A BufferingOops closure tries to separate out the cost of finding roots 34 // from the cost of applying closures to them. It maintains an array of 35 // ref-containing locations. Until the array is full, applying the closure 36 // to an oop* merely records that location in the array. Since this 37 // closure app cost is small, an elapsed timer can approximately attribute 38 // all of this cost to the cost of finding the roots. When the array fills 39 // up, the wrapped closure is applied to all elements, keeping track of 40 // this elapsed time of this process, and leaving the array empty. 41 // The caller must be sure to call "done" to process any unprocessed 42 // buffered entries. 43 44 class BufferingOopClosure: public OopClosure { 45 friend class TestBufferingOopClosure; 46 protected: 47 static const size_t BufferLength = 1024; 48 49 // We need to know if the buffered addresses contain oops or narrowOops. 50 // We can't tag the addresses the way StarTask does, because we need to 51 // be able to handle unaligned addresses coming from oops embedded in code. 52 // 53 // The addresses for the full-sized oops are filled in from the bottom, 54 // while the addresses for the narrowOops are filled in from the top. 55 OopOrNarrowOopStar _buffer[BufferLength]; 56 OopOrNarrowOopStar* _oop_top; 57 OopOrNarrowOopStar* _narrowOop_bottom; 58 59 OopClosure* _oc; 60 double _closure_app_seconds; 61 62 63 bool is_buffer_empty() { 64 return _oop_top == _buffer && _narrowOop_bottom == (_buffer + BufferLength - 1); 65 } 66 67 bool is_buffer_full() { 68 return _narrowOop_bottom < _oop_top; 69 } 70 71 // Process addresses containing full-sized oops. 72 void process_oops() { 73 for (OopOrNarrowOopStar* curr = _buffer; curr < _oop_top; ++curr) { 74 _oc->do_oop((oop*)(*curr)); 75 } 76 _oop_top = _buffer; 77 } 78 79 // Process addresses containing narrow oops. 80 void process_narrowOops() { 81 for (OopOrNarrowOopStar* curr = _buffer + BufferLength - 1; curr > _narrowOop_bottom; --curr) { 82 _oc->do_oop((narrowOop*)(*curr)); 83 } 84 _narrowOop_bottom = _buffer + BufferLength - 1; 85 } 86 87 // Apply the closure to all oops and clear the buffer. 88 // Accumulate the time it took. 89 void process_buffer() { 90 double start = os::elapsedTime(); 91 92 process_oops(); 93 process_narrowOops(); 94 95 _closure_app_seconds += (os::elapsedTime() - start); 96 } 97 98 void process_buffer_if_full() { 99 if (is_buffer_full()) { 100 process_buffer(); 101 } 102 } 103 104 void add_narrowOop(narrowOop* p) { 105 assert(!is_buffer_full(), "Buffer should not be full"); 106 *_narrowOop_bottom = (OopOrNarrowOopStar)p; 107 _narrowOop_bottom--; 108 } 109 110 void add_oop(oop* p) { 111 assert(!is_buffer_full(), "Buffer should not be full"); 112 *_oop_top = (OopOrNarrowOopStar)p; 113 _oop_top++; 114 } 115 116 public: 117 virtual void do_oop(narrowOop* p) { 118 process_buffer_if_full(); 119 add_narrowOop(p); 120 } 121 122 virtual void do_oop(oop* p) { 123 process_buffer_if_full(); 124 add_oop(p); 125 } 126 127 void done() { 128 if (!is_buffer_empty()) { 129 process_buffer(); 130 } 131 } 132 133 double closure_app_seconds() { 134 return _closure_app_seconds; 135 } 136 137 BufferingOopClosure(OopClosure *oc) : 138 _oc(oc), 139 _oop_top(_buffer), 140 _narrowOop_bottom(_buffer + BufferLength - 1), 141 _closure_app_seconds(0.0) { } 142 }; 143 144 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_BUFFERINGOOPCLOSURE_HPP