1 /* 2 * Copyright (c) 2015, 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 #ifndef SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP 25 #define SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP 26 #include "logging/logLevel.hpp" 27 #include "memory/allocation.hpp" 28 #include "runtime/atomic.hpp" 29 #include "utilities/globalDefinitions.hpp" 30 31 class LogOutput; 32 33 // Data structure to keep track of log outputs for a given tagset. 34 // Essentially a sorted linked list going from error level outputs 35 // to outputs of finer levels. Keeps an index from each level to 36 // the first node in the list for the corresponding level. 37 // This allows a log message on, for example, info level to jump 38 // straight into the list where the first info level output can 39 // be found. The log message will then be printed on that output, 40 // as well as all outputs in nodes that follow in the list (which 41 // can be additional info level outputs and/or debug and trace outputs). 42 // 43 // Each instance keeps track of the number of current readers of the list. 44 // To remove a node from the list the node must first be unlinked, 45 // and the memory for that node can be freed whenever the removing 46 // thread observes an active reader count of 0 (after unlinking it). 47 class LogOutputList { 48 private: 49 struct LogOutputNode : public CHeapObj<mtInternal> { 50 LogOutput* _value; 51 LogOutputNode* _next; 52 LogLevelType _level; 53 }; 54 55 LogOutputNode* _level_start[LogLevel::Count]; 56 volatile jint _active_readers; 57 58 LogOutputNode* find(LogOutput* output); 59 void remove_output(LogOutputNode* node); 60 void add_output(LogOutput* output, LogLevelType level); 61 void update_output_level(LogOutputNode* node, LogLevelType level); 62 63 public: 64 LogOutputList() : _active_readers(0) { 65 for (size_t i = 0; i < LogLevel::Count; i++) { 66 _level_start[i] = NULL; 67 } 68 } 69 70 // Test if the outputlist has an output for the given level. 71 bool is_level(LogLevelType level) { 72 return _level_start[level] != NULL; 73 } 74 75 // Set (add/update/remove) the output to the specified level. 76 void set_output_level(LogOutput* output, LogLevelType level); 77 78 // Bookkeeping functions to keep track of number of active readers/iterators for the list. 79 jint increase_readers(); 80 jint decrease_readers(); 81 void wait_until_no_readers() const; 82 83 class Iterator { 84 friend class LogOutputList; 85 private: 86 LogOutputNode* _current; 87 LogOutputList* _list; 88 Iterator(LogOutputList* list, LogOutputNode* start) : _current(start), _list(list) { 89 } 90 91 public: 92 ~Iterator() { 93 _list->decrease_readers(); 94 } 95 96 LogOutput* operator*() { 97 return _current->_value; 98 } 99 100 void operator++(int) { 101 _current = _current->_next; 102 } 103 104 bool operator!=(const LogOutputNode *ref) const { 105 return _current != ref; 106 } 107 }; 108 109 Iterator iterator(LogLevelType level = LogLevel::Last) { 110 increase_readers(); 111 return Iterator(this, _level_start[level]); 112 } 113 114 LogOutputNode* end() const { 115 return NULL; 116 } 117 }; 118 119 #endif