logOutputList.hpp revision 11857:d0fbf661cc16 
1/*
2 * Copyright (c) 2015, 2016, 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
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23 */
24#ifndef SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP
25#define SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP
26
27#include "logging/logLevel.hpp"
28#include "memory/allocation.hpp"
29#include "utilities/globalDefinitions.hpp"
30
31class 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).
47class LogOutputList VALUE_OBJ_CLASS_SPEC {
48 private:
49  struct LogOutputNode : public CHeapObj<mtLogging> {
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(const LogOutput* output) const;
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) const {
72    return _level_start[level] != NULL;
73  }
74
75  LogLevelType level_for(const LogOutput* output) const {
76    LogOutputNode* node = this->find(output);
77    if (node == NULL) {
78      return LogLevel::Off;
79    }
80    return node->_level;
81  }
82
83  // Set (add/update/remove) the output to the specified level.
84  void set_output_level(LogOutput* output, LogLevelType level);
85
86  // Bookkeeping functions to keep track of number of active readers/iterators for the list.
87  jint increase_readers();
88  jint decrease_readers();
89  void wait_until_no_readers() const;
90
91  class Iterator VALUE_OBJ_CLASS_SPEC {
92    friend class LogOutputList;
93   private:
94    LogOutputNode*  _current;
95    LogOutputList*  _list;
96    Iterator(LogOutputList* list, LogOutputNode* start) : _current(start), _list(list) {
97    }
98
99   public:
100    ~Iterator() {
101      _list->decrease_readers();
102    }
103
104    LogOutput* operator*() {
105      return _current->_value;
106    }
107
108    void operator++(int) {
109      _current = _current->_next;
110    }
111
112    bool operator!=(const LogOutputNode *ref) const {
113      return _current != ref;
114    }
115
116    LogLevelType level() const {
117      return _current->_level;
118    }
119  };
120
121  Iterator iterator(LogLevelType level = LogLevel::Last) {
122    increase_readers();
123    return Iterator(this, _level_start[level]);
124  }
125
126  LogOutputNode* end() const {
127    return NULL;
128  }
129};
130
131#endif // SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP
132