logOutputList.hpp revision 11209:c84a6ce067ad 
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
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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 "runtime/atomic.hpp"
30#include "utilities/globalDefinitions.hpp"
31
32class LogOutput;
33
34// Data structure to keep track of log outputs for a given tagset.
35// Essentially a sorted linked list going from error level outputs
36// to outputs of finer levels. Keeps an index from each level to
37// the first node in the list for the corresponding level.
38// This allows a log message on, for example, info level to jump
39// straight into the list where the first info level output can
40// be found. The log message will then be printed on that output,
41// as well as all outputs in nodes that follow in the list (which
42// can be additional info level outputs and/or debug and trace outputs).
43//
44// Each instance keeps track of the number of current readers of the list.
45// To remove a node from the list the node must first be unlinked,
46// and the memory for that node can be freed whenever the removing
47// thread observes an active reader count of 0 (after unlinking it).
48class LogOutputList VALUE_OBJ_CLASS_SPEC {
49 private:
50  struct LogOutputNode : public CHeapObj<mtLogging> {
51    LogOutput*      _value;
52    LogOutputNode*  _next;
53    LogLevelType    _level;
54  };
55
56  LogOutputNode*  _level_start[LogLevel::Count];
57  volatile jint   _active_readers;
58
59  LogOutputNode* find(const LogOutput* output) const;
60  void remove_output(LogOutputNode* node);
61  void add_output(LogOutput* output, LogLevelType level);
62  void update_output_level(LogOutputNode* node, LogLevelType level);
63
64 public:
65  LogOutputList() : _active_readers(0) {
66    for (size_t i = 0; i < LogLevel::Count; i++) {
67      _level_start[i] = NULL;
68    }
69  }
70
71  // Test if the outputlist has an output for the given level.
72  bool is_level(LogLevelType level) const {
73    return _level_start[level] != NULL;
74  }
75
76  LogLevelType level_for(const LogOutput* output) const {
77    LogOutputNode* node = this->find(output);
78    if (node == NULL) {
79      return LogLevel::Off;
80    }
81    return node->_level;
82  }
83
84  // Set (add/update/remove) the output to the specified level.
85  void set_output_level(LogOutput* output, LogLevelType level);
86
87  // Bookkeeping functions to keep track of number of active readers/iterators for the list.
88  jint increase_readers();
89  jint decrease_readers();
90  void wait_until_no_readers() const;
91
92  class Iterator VALUE_OBJ_CLASS_SPEC {
93    friend class LogOutputList;
94   private:
95    LogOutputNode*  _current;
96    LogOutputList*  _list;
97    Iterator(LogOutputList* list, LogOutputNode* start) : _current(start), _list(list) {
98    }
99
100   public:
101    ~Iterator() {
102      _list->decrease_readers();
103    }
104
105    LogOutput* operator*() {
106      return _current->_value;
107    }
108
109    void operator++(int) {
110      _current = _current->_next;
111    }
112
113    bool operator!=(const LogOutputNode *ref) const {
114      return _current != ref;
115    }
116
117    LogLevelType level() const {
118      return _current->_level;
119    }
120  };
121
122  Iterator iterator(LogLevelType level = LogLevel::Last) {
123    increase_readers();
124    return Iterator(this, _level_start[level]);
125  }
126
127  LogOutputNode* end() const {
128    return NULL;
129  }
130};
131
132#endif // SHARE_VM_LOGGING_LOGOUTPUTLIST_HPP
133