Line data Source code
1 : /*
2 : * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3 : *
4 : * Use of this source code is governed by a BSD-style license
5 : * that can be found in the LICENSE file in the root of the source
6 : * tree. An additional intellectual property rights grant can be found
7 : * in the file PATENTS. All contributing project authors may
8 : * be found in the AUTHORS file in the root of the source tree.
9 : */
10 :
11 : // This is a highly stripped-down version of libjingle's talk/base/logging.h.
12 : // It is a thin wrapper around WEBRTC_TRACE, maintaining the libjingle log
13 : // semantics to ease a transition to that format.
14 :
15 : // NOTE: LS_INFO maps to a new trace level which should be reserved for
16 : // infrequent, non-verbose logs. The other levels below kTraceWarning have been
17 : // rendered essentially useless due to their verbosity. Carefully consider the
18 : // impact of adding a new LS_INFO log. If it will be logged at anything
19 : // approaching a frame or packet frequency, use LS_VERBOSE if necessary, or
20 : // preferably, do not log at all.
21 :
22 : // LOG(...) an ostream target that can be used to send formatted
23 : // output to a variety of logging targets, such as debugger console, stderr,
24 : // file, or any StreamInterface.
25 : // The severity level passed as the first argument to the LOGging
26 : // functions is used as a filter, to limit the verbosity of the logging.
27 : // Static members of LogMessage documented below are used to control the
28 : // verbosity and target of the output.
29 : // There are several variations on the LOG macro which facilitate logging
30 : // of common error conditions, detailed below.
31 :
32 : // LOG(sev) logs the given stream at severity "sev", which must be a
33 : // compile-time constant of the LoggingSeverity type, without the namespace
34 : // prefix.
35 : // LOG_V(sev) Like LOG(), but sev is a run-time variable of the LoggingSeverity
36 : // type (basically, it just doesn't prepend the namespace).
37 : // LOG_F(sev) Like LOG(), but includes the name of the current function.
38 :
39 : #ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGGING_H_
40 : #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGGING_H_
41 :
42 : #include <sstream>
43 :
44 : namespace webrtc {
45 :
46 : //////////////////////////////////////////////////////////////////////
47 :
48 : // Note that the non-standard LoggingSeverity aliases exist because they are
49 : // still in broad use. The meanings of the levels are:
50 : // LS_SENSITIVE: Information which should only be logged with the consent
51 : // of the user, due to privacy concerns.
52 : // LS_VERBOSE: This level is for data which we do not want to appear in the
53 : // normal debug log, but should appear in diagnostic logs.
54 : // LS_INFO: Chatty level used in debugging for all sorts of things, the default
55 : // in debug builds.
56 : // LS_WARNING: Something that may warrant investigation.
57 : // LS_ERROR: Something that should not have occurred.
58 : enum LoggingSeverity {
59 : LS_SENSITIVE, LS_VERBOSE, LS_INFO, LS_WARNING, LS_ERROR
60 : };
61 :
62 : class LogMessage {
63 : public:
64 : LogMessage(const char* file, int line, LoggingSeverity sev);
65 : ~LogMessage();
66 :
67 : static bool Loggable(LoggingSeverity sev);
68 0 : std::ostream& stream() { return print_stream_; }
69 :
70 : private:
71 : // The ostream that buffers the formatted message before output
72 : std::ostringstream print_stream_;
73 :
74 : // The severity level of this message
75 : LoggingSeverity severity_;
76 : };
77 :
78 : //////////////////////////////////////////////////////////////////////
79 : // Macros which automatically disable logging when WEBRTC_LOGGING == 0
80 : //////////////////////////////////////////////////////////////////////
81 :
82 : #ifndef LOG
83 : // The following non-obvious technique for implementation of a
84 : // conditional log stream was stolen from google3/base/logging.h.
85 :
86 : // This class is used to explicitly ignore values in the conditional
87 : // logging macros. This avoids compiler warnings like "value computed
88 : // is not used" and "statement has no effect".
89 :
90 : class LogMessageVoidify {
91 : public:
92 0 : LogMessageVoidify() { }
93 : // This has to be an operator with a precedence lower than << but
94 : // higher than ?:
95 0 : void operator&(std::ostream&) { }
96 : };
97 :
98 : #if defined(WEBRTC_RESTRICT_LOGGING)
99 : // This should compile away logs matching the following condition.
100 : #define RESTRICT_LOGGING_PRECONDITION(sev) \
101 : sev < webrtc::LS_INFO ? (void) 0 :
102 : #else
103 : #define RESTRICT_LOGGING_PRECONDITION(sev)
104 : #endif
105 :
106 : #define LOG_SEVERITY_PRECONDITION(sev) \
107 : RESTRICT_LOGGING_PRECONDITION(sev) !(webrtc::LogMessage::Loggable(sev)) \
108 : ? (void) 0 \
109 : : webrtc::LogMessageVoidify() &
110 :
111 : #define LOG(sev) \
112 : LOG_SEVERITY_PRECONDITION(webrtc::sev) \
113 : webrtc::LogMessage(__FILE__, __LINE__, webrtc::sev).stream()
114 :
115 : // The _V version is for when a variable is passed in. It doesn't do the
116 : // namespace concatination.
117 : #define LOG_V(sev) \
118 : LOG_SEVERITY_PRECONDITION(sev) \
119 : webrtc::LogMessage(__FILE__, __LINE__, sev).stream()
120 :
121 : // The _F version prefixes the message with the current function name.
122 : #if (defined(__GNUC__) && !defined(NDEBUG)) || defined(WANT_PRETTY_LOG_F)
123 : #define LOG_F(sev) LOG(sev) << __PRETTY_FUNCTION__ << ": "
124 : #else
125 : #define LOG_F(sev) LOG(sev) << __FUNCTION__ << ": "
126 : #endif
127 :
128 : #endif // LOG
129 :
130 : } // namespace webrtc
131 :
132 : #endif // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGGING_H_
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