1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 // Logging and checks.  Avoids a dependency on base.
6 //
7 // LOG(tag) prints messages.  Tags are INFO, WARNING, ERROR and FATAL.
8 // INFO prints to stdout, the others to stderr.  FATAL aborts after printing.
9 //
10 // LOG_IF(tag, predicate) logs if predicate evaluates to true, else silent.
11 //
12 // VLOG(level) logs INFO messages where level is less than or equal to the
13 // verbosity level set with SetVerbose().
14 //
15 // VLOG_IF(level, predicate) logs INFO if predicate evaluates to true,
16 // else silent.
17 //
18 // CHECK(predicate) logs a FATAL error if predicate is false.
19 // NOTREACHED() always aborts.
20 // Log streams can be changed with SetStreams().  Logging is not thread-safe.
21 //
22 
23 #ifndef TOOLS_RELOCATION_PACKER_SRC_DEBUG_H_
24 #define TOOLS_RELOCATION_PACKER_SRC_DEBUG_H_
25 
26 #include <limits.h>
27 #include <ostream>
28 #include <sstream>
29 
30 namespace relocation_packer {
31 
32 class Logger {
33  public:
34   enum Severity {INFO = 0, WARNING, ERROR, FATAL};
35 
36   // Construct a new message logger.  Prints if level is less than or
37   // equal to the level set with SetVerbose() and predicate is true.
38   // |severity| is an enumerated severity.
39   // |level| is the verbosity level.
40   // |predicate| controls if the logger prints or is silent.
41   Logger(Severity severity, int level, bool predicate);
42 
43   // On destruction, flush and print the strings accumulated in stream_.
44   ~Logger();
45 
46   // Return the stream for this logger.
GetStream()47   std::ostream& GetStream() { return stream_; }
48 
49   // Set verbosity level.  Messages with a level less than or equal to
50   // this level are printed, others are discarded.  Static, not thread-safe.
SetVerbose(int level)51   static void SetVerbose(int level) { max_level_ = level; }
52 
53   // Set info and error logging streams.  Static, not thread-safe.
SetStreams(std::ostream * info_stream,std::ostream * error_stream)54   static void SetStreams(std::ostream* info_stream,
55                          std::ostream* error_stream) {
56     info_stream_ = info_stream;
57     error_stream_ = error_stream;
58   }
59 
60   // Reset to initial state.
61   static void Reset();
62 
63  private:
64   // Message severity, verbosity level, and predicate.
65   Severity severity_;
66   int level_;
67   bool predicate_;
68 
69   // String stream, accumulates message text.
70   std::ostringstream stream_;
71 
72   // Verbosity for INFO messages.  Not thread-safe.
73   static int max_level_;
74 
75   // Logging streams.  Not thread-safe.
76   static std::ostream* info_stream_;
77   static std::ostream* error_stream_;
78 };
79 
80 }  // namespace relocation_packer
81 
82 // Make logging severities visible globally.
83 typedef relocation_packer::Logger::Severity LogSeverity;
84 
85 // LOG(severity) prints a message with the given severity, and aborts if
86 // severity is FATAL.  LOG_IF(severity, predicate) does the same but only if
87 // predicate is true.  INT_MIN is guaranteed to be less than or equal to
88 // any verbosity level.
89 #define LOG(severity)                                                      \
90   (relocation_packer::Logger(relocation_packer::Logger::severity, INT_MIN, \
91                              true)                                         \
92        .GetStream())
93 #define LOG_IF(severity, predicate)                                        \
94   (relocation_packer::Logger(relocation_packer::Logger::severity, INT_MIN, \
95                              (predicate))                                  \
96        .GetStream())
97 
98 // VLOG(level) prints its message as INFO if level is less than or equal to
99 // the current verbosity level.
100 #define VLOG(level)                                                          \
101   (relocation_packer::Logger(relocation_packer::Logger::INFO, (level), true) \
102        .GetStream())
103 #define VLOG_IF(level, predicate)                                      \
104   (relocation_packer::Logger(relocation_packer::Logger::INFO, (level), \
105                              (predicate))                              \
106        .GetStream())
107 
108 // CHECK(predicate) fails with a FATAL log message if predicate is false.
109 #define CHECK(predicate) (LOG_IF(FATAL, !(predicate)) \
110     << __FILE__ << ":" << __LINE__ << ": " \
111     << __FUNCTION__ << ": CHECK '" #predicate "' failed")
112 
113 // NOTREACHED() always fails with a FATAL log message.
114 #define NOTREACHED(_) (LOG(FATAL) \
115     << __FILE__ << ":" << __LINE__ << ": " \
116     << __FUNCTION__ << ": NOTREACHED() hit")
117 
118 #endif  // TOOLS_RELOCATION_PACKER_SRC_DEBUG_H_
119