debug.h revision 116680a4aac90f2aa7413d9095a592090648e557 
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 <algorithm>
28#include <ostream>
29#include <sstream>
30
31namespace relocation_packer {
32
33class Logger {
34 public:
35  enum Severity {INFO = 0, WARNING, ERROR, FATAL};
36
37  // Construct a new message logger.  Prints if level is less than or
38  // equal to the level set with SetVerbose() and predicate is true.
39  // |severity| is an enumerated severity.
40  // |level| is the verbosity level.
41  // |predicate| controls if the logger prints or is silent.
42  Logger(Severity severity, int level, bool predicate);
43
44  // On destruction, flush and print the strings accumulated in stream_.
45  ~Logger();
46
47  // Return the stream for this logger.
48  std::ostream& GetStream() { return stream_; }
49
50  // Set verbosity level.  Messages with a level less than or equal to
51  // this level are printed, others are discarded.  Static, not thread-safe.
52  static void SetVerbose(int level) { max_level_ = level; }
53
54  // Set info and error logging streams.  Static, not thread-safe.
55  static void SetStreams(std::ostream* info_stream,
56                         std::ostream* error_stream) {
57    info_stream_ = info_stream;
58    error_stream_ = error_stream;
59  }
60
61  // Reset to initial state.
62  static void Reset();
63
64 private:
65  // Message severity, verbosity level, and predicate.
66  Severity severity_;
67  int level_;
68  bool predicate_;
69
70  // String stream, accumulates message text.
71  std::ostringstream stream_;
72
73  // Verbosity for INFO messages.  Not thread-safe.
74  static int max_level_;
75
76  // Logging streams.  Not thread-safe.
77  static std::ostream* info_stream_;
78  static std::ostream* error_stream_;
79};
80
81}  // namespace relocation_packer
82
83// Make logging severities visible globally.
84typedef relocation_packer::Logger::Severity LogSeverity;
85const LogSeverity INFO = relocation_packer::Logger::INFO;
86const LogSeverity WARNING = relocation_packer::Logger::WARNING;
87const LogSeverity ERROR = relocation_packer::Logger::ERROR;
88const LogSeverity FATAL = relocation_packer::Logger::FATAL;
89
90// LOG(severity) prints a message with the given severity, and aborts if
91// severity is FATAL.  LOG_IF(severity, predicate) does the same but only if
92// predicate is true.  INT_MIN is guaranteed to be less than or equal to
93// any verbosity level.
94#define LOG(severity) \
95    (relocation_packer::Logger(severity, INT_MIN, true).GetStream())
96#define LOG_IF(severity, predicate) \
97    (relocation_packer::Logger(severity, INT_MIN, (predicate)).GetStream())
98
99// VLOG(level) prints its message as INFO if level is less than or equal to
100// the current verbosity level.
101#define VLOG(level) \
102    (relocation_packer::Logger(INFO, (level), true).GetStream())
103#define VLOG_IF(level, predicate) \
104    (relocation_packer::Logger(INFO, (level), (predicate)).GetStream())
105
106// CHECK(predicate) fails with a FATAL log message if predicate is false.
107#define CHECK(predicate) (LOG_IF(FATAL, !(predicate)) \
108    << __FILE__ << ":" << __LINE__ << ": " \
109    << __FUNCTION__ << ": CHECK '" #predicate "' failed")
110
111// NOTREACHED() always fails with a FATAL log message.
112#define NOTREACHED(_) (LOG(FATAL) \
113    << __FILE__ << ":" << __LINE__ << ": " \
114    << __FUNCTION__ << ": NOTREACHED() hit")
115
116#endif  // TOOLS_RELOCATION_PACKER_SRC_DEBUG_H_
117