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      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.
     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.
     51   static void SetVerbose(int level) { max_level_ = level; }
     52 
     53   // Set info and error logging streams.  Static, not thread-safe.
     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