text: // Copyright (c) 1999, Google Inc.
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // Author: Ray Sidney
  //
  // This file contains #include information about logging-related stuff.
  // Pretty much everybody needs to #include this file so that they can
  // log various happenings.
  //
  #ifndef _LOGGING_H_
  #define _LOGGING_H_
  
  #include <errno.h>
  #include <string.h>
  #include <time.h>
  #include <iosfwd>
  #include <ostream>
  #include <sstream>
  #include <string>
  #if @ac_cv_have_unistd_h@
  # include <unistd.h>
  #endif
  #include <vector>
  
  #if defined(_MSC_VER)
  #define GLOG_MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
                                       __pragma(warning(disable:n))
  #define GLOG_MSVC_POP_WARNING() __pragma(warning(pop))
  #else
  #define GLOG_MSVC_PUSH_DISABLE_WARNING(n)
  #define GLOG_MSVC_POP_WARNING()
  #endif
  
  // Annoying stuff for windows -- makes sure clients can import these functions
  #ifndef GOOGLE_GLOG_DLL_DECL
  # if defined(_WIN32) && !defined(__CYGWIN__)
  #   define GOOGLE_GLOG_DLL_DECL  __declspec(dllimport)
  # else
  #   define GOOGLE_GLOG_DLL_DECL
  # endif
  #endif
  
  // We care a lot about number of bits things take up.  Unfortunately,
  // systems define their bit-specific ints in a lot of different ways.
  // We use our own way, and have a typedef to get there.
  // Note: these commands below may look like "#if 1" or "#if 0", but
  // that's because they were constructed that way at ./configure time.
  // Look at logging.h.in to see how they're calculated (based on your config).
  #if @ac_cv_have_stdint_h@
  #include <stdint.h>             // the normal place uint16_t is defined
  #endif
  #if @ac_cv_have_systypes_h@
  #include <sys/types.h>          // the normal place u_int16_t is defined
  #endif
  #if @ac_cv_have_inttypes_h@
  #include <inttypes.h>           // a third place for uint16_t or u_int16_t
  #endif
  
  #if @ac_cv_have_libgflags@
  #include <gflags/gflags.h>
  #endif
  
  @ac_google_start_namespace@
  
  #if @ac_cv_have_uint16_t@      // the C99 format
  typedef int32_t int32;
  typedef uint32_t uint32;
  typedef int64_t int64;
  typedef uint64_t uint64;
  #elif @ac_cv_have_u_int16_t@   // the BSD format
  typedef int32_t int32;
  typedef u_int32_t uint32;
  typedef int64_t int64;
  typedef u_int64_t uint64;
  #elif @ac_cv_have___uint16@    // the windows (vc7) format
  typedef __int32 int32;
  typedef unsigned __int32 uint32;
  typedef __int64 int64;
  typedef unsigned __int64 uint64;
  #else
  #error Do not know how to define a 32-bit integer quantity on your system
  #endif
  
  @ac_google_end_namespace@
  
  // The global value of GOOGLE_STRIP_LOG. All the messages logged to
  // LOG(XXX) with severity less than GOOGLE_STRIP_LOG will not be displayed.
  // If it can be determined at compile time that the message will not be
  // printed, the statement will be compiled out.
  //
  // Example: to strip out all INFO and WARNING messages, use the value
  // of 2 below. To make an exception for WARNING messages from a single
  // file, add "#define GOOGLE_STRIP_LOG 1" to that file _before_ including
  // base/logging.h
  #ifndef GOOGLE_STRIP_LOG
  #define GOOGLE_STRIP_LOG 0
  #endif
  
  // GCC can be told that a certain branch is not likely to be taken (for
  // instance, a CHECK failure), and use that information in static analysis.
  // Giving it this information can help it optimize for the common case in
  // the absence of better information (ie. -fprofile-arcs).
  //
  #ifndef GOOGLE_PREDICT_BRANCH_NOT_TAKEN
  #if @ac_cv_have___builtin_expect@
  #define GOOGLE_PREDICT_BRANCH_NOT_TAKEN(x) (__builtin_expect(x, 0))
  #else
  #define GOOGLE_PREDICT_BRANCH_NOT_TAKEN(x) x
  #endif
  #endif
  
  #ifndef GOOGLE_PREDICT_FALSE
  #if @ac_cv_have___builtin_expect@
  #define GOOGLE_PREDICT_FALSE(x) (__builtin_expect(x, 0))
  #else
  #define GOOGLE_PREDICT_FALSE(x) x
  #endif
  #endif
  
  #ifndef GOOGLE_PREDICT_TRUE
  #if @ac_cv_have___builtin_expect@
  #define GOOGLE_PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
  #else
  #define GOOGLE_PREDICT_TRUE(x) x
  #endif
  #endif
  
  
  // Make a bunch of macros for logging.  The way to log things is to stream
  // things to LOG(<a particular severity level>).  E.g.,
  //
  //   LOG(INFO) << "Found " << num_cookies << " cookies";
  //
  // You can capture log messages in a string, rather than reporting them
  // immediately:
  //
  //   vector<string> errors;
  //   LOG_STRING(ERROR, &errors) << "Couldn't parse cookie #" << cookie_num;
  //
  // This pushes back the new error onto 'errors'; if given a NULL pointer,
  // it reports the error via LOG(ERROR).
  //
  // You can also do conditional logging:
  //
  //   LOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
  //
  // You can also do occasional logging (log every n'th occurrence of an
  // event):
  //
  //   LOG_EVERY_N(INFO, 10) << "Got the " << google::COUNTER << "th cookie";
  //
  // The above will cause log messages to be output on the 1st, 11th, 21st, ...
  // times it is executed.  Note that the special google::COUNTER value is used
  // to identify which repetition is happening.
  //
  // You can also do occasional conditional logging (log every n'th
  // occurrence of an event, when condition is satisfied):
  //
  //   LOG_IF_EVERY_N(INFO, (size > 1024), 10) << "Got the " << google::COUNTER
  //                                           << "th big cookie";
  //
  // You can log messages the first N times your code executes a line. E.g.
  //
  //   LOG_FIRST_N(INFO, 20) << "Got the " << google::COUNTER << "th cookie";
  //
  // Outputs log messages for the first 20 times it is executed.
  //
  // Analogous SYSLOG, SYSLOG_IF, and SYSLOG_EVERY_N macros are available.
  // These log to syslog as well as to the normal logs.  If you use these at
  // all, you need to be aware that syslog can drastically reduce performance,
  // especially if it is configured for remote logging!  Don't use these
  // unless you fully understand this and have a concrete need to use them.
  // Even then, try to minimize your use of them.
  //
  // There are also "debug mode" logging macros like the ones above:
  //
  //   DLOG(INFO) << "Found cookies";
  //
  //   DLOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
  //
  //   DLOG_EVERY_N(INFO, 10) << "Got the " << google::COUNTER << "th cookie";
  //
  // All "debug mode" logging is compiled away to nothing for non-debug mode
  // compiles.
  //
  // We also have
  //
  //   LOG_ASSERT(assertion);
  //   DLOG_ASSERT(assertion);
  //
  // which is syntactic sugar for {,D}LOG_IF(FATAL, assert fails) << assertion;
  //
  // There are "verbose level" logging macros.  They look like
  //
  //   VLOG(1) << "I'm printed when you run the program with --v=1 or more";
  //   VLOG(2) << "I'm printed when you run the program with --v=2 or more";
  //
  // These always log at the INFO log level (when they log at all).
  // The verbose logging can also be turned on module-by-module.  For instance,
  //    --vmodule=mapreduce=2,file=1,gfs*=3 --v=0
  // will cause:
  //   a. VLOG(2) and lower messages to be printed from mapreduce.{h,cc}
  //   b. VLOG(1) and lower messages to be printed from file.{h,cc}
  //   c. VLOG(3) and lower messages to be printed from files prefixed with "gfs"
  //   d. VLOG(0) and lower messages to be printed from elsewhere
  //
  // The wildcarding functionality shown by (c) supports both '*' (match
  // 0 or more characters) and '?' (match any single character) wildcards.
  //
  // There's also VLOG_IS_ON(n) "verbose level" condition macro. To be used as
  //
  //   if (VLOG_IS_ON(2)) {
  //     // do some logging preparation and logging
  //     // that can't be accomplished with just VLOG(2) << ...;
  //   }
  //
  // There are also VLOG_IF, VLOG_EVERY_N and VLOG_IF_EVERY_N "verbose level"
  // condition macros for sample cases, when some extra computation and
  // preparation for logs is not needed.
  //   VLOG_IF(1, (size > 1024))
  //      << "I'm printed when size is more than 1024 and when you run the "
  //         "program with --v=1 or more";
  //   VLOG_EVERY_N(1, 10)
  //      << "I'm printed every 10th occurrence, and when you run the program "
  //         "with --v=1 or more. Present occurence is " << google::COUNTER;
  //   VLOG_IF_EVERY_N(1, (size > 1024), 10)
  //      << "I'm printed on every 10th occurence of case when size is more "
  //         " than 1024, when you run the program with --v=1 or more. ";
  //         "Present occurence is " << google::COUNTER;
  //
  // The supported severity levels for macros that allow you to specify one
  // are (in increasing order of severity) INFO, WARNING, ERROR, and FATAL.
  // Note that messages of a given severity are logged not only in the
  // logfile for that severity, but also in all logfiles of lower severity.
  // E.g., a message of severity FATAL will be logged to the logfiles of
  // severity FATAL, ERROR, WARNING, and INFO.
  //
  // There is also the special severity of DFATAL, which logs FATAL in
  // debug mode, ERROR in normal mode.
  //
  // Very important: logging a message at the FATAL severity level causes
  // the program to terminate (after the message is logged).
  //
  // Unless otherwise specified, logs will be written to the filename
  // "<program name>.<hostname>.<user name>.log.<severity level>.", followed
  // by the date, time, and pid (you can't prevent the date, time, and pid
  // from being in the filename).
  //
  // The logging code takes two flags:
  //     --v=#           set the verbose level
  //     --logtostderr   log all the messages to stderr instead of to logfiles
  
  // LOG LINE PREFIX FORMAT
  //
  // Log lines have this form:
  //
  //     Lmmdd hh:mm:ss.uuuuuu threadid file:line] msg...
  //
  // where the fields are defined as follows:
  //
  //   L                A single character, representing the log level
  //                    (eg 'I' for INFO)
  //   mm               The month (zero padded; ie May is '05')
  //   dd               The day (zero padded)
  //   hh:mm:ss.uuuuuu  Time in hours, minutes and fractional seconds
  //   threadid         The space-padded thread ID as returned by GetTID()
  //                    (this matches the PID on Linux)
  //   file             The file name
  //   line             The line number
  //   msg              The user-supplied message
  //
  // Example:
  //
  //   I1103 11:57:31.739339 24395 google.cc:2341] Command line: ./some_prog
  //   I1103 11:57:31.739403 24395 google.cc:2342] Process id 24395
  //
  // NOTE: although the microseconds are useful for comparing events on
  // a single machine, clocks on different machines may not be well
  // synchronized.  Hence, use caution when comparing the low bits of
  // timestamps from different machines.
  
  #ifndef DECLARE_VARIABLE
  #define MUST_UNDEF_GFLAGS_DECLARE_MACROS
  #define DECLARE_VARIABLE(type, shorttype, name, tn)                     \
    namespace fL##shorttype {                                             \
      extern GOOGLE_GLOG_DLL_DECL type FLAGS_##name;                      \
    }                                                                     \
    using fL##shorttype::FLAGS_##name
  
  // bool specialization
  #define DECLARE_bool(name) \
    DECLARE_VARIABLE(bool, B, name, bool)
  
  // int32 specialization
  #define DECLARE_int32(name) \
    DECLARE_VARIABLE(@ac_google_namespace@::int32, I, name, int32)
  
  // Special case for string, because we have to specify the namespace
  // std::string, which doesn't play nicely with our FLAG__namespace hackery.
  #define DECLARE_string(name)                                            \
    namespace fLS {                                                       \
      extern GOOGLE_GLOG_DLL_DECL std::string& FLAGS_##name;              \
    }                                                                     \
    using fLS::FLAGS_##name
  #endif
  
  // Set whether log messages go to stderr instead of logfiles
  DECLARE_bool(logtostderr);
  
  // Set whether log messages go to stderr in addition to logfiles.
  DECLARE_bool(alsologtostderr);
  
  // Set color messages logged to stderr (if supported by terminal).
  DECLARE_bool(colorlogtostderr);
  
  // Log messages at a level >= this flag are automatically sent to
  // stderr in addition to log files.
  DECLARE_int32(stderrthreshold);
  
  // Set whether the log prefix should be prepended to each line of output.
  DECLARE_bool(log_prefix);
  
  // Log messages at a level <= this flag are buffered.
  // Log messages at a higher level are flushed immediately.
  DECLARE_int32(logbuflevel);
  
  // Sets the maximum number of seconds which logs may be buffered for.
  DECLARE_int32(logbufsecs);
  
  // Log suppression level: messages logged at a lower level than this
  // are suppressed.
  DECLARE_int32(minloglevel);
  
  // If specified, logfiles are written into this directory instead of the
  // default logging directory.
  DECLARE_string(log_dir);
  
  // Set the log file mode.
  DECLARE_int32(logfile_mode);
  
  // Sets the path of the directory into which to put additional links
  // to the log files.
  DECLARE_string(log_link);
  
  DECLARE_int32(v);  // in vlog_is_on.cc
  
  // Sets the maximum log file size (in MB).
  DECLARE_int32(max_log_size);
  
  // Sets whether to avoid logging to the disk if the disk is full.
  DECLARE_bool(stop_logging_if_full_disk);
  
  #ifdef MUST_UNDEF_GFLAGS_DECLARE_MACROS
  #undef MUST_UNDEF_GFLAGS_DECLARE_MACROS
  #undef DECLARE_VARIABLE
  #undef DECLARE_bool
  #undef DECLARE_int32
  #undef DECLARE_string
  #endif
  
  // Log messages below the GOOGLE_STRIP_LOG level will be compiled away for
  // security reasons. See LOG(severtiy) below.
  
  // A few definitions of macros that don't generate much code.  Since
  // LOG(INFO) and its ilk are used all over our code, it's
  // better to have compact code for these operations.
  
  #if GOOGLE_STRIP_LOG == 0
  #define COMPACT_GOOGLE_LOG_INFO @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__)
  #define LOG_TO_STRING_INFO(message) @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_INFO, message)
  #else
  #define COMPACT_GOOGLE_LOG_INFO @ac_google_namespace@::NullStream()
  #define LOG_TO_STRING_INFO(message) @ac_google_namespace@::NullStream()
  #endif
  
  #if GOOGLE_STRIP_LOG <= 1
  #define COMPACT_GOOGLE_LOG_WARNING @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_WARNING)
  #define LOG_TO_STRING_WARNING(message) @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_WARNING, message)
  #else
  #define COMPACT_GOOGLE_LOG_WARNING @ac_google_namespace@::NullStream()
  #define LOG_TO_STRING_WARNING(message) @ac_google_namespace@::NullStream()
  #endif
  
  #if GOOGLE_STRIP_LOG <= 2
  #define COMPACT_GOOGLE_LOG_ERROR @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_ERROR)
  #define LOG_TO_STRING_ERROR(message) @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_ERROR, message)
  #else
  #define COMPACT_GOOGLE_LOG_ERROR @ac_google_namespace@::NullStream()
  #define LOG_TO_STRING_ERROR(message) @ac_google_namespace@::NullStream()
  #endif
  
  #if GOOGLE_STRIP_LOG <= 3
  #define COMPACT_GOOGLE_LOG_FATAL @ac_google_namespace@::LogMessageFatal( \
        __FILE__, __LINE__)
  #define LOG_TO_STRING_FATAL(message) @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_FATAL, message)
  #else
  #define COMPACT_GOOGLE_LOG_FATAL @ac_google_namespace@::NullStreamFatal()
  #define LOG_TO_STRING_FATAL(message) @ac_google_namespace@::NullStreamFatal()
  #endif
  
  #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
  #define DCHECK_IS_ON() 0
  #else
  #define DCHECK_IS_ON() 1
  #endif
  
  // For DFATAL, we want to use LogMessage (as opposed to
  // LogMessageFatal), to be consistent with the original behavior.
  #if !DCHECK_IS_ON()
  #define COMPACT_GOOGLE_LOG_DFATAL COMPACT_GOOGLE_LOG_ERROR
  #elif GOOGLE_STRIP_LOG <= 3
  #define COMPACT_GOOGLE_LOG_DFATAL @ac_google_namespace@::LogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_FATAL)
  #else
  #define COMPACT_GOOGLE_LOG_DFATAL @ac_google_namespace@::NullStreamFatal()
  #endif
  
  #define GOOGLE_LOG_INFO(counter) @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_INFO, counter, &@ac_google_namespace@::LogMessage::SendToLog)
  #define SYSLOG_INFO(counter) \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_INFO, counter, \
    &@ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  #define GOOGLE_LOG_WARNING(counter)  \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_WARNING, counter, \
    &@ac_google_namespace@::LogMessage::SendToLog)
  #define SYSLOG_WARNING(counter)  \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_WARNING, counter, \
    &@ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  #define GOOGLE_LOG_ERROR(counter)  \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_ERROR, counter, \
    &@ac_google_namespace@::LogMessage::SendToLog)
  #define SYSLOG_ERROR(counter)  \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_ERROR, counter, \
    &@ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  #define GOOGLE_LOG_FATAL(counter) \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_FATAL, counter, \
    &@ac_google_namespace@::LogMessage::SendToLog)
  #define SYSLOG_FATAL(counter) \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_FATAL, counter, \
    &@ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  #define GOOGLE_LOG_DFATAL(counter) \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::DFATAL_LEVEL, counter, \
    &@ac_google_namespace@::LogMessage::SendToLog)
  #define SYSLOG_DFATAL(counter) \
    @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::DFATAL_LEVEL, counter, \
    &@ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  
  #if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__) || defined(__CYGWIN32__)
  // A very useful logging macro to log windows errors:
  #define LOG_SYSRESULT(result) \
    if (FAILED(HRESULT_FROM_WIN32(result))) { \
      LPSTR message = NULL; \
      LPSTR msg = reinterpret_cast<LPSTR>(&message); \
      DWORD message_length = FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | \
                           FORMAT_MESSAGE_FROM_SYSTEM, \
                           0, result, 0, msg, 100, NULL); \
      if (message_length > 0) { \
        @ac_google_namespace@::LogMessage(__FILE__, __LINE__, @ac_google_namespace@::GLOG_ERROR, 0, \
            &@ac_google_namespace@::LogMessage::SendToLog).stream() \
            << reinterpret_cast<const char*>(message); \
        LocalFree(message); \
      } \
    }
  #endif
  
  // We use the preprocessor's merging operator, "##", so that, e.g.,
  // LOG(INFO) becomes the token GOOGLE_LOG_INFO.  There's some funny
  // subtle difference between ostream member streaming functions (e.g.,
  // ostream::operator<<(int) and ostream non-member streaming functions
  // (e.g., ::operator<<(ostream&, string&): it turns out that it's
  // impossible to stream something like a string directly to an unnamed
  // ostream. We employ a neat hack by calling the stream() member
  // function of LogMessage which seems to avoid the problem.
  #define LOG(severity) COMPACT_GOOGLE_LOG_ ## severity.stream()
  #define SYSLOG(severity) SYSLOG_ ## severity(0).stream()
  
  @ac_google_start_namespace@
  
  // They need the definitions of integer types.
  #include "glog/log_severity.h"
  #include "glog/vlog_is_on.h"
  
  // Initialize google's logging library. You will see the program name
  // specified by argv0 in log outputs.
  GOOGLE_GLOG_DLL_DECL void InitGoogleLogging(const char* argv0);
  
  // Shutdown google's logging library.
  GOOGLE_GLOG_DLL_DECL void ShutdownGoogleLogging();
  
  // Install a function which will be called after LOG(FATAL).
  GOOGLE_GLOG_DLL_DECL void InstallFailureFunction(void (*fail_func)());
  
  class LogSink;  // defined below
  
  // If a non-NULL sink pointer is given, we push this message to that sink.
  // For LOG_TO_SINK we then do normal LOG(severity) logging as well.
  // This is useful for capturing messages and passing/storing them
  // somewhere more specific than the global log of the process.
  // Argument types:
  //   LogSink* sink;
  //   LogSeverity severity;
  // The cast is to disambiguate NULL arguments.
  #define LOG_TO_SINK(sink, severity) \
    @ac_google_namespace@::LogMessage(                                    \
        __FILE__, __LINE__,                                               \
        @ac_google_namespace@::GLOG_ ## severity,                         \
        static_cast<@ac_google_namespace@::LogSink*>(sink), true).stream()
  #define LOG_TO_SINK_BUT_NOT_TO_LOGFILE(sink, severity)                  \
    @ac_google_namespace@::LogMessage(                                    \
        __FILE__, __LINE__,                                               \
        @ac_google_namespace@::GLOG_ ## severity,                         \
        static_cast<@ac_google_namespace@::LogSink*>(sink), false).stream()
  
  // If a non-NULL string pointer is given, we write this message to that string.
  // We then do normal LOG(severity) logging as well.
  // This is useful for capturing messages and storing them somewhere more
  // specific than the global log of the process.
  // Argument types:
  //   string* message;
  //   LogSeverity severity;
  // The cast is to disambiguate NULL arguments.
  // NOTE: LOG(severity) expands to LogMessage().stream() for the specified
  // severity.
  #define LOG_TO_STRING(severity, message) \
    LOG_TO_STRING_##severity(static_cast<string*>(message)).stream()
  
  // If a non-NULL pointer is given, we push the message onto the end
  // of a vector of strings; otherwise, we report it with LOG(severity).
  // This is handy for capturing messages and perhaps passing them back
  // to the caller, rather than reporting them immediately.
  // Argument types:
  //   LogSeverity severity;
  //   vector<string> *outvec;
  // The cast is to disambiguate NULL arguments.
  #define LOG_STRING(severity, outvec) \
    LOG_TO_STRING_##severity(static_cast<std::vector<std::string>*>(outvec)).stream()
  
  #define LOG_IF(severity, condition) \
    !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
  #define SYSLOG_IF(severity, condition) \
    !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & SYSLOG(severity)
  
  #define LOG_ASSERT(condition)  \
    LOG_IF(FATAL, !(condition)) << "Assert failed: " #condition
  #define SYSLOG_ASSERT(condition) \
    SYSLOG_IF(FATAL, !(condition)) << "Assert failed: " #condition
  
  // CHECK dies with a fatal error if condition is not true.  It is *not*
  // controlled by DCHECK_IS_ON(), so the check will be executed regardless of
  // compilation mode.  Therefore, it is safe to do things like:
  //    CHECK(fp->Write(x) == 4)
  #define CHECK(condition)  \
        LOG_IF(FATAL, GOOGLE_PREDICT_BRANCH_NOT_TAKEN(!(condition))) \
               << "Check failed: " #condition " "
  
  // A container for a string pointer which can be evaluated to a bool -
  // true iff the pointer is NULL.
  struct CheckOpString {
    CheckOpString(std::string* str) : str_(str) { }
    // No destructor: if str_ is non-NULL, we're about to LOG(FATAL),
    // so there's no point in cleaning up str_.
    operator bool() const {
      return GOOGLE_PREDICT_BRANCH_NOT_TAKEN(str_ != NULL);
    }
    std::string* str_;
  };
  
  // Function is overloaded for integral types to allow static const
  // integrals declared in classes and not defined to be used as arguments to
  // CHECK* macros. It's not encouraged though.
  template <class T>
  inline const T&       GetReferenceableValue(const T&           t) { return t; }
  inline char           GetReferenceableValue(char               t) { return t; }
  inline unsigned char  GetReferenceableValue(unsigned char      t) { return t; }
  inline signed char    GetReferenceableValue(signed char        t) { return t; }
  inline short          GetReferenceableValue(short              t) { return t; }
  inline unsigned short GetReferenceableValue(unsigned short     t) { return t; }
  inline int            GetReferenceableValue(int                t) { return t; }
  inline unsigned int   GetReferenceableValue(unsigned int       t) { return t; }
  inline long           GetReferenceableValue(long               t) { return t; }
  inline unsigned long  GetReferenceableValue(unsigned long      t) { return t; }
  inline long long      GetReferenceableValue(long long          t) { return t; }
  inline unsigned long long GetReferenceableValue(unsigned long long t) {
    return t;
  }
  
  // This is a dummy class to define the following operator.
  struct DummyClassToDefineOperator {};
  
  @ac_google_end_namespace@
  
  // Define global operator<< to declare using ::operator<<.
  // This declaration will allow use to use CHECK macros for user
  // defined classes which have operator<< (e.g., stl_logging.h).
  inline std::ostream& operator<<(
      std::ostream& out, const google::DummyClassToDefineOperator&) {
    return out;
  }
  
  @ac_google_start_namespace@
  
  // This formats a value for a failing CHECK_XX statement.  Ordinarily,
  // it uses the definition for operator<<, with a few special cases below.
  template <typename T>
  inline void MakeCheckOpValueString(std::ostream* os, const T& v) {
    (*os) << v;
  }
  
  // Overrides for char types provide readable values for unprintable
  // characters.
  template <> GOOGLE_GLOG_DLL_DECL
  void MakeCheckOpValueString(std::ostream* os, const char& v);
  template <> GOOGLE_GLOG_DLL_DECL
  void MakeCheckOpValueString(std::ostream* os, const signed char& v);
  template <> GOOGLE_GLOG_DLL_DECL
  void MakeCheckOpValueString(std::ostream* os, const unsigned char& v);
  
  // Build the error message string. Specify no inlining for code size.
  template <typename T1, typename T2>
  std::string* MakeCheckOpString(const T1& v1, const T2& v2, const char* exprtext)
      @ac_cv___attribute___noinline@;
  
  namespace base {
  namespace internal {
  
  // If "s" is less than base_logging::INFO, returns base_logging::INFO.
  // If "s" is greater than base_logging::FATAL, returns
  // base_logging::ERROR.  Otherwise, returns "s".
  LogSeverity NormalizeSeverity(LogSeverity s);
  
  }  // namespace internal
  
  // A helper class for formatting "expr (V1 vs. V2)" in a CHECK_XX
  // statement.  See MakeCheckOpString for sample usage.  Other
  // approaches were considered: use of a template method (e.g.,
  // base::BuildCheckOpString(exprtext, base::Print<T1>, &v1,
  // base::Print<T2>, &v2), however this approach has complications
  // related to volatile arguments and function-pointer arguments).
  class GOOGLE_GLOG_DLL_DECL CheckOpMessageBuilder {
   public:
    // Inserts "exprtext" and " (" to the stream.
    explicit CheckOpMessageBuilder(const char *exprtext);
    // Deletes "stream_".
    ~CheckOpMessageBuilder();
    // For inserting the first variable.
    std::ostream* ForVar1() { return stream_; }
    // For inserting the second variable (adds an intermediate " vs. ").
    std::ostream* ForVar2();
    // Get the result (inserts the closing ")").
    std::string* NewString();
  
   private:
    std::ostringstream *stream_;
  };
  
  }  // namespace base
  
  template <typename T1, typename T2>
  std::string* MakeCheckOpString(const T1& v1, const T2& v2, const char* exprtext) {
    base::CheckOpMessageBuilder comb(exprtext);
    MakeCheckOpValueString(comb.ForVar1(), v1);
    MakeCheckOpValueString(comb.ForVar2(), v2);
    return comb.NewString();
  }
  
  // Helper functions for CHECK_OP macro.
  // The (int, int) specialization works around the issue that the compiler
  // will not instantiate the template version of the function on values of
  // unnamed enum type - see comment below.
  #define DEFINE_CHECK_OP_IMPL(name, op) \
    template <typename T1, typename T2> \
    inline std::string* name##Impl(const T1& v1, const T2& v2,    \
                              const char* exprtext) { \
      if (GOOGLE_PREDICT_TRUE(v1 op v2)) return NULL; \
      else return MakeCheckOpString(v1, v2, exprtext); \
    } \
    inline std::string* name##Impl(int v1, int v2, const char* exprtext) { \
      return name##Impl<int, int>(v1, v2, exprtext); \
    }
  
  // We use the full name Check_EQ, Check_NE, etc. in case the file including
  // base/logging.h provides its own #defines for the simpler names EQ, NE, etc.
  // This happens if, for example, those are used as token names in a
  // yacc grammar.
  DEFINE_CHECK_OP_IMPL(Check_EQ, ==)  // Compilation error with CHECK_EQ(NULL, x)?
  DEFINE_CHECK_OP_IMPL(Check_NE, !=)  // Use CHECK(x == NULL) instead.
  DEFINE_CHECK_OP_IMPL(Check_LE, <=)
  DEFINE_CHECK_OP_IMPL(Check_LT, < )
  DEFINE_CHECK_OP_IMPL(Check_GE, >=)
  DEFINE_CHECK_OP_IMPL(Check_GT, > )
  #undef DEFINE_CHECK_OP_IMPL
  
  // Helper macro for binary operators.
  // Don't use this macro directly in your code, use CHECK_EQ et al below.
  
  #if defined(STATIC_ANALYSIS)
  // Only for static analysis tool to know that it is equivalent to assert
  #define CHECK_OP_LOG(name, op, val1, val2, log) CHECK((val1) op (val2))
  #elif DCHECK_IS_ON()
  // In debug mode, avoid constructing CheckOpStrings if possible,
  // to reduce the overhead of CHECK statments by 2x.
  // Real DCHECK-heavy tests have seen 1.5x speedups.
  
  // The meaning of "string" might be different between now and
  // when this macro gets invoked (e.g., if someone is experimenting
  // with other string implementations that get defined after this
  // file is included).  Save the current meaning now and use it
  // in the macro.
  typedef std::string _Check_string;
  #define CHECK_OP_LOG(name, op, val1, val2, log)                         \
    while (@ac_google_namespace@::_Check_string* _result =                \
           @ac_google_namespace@::Check##name##Impl(                      \
               @ac_google_namespace@::GetReferenceableValue(val1),        \
               @ac_google_namespace@::GetReferenceableValue(val2),        \
               #val1 " " #op " " #val2))                                  \
      log(__FILE__, __LINE__,                                             \
          @ac_google_namespace@::CheckOpString(_result)).stream()
  #else
  // In optimized mode, use CheckOpString to hint to compiler that
  // the while condition is unlikely.
  #define CHECK_OP_LOG(name, op, val1, val2, log)                         \
    while (@ac_google_namespace@::CheckOpString _result =                 \
           @ac_google_namespace@::Check##name##Impl(                      \
               @ac_google_namespace@::GetReferenceableValue(val1),        \
               @ac_google_namespace@::GetReferenceableValue(val2),        \
               #val1 " " #op " " #val2))                                  \
      log(__FILE__, __LINE__, _result).stream()
  #endif  // STATIC_ANALYSIS, DCHECK_IS_ON()
  
  #if GOOGLE_STRIP_LOG <= 3
  #define CHECK_OP(name, op, val1, val2) \
    CHECK_OP_LOG(name, op, val1, val2, @ac_google_namespace@::LogMessageFatal)
  #else
  #define CHECK_OP(name, op, val1, val2) \
    CHECK_OP_LOG(name, op, val1, val2, @ac_google_namespace@::NullStreamFatal)
  #endif // STRIP_LOG <= 3
  
  // Equality/Inequality checks - compare two values, and log a FATAL message
  // including the two values when the result is not as expected.  The values
  // must have operator<<(ostream, ...) defined.
  //
  // You may append to the error message like so:
  //   CHECK_NE(1, 2) << ": The world must be ending!";
  //
  // We are very careful to ensure that each argument is evaluated exactly
  // once, and that anything which is legal to pass as a function argument is
  // legal here.  In particular, the arguments may be temporary expressions
  // which will end up being destroyed at the end of the apparent statement,
  // for example:
  //   CHECK_EQ(string("abc")[1], 'b');
  //
  // WARNING: These don't compile correctly if one of the arguments is a pointer
  // and the other is NULL. To work around this, simply static_cast NULL to the
  // type of the desired pointer.
  
  #define CHECK_EQ(val1, val2) CHECK_OP(_EQ, ==, val1, val2)
  #define CHECK_NE(val1, val2) CHECK_OP(_NE, !=, val1, val2)
  #define CHECK_LE(val1, val2) CHECK_OP(_LE, <=, val1, val2)
  #define CHECK_LT(val1, val2) CHECK_OP(_LT, < , val1, val2)
  #define CHECK_GE(val1, val2) CHECK_OP(_GE, >=, val1, val2)
  #define CHECK_GT(val1, val2) CHECK_OP(_GT, > , val1, val2)
  
  // Check that the input is non NULL.  This very useful in constructor
  // initializer lists.
  
  #define CHECK_NOTNULL(val) \
    @ac_google_namespace@::CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non NULL", (val))
  
  // Helper functions for string comparisons.
  // To avoid bloat, the definitions are in logging.cc.
  #define DECLARE_CHECK_STROP_IMPL(func, expected) \
    GOOGLE_GLOG_DLL_DECL std::string* Check##func##expected##Impl( \
        const char* s1, const char* s2, const char* names);
  DECLARE_CHECK_STROP_IMPL(strcmp, true)
  DECLARE_CHECK_STROP_IMPL(strcmp, false)
  DECLARE_CHECK_STROP_IMPL(strcasecmp, true)
  DECLARE_CHECK_STROP_IMPL(strcasecmp, false)
  #undef DECLARE_CHECK_STROP_IMPL
  
  // Helper macro for string comparisons.
  // Don't use this macro directly in your code, use CHECK_STREQ et al below.
  #define CHECK_STROP(func, op, expected, s1, s2) \
    while (@ac_google_namespace@::CheckOpString _result = \
           @ac_google_namespace@::Check##func##expected##Impl((s1), (s2), \
                                       #s1 " " #op " " #s2)) \
      LOG(FATAL) << *_result.str_
  
  
  // String (char*) equality/inequality checks.
  // CASE versions are case-insensitive.
  //
  // Note that "s1" and "s2" may be temporary strings which are destroyed
  // by the compiler at the end of the current "full expression"
  // (e.g. CHECK_STREQ(Foo().c_str(), Bar().c_str())).
  
  #define CHECK_STREQ(s1, s2) CHECK_STROP(strcmp, ==, true, s1, s2)
  #define CHECK_STRNE(s1, s2) CHECK_STROP(strcmp, !=, false, s1, s2)
  #define CHECK_STRCASEEQ(s1, s2) CHECK_STROP(strcasecmp, ==, true, s1, s2)
  #define CHECK_STRCASENE(s1, s2) CHECK_STROP(strcasecmp, !=, false, s1, s2)
  
  #define CHECK_INDEX(I,A) CHECK(I < (sizeof(A)/sizeof(A[0])))
  #define CHECK_BOUND(B,A) CHECK(B <= (sizeof(A)/sizeof(A[0])))
  
  #define CHECK_DOUBLE_EQ(val1, val2)              \
    do {                                           \
      CHECK_LE((val1), (val2)+0.000000000000001L); \
      CHECK_GE((val1), (val2)-0.000000000000001L); \
    } while (0)
  
  #define CHECK_NEAR(val1, val2, margin)           \
    do {                                           \
      CHECK_LE((val1), (val2)+(margin));           \
      CHECK_GE((val1), (val2)-(margin));           \
    } while (0)
  
  // perror()..googly style!
  //
  // PLOG() and PLOG_IF() and PCHECK() behave exactly like their LOG* and
  // CHECK equivalents with the addition that they postpend a description
  // of the current state of errno to their output lines.
  
  #define PLOG(severity) GOOGLE_PLOG(severity, 0).stream()
  
  #define GOOGLE_PLOG(severity, counter)  \
    @ac_google_namespace@::ErrnoLogMessage( \
        __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, counter, \
        &@ac_google_namespace@::LogMessage::SendToLog)
  
  #define PLOG_IF(severity, condition) \
    !(condition) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & PLOG(severity)
  
  // A CHECK() macro that postpends errno if the condition is false. E.g.
  //
  // if (poll(fds, nfds, timeout) == -1) { PCHECK(errno == EINTR); ... }
  #define PCHECK(condition)  \
        PLOG_IF(FATAL, GOOGLE_PREDICT_BRANCH_NOT_TAKEN(!(condition))) \
                << "Check failed: " #condition " "
  
  // A CHECK() macro that lets you assert the success of a function that
  // returns -1 and sets errno in case of an error. E.g.
  //
  // CHECK_ERR(mkdir(path, 0700));
  //
  // or
  //
  // int fd = open(filename, flags); CHECK_ERR(fd) << ": open " << filename;
  #define CHECK_ERR(invocation)                                          \
  PLOG_IF(FATAL, GOOGLE_PREDICT_BRANCH_NOT_TAKEN((invocation) == -1))    \
          << #invocation
  
  // Use macro expansion to create, for each use of LOG_EVERY_N(), static
  // variables with the __LINE__ expansion as part of the variable name.
  #define LOG_EVERY_N_VARNAME(base, line) LOG_EVERY_N_VARNAME_CONCAT(base, line)
  #define LOG_EVERY_N_VARNAME_CONCAT(base, line) base ## line
  
  #define LOG_OCCURRENCES LOG_EVERY_N_VARNAME(occurrences_, __LINE__)
  #define LOG_OCCURRENCES_MOD_N LOG_EVERY_N_VARNAME(occurrences_mod_n_, __LINE__)
  
  #define SOME_KIND_OF_LOG_EVERY_N(severity, n, what_to_do) \
    static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
    ++LOG_OCCURRENCES; \
    if (++LOG_OCCURRENCES_MOD_N > n) LOG_OCCURRENCES_MOD_N -= n; \
    if (LOG_OCCURRENCES_MOD_N == 1) \
      @ac_google_namespace@::LogMessage( \
          __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
          &what_to_do).stream()
  
  #define SOME_KIND_OF_LOG_IF_EVERY_N(severity, condition, n, what_to_do) \
    static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
    ++LOG_OCCURRENCES; \
    if (condition && \
        ((LOG_OCCURRENCES_MOD_N=(LOG_OCCURRENCES_MOD_N + 1) % n) == (1 % n))) \
      @ac_google_namespace@::LogMessage( \
          __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
                   &what_to_do).stream()
  
  #define SOME_KIND_OF_PLOG_EVERY_N(severity, n, what_to_do) \
    static int LOG_OCCURRENCES = 0, LOG_OCCURRENCES_MOD_N = 0; \
    ++LOG_OCCURRENCES; \
    if (++LOG_OCCURRENCES_MOD_N > n) LOG_OCCURRENCES_MOD_N -= n; \
    if (LOG_OCCURRENCES_MOD_N == 1) \
      @ac_google_namespace@::ErrnoLogMessage( \
          __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
          &what_to_do).stream()
  
  #define SOME_KIND_OF_LOG_FIRST_N(severity, n, what_to_do) \
    static int LOG_OCCURRENCES = 0; \
    if (LOG_OCCURRENCES <= n) \
      ++LOG_OCCURRENCES; \
    if (LOG_OCCURRENCES <= n) \
      @ac_google_namespace@::LogMessage( \
          __FILE__, __LINE__, @ac_google_namespace@::GLOG_ ## severity, LOG_OCCURRENCES, \
          &what_to_do).stream()
  
  namespace glog_internal_namespace_ {
  template <bool>
  struct CompileAssert {
  };
  struct CrashReason;
  
  // Returns true if FailureSignalHandler is installed.
  bool IsFailureSignalHandlerInstalled();
  }  // namespace glog_internal_namespace_
  
  #define GOOGLE_GLOG_COMPILE_ASSERT(expr, msg) \
    typedef @ac_google_namespace@::glog_internal_namespace_::CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
  
  #define LOG_EVERY_N(severity, n)                                        \
    GOOGLE_GLOG_COMPILE_ASSERT(@ac_google_namespace@::GLOG_ ## severity < \
                               @ac_google_namespace@::NUM_SEVERITIES,     \
                               INVALID_REQUESTED_LOG_SEVERITY);           \
    SOME_KIND_OF_LOG_EVERY_N(severity, (n), @ac_google_namespace@::LogMessage::SendToLog)
  
  #define SYSLOG_EVERY_N(severity, n) \
    SOME_KIND_OF_LOG_EVERY_N(severity, (n), @ac_google_namespace@::LogMessage::SendToSyslogAndLog)
  
  #define PLOG_EVERY_N(severity, n) \
    SOME_KIND_OF_PLOG_EVERY_N(severity, (n), @ac_google_namespace@::LogMessage::SendToLog)
  
  #define LOG_FIRST_N(severity, n) \
    SOME_KIND_OF_LOG_FIRST_N(severity, (n), @ac_google_namespace@::LogMessage::SendToLog)
  
  #define LOG_IF_EVERY_N(severity, condition, n) \
    SOME_KIND_OF_LOG_IF_EVERY_N(severity, (condition), (n), @ac_google_namespace@::LogMessage::SendToLog)
  
  // We want the special COUNTER value available for LOG_EVERY_X()'ed messages
  enum PRIVATE_Counter {COUNTER};
  
  #ifdef GLOG_NO_ABBREVIATED_SEVERITIES
  // wingdi.h defines ERROR to be 0. When we call LOG(ERROR), it gets
  // substituted with 0, and it expands to COMPACT_GOOGLE_LOG_0. To allow us
  // to keep using this syntax, we define this macro to do the same thing
  // as COMPACT_GOOGLE_LOG_ERROR.
  #define COMPACT_GOOGLE_LOG_0 COMPACT_GOOGLE_LOG_ERROR
  #define SYSLOG_0 SYSLOG_ERROR
  #define LOG_TO_STRING_0 LOG_TO_STRING_ERROR
  // Needed for LOG_IS_ON(ERROR).
  const LogSeverity GLOG_0 = GLOG_ERROR;
  #else
  // Users may include windows.h after logging.h without
  // GLOG_NO_ABBREVIATED_SEVERITIES nor WIN32_LEAN_AND_MEAN.
  // For this case, we cannot detect if ERROR is defined before users
  // actually use ERROR. Let's make an undefined symbol to warn users.
  # define GLOG_ERROR_MSG ERROR_macro_is_defined_Define_GLOG_NO_ABBREVIATED_SEVERITIES_before_including_logging_h_See_the_document_for_detail
  # define COMPACT_GOOGLE_LOG_0 GLOG_ERROR_MSG
  # define SYSLOG_0 GLOG_ERROR_MSG
  # define LOG_TO_STRING_0 GLOG_ERROR_MSG
  # define GLOG_0 GLOG_ERROR_MSG
  #endif
  
  // Plus some debug-logging macros that get compiled to nothing for production
  
  #if DCHECK_IS_ON()
  
  #define DLOG(severity) LOG(severity)
  #define DVLOG(verboselevel) VLOG(verboselevel)
  #define DLOG_IF(severity, condition) LOG_IF(severity, condition)
  #define DLOG_EVERY_N(severity, n) LOG_EVERY_N(severity, n)
  #define DLOG_IF_EVERY_N(severity, condition, n) \
    LOG_IF_EVERY_N(severity, condition, n)
  #define DLOG_ASSERT(condition) LOG_ASSERT(condition)
  
  // debug-only checking.  executed if DCHECK_IS_ON().
  #define DCHECK(condition) CHECK(condition)
  #define DCHECK_EQ(val1, val2) CHECK_EQ(val1, val2)
  #define DCHECK_NE(val1, val2) CHECK_NE(val1, val2)
  #define DCHECK_LE(val1, val2) CHECK_LE(val1, val2)
  #define DCHECK_LT(val1, val2) CHECK_LT(val1, val2)
  #define DCHECK_GE(val1, val2) CHECK_GE(val1, val2)
  #define DCHECK_GT(val1, val2) CHECK_GT(val1, val2)
  #define DCHECK_NOTNULL(val) CHECK_NOTNULL(val)
  #define DCHECK_STREQ(str1, str2) CHECK_STREQ(str1, str2)
  #define DCHECK_STRCASEEQ(str1, str2) CHECK_STRCASEEQ(str1, str2)
  #define DCHECK_STRNE(str1, str2) CHECK_STRNE(str1, str2)
  #define DCHECK_STRCASENE(str1, str2) CHECK_STRCASENE(str1, str2)
  
  #else  // !DCHECK_IS_ON()
  
  #define DLOG(severity) \
    true ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
  
  #define DVLOG(verboselevel) \
    (true || !VLOG_IS_ON(verboselevel)) ?\
      (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(INFO)
  
  #define DLOG_IF(severity, condition) \
    (true || !(condition)) ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
  
  #define DLOG_EVERY_N(severity, n) \
    true ? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
  
  #define DLOG_IF_EVERY_N(severity, condition, n) \
    (true || !(condition))? (void) 0 : @ac_google_namespace@::LogMessageVoidify() & LOG(severity)
  
  #define DLOG_ASSERT(condition) \
    true ? (void) 0 : LOG_ASSERT(condition)
  
  // MSVC warning C4127: conditional expression is constant
  #define DCHECK(condition) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK(condition)
  
  #define DCHECK_EQ(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_EQ(val1, val2)
  
  #define DCHECK_NE(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_NE(val1, val2)
  
  #define DCHECK_LE(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_LE(val1, val2)
  
  #define DCHECK_LT(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_LT(val1, val2)
  
  #define DCHECK_GE(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_GE(val1, val2)
  
  #define DCHECK_GT(val1, val2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_GT(val1, val2)
  
  // You may see warnings in release mode if you don't use the return
  // value of DCHECK_NOTNULL. Please just use DCHECK for such cases.
  #define DCHECK_NOTNULL(val) (val)
  
  #define DCHECK_STREQ(str1, str2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_STREQ(str1, str2)
  
  #define DCHECK_STRCASEEQ(str1, str2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_STRCASEEQ(str1, str2)
  
  #define DCHECK_STRNE(str1, str2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_STRNE(str1, str2)
  
  #define DCHECK_STRCASENE(str1, str2) \
    GLOG_MSVC_PUSH_DISABLE_WARNING(4127) \
    while (false) \
      GLOG_MSVC_POP_WARNING() CHECK_STRCASENE(str1, str2)
  
  #endif  // DCHECK_IS_ON()
  
  // Log only in verbose mode.
  
  #define VLOG(verboselevel) LOG_IF(INFO, VLOG_IS_ON(verboselevel))
  
  #define VLOG_IF(verboselevel, condition) \
    LOG_IF(INFO, (condition) && VLOG_IS_ON(verboselevel))
  
  #define VLOG_EVERY_N(verboselevel, n) \
    LOG_IF_EVERY_N(INFO, VLOG_IS_ON(verboselevel), n)
  
  #define VLOG_IF_EVERY_N(verboselevel, condition, n) \
    LOG_IF_EVERY_N(INFO, (condition) && VLOG_IS_ON(verboselevel), n)
  
  namespace base_logging {
  
  // LogMessage::LogStream is a std::ostream backed by this streambuf.
  // This class ignores overflow and leaves two bytes at the end of the
  // buffer to allow for a '\n' and '\0'.
  class GOOGLE_GLOG_DLL_DECL LogStreamBuf : public std::streambuf {
   public:
    // REQUIREMENTS: "len" must be >= 2 to account for the '\n' and '\n'.
    LogStreamBuf(char *buf, int len) {
      setp(buf, buf + len - 2);
    }
    // This effectively ignores overflow.
    virtual int_type overflow(int_type ch) {
      return ch;
    }
  
    // Legacy public ostrstream method.
    size_t pcount() const { return pptr() - pbase(); }
    char* pbase() const { return std::streambuf::pbase(); }
  };
  
  }  // namespace base_logging
  
  //
  // This class more or less represents a particular log message.  You
  // create an instance of LogMessage and then stream stuff to it.
  // When you finish streaming to it, ~LogMessage is called and the
  // full message gets streamed to the appropriate destination.
  //
  // You shouldn't actually use LogMessage's constructor to log things,
  // though.  You should use the LOG() macro (and variants thereof)
  // above.
  class GOOGLE_GLOG_DLL_DECL LogMessage {
  public:
    enum {
      // Passing kNoLogPrefix for the line number disables the
      // log-message prefix. Useful for using the LogMessage
      // infrastructure as a printing utility. See also the --log_prefix
      // flag for controlling the log-message prefix on an
      // application-wide basis.
      kNoLogPrefix = -1
    };
  
    // LogStream inherit from non-DLL-exported class (std::ostrstream)
    // and VC++ produces a warning for this situation.
    // However, MSDN says "C4275 can be ignored in Microsoft Visual C++
    // 2005 if you are deriving from a type in the Standard C++ Library"
    // http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
    // Let's just ignore the warning.
  #ifdef _MSC_VER
  # pragma warning(disable: 4275)
  #endif
    class GOOGLE_GLOG_DLL_DECL LogStream : public std::ostream {
  #ifdef _MSC_VER
  # pragma warning(default: 4275)
  #endif
    public:
      LogStream(char *buf, int len, int ctr)
          : std::ostream(NULL),
            streambuf_(buf, len),
            ctr_(ctr),
            self_(this) {
        rdbuf(&streambuf_);
      }
  
      int ctr() const { return ctr_; }
      void set_ctr(int ctr) { ctr_ = ctr; }
      LogStream* self() const { return self_; }
  
      // Legacy std::streambuf methods.
      size_t pcount() const { return streambuf_.pcount(); }
      char* pbase() const { return streambuf_.pbase(); }
      char* str() const { return pbase(); }
  
    private:
      LogStream(const LogStream&);
      LogStream& operator=(const LogStream&);
      base_logging::LogStreamBuf streambuf_;
      int ctr_;  // Counter hack (for the LOG_EVERY_X() macro)
      LogStream *self_;  // Consistency check hack
    };
  
  public:
    // icc 8 requires this typedef to avoid an internal compiler error.
    typedef void (LogMessage::*SendMethod)();
  
    LogMessage(const char* file, int line, LogSeverity severity, int ctr,
               SendMethod send_method);
  
    // Two special constructors that generate reduced amounts of code at
    // LOG call sites for common cases.
  
    // Used for LOG(INFO): Implied are:
    // severity = INFO, ctr = 0, send_method = &LogMessage::SendToLog.
    //
    // Using this constructor instead of the more complex constructor above
    // saves 19 bytes per call site.
    LogMessage(const char* file, int line);
  
    // Used for LOG(severity) where severity != INFO.  Implied
    // are: ctr = 0, send_method = &LogMessage::SendToLog
    //
    // Using this constructor instead of the more complex constructor above
    // saves 17 bytes per call site.
    LogMessage(const char* file, int line, LogSeverity severity);
  
    // Constructor to log this message to a specified sink (if not NULL).
    // Implied are: ctr = 0, send_method = &LogMessage::SendToSinkAndLog if
    // also_send_to_log is true, send_method = &LogMessage::SendToSink otherwise.
    LogMessage(const char* file, int line, LogSeverity severity, LogSink* sink,
               bool also_send_to_log);
  
    // Constructor where we also give a vector<string> pointer
    // for storing the messages (if the pointer is not NULL).
    // Implied are: ctr = 0, send_method = &LogMessage::SaveOrSendToLog.
    LogMessage(const char* file, int line, LogSeverity severity,
               std::vector<std::string>* outvec);
  
    // Constructor where we also give a string pointer for storing the
    // message (if the pointer is not NULL).  Implied are: ctr = 0,
    // send_method = &LogMessage::WriteToStringAndLog.
    LogMessage(const char* file, int line, LogSeverity severity,
               std::string* message);
  
    // A special constructor used for check failures
    LogMessage(const char* file, int line, const CheckOpString& result);
  
    ~LogMessage();
  
    // Flush a buffered message to the sink set in the constructor.  Always
    // called by the destructor, it may also be called from elsewhere if
    // needed.  Only the first call is actioned; any later ones are ignored.
    void Flush();
  
    // An arbitrary limit on the length of a single log message.  This
    // is so that streaming can be done more efficiently.
    static const size_t kMaxLogMessageLen;
  
    // Theses should not be called directly outside of logging.*,
    // only passed as SendMethod arguments to other LogMessage methods:
    void SendToLog();  // Actually dispatch to the logs
    void SendToSyslogAndLog();  // Actually dispatch to syslog and the logs
  
    // Call abort() or similar to perform LOG(FATAL) crash.
    static void @ac_cv___attribute___noreturn@ Fail();
  
    std::ostream& stream();
  
    int preserved_errno() const;
  
    // Must be called without the log_mutex held.  (L < log_mutex)
    static int64 num_messages(int severity);
  
    struct LogMessageData;
  
  private:
    // Fully internal SendMethod cases:
    void SendToSinkAndLog();  // Send to sink if provided and dispatch to the logs
    void SendToSink();  // Send to sink if provided, do nothing otherwise.
  
    // Write to string if provided and dispatch to the logs.
    void WriteToStringAndLog();
  
    void SaveOrSendToLog();  // Save to stringvec if provided, else to logs
  
    void Init(const char* file, int line, LogSeverity severity,
              void (LogMessage::*send_method)());
  
    // Used to fill in crash information during LOG(FATAL) failures.
    void RecordCrashReason(glog_internal_namespace_::CrashReason* reason);
  
    // Counts of messages sent at each priority:
    static int64 num_messages_[NUM_SEVERITIES];  // under log_mutex
  
    // We keep the data in a separate struct so that each instance of
    // LogMessage uses less stack space.
    LogMessageData* allocated_;
    LogMessageData* data_;
  
    friend class LogDestination;
  
    LogMessage(const LogMessage&);
    void operator=(const LogMessage&);
  };
  
  // This class happens to be thread-hostile because all instances share
  // a single data buffer, but since it can only be created just before
  // the process dies, we don't worry so much.
  class GOOGLE_GLOG_DLL_DECL LogMessageFatal : public LogMessage {
   public:
    LogMessageFatal(const char* file, int line);
    LogMessageFatal(const char* file, int line, const CheckOpString& result);
    @ac_cv___attribute___noreturn@ ~LogMessageFatal();
  };
  
  // A non-macro interface to the log facility; (useful
  // when the logging level is not a compile-time constant).
  inline void LogAtLevel(int const severity, std::string const &msg) {
    LogMessage(__FILE__, __LINE__, severity).stream() << msg;
  }
  
  // A macro alternative of LogAtLevel. New code may want to use this
  // version since there are two advantages: 1. this version outputs the
  // file name and the line number where this macro is put like other
  // LOG macros, 2. this macro can be used as C++ stream.
  #define LOG_AT_LEVEL(severity) @ac_google_namespace@::LogMessage(__FILE__, __LINE__, severity).stream()
  
  // Check if it's compiled in C++11 mode.
  //
  // GXX_EXPERIMENTAL_CXX0X is defined by gcc and clang up to at least
  // gcc-4.7 and clang-3.1 (2011-12-13).  __cplusplus was defined to 1
  // in gcc before 4.7 (Crosstool 16) and clang before 3.1, but is
  // defined according to the language version in effect thereafter.
  // Microsoft Visual Studio 14 (2015) sets __cplusplus==199711 despite
  // reasonably good C++11 support, so we set LANG_CXX for it and
  // newer versions (_MSC_VER >= 1900).
  #if (defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L || \
       (defined(_MSC_VER) && _MSC_VER >= 1900))
  // Helper for CHECK_NOTNULL().
  //
  // In C++11, all cases can be handled by a single function. Since the value
  // category of the argument is preserved (also for rvalue references),
  // member initializer lists like the one below will compile correctly:
  //
  //   Foo()
  //     : x_(CHECK_NOTNULL(MethodReturningUniquePtr())) {}
  template <typename T>
  T CheckNotNull(const char* file, int line, const char* names, T&& t) {
   if (t == nullptr) {
     LogMessageFatal(file, line, new std::string(names));
   }
   return std::forward<T>(t);
  }
  
  #else
  
  // A small helper for CHECK_NOTNULL().
  template <typename T>
  T* CheckNotNull(const char *file, int line, const char *names, T* t) {
    if (t == NULL) {
      LogMessageFatal(file, line, new std::string(names));
    }
    return t;
  }
  #endif
  
  // Allow folks to put a counter in the LOG_EVERY_X()'ed messages. This
  // only works if ostream is a LogStream. If the ostream is not a
  // LogStream you'll get an assert saying as much at runtime.
  GOOGLE_GLOG_DLL_DECL std::ostream& operator<<(std::ostream &os,
                                                const PRIVATE_Counter&);
  
  
  // Derived class for PLOG*() above.
  class GOOGLE_GLOG_DLL_DECL ErrnoLogMessage : public LogMessage {
   public:
  
    ErrnoLogMessage(const char* file, int line, LogSeverity severity, int ctr,
                    void (LogMessage::*send_method)());
  
    // Postpends ": strerror(errno) [errno]".
    ~ErrnoLogMessage();
  
   private:
    ErrnoLogMessage(const ErrnoLogMessage&);
    void operator=(const ErrnoLogMessage&);
  };
  
  
  // This class is used to explicitly ignore values in the conditional
  // logging macros.  This avoids compiler warnings like "value computed
  // is not used" and "statement has no effect".
  
  class GOOGLE_GLOG_DLL_DECL LogMessageVoidify {
   public:
    LogMessageVoidify() { }
    // This has to be an operator with a precedence lower than << but
    // higher than ?:
    void operator&(std::ostream&) { }
  };
  
  
  // Flushes all log files that contains messages that are at least of
  // the specified severity level.  Thread-safe.
  GOOGLE_GLOG_DLL_DECL void FlushLogFiles(LogSeverity min_severity);
  
  // Flushes all log files that contains messages that are at least of
  // the specified severity level. Thread-hostile because it ignores
  // locking -- used for catastrophic failures.
  GOOGLE_GLOG_DLL_DECL void FlushLogFilesUnsafe(LogSeverity min_severity);
  
  //
  // Set the destination to which a particular severity level of log
  // messages is sent.  If base_filename is "", it means "don't log this
  // severity".  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void SetLogDestination(LogSeverity severity,
                                              const char* base_filename);
  
  //
  // Set the basename of the symlink to the latest log file at a given
  // severity.  If symlink_basename is empty, do not make a symlink.  If
  // you don't call this function, the symlink basename is the
  // invocation name of the program.  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void SetLogSymlink(LogSeverity severity,
                                          const char* symlink_basename);
  
  //
  // Used to send logs to some other kind of destination
  // Users should subclass LogSink and override send to do whatever they want.
  // Implementations must be thread-safe because a shared instance will
  // be called from whichever thread ran the LOG(XXX) line.
  class GOOGLE_GLOG_DLL_DECL LogSink {
   public:
    virtual ~LogSink();
  
    // Sink's logging logic (message_len is such as to exclude '\n' at the end).
    // This method can't use LOG() or CHECK() as logging system mutex(s) are held
    // during this call.
    virtual void send(LogSeverity severity, const char* full_filename,
                      const char* base_filename, int line,
                      const struct ::tm* tm_time,
                      const char* message, size_t message_len) = 0;
  
    // Redefine this to implement waiting for
    // the sink's logging logic to complete.
    // It will be called after each send() returns,
    // but before that LogMessage exits or crashes.
    // By default this function does nothing.
    // Using this function one can implement complex logic for send()
    // that itself involves logging; and do all this w/o causing deadlocks and
    // inconsistent rearrangement of log messages.
    // E.g. if a LogSink has thread-specific actions, the send() method
    // can simply add the message to a queue and wake up another thread that
    // handles real logging while itself making some LOG() calls;
    // WaitTillSent() can be implemented to wait for that logic to complete.
    // See our unittest for an example.
    virtual void WaitTillSent();
  
    // Returns the normal text output of the log message.
    // Can be useful to implement send().
    static std::string ToString(LogSeverity severity, const char* file, int line,
                                const struct ::tm* tm_time,
                                const char* message, size_t message_len);
  };
  
  // Add or remove a LogSink as a consumer of logging data.  Thread-safe.
  GOOGLE_GLOG_DLL_DECL void AddLogSink(LogSink *destination);
  GOOGLE_GLOG_DLL_DECL void RemoveLogSink(LogSink *destination);
  
  //
  // Specify an "extension" added to the filename specified via
  // SetLogDestination.  This applies to all severity levels.  It's
  // often used to append the port we're listening on to the logfile
  // name.  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void SetLogFilenameExtension(
      const char* filename_extension);
  
  //
  // Make it so that all log messages of at least a particular severity
  // are logged to stderr (in addition to logging to the usual log
  // file(s)).  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void SetStderrLogging(LogSeverity min_severity);
  
  //
  // Make it so that all log messages go only to stderr.  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void LogToStderr();
  
  //
  // Make it so that all log messages of at least a particular severity are
  // logged via email to a list of addresses (in addition to logging to the
  // usual log file(s)).  The list of addresses is just a string containing
  // the email addresses to send to (separated by spaces, say).  Thread-safe.
  //
  GOOGLE_GLOG_DLL_DECL void SetEmailLogging(LogSeverity min_severity,
                                            const char* addresses);
  
  // A simple function that sends email. dest is a commma-separated
  // list of addressess.  Thread-safe.
  GOOGLE_GLOG_DLL_DECL bool SendEmail(const char *dest,
                                      const char *subject, const char *body);
  
  GOOGLE_GLOG_DLL_DECL const std::vector<std::string>& GetLoggingDirectories();
  
  // For tests only:  Clear the internal [cached] list of logging directories to
  // force a refresh the next time GetLoggingDirectories is called.
  // Thread-hostile.
  void TestOnly_ClearLoggingDirectoriesList();
  
  // Returns a set of existing temporary directories, which will be a
  // subset of the directories returned by GetLogginDirectories().
  // Thread-safe.
  GOOGLE_GLOG_DLL_DECL void GetExistingTempDirectories(
      std::vector<std::string>* list);
  
  // Print any fatal message again -- useful to call from signal handler
  // so that the last thing in the output is the fatal message.
  // Thread-hostile, but a race is unlikely.
  GOOGLE_GLOG_DLL_DECL void ReprintFatalMessage();
  
  // Truncate a log file that may be the append-only output of multiple
  // processes and hence can't simply be renamed/reopened (typically a
  // stdout/stderr).  If the file "path" is > "limit" bytes, copy the
  // last "keep" bytes to offset 0 and truncate the rest. Since we could
  // be racing with other writers, this approach has the potential to
  // lose very small amounts of data. For security, only follow symlinks
  // if the path is /proc/self/fd/*
  GOOGLE_GLOG_DLL_DECL void TruncateLogFile(const char *path,
                                            int64 limit, int64 keep);
  
  // Truncate stdout and stderr if they are over the value specified by
  // --max_log_size; keep the final 1MB.  This function has the same
  // race condition as TruncateLogFile.
  GOOGLE_GLOG_DLL_DECL void TruncateStdoutStderr();
  
  // Return the string representation of the provided LogSeverity level.
  // Thread-safe.
  GOOGLE_GLOG_DLL_DECL const char* GetLogSeverityName(LogSeverity severity);
  
  // ---------------------------------------------------------------------
  // Implementation details that are not useful to most clients
  // ---------------------------------------------------------------------
  
  // A Logger is the interface used by logging modules to emit entries
  // to a log.  A typical implementation will dump formatted data to a
  // sequence of files.  We also provide interfaces that will forward
  // the data to another thread so that the invoker never blocks.
  // Implementations should be thread-safe since the logging system
  // will write to them from multiple threads.
  
  namespace base {
  
  class GOOGLE_GLOG_DLL_DECL Logger {
   public:
    virtual ~Logger();
  
    // Writes "message[0,message_len-1]" corresponding to an event that
    // occurred at "timestamp".  If "force_flush" is true, the log file
    // is flushed immediately.
    //
    // The input message has already been formatted as deemed
    // appropriate by the higher level logging facility.  For example,
    // textual log messages already contain timestamps, and the
    // file:linenumber header.
    virtual void Write(bool force_flush,
                       time_t timestamp,
                       const char* message,
                       int message_len) = 0;
  
    // Flush any buffered messages
    virtual void Flush() = 0;
  
    // Get the current LOG file size.
    // The returned value is approximate since some
    // logged data may not have been flushed to disk yet.
    virtual uint32 LogSize() = 0;
  };
  
  // Get the logger for the specified severity level.  The logger
  // remains the property of the logging module and should not be
  // deleted by the caller.  Thread-safe.
  extern GOOGLE_GLOG_DLL_DECL Logger* GetLogger(LogSeverity level);
  
  // Set the logger for the specified severity level.  The logger
  // becomes the property of the logging module and should not
  // be deleted by the caller.  Thread-safe.
  extern GOOGLE_GLOG_DLL_DECL void SetLogger(LogSeverity level, Logger* logger);
  
  }
  
  // glibc has traditionally implemented two incompatible versions of
  // strerror_r(). There is a poorly defined convention for picking the
  // version that we want, but it is not clear whether it even works with
  // all versions of glibc.
  // So, instead, we provide this wrapper that automatically detects the
  // version that is in use, and then implements POSIX semantics.
  // N.B. In addition to what POSIX says, we also guarantee that "buf" will
  // be set to an empty string, if this function failed. This means, in most
  // cases, you do not need to check the error code and you can directly
  // use the value of "buf". It will never have an undefined value.
  // DEPRECATED: Use StrError(int) instead.
  GOOGLE_GLOG_DLL_DECL int posix_strerror_r(int err, char *buf, size_t len);
  
  // A thread-safe replacement for strerror(). Returns a string describing the
  // given POSIX error code.
  GOOGLE_GLOG_DLL_DECL std::string StrError(int err);
  
  // A class for which we define operator<<, which does nothing.
  class GOOGLE_GLOG_DLL_DECL NullStream : public LogMessage::LogStream {
   public:
    // Initialize the LogStream so the messages can be written somewhere
    // (they'll never be actually displayed). This will be needed if a
    // NullStream& is implicitly converted to LogStream&, in which case
    // the overloaded NullStream::operator<< will not be invoked.
    NullStream() : LogMessage::LogStream(message_buffer_, 1, 0) { }
    NullStream(const char* /*file*/, int /*line*/,
               const CheckOpString& /*result*/) :
        LogMessage::LogStream(message_buffer_, 1, 0) { }
    NullStream &stream() { return *this; }
   private:
    // A very short buffer for messages (which we discard anyway). This
    // will be needed if NullStream& converted to LogStream& (e.g. as a
    // result of a conditional expression).
    char message_buffer_[2];
  };
  
  // Do nothing. This operator is inline, allowing the message to be
  // compiled away. The message will not be compiled away if we do
  // something like (flag ? LOG(INFO) : LOG(ERROR)) << message; when
  // SKIP_LOG=WARNING. In those cases, NullStream will be implicitly
  // converted to LogStream and the message will be computed and then
  // quietly discarded.
  template<class T>
  inline NullStream& operator<<(NullStream &str, const T &) { return str; }
  
  // Similar to NullStream, but aborts the program (without stack
  // trace), like LogMessageFatal.
  class GOOGLE_GLOG_DLL_DECL NullStreamFatal : public NullStream {
   public:
    NullStreamFatal() { }
    NullStreamFatal(const char* file, int line, const CheckOpString& result) :
        NullStream(file, line, result) { }
    @ac_cv___attribute___noreturn@ ~NullStreamFatal() throw () { _exit(1); }
  };
  
  // Install a signal handler that will dump signal information and a stack
  // trace when the program crashes on certain signals.  We'll install the
  // signal handler for the following signals.
  //
  // SIGSEGV, SIGILL, SIGFPE, SIGABRT, SIGBUS, and SIGTERM.
  //
  // By default, the signal handler will write the failure dump to the
  // standard error.  You can customize the destination by installing your
  // own writer function by InstallFailureWriter() below.
  //
  // Note on threading:
  //
  // The function should be called before threads are created, if you want
  // to use the failure signal handler for all threads.  The stack trace
  // will be shown only for the thread that receives the signal.  In other
  // words, stack traces of other threads won't be shown.
  GOOGLE_GLOG_DLL_DECL void InstallFailureSignalHandler();
  
  // Installs a function that is used for writing the failure dump.  "data"
  // is the pointer to the beginning of a message to be written, and "size"
  // is the size of the message.  You should not expect the data is
  // terminated with '\0'.
  GOOGLE_GLOG_DLL_DECL void InstallFailureWriter(
      void (*writer)(const char* data, int size));
  
  @ac_google_end_namespace@
  
  #endif // _LOGGING_H_
  