src/gromacs/utility/logger.h

   1 /*
   2  * This file is part of the GROMACS molecular simulation package.
   3  *
   4  * Copyright (c) 2016,2017,2018,2019, by the GROMACS development team, led by
   5  * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
   6  * and including many others, as listed in the AUTHORS file in the
   7  * top-level source directory and at http://www.gromacs.org.
   8  *
   9  * GROMACS is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * as published by the Free Software Foundation; either version 2.1
  12  * of the License, or (at your option) any later version.
  13  *
  14  * GROMACS is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with GROMACS; if not, see
  21  * http://www.gnu.org/licenses, or write to the Free Software Foundation,
  22  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
  23  *
  24  * If you want to redistribute modifications to GROMACS, please
  25  * consider that scientific software is very special. Version
  26  * control is crucial - bugs must be traceable. We will be happy to
  27  * consider code for inclusion in the official distribution, but
  28  * derived work must not be called official GROMACS. Details are found
  29  * in the README & COPYING files - if they are missing, get the
  30  * official version at http://www.gromacs.org.
  31  *
  32  * To help us fund GROMACS development, we humbly ask that you cite
  33  * the research papers on the package. Check out http://www.gromacs.org.
  34  */
  35 /*! \libinternal \file
  36  * \brief
  37  * Declares functionality for logging.
  38  *
  39  * See \ref page_logging for an overview of the functionality.
  40  *
  41  * \inlibraryapi
  42  * \ingroup module_utility
  43  */
  44 #ifndef GMX_UTILITY_LOGGER_H
  45 #define GMX_UTILITY_LOGGER_H
  46
  47 #include <string>
  48
  49 #include "gromacs/utility/stringutil.h"
  50
  51 namespace gmx
  52 {
  53
  54 struct LogEntry
  55 {
  56     LogEntry() : asParagraph(false) {}
  57
  58     std::string text;
  59     bool        asParagraph;
  60 };
  61
  62 /*! \libinternal \brief
  63  * Target where log output can be written.
  64  *
  65  * \ingroup module_utility
  66  */
  67 class ILogTarget
  68 {
  69 public:
  70     virtual ~ILogTarget();
  71
  72     //! Writes a log entry to this target.
  73     virtual void writeEntry(const LogEntry& entry) = 0;
  74 };
  75
  76 /*! \libinternal \brief
  77  * Helper class for creating log entries with ::GMX_LOG.
  78  *
  79  * \ingroup module_utility
  80  */
  81 class LogEntryWriter
  82 {
  83 public:
  84     //! Appends given text as a line in the log entry.
  85     LogEntryWriter& appendText(const char* text)
  86     {
  87         entry_.text.append(text);
  88         return *this;
  89     }
  90     //! Appends given text as a line in the log entry.
  91     LogEntryWriter& appendText(const std::string& text)
  92     {
  93         entry_.text.append(text);
  94         return *this;
  95     }
  96     //! Appends given text as a line in the log entry, with printf-style formatting.
  97     LogEntryWriter& appendTextFormatted(gmx_fmtstr const char* fmt, ...) gmx_format(printf, 2, 3);
  98     //! Writes the log entry with empty lines before and after.
  99     LogEntryWriter& asParagraph()
 100     {
 101         entry_.asParagraph = true;
 102         return *this;
 103     }
 104
 105 private:
 106     LogEntry entry_;
 107
 108     friend class LogWriteHelper;
 109 };
 110
 111 /*! \internal \brief
 112  * Helper class for implementing ::GMX_LOG.
 113  *
 114  * \ingroup module_utility
 115  */
 116 class LogWriteHelper
 117 {
 118 public:
 119     //! Initializes a helper for writing to the given target.
 120     explicit LogWriteHelper(ILogTarget* target) : target_(target) {}
 121
 122     // Should be explicit, once that works in CUDA.
 123     /*! \brief
 124      * Returns whether anything needs to be written.
 125      *
 126      * Note that the return value is unintuitively `false` when the target
 127      * is active, to allow implementing ::GMX_LOG like it is now.
 128      */
 129     operator bool() const { return target_ == nullptr; }
 130
 131     /*! \brief
 132      * Writes the entry from the given writer to the log target.
 133      *
 134      * This is implemented as an assignment operator to get proper
 135      * precedence for operations for the ::GMX_LOG macro; this is a common
 136      * technique for implementing macros that allow streming information to
 137      * them (see, e.g., Google Test).
 138      */
 139     LogWriteHelper& operator=(const LogEntryWriter& entryWriter)
 140     {
 141         target_->writeEntry(entryWriter.entry_);
 142         return *this;
 143     }
 144
 145 private:
 146     ILogTarget* target_;
 147 };
 148
 149 /*! \libinternal \brief
 150  * Represents a single logging level.
 151  *
 152  * Typically this type is not used directly, but instances in MDLogger are
 153  * simply accessed through ::GMX_LOG in code that writes to the log.
 154  *
 155  * \ingroup module_utility
 156  */
 157 class LogLevelHelper
 158 {
 159 public:
 160     //! Initializes a helper for writing to the given target.
 161     explicit LogLevelHelper(ILogTarget* target) : target_(target) {}
 162
 163     // Both of the below should be explicit, once that works in CUDA.
 164     //! Returns whether the output for this log level goes anywhere.
 165     operator bool() const { return target_ != nullptr; }
 166
 167     //! Creates a helper for ::GMX_LOG.
 168     operator LogWriteHelper() const { return LogWriteHelper(target_); }
 169
 170 private:
 171     ILogTarget* target_;
 172 };
 173
 174 /*! \libinternal \brief
 175  * Declares a logging interface.
 176  *
 177  * Typically, this object is not created directly, but instead through
 178  * LoggerBuilder.
 179  *
 180  * For now, this is named MDLogger, since it is used only there, and it is not
 181  * clear whether the logging levels can be the same throughout the code.  It
 182  * should be relatively straightforward to split this into multiple classes
 183  * with different supported logging levels without changing calling code, or to
 184  * rename it to Logger if we do not need any specialization.
 185  *
 186  * \ingroup module_utility
 187  */
 188 class MDLogger
 189 {
 190 public:
 191     //! Supported logging levels.
 192     enum class LogLevel
 193     {
 194         Error,
 195         Warning,
 196         Info,
 197         Debug,
 198         VerboseDebug,
 199         Count
 200     };
 201     //! Number of logging levels.
 202     static const int LogLevelCount = static_cast<int>(LogLevel::Count);
 203
 204     MDLogger();
 205     //! Creates a logger with the given targets.
 206     explicit MDLogger(ILogTarget* targets[LogLevelCount]);
 207
 208     //! For writing at LogLevel::Warning level.
 209     LogLevelHelper warning;
 210     //! For writing at LogLevel::Error level.
 211     LogLevelHelper error;
 212     //! For writing at LogLevel::Debug level.
 213     LogLevelHelper debug;
 214     //! For writing at LogLevel::VerboseDebug level.
 215     LogLevelHelper verboseDebug;
 216     //! For writing at LogLevel::Info level.
 217     LogLevelHelper info;
 218 };
 219
 220 /*! \brief
 221  * Helper to log information using gmx::MDLogger.
 222  *
 223  * \param  logger  LogLevelHelper instance to use for logging.
 224  *
 225  * Used as
 226  * \code
 227    GMX_LOG(logger.warning).appendText(...);
 228    \endcode
 229  * and ensures that the code to format the output is only executed when the
 230  * output goes somewhere.
 231  *
 232  * See LogEntryWriter for functions that can be used with the macro (such as
 233  * the appendText() in the example).
 234  *
 235  * \ingroup module_utility
 236  */
 237 #define GMX_LOG(logger)                                                  \
 238     if (::gmx::LogWriteHelper helper = ::gmx::LogWriteHelper(logger)) {} \
 239     else                                                                 \
 240         helper = ::gmx::LogEntryWriter()
 241
 242 } // namespace gmx
 243
 244 #endif