ucx/logging.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2016 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. 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.
 *
 * 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 HOLDER 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.
 */
/**
 * Logging API.
 * 
 * @file   logging.h
 * @author Mike Becker, Olaf Wintermann
 */
#ifndef UCX_LOGGING_H
#define UCX_LOGGING_H

#include "ucx.h"
#include "map.h"
#include "string.h"
#include <stdio.h>

#ifdef __cplusplus
extern "C" {
#endif

/* leave enough space for custom log levels */

/** Log level for error messages. */
#define UCX_LOGGER_ERROR        0x00
    
/** Log level for warning messages. */
#define UCX_LOGGER_WARN         0x10

/** Log level for information messages. */
#define UCX_LOGGER_INFO         0x20

/** Log level for debug messages. */
#define UCX_LOGGER_DEBUG        0x30

/** Log level for trace messages. */
#define UCX_LOGGER_TRACE        0x40

/**
 * Output flag for the log level. 
 * If this flag is set, the log message will contain the log level.
 * @see UcxLogger.mask
 */
#define UCX_LOGGER_LEVEL        0x01

/**
 * Output flag for the timestmap.
 * If this flag is set, the log message will contain the timestmap.
 * @see UcxLogger.mask
 */
#define UCX_LOGGER_TIMESTAMP    0x02

/**
 * Output flag for the source.
 * If this flag is set, the log message will contain the source file and line
 * number.
 * @see UcxLogger.mask
 */
#define UCX_LOGGER_SOURCE       0x04

/**
 * The UCX Logger object.
 */
typedef struct {
    /** The stream this logger writes its messages to.*/
    void *stream;

    /**
     * The write function that shall be used.
     * For standard file or stdout loggers this might be standard fwrite
     * (default).
     */
    write_func writer;

    /**
     * The date format for timestamp outputs including the delimiter
     * (default: <code>"%F %T %z "</code>).
     * @see UCX_LOGGER_TIMESTAMP
     */
    char *dateformat;

    /**
     * The level, this logger operates on.
     * If a log command is issued, the message will only be logged, if the log
     * level of the message is less or equal than the log level of the logger.
     */
    unsigned int level;

    /**
     * A configuration mask for automatic output. 
     * For each flag that is set, the logger automatically outputs some extra
     * information like the timestamp or the source file and line number.
     * See the documentation for the flags for details.
     */
    unsigned int mask;

    /**
     * A map of valid log levels for this logger.
     * 
     * The keys represent all valid log levels and the values provide string
     * representations, that are used, if the UCX_LOGGER_LEVEL flag is set.
     * 
     * The exact data types are <code>unsigned int</code> for the key and
     * <code>const char*</code> for the value.
     * 
     * @see UCX_LOGGER_LEVEL
     */
    UcxMap* levels;
} UcxLogger;

/**
 * Creates a new logger.
 * @param stream the stream, which the logger shall write to
 * @param level the level on which the logger shall operate
 * @param mask configuration mask (cf. UcxLogger.mask)
 * @return a new logger object
 */
UcxLogger *ucx_logger_new(void *stream, unsigned int level, unsigned int mask);

/**
 * Destroys the logger.
 * 
 * The map containing the valid log levels is also automatically destroyed.
 * 
 * @param logger the logger to destroy
 */
void ucx_logger_free(UcxLogger* logger);

/**
 * Internal log function - use macros instead.
 * 
 * This function uses the <code>format</code> and variadic arguments for a
 * printf()-style output of the log message.
 * 
 * Dependent on the UcxLogger.mask some information is prepended. The complete
 * format is:
 * 
 * <code>[LEVEL] [TIMESTAMP] [SOURCEFILE]:[LINENO] message</code>
 * 
 * <b>Attention:</b> the message (including automatically generated information)
 * is limited to 4096 characters. The level description is limited to
 * 256 characters and the timestamp string is limited to 128 characters.
 * 
 * @param logger the logger to use
 * @param level the level to log on
 * @param file information about the source file
 * @param line information about the source line number
 * @param format format string
 * @param ... arguments
 * @see ucx_logger_log()
 */
void ucx_logger_logf(UcxLogger *logger, unsigned int level, const char* file,
        const unsigned int line, const char* format, ...);

/**
 * Logs a message at the specified level.
 * @param logger the logger to use
 * @param level the level to log the message on
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_log(logger, level, ...) \
    ucx_logger_logf(logger, level, __FILE__, __LINE__, __VA_ARGS__)

/**
 * Shortcut for logging an error message.
 * @param logger the logger to use
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_error(logger, ...) \
    ucx_logger_log(logger, UCX_LOGGER_ERROR, __VA_ARGS__)

/**
 * Shortcut for logging an information message.
 * @param logger the logger to use
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_info(logger, ...) \
    ucx_logger_log(logger, UCX_LOGGER_INFO, __VA_ARGS__)

/**
 * Shortcut for logging a warning message.
 * @param logger the logger to use
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_warn(logger, ...) \
    ucx_logger_log(logger, UCX_LOGGER_WARN, __VA_ARGS__)

/**
 * Shortcut for logging a debug message.
 * @param logger the logger to use
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_debug(logger, ...) \
    ucx_logger_log(logger, UCX_LOGGER_DEBUG, __VA_ARGS__)

/**
 * Shortcut for logging a trace message.
 * @param logger the logger to use
 * @param ... format string and arguments
 * @see ucx_logger_logf()
 */
#define ucx_logger_trace(logger, ...) \
    ucx_logger_log(logger, UCX_LOGGER_TRACE, __VA_ARGS__)

#ifdef __cplusplus
}
#endif

#endif /* UCX_LOGGING_H */