On 02/07/2013 02:12 PM, Peter Schiffer wrote:
> Whole new logging with following goals is here:
> - more log levels.
> - allow applications to log somewhere else than stdout using their custom
> callback.
> - provide simple stdout logger for 'lazy' applications.
>
> The logging is off by default, i.e. no message appears on stdout unless
> application initializes the logging explicitly. But see following patches!
>
> Internally, nothing changes, cgroup_dbg is still working. In addition,
> cgroup_err, cgroup_warn and cgroup_info appeared. Description what message
> should use which log level is in doxygen info, together with new public API
> incl. simple example, I won't copy it here
>
> Also the cgroup_log function is made public. I am not sure if it is the
> right thing to do, but that's currently the simplest way how to use the
> logging from our tools (which link only the public libcgroup API).
>
> Changelog:
> - fixed typo in cgroup_log doxygen comment
>
> Signed-off-by: Peter Schiffer <pschi...@redhat.com>
> ---
> include/Makefile.am | 2 -
> include/libcgroup.h | 1
> include/libcgroup/log.h | 138
> ++++++++++++++++++++++++++++++++++++++++++++++
> src/Makefile.am | 2 -
> src/libcgroup-internal.h | 8 ++-
> src/libcgroup.map | 4 +
> src/log.c | 76 +++++++++++++++++++++++++
> 7 files changed, 228 insertions(+), 3 deletions(-)
> create mode 100644 include/libcgroup/log.h
> create mode 100644 src/log.c
>
> diff --git a/include/Makefile.am b/include/Makefile.am
> index a7602a9..752a624 100644
> --- a/include/Makefile.am
> +++ b/include/Makefile.am
> @@ -1,2 +1,2 @@
> # Using 'nobase_', we what groups.h in /usr/include/libcgroup/ directory
> -nobase_include_HEADERS = libcgroup.h libcgroup/error.h libcgroup/init.h
> libcgroup/groups.h libcgroup/tasks.h libcgroup/iterators.h libcgroup/config.h
> +nobase_include_HEADERS = libcgroup.h libcgroup/error.h libcgroup/init.h
> libcgroup/groups.h libcgroup/tasks.h libcgroup/iterators.h libcgroup/config.h
> libcgroup/log.h
> diff --git a/include/libcgroup.h b/include/libcgroup.h
> index 543bd13..1c7d409 100644
> --- a/include/libcgroup.h
> +++ b/include/libcgroup.h
> @@ -24,6 +24,7 @@
> #include <libcgroup/groups.h>
> #include <libcgroup/tasks.h>
> #include <libcgroup/config.h>
> +#include <libcgroup/log.h>
>
> #undef _LIBCGROUP_H_INSIDE
>
> diff --git a/include/libcgroup/log.h b/include/libcgroup/log.h
> new file mode 100644
> index 0000000..cd4f11d
> --- /dev/null
> +++ b/include/libcgroup/log.h
> @@ -0,0 +1,138 @@
> +#ifndef _LIBCGROUP_LOG_H
> +#define _LIBCGROUP_LOG_H
> +
> +#ifndef _LIBCGROUP_H_INSIDE
> +#error "Only <libcgroup.h> should be included directly."
> +#endif
> +
> +#ifndef SWIG
> +#include <features.h>
> +#endif
> +
> +#include <stdarg.h>
> +
> +__BEGIN_DECLS
> +
> +/**
> + * @defgroup group_log 7. Logging
> + * @{
> + *
> + * @name Logging
> + * @{
> + * Libcgroup allows applications to register a callback function which
> + * libcgroup will call when it wants to log something. Each log message
> + * has associated a log level. As described in previous chapter, most
> libcgroup
> + * functions return an error code, which described root cause of the failure
> + * and log messages might provide further details about these failures and
> other
> + * notable events.
> + *
> + * @par
> + * The logging callback can be set at any time, but setting the callback
> before
> + * any other libcgroup function (including cgroup_init()) is highly
> recommended.
> + *
> + * @par Setting log level
> + * Some of the functions below set the log level as integer.
> + * Application can set directly a value of enum #cgroup_log_level or use
> + * value <tt>-1</tt> to set the log level automatically. In this case,
> libcgroup
> + * inspects environment variable <tt>CGROUP_LOGLEVEL</tt> if it is set
> + * and contains any of these values: <tt>ERROR</tt>, <tt>WARNING</tt>,
> + * <tt>INFO</tt>, <tt>DEBUG</tt> or integer number representing value from
> + * enum #cgroup_log_level. If <tt>CGROUP_LOGLEVEL</tt> is not set or its
> value
> + * is not valid, <tt>CGROUP_LOG_WARNING</tt> is set as default log level.
If I read the patches correctly, the default is now CGROUP_LOG_ERROR and
not CGROUP_LOG_WARNING.
Otherwise, Acked-By: Jan Safranek <jsafr...@redhat.com>
> + *
> + * @par Example:
> + * Following short example shows custom libcgroup logger sending all log
> + * messages to <tt>stderr</tt>:
> + * @code
> + * static void my_logger(void *userdata, int level, const char *fmt, va_list
> ap)
> + * {
> + * vfprintf(stderr, fmt, ap);
> + * }
> + *
> + * int main(int argc, char **argv)
> + * {
> + * int ret;
> + *
> + * cgroup_set_logger(my_logger, -1, NULL);
> + * ret = cgroup_init();
> + * if (ret) {
> + * ...
> + * }
> + * ...
> + * @endcode
> + */
> +
> +/**
> + * Level of importance of a log message.
> + */
> +enum cgroup_log_level {
> + /**
> + * Something serious happened and libcgroup failed to perform requested
> + * operation.
> + */
> + CGROUP_LOG_ERROR = 1,
> + /**
> + * Something bad happened but libcgroup recovered from the error.
> + */
> + CGROUP_LOG_WARNING,
> + /**
> + * Something interesting happened and the message might be useful to the
> + * user.
> + */
> + CGROUP_LOG_INFO,
> + /**
> + * Debugging messages useful to libcgroup developers.
> + */
> + CGROUP_LOG_DEBUG,
> +};
> +
> +typedef void (*cgroup_logger_callback)(void *userdata, int level,
> + const char *fmt, va_list ap);
> +
> +/**
> + * Set libcgroup logging callback. All log messages with equal or lower log
> + * level will be sent to the application's callback. There can be only
> + * one callback logger set, the previous callback is replaced with the new
> one
> + * by calling this function.
> + * Use NULL as the logger callback to completely disable libcgroup logging.
> + *
> + * @param logger The callback.
> + * @param loglevel The log level. Use value -1 to automatically discover the
> + * level from CGROUP_LOGLEVEL environment variable.
> + * @param userdata Application's data which will be provided back to the
> + * callback.
> + */
> +extern void cgroup_set_logger(cgroup_logger_callback logger, int loglevel,
> + void *userdata);
> +
> +/**
> + * Set libcgroup logging to stdout. All messages with the given loglevel
> + * or below will be sent to standard output. Previous logger set by
> + * cgroup_set_logger() is replaced.
> + *
> + * @param loglevel The log level. Use value -1 to automatically discover the
> + * level from CGROUP_LOGLEVEL environment variable.
> + */
> +extern void cgroup_set_default_logger(int loglevel);
> +
> +/**
> + * Change current loglevel.
> + * @param loglevel The log level. Use value -1 to automatically discover the
> + * level from CGROUP_LOGLEVEL environment variable.
> + */
> +extern void cgroup_set_loglevel(int loglevel);
> +
> +/**
> + * Libcgroup log function. This is for applications which are too lazy to set
> + * up their own complex logging and miss-use libcgroup for that purpose.
> + * I.e. this function should be used only by simple command-line tools.
> + * This logging automatically benefits from CGROUP_LOGLEVEL env. variable.
> + */
> +extern void cgroup_log(int loglevel, const char *fmt, ...);
> +/**
> + * @}
> + * @}
> + */
> +__END_DECLS
> +
> +#endif /* _LIBCGROUP_LOG_H */
> diff --git a/src/Makefile.am b/src/Makefile.am
> index 18a2ef0..3a92d59 100644
> --- a/src/Makefile.am
> +++ b/src/Makefile.am
> @@ -11,7 +11,7 @@ CLEANFILES = lex.c parse.c parse.h
>
> INCLUDES = -I$(top_srcdir)/include
> lib_LTLIBRARIES = libcgroup.la
> -libcgroup_la_SOURCES = parse.h parse.y lex.l api.c config.c
> libcgroup-internal.h libcgroup.map wrapper.c
> +libcgroup_la_SOURCES = parse.h parse.y lex.l api.c config.c
> libcgroup-internal.h libcgroup.map wrapper.c log.c
> libcgroup_la_LIBADD = -lpthread
> libcgroup_la_LDFLAGS = -Wl,--version-script,$(srcdir)/libcgroup.map \
> -version-number
> $(LIBRARY_VERSION_MAJOR):$(LIBRARY_VERSION_MINOR):$(LIBRARY_VERSION_RELEASE)
> diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
> index dbb8e9a..47ee2ab 100644
> --- a/src/libcgroup-internal.h
> +++ b/src/libcgroup-internal.h
> @@ -61,12 +61,18 @@ __BEGIN_DECLS
> #define CGROUP_RULE_MAXLINE (FILENAME_MAX + CGROUP_RULE_MAXKEY + \
> CG_CONTROLLER_MAX + 3)
>
> +#define cgroup_err(x...) cgroup_log(CGROUP_LOG_ERROR, x)
> +#define cgroup_warn(x...) cgroup_log(CGROUP_LOG_WARNING, x)
> +#define cgroup_info(x...) cgroup_log(CGROUP_LOG_INFO, x)
> +
> #ifdef CGROUP_DEBUG
> -#define cgroup_dbg(x...) printf(x)
> +#define cgroup_dbg(x...) cgroup_log(CGROUP_LOG_DEBUG, x)
> #else
> #define cgroup_dbg(x...) do {} while (0)
> #endif
>
> +#define CGROUP_DEFAULT_LOGLEVEL CGROUP_LOG_ERROR
> +
> #define max(x,y) ((y)<(x)?(x):(y))
> #define min(x,y) ((y)>(x)?(x):(y))
>
> diff --git a/src/libcgroup.map b/src/libcgroup.map
> index b550a58..fc850b3 100644
> --- a/src/libcgroup.map
> +++ b/src/libcgroup.map
> @@ -110,4 +110,8 @@ CGROUP_0.39 {
> cgroup_reload_cached_templates;
> cgroup_init_templates_cache;
> cgroup_config_create_template_group;
> + cgroup_set_logger;
> + cgroup_set_default_logger;
> + cgroup_set_loglevel;
> + cgroup_log;
> } CGROUP_0.38;
> diff --git a/src/log.c b/src/log.c
> new file mode 100644
> index 0000000..d0a6854
> --- /dev/null
> +++ b/src/log.c
> @@ -0,0 +1,76 @@
> +/*
> + * Copyright Red Hat, Inc. 2012
> + *
> + * Author: Jan Safranek <jsafr...@redhat.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of version 2.1 of the GNU Lesser General Public License
> + * as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> + */
> +
> +#include <libcgroup.h>
> +#include <libcgroup-internal.h>
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <errno.h>
> +
> +static cgroup_logger_callback cgroup_logger;
> +static void *cgroup_logger_userdata;
> +static int cgroup_loglevel;
> +
> +static void cgroup_default_logger(void *userdata, int level, const char *fmt,
> + va_list ap)
> +{
> + vfprintf(stdout, fmt, ap);
> +}
> +
> +void cgroup_log(int level, const char *fmt, ...)
> +{
> + va_list ap;
> +
> + if (!cgroup_logger)
> + return;
> +
> + if (level > cgroup_loglevel)
> + return;
> +
> + va_start(ap, fmt);
> + cgroup_logger(cgroup_logger_userdata, level, fmt, ap);
> + va_end(ap);
> +}
> +
> +void cgroup_set_logger(cgroup_logger_callback logger, int loglevel,
> + void *userdata)
> +{
> + cgroup_logger = logger;
> + cgroup_set_loglevel(loglevel);
> + cgroup_logger_userdata = userdata;
> +}
> +
> +void cgroup_set_default_logger(int level)
> +{
> + if (!cgroup_logger)
> + cgroup_set_logger(cgroup_default_logger, level, NULL);
> +}
> +
> +void cgroup_set_loglevel(int loglevel)
> +{
> + if (loglevel != -1)
> + cgroup_loglevel = loglevel;
> + else {
> + char *level_str = getenv("CGROUP_LOGLEVEL");
> + if (level_str != NULL)
> + /*
> + * TODO: add better loglevel detection, e.g. strings
> + * instead of plain numbers.
> + */
> + cgroup_loglevel = atoi(level_str);
> + else
> + cgroup_loglevel = CGROUP_DEFAULT_LOGLEVEL;
> + }
> +}
>
>
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