[libcamera-devel] [PATCH v2 2/4] libcamera: log: Get log levels from the environment
Jacopo Mondi
jacopo at jmondi.org
Tue Jan 22 09:46:34 CET 2019
Hi Laurent,
On Mon, Jan 21, 2019 at 09:56:04PM +0200, Laurent Pinchart wrote:
> Set the log level for each log category from the environment variable
> LIBCAMERA_LOG_LEVELS.
>
Very nice indeed, but aren't log level numbers supposed to be used the
other way around?
Right now LIBCAMERA_LOG_LEVELS=0 is "DEBUG" and LIBCAMERA_LOG_LEVELS=4
is "FATAL" only. I would have expect to have 4 = maximum debug, 0 =
only fatal, right now is the other way around...
Also, stupid thing but, isn't LIBCAMERA_LOG_LEVELS a bit long?
gstreamer has a more compact GST_DBG which is shorter to type...
LIBCAM_DBG maybe?
The patch itself is good, please add my
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
Thanks
j
> The variable contains a comma-separated list of category:level pairs,
> and category names can include wildcards.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> src/libcamera/log.cpp | 202 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 202 insertions(+)
>
> diff --git a/src/libcamera/log.cpp b/src/libcamera/log.cpp
> index 20503fdcfcc1..23bb9edb9d14 100644
> --- a/src/libcamera/log.cpp
> +++ b/src/libcamera/log.cpp
> @@ -9,7 +9,9 @@
> #include <cstdlib>
> #include <ctime>
> #include <iomanip>
> +#include <list>
> #include <string.h>
> +#include <unordered_set>
>
> #include "log.h"
> #include "utils.h"
> @@ -17,10 +19,208 @@
> /**
> * \file log.h
> * \brief Logging infrastructure
> + *
> + * libcamera includes a logging infrastructure used through the library that
> + * allows inspection of internal operation in a user-configurable way. The log
> + * messages are grouped in categories that represent areas of libcamera, and
> + * output of messages for each category can be controlled by independent log
> + * levels.
> + *
> + * The levels are configurable through the LIBCAMERA_LOG_LEVELS environment
> + * variable that contains a comma-separated list of 'category=level' pairs.
> + *
> + * The category names are strings and can include a wildcard ('*') character at
> + * the end to match multiple categories.
> + *
> + * The level are either numeric values, or strings containing the log level
> + * name. The available log levels are DEBUG, INFO, WARN, ERROR and FATAL. Log
> + * message with a level higher than or equal to the configured log level for
> + * their category are output to the log, while other messages are silently
> + * discarded.
> */
>
> namespace libcamera {
>
> +/**
> + * \brief Message logger
> + *
> + * The Logger class handles log configuration.
> + */
> +class Logger
> +{
> +public:
> + static Logger *instance();
> +
> +private:
> + Logger();
> +
> + void parseLogLevels();
> + static LogSeverity parseLogLevel(const std::string &level);
> +
> + friend LogCategory;
> + void registerCategory(LogCategory *category);
> + void unregisterCategory(LogCategory *category);
> +
> + std::unordered_set<LogCategory *> categories_;
> + std::list<std::pair<std::string, LogSeverity>> levels_;
> +};
> +
> +/**
> + * \brief Retrieve the logger instance
> + *
> + * The Logger is a singleton and can't be constructed manually. This function
> + * shall instead be used to retrieve the single global instance of the logger.
> + *
> + * \return The logger instance
> + */
> +Logger *Logger::instance()
> +{
> + static Logger instance;
> + return &instance;
> +}
> +
> +/**
> + * \brief Construct a logger
> + */
> +Logger::Logger()
> +{
> + parseLogLevels();
> +}
> +
> +/**
> + * \brief Parse the log levels from the environment
> + *
> + * The logr levels are stored in LIBCAMERA_LOG_LEVELS environement variable as a list
> + * of "category=level" pairs, separated by commas (','). Parse the variable and
> + * store the levels to configure all log categories.
> + */
> +void Logger::parseLogLevels()
> +{
> + const char *debug = secure_getenv("LIBCAMERA_LOG_LEVELS");
> + if (!debug)
> + return;
> +
> + for (const char *pair = debug; *debug != '\0'; pair = debug) {
> + const char *comma = strchrnul(debug, ',');
> + size_t len = comma - pair;
> +
> + /* Skip over the comma. */
> + debug = *comma == ',' ? comma + 1 : comma;
> +
> + /* Skip to the next pair if the pair is empty. */
> + if (!len)
> + continue;
> +
> + std::string category;
> + std::string level;
> +
> + const char *colon = static_cast<const char *>(memchr(pair, ':', len));
> + if (!colon) {
> + /* 'x' is a shortcut for '*:x'. */
> + category = "*";
> + level = std::string(pair, len);
> + } else {
> + category = std::string(pair, colon - pair);
> + level = std::string(colon + 1, comma - colon - 1);
> + }
> +
> + /* Both the category and the level must be specified. */
> + if (category.empty() || level.empty())
> + continue;
> +
> + LogSeverity severity = parseLogLevel(level);
> + if (severity == -1)
> + continue;
> +
> + levels_.push_back({ category, severity });
> + }
> +}
> +
> +/**
> + * \brief Parse a log level string into a LogSeverity
> + * \param[in] level The log level string
> + *
> + * Log levels can be specified as an integer value in the range from LogDebug to
> + * LogFatal, or as a string corresponding to the severity name in uppercase. Any
> + * other value is invalid.
> + *
> + * \return The log severity, or -1 if the string is invalid
> + */
> +LogSeverity Logger::parseLogLevel(const std::string &level)
> +{
> + static const char *const names[] = {
> + "DEBUG",
> + "INFO",
> + "WARN",
> + "ERROR",
> + "FATAL",
> + };
> +
> + int severity;
> +
> + if (std::isdigit(level[0])) {
> + char *endptr;
> + severity = strtoul(level.c_str(), &endptr, 10);
> + if (*endptr != '\0' || severity > LogFatal)
> + severity = -1;
> + } else {
> + severity = -1;
> + for (unsigned int i = 0; i < ARRAY_SIZE(names); ++i) {
> + if (names[i] == level) {
> + severity = i;
> + break;
> + }
> + }
> + }
> +
> + return static_cast<LogSeverity>(severity);
> +}
> +
> +/**
> + * \brief Register a log category with the logger
> + * \param[in] category The log category
> + *
> + * Log categories must have unique names. If a category with the same name
> + * already exists this function performs no operation.
> + */
> +void Logger::registerCategory(LogCategory *category)
> +{
> + categories_.insert(category);
> +
> + const std::string &name = category->name();
> + for (const std::pair<std::string, LogSeverity> &level : levels_) {
> + bool match = true;
> +
> + for (unsigned int i = 0; i < level.first.size(); ++i) {
> + if (level.first[i] == '*')
> + break;
> +
> + if (i >= name.size() ||
> + name[i] != level.first[i]) {
> + match = false;
> + break;
> + }
> + }
> +
> + if (match) {
> + category->setSeverity(level.second);
> + break;
> + }
> + }
> +}
> +
> +/**
> + * \brief Unregister a log category from the logger
> + * \param[in] category The log category
> + *
> + * If the \a category hasn't been registered with the logger this function
> + * performs no operation.
> + */
> +void Logger::unregisterCategory(LogCategory *category)
> +{
> + categories_.erase(category);
> +}
> +
> /**
> * \enum LogSeverity
> * Log message severity
> @@ -52,10 +252,12 @@ namespace libcamera {
> LogCategory::LogCategory(const char *name)
> : name_(name), severity_(LogSeverity::LogInfo)
> {
> + Logger::instance()->registerCategory(this);
> }
>
> LogCategory::~LogCategory()
> {
> + Logger::instance()->unregisterCategory(this);
> }
>
> /**
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <https://lists.libcamera.org/pipermail/libcamera-devel/attachments/20190122/c3539667/attachment-0001.sig>
More information about the libcamera-devel
mailing list