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<?xml version="1.0" encoding="utf-8"?>
<page xmlns="http://projectmallard.org/1.0/" xmlns:its="http://www.w3.org/2005/11/its" xmlns:xi="http://www.w3.org/2003/XInclude" type="topic" id="logging" xml:lang="es">
<info>
<link type="guide" xref="index#specific-how-tos"/>
<credit type="author copyright">
<name>Philip Withnall</name>
<email its:translate="no">philip.withnall@collabora.co.uk</email>
<years>2015</years>
</credit>
<include xmlns="http://www.w3.org/2001/XInclude" href="cc-by-sa-3-0.xml"/>
<desc>Registro de depuración y salida de información de bibliotecas y programas</desc>
<mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
<mal:name>Daniel Mustieles</mal:name>
<mal:email>daniel.mustieles@gmail.com</mal:email>
<mal:years>2016-2020</mal:years>
</mal:credit>
<mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
<mal:name>Javier Mazorra</mal:name>
<mal:email>mazi.debian@gmail.com</mal:email>
<mal:years>2016, 2020</mal:years>
</mal:credit>
</info>
<title>Registro</title>
<synopsis>
<title>Resumen</title>
<p>El registro de la depuración y la salida informativa de bibliotecas y programas es un problema abierto, y existen varios métodos para convertir múltiples flujos de salida de registro en los flujos stdout y stderr habituales. A continuación se presentan algunas sugerencias sobre cómo implementar el registro. Sin embargo, lo más importante es garantizar que el registro sea coherente, de modo que se pueda acceder a los datos de registro y buscarlos con un mínimo de esfuerzo, ya que para eso se utilizan. El uso de diferentes mecanismos y formatos de registro en diferentes proyectos no es el enfoque correcto.</p>
<list>
<item><p>
Use the GLib logging framework instead of logging directly to stderr and
stdout. (<link xref="#glib-logging-framework"/>)
</p></item>
<item><p>
If systemd can be a dependency of the project, consider logging directly
to the journal. (<link xref="#journald-integration"/>)
</p></item>
<item><p>
Do not implement log rotation and deletion; leave that to system
services. (<link xref="#log-rotation"/>)
</p></item>
</list>
</synopsis>
<section id="glib-logging-framework">
<title>Entorno de trabajo de registro de GLib</title>
<p>
GLib provides
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html">a
logging framework</link> based around the
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-log"><code>g_log()</code></link>
function, with convenience wrappers
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-debug"><code>g_debug()</code></link>,
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-message"><code>g_message()</code></link>,
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-warning"><code>g_warning()</code></link>
and
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-error"><code>g_error()</code></link>.
The GLib logging framework has a few useful features:
</p>
<list>
<item><p>
Programmatic redirection of log messages using
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#g-log-set-handler"><code>g_log_set_handler()</code></link>.
</p></item>
<item><p>
Multiple logging domains, which can be processed separately.
</p></item>
<item><p>
Multiple log levels, which can be processed separately. For example,
this allows debug messages to be turned on and off at runtime.
</p></item>
<item><p>
Support for automatically aborting a program on ‘fatal’ messages.
</p></item>
</list>
<p>
These should be used in preference to functions like
<code>printf()</code>,
<link href="https://developer.gnome.org/glib/stable/glib-Warnings-and-Assertions.html#g-print"><code>g_print()</code></link>
and
<link href="https://developer.gnome.org/glib/stable/glib-Warnings-and-Assertions.html#g-printerr"><code>g_printerr()</code></link>,
due to their enhanced flexibility. The logging functions allow log
processing to be done in code, rather than by external shell scripting,
which simplifies everything.
</p>
<p>
A key reason to use the logging framework is that it is used in GLib and
other related libraries already; by using it, all log messages are then
going through the same system and can be processed similarly.
</p>
<p>
To use the GLib logging framework, define
<link href="https://developer.gnome.org/glib/stable/glib-Message-Logging.html#G-LOG-DOMAIN:CAPS"><code>G_LOG_DOMAIN</code></link>
for the project so it’s unique from all other projects. Call
<code>g_debug("Message")</code> to log a debug message.
</p>
<p>
If the default GLib log handlers are not sufficient, for example if log
messages need to be in a custom format or
<link xref="#journald-integration">journald integration</link> is needed,
set up a log handler with the following code:
</p>
<code mime="text/x-csrc">
static const gchar *
log_level_to_string (GLogLevelFlags level)
{
switch (level)
{
case G_LOG_LEVEL_ERROR: return "ERROR";
case G_LOG_LEVEL_CRITICAL: return "CRITICAL";
case G_LOG_LEVEL_WARNING: return "WARNING";
case G_LOG_LEVEL_MESSAGE: return "MESSAGE";
case G_LOG_LEVEL_INFO: return "INFO";
case G_LOG_LEVEL_DEBUG: return "DEBUG";
default: return "UNKNOWN";
}
}
static void
log_handler_cb (const gchar *log_domain,
GLogLevelFlags log_level,
const gchar *message,
gpointer user_data)
{
const gchar *log_level_str;
/* Ignore debug messages if disabled. */
if (!debug_enabled && (log_level & G_LOG_LEVEL_DEBUG))
{
return;
}
log_level_str = log_level_to_string (log_level & G_LOG_LEVEL_MASK);
/* Use g_printerr() for warnings and g_print() otherwise. */
if (flags <= G_LOG_LEVEL_WARNING)
{
g_printerr ("%s: %s: %s\n", log_domain, log_level_str, message);
}
else
{
g_print ("%s: %s: %s\n", log_domain, log_level_str, message);
}
}
g_log_set_handler ("log-domain",
G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL | G_LOG_FLAG_RECURSION,
log_handler_cb, NULL);</code>
<section id="exceptions">
<title>Excepciones</title>
<list>
<item><p>
Do not use <code>g_message()</code> in normal code to print output.
Printing output should be done at the top level of an application,
using <code>g_print()</code>, and should be quite rare; i.e. only done
in command line applications.
</p></item>
<item><p>
Do not use <code>g_warning()</code> in library code. Use
<link xref="gerror"><code>GError</code>s</link> instead.
</p></item>
<item><p>Del mismo modo, no configure controladores de registro en el código de la biblioteca. Los mensajes de registro deben propagarse a través del código de la biblioteca y manejarse en un controlador de registro en el nivel superior de una aplicación.</p></item>
</list>
</section>
</section>
<section id="journald-integration">
<title>Integración con journald</title>
<p>
Compared to conventional syslog-style logs, journald supports storage of
structured logging data, which can make post-hoc analysis of logs much
easier. If it’s possible to add <code>systemd-journal</code> as a
dependency to a project, the project’s log handling function could be
extended to use
<link href="http://0pointer.de/public/systemd-man/sd_journal_send.html"><code>sd_journal_print()</code>
and <code>sd_journal_send()</code></link> instead of
<code>g_print()</code> and <code>g_printerr()</code>.
</p>
<p>
For more information, see this
<link href="http://0pointer.de/blog/projects/journal-submit.html">article
on logging to the journal</link>.
</p>
</section>
<section id="log-rotation">
<title>Rotación de registros</title>
<p>
Log file rotation is one feature which is out of scope of the GLib logging
system. It should be handled by the normal system logging mechanisms, such
as <cmd>logrotate</cmd> or <cmd>systemd-journald</cmd>.
</p>
</section>
</page>
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