75 lines
2.8 KiB
Plaintext
75 lines
2.8 KiB
Plaintext
#
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# read this with 'perldoc README.logging' ...
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#
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=head1 qpsmtpd logging system; developer documentation
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Qpsmtpd now (as of 0.30-dev) supports a plugable logging architecture, so
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that different logging plugins can be supported. See the example logging
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plugins in plugins/logging, specifically the L<plugins/logging/warn> and
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L<plugins/logging/adaptive> files for examples of how to write your own
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logging plugins.
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=head1 Internal support for pluggable logging
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Any code in the core can call C<$self->log()> and those log lines will be
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dispatched to each of the registered logging plugins. When C<log()> is
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called from a plugin, the plugin and hook names are automatically included
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in the parameters passed the logging hooks. All plugins which register for
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the logging hook should expect the following parameters to be passed:
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$self, $transaction, $trace, $hook, $plugin, @log
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where those terms are:
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=over 4
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=item C<$self>
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The object which was used to call the log() method; this can be any object
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within the system, since the core code will automatically load logging
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plugins on behalf of any object.
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=item C<$transaction>
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This is the current SMTP transaction (defined as everything that happens
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between HELO/EHLO and QUIT/RSET). If you want to defer outputting certain
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log lines, you can store them in the transaction object, but you will need
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to bind the C<reset_transaction> hook in order to retrieve that information
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before it is discarded when the transaction is closed (see the
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L<logging/adaptive> plugin for an example of doing this).
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=item C<$trace>
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This is the log level (as shown in config.sample/loglevel) that the caller
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asserted when calling log(). If you want to output the textural
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representation (e.g. C<LOGERROR>) of this in your log messages, you can use
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the log_level() function exported by Qpsmtpd::Constants (which is
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automatically available to all plugins).
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=item C<$hook>
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This is the hook that is currently being executed. If log() is called by
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any core code (i.e. not as part of a hook), this term will be C<undef>.
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=item C<$plugin>
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This is the plugin name that executed the log(). Like C<$hook>, if part of
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the core code calls log(), this wil be C<undef>. See L<logging/warn> for a
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way to prevent logging your own plugin's log entries from within that
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plugin (the system will not infinitely recurse in any case).
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=item C<@log>
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The remaining arguments are as passed by the caller, which may be a single
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term or may be a list of values. It is usually sufficient to call
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C<join(" ",@log)> to deal with these terms, but it is possible that some
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plugin might pass additional arguments with signficance.
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=back
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Note: if you register a handler for certain hooks, e.g. C<deny>, there may
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be additional terms passed between C<$self> and C<$transaction>. See
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L<logging/adaptive> for and example.
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