1Appender::Buffer(3)   User Contributed Perl Documentation  Appender::Buffer(3)
2
3
4

NAME

6       Log::Log4perl::Appender::Buffer - Buffering Appender
7

SYNOPSIS

9           use Log::Log4perl qw(:easy);
10
11           my $conf = qq(
12           log4perl.category                  = DEBUG, Buffer
13
14               # Regular Screen Appender
15           log4perl.appender.Screen           = Log::Log4perl::Appender::Screen
16           log4perl.appender.Screen.stdout    = 1
17           log4perl.appender.Screen.layout    = PatternLayout
18           log4perl.appender.Screen.layout.ConversionPattern = %d %p %c %m %n
19
20               # Buffering appender, using the appender above as outlet
21           log4perl.appender.Buffer               = Log::Log4perl::Appender::Buffer
22           log4perl.appender.Buffer.appender      = Screen
23           log4perl.appender.Buffer.trigger_level = ERROR
24           );
25
26           Log::Log4perl->init(\$conf);
27
28           DEBUG("This message gets buffered.");
29           INFO("This message gets buffered also.");
30
31           # Time passes. Nothing happens. But then ...
32
33           print "It's GO time!!!\n";
34
35           ERROR("This message triggers a buffer flush.");
36

DESCRIPTION

38       "Log::Log4perl::Appender::Buffer" takes these arguments:
39
40       "appender"
41           Specifies the name of the appender it buffers messages for. The
42           appender specified must be defined somewhere in the configuration
43           file, not necessarily before the definition of
44           "Log::Log4perl::Appender::Buffer".
45
46       "max_messages"
47           Specifies the maximum number of messages the appender will hold in
48           its ring buffer. "max_messages" is optional. By default,
49           "Log::Log4perl::Appender::Buffer" will not limit the number of
50           messages buffered. This might be undesirable in long-running
51           processes accumulating lots of messages before a flush happens. If
52           "max_messages" is set to a numeric value,
53           "Log::Log4perl::Appender::Buffer" will displace old messages in its
54           buffer to make room if the buffer is full.
55
56       "trigger_level"
57           If trigger_level is set to one of Log4perl's levels (see
58           Log::Log4perl::Level), a "trigger" function will be defined
59           internally to flush the buffer if a message with a priority of
60           $level or higher comes along. This is just a convenience function.
61           Defining
62
63               log4perl.appender.Buffer.trigger_level = ERROR
64
65           is equivalent to creating a trigger function like
66
67               log4perl.appender.Buffer.trigger = sub {   \
68                   my($self, $params) = @_;               \
69                   return $params->{log4p_level} >=       \
70                          $Log::Log4perl::Level::ERROR; }
71
72           See the next section for defining generic trigger functions.
73
74       "trigger"
75           "trigger" holds a reference to a subroutine, which
76           "Log::Log4perl::Appender::Buffer" will call on every incoming
77           message with the same parameters as the appender's "log()" method:
78
79                   my($self, $params) = @_;
80
81           $params references a hash containing the message priority (key
82           "l4p_level"), the message category (key "l4p_category") and the
83           content of the message (key "message").
84
85           If the subroutine returns 1, it will trigger a flush of buffered
86           messages.
87
88           Shortcut
89

DEVELOPMENT NOTES

91       "Log::Log4perl::Appender::Buffer" is a composite appender.  Unlike
92       other appenders, it doesn't log any messages, it just passes them on to
93       its attached sub-appender.  For this reason, it doesn't need a layout
94       (contrary to regular appenders).  If it defines none, messages are
95       passed on unaltered.
96
97       Custom filters are also applied to the composite appender only.  They
98       are not applied to the sub-appender. Same applies to appender
99       thresholds. This behaviour might change in the future.
100

LICENSE

102       Copyright 2002-2013 by Mike Schilli <m@perlmeister.com> and Kevin Goess
103       <cpan@goess.org>.
104
105       This library is free software; you can redistribute it and/or modify it
106       under the same terms as Perl itself.
107

AUTHOR

109       Please contribute patches to the project on Github:
110
111           http://github.com/mschilli/log4perl
112
113       Send bug reports or requests for enhancements to the authors via our
114
115       MAILING LIST (questions, bug reports, suggestions/patches):
116       log4perl-devel@lists.sourceforge.net
117
118       Authors (please contact them via the list above, not directly): Mike
119       Schilli <m@perlmeister.com>, Kevin Goess <cpan@goess.org>
120
121       Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens
122       Berthold, Jeremy Bopp, Hutton Davidson, Chris R. Donnelly, Matisse
123       Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon, Carl Franks, Dennis
124       Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier  David
125       Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter,
126       Brett Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars
127       Thegler, David Viner, Mac Yang.
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131perl v5.34.0                      2021-07-22               Appender::Buffer(3)