1Log::ger(3) User Contributed Perl Documentation Log::ger(3)
2
6 Log::ger - A lightweight, flexible logging framework
7
9 version 0.038
10
12 Producing logs
13 In your module (producer):
14 package Foo;
16 use Log::ger; # will install some logger routines e.g. log_warn, log_error
17 sub foo {
19 ...
20 # produce some logs. no need to configure output or level.
21 log_error "an error occured: %03d - %s", $errcode, $errmsg;
22 ...
23 log_debug "http response: %s", $http; # automatic dumping of data
24 }
25 1;
26 Consuming logs
28 Choosing an output
29 In your application (consumer/listener):
31 use Foo;
33 use Log::ger::Output 'Screen'; # configure output
34 # level is by default 'warn'
35 foo(); # the error message is shown, but debug message is not.
36 Choosing multiple outputs
38 Instead of screen, you can output to multiple outputs (including
40 multiple files):
41 use Log::ger::Output 'Composite' => (
43 outputs => {
44 Screen => {},
45 File => [
46 {conf=>{path=>'/path/to/app.log'}},
47 ...
48 ],
49 ...
50 },
51 );
52 See Log::ger::Manual::Tutorial::481_Output_Composite for more examples.
54 Choosing level
56 One way to set level:
58 use Log::ger::Util;
60 Log::ger::Util::set_level('debug'); # be more verbose
61 foo(); # the error message as well as debug message are now shown
62 There are better ways, e.g. letting users configure log level via
64 configuration file or command-line option. See
65 Log::ger::Manual::Tutorial::300_Level for more details.
66
68 Log::ger is yet another logging framework with the following features:
69 • Separation of producers and consumers/listeners
71 Like Log::Any, this offers a very easy way for modules to produce
73 some logs without having to configure anything. Configuring output,
74 level, etc can be done in the application as log
75 consumers/listeners. To read more about this, see the documentation
76 of Log::Any or Log::ger::Manual (but nevertheless see
77 Log::ger::Manual on why you might prefer Log::ger to Log::Any).
78 • Lightweight and fast
80 Slim distribution. No non-core dependencies, extra functionalities
82 are provided in separate distributions to be pulled as needed.
83 Low startup overhead. Only ~0.5-1ms. For comparison, strict
85 ~0.2-0.5ms, warnings ~2ms, Log::Any (v0.15) ~2-3ms, Log::Any
86 (v1.049) ~8-10ms, Log::Log4perl ~35ms. This is measured on a
87 2014-2015 PC and before doing any output configuration. I strive to
88 make "use Log::ger;" statement to be roughly as light as "use
89 strict;" or "use warnings;" so the impact of adding the statement
90 is really minimal and you can just add logging without much thought
91 to most of your modules. This is important to me because I want
92 logging to be pervasive.
93 To test for yourself, try e.g. with bencher-code:
95 % bencher-code 'use Log::ger' 'use Log::Any' --startup
97 Fast. Low null-/stealth-logging overhead, about 1.5x faster than
99 Log::Any, 3x faster than Log4perl, 5x faster than Log::Fast, ~40x
100 faster than Log::Contextual, and ~100x faster than Log::Dispatch.
101 For more benchmarks, see Bencher::Scenarios::LogGer.
103 Conditional compilation. There is a plugin to optimize away
105 unneeded logging statements, like assertion/conditional
106 compilation, so they have zero runtime performance cost. See
107 Log::ger::Plugin::OptAway.
108 Being lightweight means the module can be used more universally,
110 from CLI to long-running daemons to inside routines with tight
111 loops.
112 • Flexible
114 Customizable levels and routine/method names. Can be used in a
116 procedural or OO style. Log::ger can mimic the interface of
117 Log::Any, Log::Contextual, Log::Log4perl, or some other popular
118 logging frameworks, to ease migration or adjust with your personal
119 style.
120 Per-package settings. Each importer package can use its own
122 format/layout, output. For example, a module that is migrated from
123 Log::Any uses Log::Any-style logging, while another uses native
124 Log::ger style, and yet some other uses block formatting like
125 Log::Contextual. This eases code migration and teamwork. Each
126 module author can preserve her own logging style, if wanted, and
127 all the modules still use the same framework.
128 Dynamic. Outputs and levels can be changed anytime during run-time
130 and logger routines will be updated automatically. This is useful
131 in situation like a long-running server application: you can turn
132 on tracing logs temporarily to debug problems, then turn them off
133 again, without restarting your server.
134 Interoperability. There are modules to interop with Log::Any,
136 either consume Log::Any logs (see Log::Any::Adapter::LogGer) or
137 produce logs to be consumed by Log::Any (see
138 Log::ger::Output::LogAny).
139 Many output modules and plugins. See "Log::ger::Output::*",
141 "Log::ger::Format::*", "Log::ger::Layout::*",
142 "Log::ger::Plugin::*". Writing an output module in Log::ger is
143 easier than writing a Log::Any::Adapter::*.
144 For more documentation, start with Log::ger::Manual.
146
148 Some other popular logging frameworks: Log::Any, Log::Contextual,
149 Log::Log4perl, Log::Dispatch, Log::Dispatchouli.
150 If you still prefer debugging using the good old "print()", there's
152 Debug::Print.
153
155 perlancar <perlancar@cpan.org>
156
158 This software is copyright (c) 2021, 2020, 2019, 2018, 2017 by
159 perlancar@cpan.org.
160 This is free software; you can redistribute it and/or modify it under
162 the same terms as the Perl 5 programming language system itself.
163perl v5.34.0 2022-01-21 Log::ger(3)