1 |
=head1 NAME |
2 |
|
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AnyEvent::Log - simple logging "framework" |
4 |
|
5 |
=head1 SYNOPSIS |
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|
7 |
# simple use |
8 |
use AnyEvent; |
9 |
|
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AE::log debug => "hit my knee"; |
11 |
AE::log warn => "it's a bit too hot"; |
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AE::log error => "the flag was false!"; |
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AE::log fatal => "the bit toggled! run!"; |
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|
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# "complex" use |
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use AnyEvent::Log; |
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|
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my $tracer = AnyEvent::Log::logger trace => \$my $trace; |
19 |
|
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$tracer->("i am here") if $trace; |
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$tracer->(sub { "lots of data: " . Dumper $self }) if $trace; |
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|
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# configuration |
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|
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# set logging for this package to errors and higher only |
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AnyEvent::Log::ctx->level ("error"); |
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|
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# set logging globally to anything below debug |
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$AnyEvent::Log::Root->level ("notice"); |
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|
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# see also EXAMPLES, below |
32 |
|
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=head1 DESCRIPTION |
34 |
|
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This module implements a relatively simple "logging framework". It doesn't |
36 |
attempt to be "the" logging solution or even "a" logging solution for |
37 |
AnyEvent - AnyEvent simply creates logging messages internally, and this |
38 |
module more or less exposes the mechanism, with some extra spiff to allow |
39 |
using it from other modules as well. |
40 |
|
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Remember that the default verbosity level is C<0>, so nothing will be |
42 |
logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number before |
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starting your program, or change the logging level at runtime with |
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something like: |
45 |
|
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use AnyEvent; |
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(AnyEvent::Log::ctx "")->level ("info"); |
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|
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The design goal behind this module was to keep it simple (and small), |
50 |
but make it powerful enough to be potentially useful for any module, and |
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extensive enough for the most common tasks, such as logging to multiple |
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targets, or being able to log into a database. |
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|
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The amount of documentation might indicate otherwise, but the module is |
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still just 240 lines or so. |
56 |
|
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=head1 LOGGING FUNCTIONS |
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|
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These functions allow you to log messages. They always use the caller's |
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package as a "logging module/source". Also, the main logging function is |
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callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is |
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loaded. |
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|
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=over 4 |
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|
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=cut |
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|
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package AnyEvent::Log; |
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|
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use Carp (); |
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use POSIX (); |
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|
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use AnyEvent (); BEGIN { AnyEvent::common_sense } |
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use AnyEvent::Util (); |
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|
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our $VERSION = $AnyEvent::VERSION; |
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|
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our ($now_int, $now_str1, $now_str2); |
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|
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# Format Time, not public - yet? |
81 |
sub ft($) { |
82 |
my $i = int $_[0]; |
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my $f = sprintf "%06d", 1e6 * ($_[0] - $i); |
84 |
|
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($now_int, $now_str1, $now_str2) = ($i, split /\x01/, POSIX::strftime "%Y-%m-%d %H:%M:%S.\x01 %z", localtime $i) |
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if $now_int != $i; |
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|
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"$now_str1$f$now_str2" |
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} |
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|
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our %CTX; # all logging contexts |
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|
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# creates a default package context object for the given package |
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sub _pkg_ctx($) { |
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my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx"; |
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|
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# link "parent" package |
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my $pkg = $_[0] =~ /^(.+)::/ ? $1 : "AE::Log::Top"; |
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|
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$pkg = $CTX{$pkg} ||= &_pkg_ctx ($pkg); |
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$ctx->[2]{$pkg+0} = $pkg; |
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|
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$ctx |
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} |
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|
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=item AnyEvent::Log::log $level, $msg[, @args] |
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|
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Requests logging of the given C<$msg> with the given log level (1..9). |
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You can also use the following strings as log level: C<fatal> (1), |
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C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6), |
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C<info> (7), C<debug> (8), C<trace> (9). |
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|
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For C<fatal> log levels, the program will abort. |
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|
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If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the |
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C<$msg> is interpreted as an sprintf format string. |
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|
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The C<$msg> should not end with C<\n>, but may if that is convenient for |
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you. Also, multiline messages are handled properly. |
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|
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Last not least, C<$msg> might be a code reference, in which case it is |
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supposed to return the message. It will be called only then the message |
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actually gets logged, which is useful if it is costly to create the |
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message in the first place. |
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|
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Whether the given message will be logged depends on the maximum log level |
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and the caller's package. |
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|
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Note that you can (and should) call this function as C<AnyEvent::log> or |
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C<AE::log>, without C<use>-ing this module if possible (i.e. you don't |
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need any additional functionality), as those functions will load the |
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logging module on demand only. They are also much shorter to write. |
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|
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Also, if you optionally generate a lot of debug messages (such as when |
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tracing some code), you should look into using a logger callback and a |
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boolean enabler (see C<logger>, below). |
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|
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Example: log something at error level. |
139 |
|
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AE::log error => "something"; |
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|
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Example: use printf-formatting. |
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|
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AE::log info => "%5d %-10.10s %s", $index, $category, $msg; |
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|
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Example: only generate a costly dump when the message is actually being logged. |
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|
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AE::log debug => sub { require Data::Dump; Data::Dump::dump \%cache }; |
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|
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=cut |
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|
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# also allow syslog equivalent names |
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our %STR2LEVEL = ( |
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fatal => 1, emerg => 1, |
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alert => 2, |
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critical => 3, crit => 3, |
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error => 4, err => 4, |
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warn => 5, warning => 5, |
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note => 6, notice => 6, |
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info => 7, |
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debug => 8, |
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trace => 9, |
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); |
164 |
|
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sub now () { time } |
166 |
|
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AnyEvent::post_detect { |
168 |
*now = \&AE::now; |
169 |
}; |
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|
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our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace); |
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|
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# time, ctx, level, msg |
174 |
sub _format($$$$) { |
175 |
my $ts = ft $_[0]; |
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my $ct = " "; |
177 |
|
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my @res; |
179 |
|
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for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) { |
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push @res, "$ts$ct$_\n"; |
182 |
$ct = " + "; |
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} |
184 |
|
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join "", @res |
186 |
} |
187 |
|
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sub _log { |
189 |
my ($ctx, $level, $format, @args) = @_; |
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|
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$level = $level > 0 && $level <= 9 |
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? $level+0 |
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: $STR2LEVEL{$level} || Carp::croak "$level: not a valid logging level, caught"; |
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|
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my $mask = 1 << $level; |
196 |
|
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my (%seen, @ctx, $now, $fmt); |
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|
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do |
200 |
{ |
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# skip if masked |
202 |
if ($ctx->[1] & $mask && !$seen{$ctx+0}++) { |
203 |
if ($ctx->[3]) { |
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# logging target found |
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|
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# now get raw message, unless we have it already |
207 |
unless ($now) { |
208 |
$format = $format->() if ref $format; |
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$format = sprintf $format, @args if @args; |
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$format =~ s/\n$//; |
211 |
$now = AE::now; |
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}; |
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|
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# format msg |
215 |
my $str = $ctx->[4] |
216 |
? $ctx->[4]($now, $_[0], $level, $format) |
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: $fmt ||= _format $now, $_[0], $level, $format; |
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|
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$ctx->[3]($str); |
220 |
} |
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|
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# not masked, not consumed - propagate to parent contexts |
223 |
push @ctx, values %{ $ctx->[2] }; |
224 |
} |
225 |
} |
226 |
while $ctx = pop @ctx; |
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|
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exit 1 if $level <= 1; |
229 |
} |
230 |
|
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sub log($$;@) { |
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_log |
233 |
$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0], |
234 |
@_; |
235 |
} |
236 |
|
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*AnyEvent::log = *AE::log = \&log; |
238 |
|
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=item $logger = AnyEvent::Log::logger $level[, \$enabled] |
240 |
|
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Creates a code reference that, when called, acts as if the |
242 |
C<AnyEvent::Log::log> function was called at this point with the givne |
243 |
level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with |
244 |
the C<AnyEvent::Log::log> function: |
245 |
|
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my $debug_log = AnyEvent::Log::logger "debug"; |
247 |
|
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$debug_log->("debug here"); |
249 |
$debug_log->("%06d emails processed", 12345); |
250 |
$debug_log->(sub { $obj->as_string }); |
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|
252 |
The idea behind this function is to decide whether to log before actually |
253 |
logging - when the C<logger> function is called once, but the returned |
254 |
logger callback often, then this can be a tremendous speed win. |
255 |
|
256 |
Despite this speed advantage, changes in logging configuration will |
257 |
still be reflected by the logger callback, even if configuration changes |
258 |
I<after> it was created. |
259 |
|
260 |
To further speed up logging, you can bind a scalar variable to the logger, |
261 |
which contains true if the logger should be called or not - if it is |
262 |
false, calling the logger can be safely skipped. This variable will be |
263 |
updated as long as C<$logger> is alive. |
264 |
|
265 |
Full example: |
266 |
|
267 |
# near the init section |
268 |
use AnyEvent::Log; |
269 |
|
270 |
my $debug_log = AnyEvent:Log::logger debug => \my $debug; |
271 |
|
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# and later in your program |
273 |
$debug_log->("yo, stuff here") if $debug; |
274 |
|
275 |
$debug and $debug_log->("123"); |
276 |
|
277 |
=cut |
278 |
|
279 |
our %LOGGER; |
280 |
|
281 |
# re-assess logging status for all loggers |
282 |
sub _reassess { |
283 |
local $SIG{__DIE__}; |
284 |
my $die = sub { die }; |
285 |
|
286 |
for (@_ ? $LOGGER{$_[0]} : values %LOGGER) { |
287 |
my ($ctx, $level, $renabled) = @$_; |
288 |
|
289 |
# to detect whether a message would be logged, we actually |
290 |
# try to log one and die. this isn't fast, but we can be |
291 |
# sure that the logging decision is correct :) |
292 |
|
293 |
$$renabled = !eval { |
294 |
_log $ctx, $level, $die; |
295 |
|
296 |
1 |
297 |
}; |
298 |
} |
299 |
} |
300 |
|
301 |
sub _logger { |
302 |
my ($ctx, $level, $renabled) = @_; |
303 |
|
304 |
$$renabled = 1; |
305 |
|
306 |
my $logger = [$ctx, $level, $renabled]; |
307 |
|
308 |
$LOGGER{$logger+0} = $logger; |
309 |
|
310 |
_reassess $logger+0; |
311 |
|
312 |
my $guard = AnyEvent::Util::guard { |
313 |
# "clean up" |
314 |
delete $LOGGER{$logger+0}; |
315 |
}; |
316 |
|
317 |
sub { |
318 |
$guard if 0; # keep guard alive, but don't cause runtime overhead |
319 |
|
320 |
_log $ctx, $level, @_ |
321 |
if $$renabled; |
322 |
} |
323 |
} |
324 |
|
325 |
sub logger($;$) { |
326 |
_logger |
327 |
$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0], |
328 |
@_ |
329 |
} |
330 |
|
331 |
=back |
332 |
|
333 |
=head1 LOGGING CONTEXTS |
334 |
|
335 |
This module associates every log message with a so-called I<logging |
336 |
context>, based on the package of the caller. Every perl package has its |
337 |
own logging context. |
338 |
|
339 |
A logging context has three major responsibilities: filtering, logging and |
340 |
propagating the message. |
341 |
|
342 |
For the first purpose, filtering, each context has a set of logging |
343 |
levels, called the log level mask. Messages not in the set will be ignored |
344 |
by this context (masked). |
345 |
|
346 |
For logging, the context stores a formatting callback (which takes the |
347 |
timestamp, context, level and string message and formats it in the way |
348 |
it should be logged) and a logging callback (which is responsible for |
349 |
actually logging the formatted message and telling C<AnyEvent::Log> |
350 |
whether it has consumed the message, or whether it should be propagated). |
351 |
|
352 |
For propagation, a context can have any number of attached I<parent |
353 |
contexts>. Any message that is neither masked by the logging mask nor |
354 |
masked by the logging callback returning true will be passed to all parent |
355 |
contexts. |
356 |
|
357 |
Each call to a logging function will log the message at most once per |
358 |
context, so it does not matter (much) if there are cycles or if the |
359 |
message can arrive at the same context via multiple paths. |
360 |
|
361 |
=head2 DEFAULTS |
362 |
|
363 |
By default, all logging contexts have an full set of log levels ("all"), a |
364 |
disabled logging callback and the default formatting callback. |
365 |
|
366 |
Package contexts have the package name as logging title by default. |
367 |
|
368 |
They have exactly one parent - the context of the "parent" package. The |
369 |
parent package is simply defined to be the package name without the last |
370 |
component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>, |
371 |
and C<AnyEvent> becomes ... C<AnyEvent::Log::Top> which is the |
372 |
exception of the rule - just like the parent of any package name in |
373 |
Perl is C<main>, the default parent of any top-level package context is |
374 |
C<AnyEvent::Log::Top>. |
375 |
|
376 |
Since perl packages form only an approximate hierarchy, this parent |
377 |
context can of course be removed. |
378 |
|
379 |
All other (anonymous) contexts have no parents and an empty title by |
380 |
default. |
381 |
|
382 |
When the module is loaded it creates the default context called |
383 |
C<AnyEvent::Log::Default> (also stored in C<$AnyEvent::Log::Default>), |
384 |
which simply logs everything via C<warn> and doesn't propagate anything |
385 |
anywhere by default. The purpose of the default context is to provide |
386 |
a convenient place to override the global logging target or to attach |
387 |
additional log targets. It's not meant for filtering. |
388 |
|
389 |
It then creates the root context called C<AnyEvent::Log::Root> (also |
390 |
stored in C<$AnyEvent::Log::Root>) and sets its log level set to all |
391 |
levels up to the one specified by C<$ENV{PERL_ANYEVENT_VERBOSE}>. It |
392 |
then attached the default logging context to it. The purpose of the root |
393 |
context is to simply provide filtering according to some global log level. |
394 |
|
395 |
Finally it creates the top-level package context called |
396 |
C<AnyEvent::Log::Top> (also stored in, you might have guessed, |
397 |
C<$AnyEvent::Log::Top>) and attached the root context but otherwise leaves |
398 |
it at default config. It's purpose is simply to collect all log messages |
399 |
system-wide. |
400 |
|
401 |
These three special contexts can also be referred to by the |
402 |
package/context names C<AE::Log::Default>, C<AE::Log::Root> and |
403 |
C<AE::Log::Top>. |
404 |
|
405 |
The effect of all this is that log messages, by default, wander up |
406 |
to the root context where log messages with lower priority then |
407 |
C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered away and then to the |
408 |
AnyEvent::Log::Default context to be passed to C<warn>. |
409 |
|
410 |
Splitting the top level context into three contexts makes it easy to set |
411 |
a global logging level (by modifying the root context), but still allow |
412 |
other contexts to log, for example, their debug and trace messages to the |
413 |
default target despite the global logging level, or to attach additional |
414 |
log targets that log messages, regardless of the global logging level. |
415 |
|
416 |
It also makes it easy to replace the default warn-logger by something that |
417 |
logs to a file, or to attach additional logging targets. |
418 |
|
419 |
=head2 CREATING/FINDING/DESTROYING CONTEXTS |
420 |
|
421 |
=over 4 |
422 |
|
423 |
=item $ctx = AnyEvent::Log::ctx [$pkg] |
424 |
|
425 |
This function creates or returns a logging context (which is an object). |
426 |
|
427 |
If a package name is given, then the context for that packlage is |
428 |
returned. If it is called without any arguments, then the context for the |
429 |
callers package is returned (i.e. the same context as a C<AE::log> call |
430 |
would use). |
431 |
|
432 |
If C<undef> is given, then it creates a new anonymous context that is not |
433 |
tied to any package and is destroyed when no longer referenced. |
434 |
|
435 |
=cut |
436 |
|
437 |
sub ctx(;$) { |
438 |
my $pkg = @_ ? shift : (caller)[0]; |
439 |
|
440 |
ref $pkg |
441 |
? $pkg |
442 |
: defined $pkg |
443 |
? $CTX{$pkg} ||= AnyEvent::Log::_pkg_ctx $pkg |
444 |
: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx" |
445 |
} |
446 |
|
447 |
=item AnyEvent::Log::reset |
448 |
|
449 |
Resets all package contexts and recreates the default hierarchy if |
450 |
necessary, i.e. resets the logging subsystem to defaults, as much as |
451 |
possible. This process keeps references to contexts held by other parts of |
452 |
the program intact. |
453 |
|
454 |
This can be used to implement config-file (re-)loading: before loading a |
455 |
configuration, reset all contexts. |
456 |
|
457 |
=cut |
458 |
|
459 |
sub reset { |
460 |
# hard to kill complex data structures |
461 |
# we recreate all package loggers and reset the hierarchy |
462 |
while (my ($k, $v) = each %CTX) { |
463 |
@$v = ($k, (1 << 10) - 1 - 1, { }); |
464 |
|
465 |
my $pkg = $k =~ /^(.+)::/ ? $1 : "AE::Log::Top"; |
466 |
$v->attach ($CTX{$pkg}); |
467 |
} |
468 |
|
469 |
$AnyEvent::Log::Default->parents; |
470 |
$AnyEvent::Log::Default->title ("AnyEvent::Log::Default"); |
471 |
$AnyEvent::Log::Default->log_cb (sub { |
472 |
warn shift; |
473 |
0 |
474 |
}); |
475 |
$CTX{"AnyEvent::Log::Default"} = $CTX{"AE::Log::Default"} = $AnyEvent::Log::Default; |
476 |
|
477 |
$AnyEvent::Log::Root->parents ($AnyEvent::Log::Default); |
478 |
$AnyEvent::Log::Root->title ("AnyEvent::Log::Root"); |
479 |
$AnyEvent::Log::Root->level ($AnyEvent::VERBOSE); |
480 |
$CTX{"AnyEvent::Log::Root"} = $CTX{"AE::Log::Root"} = $AnyEvent::Log::Root; |
481 |
|
482 |
$AnyEvent::Log::Top->parents ($AnyEvent::Log::Root); |
483 |
$AnyEvent::Log::Top->title ("AnyEvent::Log::Top"); |
484 |
$CTX{"AnyEvent::Log::Top"} = $CTX{"AE::Log::Top"} = $AnyEvent::Log::Top; |
485 |
|
486 |
_reassess; |
487 |
} |
488 |
|
489 |
# create the default logger contexts |
490 |
$AnyEvent::Log::Default = ctx undef; |
491 |
$AnyEvent::Log::Root = ctx undef; |
492 |
$AnyEvent::Log::Top = ctx undef; |
493 |
|
494 |
AnyEvent::Log::reset; |
495 |
|
496 |
# hello, CPAN, please catch me |
497 |
package AnyEvent::Log::Default; |
498 |
package AE::Log::Default; |
499 |
package AnyEvent::Log::Root; |
500 |
package AE::Log::Root; |
501 |
package AnyEvent::Log::Top; |
502 |
package AE::Log::Top; |
503 |
|
504 |
package AnyEvent::Log::Ctx; |
505 |
|
506 |
# 0 1 2 3 4 |
507 |
# [$title, $level, %$parents, &$logcb, &$fmtcb] |
508 |
|
509 |
=item $ctx = new AnyEvent::Log::Ctx methodname => param... |
510 |
|
511 |
This is a convenience constructor that makes it simpler to construct |
512 |
anonymous logging contexts. |
513 |
|
514 |
Each key-value pair results in an invocation of the method of the same |
515 |
name as the key with the value as parameter, unless the value is an |
516 |
arrayref, in which case it calls the method with the contents of the |
517 |
array. The methods are called in the same order as specified. |
518 |
|
519 |
Example: create a new logging context and set both the default logging |
520 |
level, some parent contexts and a logging callback. |
521 |
|
522 |
$ctx = new AnyEvent::Log::Ctx |
523 |
title => "dubious messages", |
524 |
level => "error", |
525 |
log_cb => sub { print STDOUT shift; 0 }, |
526 |
parents => [$ctx1, $ctx, $ctx2], |
527 |
; |
528 |
|
529 |
=back |
530 |
|
531 |
=cut |
532 |
|
533 |
sub new { |
534 |
my $class = shift; |
535 |
|
536 |
my $ctx = AnyEvent::Log::ctx undef; |
537 |
|
538 |
while (@_) { |
539 |
my ($k, $v) = splice @_, 0, 2; |
540 |
$ctx->$k (ref $v eq "ARRAY" ? @$v : $v); |
541 |
} |
542 |
|
543 |
bless $ctx, $class # do we really support subclassing, hmm? |
544 |
} |
545 |
|
546 |
|
547 |
=head2 CONFIGURING A LOG CONTEXT |
548 |
|
549 |
The following methods can be used to configure the logging context. |
550 |
|
551 |
=over 4 |
552 |
|
553 |
=item $ctx->title ([$new_title]) |
554 |
|
555 |
Returns the title of the logging context - this is the package name, for |
556 |
package contexts, and a user defined string for all others. |
557 |
|
558 |
If C<$new_title> is given, then it replaces the package name or title. |
559 |
|
560 |
=cut |
561 |
|
562 |
sub title { |
563 |
$_[0][0] = $_[1] if @_ > 1; |
564 |
$_[0][0] |
565 |
} |
566 |
|
567 |
=back |
568 |
|
569 |
=head3 LOGGING LEVELS |
570 |
|
571 |
The following methods deal with the logging level set associated with the |
572 |
log context. |
573 |
|
574 |
The most common method to use is probably C<< $ctx->level ($level) >>, |
575 |
which configures the specified and any higher priority levels. |
576 |
|
577 |
All functions which accept a list of levels also accept the special string |
578 |
C<all> which expands to all logging levels. |
579 |
|
580 |
=over 4 |
581 |
|
582 |
=item $ctx->levels ($level[, $level...) |
583 |
|
584 |
Enables logging for the given levels and disables it for all others. |
585 |
|
586 |
=item $ctx->level ($level) |
587 |
|
588 |
Enables logging for the given level and all lower level (higher priority) |
589 |
ones. In addition to normal logging levels, specifying a level of C<0> or |
590 |
C<off> disables all logging for this level. |
591 |
|
592 |
Example: log warnings, errors and higher priority messages. |
593 |
|
594 |
$ctx->level ("warn"); |
595 |
$ctx->level (5); # same thing, just numeric |
596 |
|
597 |
=item $ctx->enable ($level[, $level...]) |
598 |
|
599 |
Enables logging for the given levels, leaving all others unchanged. |
600 |
|
601 |
=item $ctx->disable ($level[, $level...]) |
602 |
|
603 |
Disables logging for the given levels, leaving all others unchanged. |
604 |
|
605 |
=cut |
606 |
|
607 |
sub _lvl_lst { |
608 |
map { |
609 |
$_ > 0 && $_ <= 9 ? $_+0 |
610 |
: $_ eq "all" ? (1 .. 9) |
611 |
: $STR2LEVEL{$_} || Carp::croak "$_: not a valid logging level, caught" |
612 |
} @_ |
613 |
} |
614 |
|
615 |
our $NOP_CB = sub { 0 }; |
616 |
|
617 |
sub levels { |
618 |
my $ctx = shift; |
619 |
$ctx->[1] = 0; |
620 |
$ctx->[1] |= 1 << $_ |
621 |
for &_lvl_lst; |
622 |
AnyEvent::Log::_reassess; |
623 |
} |
624 |
|
625 |
sub level { |
626 |
my $ctx = shift; |
627 |
my $lvl = $_[0] =~ /^(?:0|off|none)$/ ? 0 : (_lvl_lst $_[0])[-1]; |
628 |
|
629 |
$ctx->[1] = ((1 << $lvl) - 1) << 1; |
630 |
AnyEvent::Log::_reassess; |
631 |
} |
632 |
|
633 |
sub enable { |
634 |
my $ctx = shift; |
635 |
$ctx->[1] |= 1 << $_ |
636 |
for &_lvl_lst; |
637 |
AnyEvent::Log::_reassess; |
638 |
} |
639 |
|
640 |
sub disable { |
641 |
my $ctx = shift; |
642 |
$ctx->[1] &= ~(1 << $_) |
643 |
for &_lvl_lst; |
644 |
AnyEvent::Log::_reassess; |
645 |
} |
646 |
|
647 |
=back |
648 |
|
649 |
=head3 PARENT CONTEXTS |
650 |
|
651 |
The following methods attach and detach another logging context to a |
652 |
logging context. |
653 |
|
654 |
Log messages are propagated to all parent contexts, unless the logging |
655 |
callback consumes the message. |
656 |
|
657 |
=over 4 |
658 |
|
659 |
=item $ctx->attach ($ctx2[, $ctx3...]) |
660 |
|
661 |
Attaches the given contexts as parents to this context. It is not an error |
662 |
to add a context twice (the second add will be ignored). |
663 |
|
664 |
A context can be specified either as package name or as a context object. |
665 |
|
666 |
=item $ctx->detach ($ctx2[, $ctx3...]) |
667 |
|
668 |
Removes the given parents from this context - it's not an error to attempt |
669 |
to remove a context that hasn't been added. |
670 |
|
671 |
A context can be specified either as package name or as a context object. |
672 |
|
673 |
=item $ctx->parents ($ctx2[, $ctx3...]) |
674 |
|
675 |
Replaces all parents attached to this context by the ones given. |
676 |
|
677 |
=cut |
678 |
|
679 |
sub attach { |
680 |
my $ctx = shift; |
681 |
|
682 |
$ctx->[2]{$_+0} = $_ |
683 |
for map { AnyEvent::Log::ctx $_ } @_; |
684 |
} |
685 |
|
686 |
sub detach { |
687 |
my $ctx = shift; |
688 |
|
689 |
delete $ctx->[2]{$_+0} |
690 |
for map { AnyEvent::Log::ctx $_ } @_; |
691 |
} |
692 |
|
693 |
sub parents { |
694 |
undef $_[0][2]; |
695 |
&attach; |
696 |
} |
697 |
|
698 |
=back |
699 |
|
700 |
=head3 MESSAGE LOGGING |
701 |
|
702 |
The following methods configure how the logging context actually does |
703 |
the logging (which consists of formatting the message and printing it or |
704 |
whatever it wants to do with it) and also allows you to log messages |
705 |
directly to a context, without going via your package context. |
706 |
|
707 |
=over 4 |
708 |
|
709 |
=item $ctx->log_cb ($cb->($str)) |
710 |
|
711 |
Replaces the logging callback on the context (C<undef> disables the |
712 |
logging callback). |
713 |
|
714 |
The logging callback is responsible for handling formatted log messages |
715 |
(see C<fmt_cb> below) - normally simple text strings that end with a |
716 |
newline (and are possibly multiline themselves). |
717 |
|
718 |
It also has to return true iff it has consumed the log message, and false |
719 |
if it hasn't. Consuming a message means that it will not be sent to any |
720 |
parent context. When in doubt, return C<0> from your logging callback. |
721 |
|
722 |
Example: a very simple logging callback, simply dump the message to STDOUT |
723 |
and do not consume it. |
724 |
|
725 |
$ctx->log_cb (sub { print STDERR shift; 0 }); |
726 |
|
727 |
You can filter messages by having a log callback that simply returns C<1> |
728 |
and does not do anything with the message, but this counts as "message |
729 |
being logged" and might not be very efficient. |
730 |
|
731 |
Example: propagate all messages except for log levels "debug" and |
732 |
"trace". The messages will still be generated, though, which can slow down |
733 |
your program. |
734 |
|
735 |
$ctx->levels ("debug", "trace"); |
736 |
$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages |
737 |
|
738 |
=item $ctx->fmt_cb ($fmt_cb->($timestamp, $ctx, $level, $message)) |
739 |
|
740 |
Replaces the formatting callback on the context (C<undef> restores the |
741 |
default formatter). |
742 |
|
743 |
The callback is passed the (possibly fractional) timestamp, the original |
744 |
logging context, the (numeric) logging level and the raw message string and needs to |
745 |
return a formatted log message. In most cases this will be a string, but |
746 |
it could just as well be an array reference that just stores the values. |
747 |
|
748 |
Example: format just the raw message, with numeric log level in angle |
749 |
brackets. |
750 |
|
751 |
$ctx->fmt_cb (sub { |
752 |
my ($time, $ctx, $lvl, $msg) = @_; |
753 |
|
754 |
"<$lvl>$msg\n" |
755 |
}); |
756 |
|
757 |
Example: return an array reference with just the log values, and use |
758 |
C<PApp::SQL::sql_exec> to store the emssage in a database. |
759 |
|
760 |
$ctx->fmt_cb (sub { \@_ }); |
761 |
$ctx->log_cb (sub { |
762 |
my ($msg) = @_; |
763 |
|
764 |
sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)", |
765 |
$msg->[0] + 0, |
766 |
"$msg->[1]", |
767 |
$msg->[2] + 0, |
768 |
"$msg->[3]"; |
769 |
|
770 |
0 |
771 |
}); |
772 |
|
773 |
=cut |
774 |
|
775 |
sub log_cb { |
776 |
my ($ctx, $cb) = @_; |
777 |
|
778 |
$ctx->[3] = $cb; |
779 |
} |
780 |
|
781 |
sub fmt_cb { |
782 |
my ($ctx, $cb) = @_; |
783 |
|
784 |
$ctx->[4] = $cb; |
785 |
} |
786 |
|
787 |
=item $ctx->log ($level, $msg[, @params]) |
788 |
|
789 |
Same as C<AnyEvent::Log::log>, but uses the given context as log context. |
790 |
|
791 |
=item $logger = $ctx->logger ($level[, \$enabled]) |
792 |
|
793 |
Same as C<AnyEvent::Log::logger>, but uses the given context as log |
794 |
context. |
795 |
|
796 |
=cut |
797 |
|
798 |
*log = \&AnyEvent::Log::_log; |
799 |
*logger = \&AnyEvent::Log::_logger; |
800 |
|
801 |
1; |
802 |
|
803 |
=back |
804 |
|
805 |
=head1 EXAMPLES |
806 |
|
807 |
This section shows some common configurations. |
808 |
|
809 |
=over 4 |
810 |
|
811 |
=item Setting the global logging level. |
812 |
|
813 |
Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before |
814 |
running your program, or modify the log level of the root context: |
815 |
|
816 |
PERL_ANYEVENT_VERBOSE=5 ./myprog |
817 |
|
818 |
$AnyEvent::Log::Root->level ("warn"); |
819 |
|
820 |
=item Append all messages to a file instead of sending them to STDERR. |
821 |
|
822 |
This is affected by the global logging level. |
823 |
|
824 |
open my $fh, ">>", $path |
825 |
or die "$path: $!"; |
826 |
|
827 |
$AnyEvent::Log::Default->log_cb (sub { |
828 |
syswrite $fh, shift; |
829 |
0 |
830 |
}); |
831 |
|
832 |
=item Write all messages with priority C<error> and higher to a file. |
833 |
|
834 |
This writes them only when the global logging level allows it, because |
835 |
it is attached to the default context which is invoked I<after> global |
836 |
filtering. |
837 |
|
838 |
open my $fh, ">>", $path |
839 |
or die "$path: $!"; |
840 |
|
841 |
$AnyEvent::Log::Default->attach (new AnyEvent::Log::Ctx |
842 |
log_cb => sub { syswrite $fh, shift; 0 }); |
843 |
|
844 |
This writes them regardless of the global logging level, because it is |
845 |
attached to the toplevel context, which receives all messages I<before> |
846 |
the global filtering. |
847 |
|
848 |
$AnyEvent::Log::Top->attach (new AnyEvent::Log::Ctx |
849 |
log_cb => sub { syswrite $fh, shift; 0 }); |
850 |
|
851 |
In both cases, messages are still written to STDOUT. |
852 |
|
853 |
=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s). |
854 |
|
855 |
Attach the CyAnyEvent::Log::Default> context to the C<AnyEvent::Debug> |
856 |
context and increase the C<AnyEvent::Debug> logging level - this simply |
857 |
circumvents the global filtering for trace messages. |
858 |
|
859 |
my $debug = AnyEvent::Debug->AnyEvent::Log::ctx; |
860 |
$debug->attach ($AnyEvent::Log::Default); |
861 |
$debug->levels ("trace"); # not "level"! |
862 |
|
863 |
This of course works for any package. |
864 |
|
865 |
=back |
866 |
|
867 |
=head1 AUTHOR |
868 |
|
869 |
Marc Lehmann <schmorp@schmorp.de> |
870 |
http://home.schmorp.de/ |
871 |
|
872 |
=cut |