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Revision 1.2 by root, Tue Aug 16 14:47:27 2011 UTC vs.
Revision 1.50 by root, Thu Mar 22 01:24:19 2012 UTC

…		…
2		2
3	AnyEvent::Log - simple logging "framework"	3	AnyEvent::Log - simple logging "framework"
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
		7	Simple uses:
		8
		9	use AnyEvent;
		10
		11	AE::log trace => "going to call function abc";
		12	AE::log debug => "the function returned 3";
		13	AE::log info => "file soandso successfully deleted";
		14	AE::log note => "wanted to create config, but config was already created";
		15	AE::log warn => "couldn't delete the file";
		16	AE::log error => "failed to retrieve data";
		17	AE::log crit => "the battery temperature is too hot";
		18	AE::log alert => "the battery died";
		19	AE::log fatal => "no config found, cannot continue"; # never returns
		20
		21	Log level overview:
		22
		23	LVL NAME SYSLOG PERL NOTE
		24	1 fatal emerg exit system unusable, aborts program!
		25	2 alert failure in primary system
		26	3 critical crit failure in backup system
		27	4 error err die non-urgent program errors, a bug
		28	5 warn warning possible problem, not necessarily error
		29	6 note notice unusual conditions
		30	7 info normal messages, no action required
		31	8 debug debugging messages for development
		32	9 trace copious tracing output
		33
		34	"Complex" uses (for speed sensitive code, e.g. trace/debug messages):
		35
7	use AnyEvent::Log;	36	use AnyEvent::Log;
		37
		38	my $tracer = AnyEvent::Log::logger trace => \$my $trace;
		39
		40	$tracer->("i am here") if $trace;
		41	$tracer->(sub { "lots of data: " . Dumper $self }) if $trace;
		42
		43	Configuration (also look at the EXAMPLES section):
		44
		45	# set logging for the current package to errors and higher only
		46	AnyEvent::Log::ctx->level ("error");
		47
		48	# set logging level to suppress anything below "notice"
		49	$AnyEvent::Log::FILTER->level ("notice");
		50
		51	# send all critical and higher priority messages to syslog,
		52	# regardless of (most) other settings
		53	$AnyEvent::Log::COLLECT->attach (new AnyEvent::Log::Ctx
		54	level => "critical",
		55	log_to_syslog => "user",
		56	);
8		57
9	=head1 DESCRIPTION	58	=head1 DESCRIPTION
10		59
11	This module implements a relatively simple "logging framework". It doesn't	60	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	61	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	62	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	63	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	64	using it from other modules as well.
16		65
17	Remember that the default verbosity level is C<0>, so nothing	66	Remember that the default verbosity level is C<3> (C<critical>), so little
18	will be logged, ever, unless you set C<$Anyvent::VERBOSE> or	67	will be logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number
19	C<PERL_ANYEVENT_VERBOSE> to a higher number.	68	before starting your program, or change the logging level at runtime with
		69	something like:
20		70
21	Possible future extensions are to allow custom log targets (where the	71	use AnyEvent::Log;
22	level is an object), log filtering based on package, formatting, aliasing	72	$AnyEvent::Log::FILTER->level ("info");
23	or package groups.
24		73
		74	The design goal behind this module was to keep it simple (and small),
		75	but make it powerful enough to be potentially useful for any module, and
		76	extensive enough for the most common tasks, such as logging to multiple
		77	targets, or being able to log into a database.
		78
		79	The module is also usable before AnyEvent itself is initialised, in which
		80	case some of the functionality might be reduced.
		81
		82	The amount of documentation might indicate otherwise, but the runtime part
		83	of the module is still just below 300 lines of code.
		84
		85	=head1 LOGGING LEVELS
		86
		87	Logging levels in this module range from C<1> (highest priority) to C<9>
		88	(lowest priority). Note that the lowest numerical value is the highest
		89	priority, so when this document says "higher priority" it means "lower
		90	numerical value".
		91
		92	Instead of specifying levels by name you can also specify them by aliases:
		93
		94	LVL NAME SYSLOG PERL NOTE
		95	1 fatal emerg exit system unusable, aborts program!
		96	2 alert failure in primary system
		97	3 critical crit failure in backup system
		98	4 error err die non-urgent program errors, a bug
		99	5 warn warning possible problem, not necessarily error
		100	6 note notice unusual conditions
		101	7 info normal messages, no action required
		102	8 debug debugging messages for development
		103	9 trace copious tracing output
		104
		105	As you can see, some logging levels have multiple aliases - the first one
		106	is the "official" name, the second one the "syslog" name (if it differs)
		107	and the third one the "perl" name, suggesting (only!) that you log C<die>
		108	messages at C<error> priority. The NOTE column tries to provide some
		109	rationale on how to chose a logging level.
		110
		111	As a rough guideline, levels 1..3 are primarily meant for users of the
		112	program (admins, staff), and are the only ones logged to STDERR by
		113	default. Levels 4..6 are meant for users and developers alike, while
		114	levels 7..9 are usually meant for developers.
		115
		116	You can normally only log a message once at highest priority level (C<1>,
		117	C<fatal>), because logging a fatal message will also quit the program - so
		118	use it sparingly :)
		119
		120	Some methods also offer some extra levels, such as C<0>, C<off>, C<none>
		121	or C<all> - these are only valid for the methods that documented them.
		122
25	=head1 LOG FUNCTIONS	123	=head1 LOGGING FUNCTIONS
26		124
27	These functions allow you to log messages. They always use the caller's	125	The following functions allow you to log messages. They always use the
28	package as a "logging module/source". Also, The main logging function is	126	caller's package as a "logging context". Also, the main logging function,
29	easily available as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent>	127	C<log>, is aliased to C<AnyEvent::log> and C<AE::log> when the C<AnyEvent>
30	module is loaded.	128	module is loaded.
31		129
32	=over 4	130	=over 4
33		131
34	=cut	132	=cut
…		…
36	package AnyEvent::Log;	134	package AnyEvent::Log;
37		135
38	use Carp ();	136	use Carp ();
39	use POSIX ();	137	use POSIX ();
40		138
		139	# layout of a context
		140	# 0 1 2 3 4, 5
		141	# [$title, $level, %$slaves, &$logcb, &$fmtcb, $cap]
		142
41	use AnyEvent (); BEGIN { AnyEvent::common_sense }	143	use AnyEvent (); BEGIN { AnyEvent::common_sense }
		144	#use AnyEvent::Util (); need to load this in a delayed fashion, as it uses AE::log
		145
		146	our $VERSION = $AnyEvent::VERSION;
		147
		148	our ($COLLECT, $FILTER, $LOG);
42		149
43	our ($now_int, $now_str1, $now_str2);	150	our ($now_int, $now_str1, $now_str2);
44		151
45	# Format Time, not public - yet?	152	# Format Time, not public - yet?
46	sub ft($) {	153	sub ft($) {
…		…
51	if $now_int != $i;	158	if $now_int != $i;
52		159
53	"$now_str1$f$now_str2"	160	"$now_str1$f$now_str2"
54	}	161	}
55		162
		163	our %CTX; # all package contexts
		164
		165	# creates a default package context object for the given package
		166	sub _pkg_ctx($) {
		167	my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx";
		168
		169	# link "parent" package
		170	my $parent = $_[0] =~ /^(.+)::/
		171	? $CTX{$1} ||= &_pkg_ctx ("$1")
		172	: $COLLECT;
		173
		174	$ctx->[2]{$parent+0} = $parent;
		175
		176	$ctx
		177	}
		178
56	=item AnyEvent::Log::log $level, $msg[, @args]	179	=item AnyEvent::Log::log $level, $msg[, @args]
57		180
58	Requests logging of the given C<$msg> with the given log level (1..9).	181	Requests logging of the given C<$msg> with the given log level, and
59	You can also use the following strings as log level: C<fatal> (1),	182	returns true if the message was logged I<somewhere>.
60	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
61	C<info> (7), C<debug> (8), C<trace> (9).
62		183
63	For C<fatal> log levels, the program will abort.	184	For loglevel C<fatal>, the program will abort.
64		185
65	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	186	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the
66	C<$msg> is interpreted as an sprintf format string.	187	C<$msg> is interpreted as an sprintf format string.
67		188
68	The C<$msg> should not end with C<\n>, but may if that is convenient for	189	The C<$msg> should not end with C<\n>, but may if that is convenient for
69	you. Also, multiline messages are handled properly.	190	you. Also, multiline messages are handled properly.
70		191
71	In addition, for possible future expansion, C<$msg> must not start with an	192	Last not least, C<$msg> might be a code reference, in which case it is
72	angle bracket (C<< < >>).	193	supposed to return the message. It will be called only then the message
		194	actually gets logged, which is useful if it is costly to create the
		195	message in the first place.
		196
		197	This function takes care of saving and restoring C<$!> and C<$@>, so you
		198	don't have to.
73		199
74	Whether the given message will be logged depends on the maximum log level	200	Whether the given message will be logged depends on the maximum log level
75	and the caller's package.	201	and the caller's package. The return value can be used to ensure that
		202	messages or not "lost" - for example, when L<AnyEvent::Debug> detects a
		203	runtime error it tries to log it at C<die> level, but if that message is
		204	lost it simply uses warn.
76		205
77	Note that you can (and should) call this function as C<AnyEvent::log> or	206	Note that you can (and should) call this function as C<AnyEvent::log> or
78	C<AE::log>, without C<use>-ing this module if possible, as those functions	207	C<AE::log>, without C<use>-ing this module if possible (i.e. you don't
79	will laod the logging module on demand only.	208	need any additional functionality), as those functions will load the
		209	logging module on demand only. They are also much shorter to write.
		210
		211	Also, if you optionally generate a lot of debug messages (such as when
		212	tracing some code), you should look into using a logger callback and a
		213	boolean enabler (see C<logger>, below).
		214
		215	Example: log something at error level.
		216
		217	AE::log error => "something";
		218
		219	Example: use printf-formatting.
		220
		221	AE::log info => "%5d %-10.10s %s", $index, $category, $msg;
		222
		223	Example: only generate a costly dump when the message is actually being logged.
		224
		225	AE::log debug => sub { require Data::Dump; Data::Dump::dump \%cache };
80		226
81	=cut	227	=cut
82		228
83	# also allow syslog equivalent names	229	# also allow syslog equivalent names
84	our %STR2LEVEL = (	230	our %STR2LEVEL = (
85	fatal => 1, emerg => 1,	231	fatal => 1, emerg => 1, exit => 1,
86	alert => 2,	232	alert => 2,
87	critical => 3, crit => 3,	233	critical => 3, crit => 3,
88	error => 4, err => 4,	234	error => 4, err => 4, die => 4,
89	warn => 5, warning => 5,	235	warn => 5, warning => 5,
90	note => 6, notice => 6,	236	note => 6, notice => 6,
91	info => 7,	237	info => 7,
92	debug => 8,	238	debug => 8,
93	trace => 9,	239	trace => 9,
94	);	240	);
95		241
		242	our $TIME_EXACT;
		243
		244	sub exact_time($) {
		245	$TIME_EXACT = shift;
		246	*_ts = $AnyEvent::MODEL
		247	? $TIME_EXACT ? \&AE::now : \&AE::time
		248	: sub () { $TIME_EXACT ? do { require Time::HiRes; Time::HiRes::time () } : time };
		249	}
		250
		251	BEGIN {
		252	exact_time 0;
		253	}
		254
		255	AnyEvent::post_detect {
		256	exact_time $TIME_EXACT;
		257	};
		258
96	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	259	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
97		260
		261	# time, ctx, level, msg
		262	sub _format($$$$) {
		263	my $ts = ft $_[0];
		264	my $ct = " ";
		265
		266	my @res;
		267
		268	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		269	push @res, "$ts$ct$_\n";
		270	$ct = " + ";
		271	}
		272
		273	join "", @res
		274	}
		275
		276	sub fatal_exit() {
		277	exit 1;
		278	}
		279
		280	sub _log {
		281	my ($ctx, $level, $format, @args) = @_;
		282
		283	$level = $level > 0 && $level <= 9
		284	? $level+0
		285	: $STR2LEVEL{$level} || Carp::croak "$level: not a valid logging level, caught";
		286
		287	my $mask = 1 << $level;
		288
		289	my ($success, %seen, @ctx, $now, @fmt);
		290
		291	do
		292	{
		293	# if !ref, then it's a level number
		294	if (!ref $ctx) {
		295	$level = $ctx;
		296	} elsif ($ctx->[1] & $mask and !$seen{$ctx+0}++) {
		297	# logging/recursing into this context
		298
		299	# level cap
		300	if ($ctx->[5] > $level) {
		301	push @ctx, $level; # restore level when going up in tree
		302	$level = $ctx->[5];
		303	}
		304
		305	# log if log cb
		306	if ($ctx->[3]) {
		307	# logging target found
		308
		309	local ($!, $@);
		310
		311	# now get raw message, unless we have it already
		312	unless ($now) {
		313	$format = $format->() if ref $format;
		314	$format = sprintf $format, @args if @args;
		315	$format =~ s/\n$//;
		316	$now = _ts;
		317	};
		318
		319	# format msg
		320	my $str = $ctx->[4]
		321	? $ctx->[4]($now, $_[0], $level, $format)
		322	: ($fmt[$level] ||= _format $now, $_[0], $level, $format);
		323
		324	$success = 1;
		325
		326	$ctx->[3]($str)
		327	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
		328	} else {
		329	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		330	}
		331	}
		332	}
		333	while $ctx = pop @ctx;
		334
		335	fatal_exit if $level <= 1;
		336
		337	$success
		338	}
		339
98	sub log($$;@) {	340	sub log($$;@) {
99	my ($targ, $msg, @args) = @_;	341	_log
		342	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		343	@_;
		344	}
100		345
101	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	346	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
102	: $targ > 0 && $targ <= 9 ? $targ+0
103	: $STR2LEVEL{$targ} || Carp::croak "$targ: not a valid logging level, caught";
104		347
105	return if $level > $AnyEvent::VERBOSE;	348	Creates a code reference that, when called, acts as if the
		349	C<AnyEvent::Log::log> function was called at this point with the given
		350	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
		351	the C<AnyEvent::Log::log> function:
106		352
107	my $pkg = (caller)[0];	353	my $debug_log = AnyEvent::Log::logger "debug";
108		354
109	$msg = sprintf $msg, @args if @args;	355	$debug_log->("debug here");
110	$msg =~ s/\n$//;	356	$debug_log->("%06d emails processed", 12345);
		357	$debug_log->(sub { $obj->as_string });
111		358
112	# now we have a message, log it	359	The idea behind this function is to decide whether to log before actually
113	#TODO: could do LOTS of stuff here, and should, at least in some later version	360	logging - when the C<logger> function is called once, but the returned
		361	logger callback often, then this can be a tremendous speed win.
114		362
115	$msg = sprintf "%5s (%s) %s", $LEVEL2STR[$level], $pkg, $msg;	363	Despite this speed advantage, changes in logging configuration will
116	my $pfx = ft AE::now;	364	still be reflected by the logger callback, even if configuration changes
		365	I<after> it was created.
117		366
118	for (split /\n/, $msg) {	367	To further speed up logging, you can bind a scalar variable to the logger,
119	printf STDERR "$pfx $_\n";	368	which contains true if the logger should be called or not - if it is
120	$pfx = "\t";	369	false, calling the logger can be safely skipped. This variable will be
		370	updated as long as C<$logger> is alive.
		371
		372	Full example:
		373
		374	# near the init section
		375	use AnyEvent::Log;
		376
		377	my $debug_log = AnyEvent:Log::logger debug => \my $debug;
		378
		379	# and later in your program
		380	$debug_log->("yo, stuff here") if $debug;
		381
		382	$debug and $debug_log->("123");
		383
		384	=cut
		385
		386	our %LOGGER;
		387
		388	# re-assess logging status for all loggers
		389	sub _reassess {
		390	local $SIG{__DIE__};
		391	my $die = sub { die };
		392
		393	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
		394	my ($ctx, $level, $renabled) = @$_;
		395
		396	# to detect whether a message would be logged, we actually
		397	# try to log one and die. this isn't fast, but we can be
		398	# sure that the logging decision is correct :)
		399
		400	$$renabled = !eval {
		401	_log $ctx, $level, $die;
		402
		403	1
		404	};
121	}	405	}
122
123	exit 1 if $level <= 1;
124	}	406	}
125		407
126	*AnyEvent::log = *AE::log = \&log;	408	sub _logger {
		409	my ($ctx, $level, $renabled) = @_;
127		410
128	#TODO	411	$$renabled = 1;
		412
		413	my $logger = [$ctx, $level, $renabled];
		414
		415	$LOGGER{$logger+0} = $logger;
		416
		417	_reassess $logger+0;
		418
		419	require AnyEvent::Util unless $AnyEvent::Util::VERSION;
		420	my $guard = AnyEvent::Util::guard (sub {
		421	# "clean up"
		422	delete $LOGGER{$logger+0};
		423	});
		424
		425	sub {
		426	$guard if 0; # keep guard alive, but don't cause runtime overhead
		427
		428	_log $ctx, $level, @_
		429	if $$renabled;
		430	}
		431	}
		432
		433	sub logger($;$) {
		434	_logger
		435	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		436	@_
		437	}
		438
		439	=item AnyEvent::Log::exact_time $on
		440
		441	By default, C<AnyEvent::Log> will use C<AE::now>, i.e. the cached
		442	eventloop time, for the log timestamps. After calling this function with a
		443	true value it will instead resort to C<AE::time>, i.e. fetch the current
		444	time on each log message. This only makes a difference for event loops
		445	that actually cache the time (such as L<EV> or L<AnyEvent::Loop>).
		446
		447	This setting can be changed at any time by calling this function.
		448
		449	Since C<AnyEvent::Log> has to work even before the L<AnyEvent> has been
		450	initialised, this switch will also decide whether to use C<CORE::time> or
		451	C<Time::HiRes::time> when logging a message before L<AnyEvent> becomes
		452	available.
129		453
130	=back	454	=back
131		455
132	=head1 CONFIGURATION FUNCTIONALITY	456	=head1 LOGGING CONTEXTS
133		457
134	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	458	This module associates every log message with a so-called I<logging
		459	context>, based on the package of the caller. Every perl package has its
		460	own logging context.
		461
		462	A logging context has three major responsibilities: filtering, logging and
		463	propagating the message.
		464
		465	For the first purpose, filtering, each context has a set of logging
		466	levels, called the log level mask. Messages not in the set will be ignored
		467	by this context (masked).
		468
		469	For logging, the context stores a formatting callback (which takes the
		470	timestamp, context, level and string message and formats it in the way
		471	it should be logged) and a logging callback (which is responsible for
		472	actually logging the formatted message and telling C<AnyEvent::Log>
		473	whether it has consumed the message, or whether it should be propagated).
		474
		475	For propagation, a context can have any number of attached I<slave
		476	contexts>. Any message that is neither masked by the logging mask nor
		477	masked by the logging callback returning true will be passed to all slave
		478	contexts.
		479
		480	Each call to a logging function will log the message at most once per
		481	context, so it does not matter (much) if there are cycles or if the
		482	message can arrive at the same context via multiple paths.
		483
		484	=head2 DEFAULTS
		485
		486	By default, all logging contexts have an full set of log levels ("all"), a
		487	disabled logging callback and the default formatting callback.
		488
		489	Package contexts have the package name as logging title by default.
		490
		491	They have exactly one slave - the context of the "parent" package. The
		492	parent package is simply defined to be the package name without the last
		493	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		494	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		495	exception of the rule - just like the "parent" of any single-component
		496	package name in Perl is C<main>, the default slave of any top-level
		497	package context is C<$AnyEvent::Log::COLLECT>.
		498
		499	Since perl packages form only an approximate hierarchy, this slave
		500	context can of course be removed.
		501
		502	All other (anonymous) contexts have no slaves and an empty title by
		503	default.
		504
		505	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		506	context that simply logs everything via C<warn>, without propagating
		507	anything anywhere by default. The purpose of this context is to provide
		508	a convenient place to override the global logging target or to attach
		509	additional log targets. It's not meant for filtering.
		510
		511	It then creates the C<$AnyEvent::Log::FILTER> context whose
		512	purpose is to suppress all messages with priority higher
		513	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		514	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		515	is to simply provide filtering according to some global log level.
		516
		517	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		518	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		519	leaves it at default config. Its purpose is simply to collect all log
		520	messages system-wide.
		521
		522	The hierarchy is then:
		523
		524	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		525
		526	The effect of all this is that log messages, by default, wander up to the
		527	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		528	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		529	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		530	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		531
		532	This makes it easy to set a global logging level (by modifying $FILTER),
		533	but still allow other contexts to send, for example, their debug and trace
		534	messages to the $LOG target despite the global logging level, or to attach
		535	additional log targets that log messages, regardless of the global logging
		536	level.
		537
		538	It also makes it easy to modify the default warn-logger ($LOG) to
		539	something that logs to a file, or to attach additional logging targets
		540	(such as loggign to a file) by attaching it to $FILTER.
		541
		542	=head2 CREATING/FINDING/DESTROYING CONTEXTS
135		543
136	=over 4	544	=over 4
137		545
		546	=item $ctx = AnyEvent::Log::ctx [$pkg]
		547
		548	This function creates or returns a logging context (which is an object).
		549
		550	If a package name is given, then the context for that packlage is
		551	returned. If it is called without any arguments, then the context for the
		552	callers package is returned (i.e. the same context as a C<AE::log> call
		553	would use).
		554
		555	If C<undef> is given, then it creates a new anonymous context that is not
		556	tied to any package and is destroyed when no longer referenced.
		557
138	=cut	558	=cut
139		559
		560	sub ctx(;$) {
		561	my $pkg = @_ ? shift : (caller)[0];
		562
		563	ref $pkg
		564	? $pkg
		565	: defined $pkg
		566	? $CTX{$pkg} ||= AnyEvent::Log::_pkg_ctx $pkg
		567	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		568	}
		569
		570	=item AnyEvent::Log::reset
		571
		572	Resets all package contexts and recreates the default hierarchy if
		573	necessary, i.e. resets the logging subsystem to defaults, as much as
		574	possible. This process keeps references to contexts held by other parts of
		575	the program intact.
		576
		577	This can be used to implement config-file (re-)loading: before loading a
		578	configuration, reset all contexts.
		579
		580	=cut
		581
		582	our $ORIG_VERBOSE = $AnyEvent::VERBOSE;
		583	$AnyEvent::VERBOSE = 9;
		584
		585	sub reset {
		586	# hard to kill complex data structures
		587	# we "recreate" all package loggers and reset the hierarchy
		588	while (my ($k, $v) = each %CTX) {
		589	@$v = ($k, (1 << 10) - 1 - 1, { });
		590
		591	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
		592	}
		593
		594	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		595	for $LOG, $FILTER, $COLLECT;
		596
		597	#$LOG->slaves;
		598	$LOG->title ('$AnyEvent::Log::LOG');
		599	$LOG->log_to_warn;
		600
		601	$FILTER->slaves ($LOG);
		602	$FILTER->title ('$AnyEvent::Log::FILTER');
		603	$FILTER->level ($ORIG_VERBOSE);
		604
		605	$COLLECT->slaves ($FILTER);
		606	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		607
		608	_reassess;
		609	}
		610
		611	# override AE::log/logger
		612	*AnyEvent::log = *AE::log = \&log;
		613	*AnyEvent::logger = *AE::logger = \&logger;
		614
		615	# convert AnyEvent loggers to AnyEvent::Log loggers
		616	$_->[0] = ctx $_->[0] # convert "pkg" to "ctx"
		617	for values %LOGGER;
		618
		619	# create the default logger contexts
		620	$LOG = ctx undef;
		621	$FILTER = ctx undef;
		622	$COLLECT = ctx undef;
		623
		624	AnyEvent::Log::reset;
		625
		626	# hello, CPAN, please catch me
		627	package AnyEvent::Log::LOG;
		628	package AE::Log::LOG;
		629	package AnyEvent::Log::FILTER;
		630	package AE::Log::FILTER;
		631	package AnyEvent::Log::COLLECT;
		632	package AE::Log::COLLECT;
		633
		634	package AnyEvent::Log::Ctx;
		635
		636	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		637
		638	This is a convenience constructor that makes it simpler to construct
		639	anonymous logging contexts.
		640
		641	Each key-value pair results in an invocation of the method of the same
		642	name as the key with the value as parameter, unless the value is an
		643	arrayref, in which case it calls the method with the contents of the
		644	array. The methods are called in the same order as specified.
		645
		646	Example: create a new logging context and set both the default logging
		647	level, some slave contexts and a logging callback.
		648
		649	$ctx = new AnyEvent::Log::Ctx
		650	title => "dubious messages",
		651	level => "error",
		652	log_cb => sub { print STDOUT shift; 0 },
		653	slaves => [$ctx1, $ctx, $ctx2],
		654	;
		655
		656	=back
		657
		658	=cut
		659
		660	sub new {
		661	my $class = shift;
		662
		663	my $ctx = AnyEvent::Log::ctx undef;
		664
		665	while (@_) {
		666	my ($k, $v) = splice @_, 0, 2;
		667	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		668	}
		669
		670	bless $ctx, $class # do we really support subclassing, hmm?
		671	}
		672
		673
		674	=head2 CONFIGURING A LOG CONTEXT
		675
		676	The following methods can be used to configure the logging context.
		677
		678	=over 4
		679
		680	=item $ctx->title ([$new_title])
		681
		682	Returns the title of the logging context - this is the package name, for
		683	package contexts, and a user defined string for all others.
		684
		685	If C<$new_title> is given, then it replaces the package name or title.
		686
		687	=cut
		688
		689	sub title {
		690	$_[0][0] = $_[1] if @_ > 1;
		691	$_[0][0]
		692	}
		693
		694	=back
		695
		696	=head3 LOGGING LEVELS
		697
		698	The following methods deal with the logging level set associated with the
		699	log context.
		700
		701	The most common method to use is probably C<< $ctx->level ($level) >>,
		702	which configures the specified and any higher priority levels.
		703
		704	All functions which accept a list of levels also accept the special string
		705	C<all> which expands to all logging levels.
		706
		707	=over 4
		708
		709	=item $ctx->levels ($level[, $level...)
		710
		711	Enables logging for the given levels and disables it for all others.
		712
		713	=item $ctx->level ($level)
		714
		715	Enables logging for the given level and all lower level (higher priority)
		716	ones. In addition to normal logging levels, specifying a level of C<0> or
		717	C<off> disables all logging for this level.
		718
		719	Example: log warnings, errors and higher priority messages.
		720
		721	$ctx->level ("warn");
		722	$ctx->level (5); # same thing, just numeric
		723
		724	=item $ctx->enable ($level[, $level...])
		725
		726	Enables logging for the given levels, leaving all others unchanged.
		727
		728	=item $ctx->disable ($level[, $level...])
		729
		730	Disables logging for the given levels, leaving all others unchanged.
		731
		732	=item $ctx->cap ($level)
		733
		734	Caps the maximum priority to the given level, for all messages logged
		735	to, or passing through, this context. That is, while this doesn't affect
		736	whether a message is logged or passed on, the maximum priority of messages
		737	will be limited to the specified level - messages with a higher priority
		738	will be set to the specified priority.
		739
		740	Another way to view this is that C<< ->level >> filters out messages with
		741	a too low priority, while C<< ->cap >> modifies messages with a too high
		742	priority.
		743
		744	This is useful when different log targets have different interpretations
		745	of priority. For example, for a specific command line program, a wrong
		746	command line switch might well result in a C<fatal> log message, while the
		747	same message, logged to syslog, is likely I<not> fatal to the system or
		748	syslog facility as a whole, but more likely a mere C<error>.
		749
		750	This can be modeled by having a stderr logger that logs messages "as-is"
		751	and a syslog logger that logs messages with a level cap of, say, C<error>,
		752	or, for truly system-critical components, actually C<critical>.
		753
		754	=cut
		755
		756	sub _lvl_lst {
		757	map {
		758	$_ > 0 && $_ <= 9 ? $_+0
		759	: $_ eq "all" ? (1 .. 9)
		760	: $STR2LEVEL{$_} || Carp::croak "$_: not a valid logging level, caught"
		761	} @_
		762	}
		763
		764	sub _lvl {
		765	$_[0] =~ /^(?:0|off|none)$/ ? 0 : (_lvl_lst $_[0])[-1]
		766	}
		767
		768	our $NOP_CB = sub { 0 };
		769
		770	sub levels {
		771	my $ctx = shift;
		772	$ctx->[1] = 0;
		773	$ctx->[1] |= 1 << $_
		774	for &_lvl_lst;
		775	AnyEvent::Log::_reassess;
		776	}
		777
		778	sub level {
		779	my $ctx = shift;
		780	$ctx->[1] = ((1 << &_lvl) - 1) << 1;
		781	AnyEvent::Log::_reassess;
		782	}
		783
		784	sub enable {
		785	my $ctx = shift;
		786	$ctx->[1] |= 1 << $_
		787	for &_lvl_lst;
		788	AnyEvent::Log::_reassess;
		789	}
		790
		791	sub disable {
		792	my $ctx = shift;
		793	$ctx->[1] &= ~(1 << $_)
		794	for &_lvl_lst;
		795	AnyEvent::Log::_reassess;
		796	}
		797
		798	sub cap {
		799	my $ctx = shift;
		800	$ctx->[5] = &_lvl;
		801	}
		802
		803	=back
		804
		805	=head3 SLAVE CONTEXTS
		806
		807	The following methods attach and detach another logging context to a
		808	logging context.
		809
		810	Log messages are propagated to all slave contexts, unless the logging
		811	callback consumes the message.
		812
		813	=over 4
		814
		815	=item $ctx->attach ($ctx2[, $ctx3...])
		816
		817	Attaches the given contexts as slaves to this context. It is not an error
		818	to add a context twice (the second add will be ignored).
		819
		820	A context can be specified either as package name or as a context object.
		821
		822	=item $ctx->detach ($ctx2[, $ctx3...])
		823
		824	Removes the given slaves from this context - it's not an error to attempt
		825	to remove a context that hasn't been added.
		826
		827	A context can be specified either as package name or as a context object.
		828
		829	=item $ctx->slaves ($ctx2[, $ctx3...])
		830
		831	Replaces all slaves attached to this context by the ones given.
		832
		833	=cut
		834
		835	sub attach {
		836	my $ctx = shift;
		837
		838	$ctx->[2]{$_+0} = $_
		839	for map { AnyEvent::Log::ctx $_ } @_;
		840	}
		841
		842	sub detach {
		843	my $ctx = shift;
		844
		845	delete $ctx->[2]{$_+0}
		846	for map { AnyEvent::Log::ctx $_ } @_;
		847	}
		848
		849	sub slaves {
		850	undef $_[0][2];
		851	&attach;
		852	}
		853
		854	=back
		855
		856	=head3 LOG TARGETS
		857
		858	The following methods configure how the logging context actually does
		859	the logging (which consists of formatting the message and printing it or
		860	whatever it wants to do with it).
		861
		862	=over 4
		863
		864	=item $ctx->log_cb ($cb->($str)
		865
		866	Replaces the logging callback on the context (C<undef> disables the
		867	logging callback).
		868
		869	The logging callback is responsible for handling formatted log messages
		870	(see C<fmt_cb> below) - normally simple text strings that end with a
		871	newline (and are possibly multiline themselves).
		872
		873	It also has to return true iff it has consumed the log message, and false
		874	if it hasn't. Consuming a message means that it will not be sent to any
		875	slave context. When in doubt, return C<0> from your logging callback.
		876
		877	Example: a very simple logging callback, simply dump the message to STDOUT
		878	and do not consume it.
		879
		880	$ctx->log_cb (sub { print STDERR shift; 0 });
		881
		882	You can filter messages by having a log callback that simply returns C<1>
		883	and does not do anything with the message, but this counts as "message
		884	being logged" and might not be very efficient.
		885
		886	Example: propagate all messages except for log levels "debug" and
		887	"trace". The messages will still be generated, though, which can slow down
		888	your program.
		889
		890	$ctx->levels ("debug", "trace");
		891	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		892
		893	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		894
		895	Replaces the formatting callback on the context (C<undef> restores the
		896	default formatter).
		897
		898	The callback is passed the (possibly fractional) timestamp, the original
		899	logging context (object, not title), the (numeric) logging level and
		900	the raw message string and needs to return a formatted log message. In
		901	most cases this will be a string, but it could just as well be an array
		902	reference that just stores the values.
		903
		904	If, for some reason, you want to use C<caller> to find out more about the
		905	logger then you should walk up the call stack until you are no longer
		906	inside the C<AnyEvent::Log> package.
		907
		908	Example: format just the raw message, with numeric log level in angle
		909	brackets.
		910
		911	$ctx->fmt_cb (sub {
		912	my ($time, $ctx, $lvl, $msg) = @_;
		913
		914	"<$lvl>$msg\n"
		915	});
		916
		917	Example: return an array reference with just the log values, and use
		918	C<PApp::SQL::sql_exec> to store the message in a database.
		919
		920	$ctx->fmt_cb (sub { \@_ });
		921	$ctx->log_cb (sub {
		922	my ($msg) = @_;
		923
		924	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		925	$msg->[0] + 0,
		926	"$msg->[1]",
		927	$msg->[2] + 0,
		928	"$msg->[3]";
		929
		930	0
		931	});
		932
		933	=item $ctx->log_to_warn
		934
		935	Sets the C<log_cb> to simply use C<CORE::warn> to report any messages
		936	(usually this logs to STDERR).
		937
		938	=item $ctx->log_to_file ($path)
		939
		940	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		941
		942	=item $ctx->log_to_path ($path)
		943
		944	Same as C<< ->log_to_file >>, but opens the file for each message. This
		945	is much slower, but allows you to change/move/rename/delete the file at
		946	basically any time.
		947
		948	Needless(?) to say, if you do not want to be bitten by some evil person
		949	calling C<chdir>, the path should be absolute. Doesn't help with
		950	C<chroot>, but hey...
		951
		952	=item $ctx->log_to_syslog ([$facility])
		953
		954	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and
		955	all the others in the obvious way. If specified, then the C<$facility> is
		956	used as the facility (C<user>, C<auth>, C<local0> and so on). The default
		957	facility is C<user>.
		958
		959	Note that this function also sets a C<fmt_cb> - the logging part requires
		960	an array reference with [$level, $str] as input.
		961
		962	=cut
		963
		964	sub log_cb {
		965	my ($ctx, $cb) = @_;
		966
		967	$ctx->[3] = $cb;
		968	}
		969
		970	sub fmt_cb {
		971	my ($ctx, $cb) = @_;
		972
		973	$ctx->[4] = $cb;
		974	}
		975
		976	sub log_to_warn {
		977	my ($ctx, $path) = @_;
		978
		979	$ctx->log_cb (sub {
		980	warn shift;
		981	0
		982	});
		983	}
		984
		985	sub log_to_file {
		986	my ($ctx, $path) = @_;
		987
		988	open my $fh, ">>", $path
		989	or die "$path: $!";
		990
		991	$ctx->log_cb (sub {
		992	syswrite $fh, shift;
		993	0
		994	});
		995	}
		996
		997	sub log_to_path {
		998	my ($ctx, $path) = @_;
		999
		1000	$ctx->log_cb (sub {
		1001	open my $fh, ">>", $path
		1002	or die "$path: $!";
		1003
		1004	syswrite $fh, shift;
		1005	0
		1006	});
		1007	}
		1008
		1009	sub log_to_syslog {
		1010	my ($ctx, $facility) = @_;
		1011
		1012	require Sys::Syslog;
		1013
		1014	$ctx->fmt_cb (sub {
		1015	my $str = $_[3];
		1016	$str =~ s/\n(?=.)/\n+ /g;
		1017
		1018	[$_[2], "($_[1][0]) $str"]
		1019	});
		1020
		1021	$facility ||= "user";
		1022
		1023	$ctx->log_cb (sub {
		1024	my $lvl = $_[0][0] < 9 ? $_[0][0] : 8;
		1025
		1026	Sys::Syslog::syslog ("$facility|" . ($lvl - 1), $_)
		1027	for split /\n/, $_[0][1];
		1028
		1029	0
		1030	});
		1031	}
		1032
		1033	=back
		1034
		1035	=head3 MESSAGE LOGGING
		1036
		1037	These methods allow you to log messages directly to a context, without
		1038	going via your package context.
		1039
		1040	=over 4
		1041
		1042	=item $ctx->log ($level, $msg[, @params])
		1043
		1044	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		1045
		1046	=item $logger = $ctx->logger ($level[, \$enabled])
		1047
		1048	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		1049	context.
		1050
		1051	=cut
		1052
		1053	*log = \&AnyEvent::Log::_log;
		1054	*logger = \&AnyEvent::Log::_logger;
		1055
		1056	=back
		1057
		1058	=cut
		1059
		1060	package AnyEvent::Log;
		1061
		1062	=head1 CONFIGURATION VIA $ENV{PERL_ANYEVENT_LOG}
		1063
		1064	Logging can also be configured by setting the environment variable
		1065	C<PERL_ANYEVENT_LOG> (or C<AE_LOG>).
		1066
		1067	The value consists of one or more logging context specifications separated
		1068	by C<:> or whitespace. Each logging specification in turn starts with a
		1069	context name, followed by C<=>, followed by zero or more comma-separated
		1070	configuration directives, here are some examples:
		1071
		1072	# set default logging level
		1073	filter=warn
		1074
		1075	# log to file instead of to stderr
		1076	log=file=/tmp/mylog
		1077
		1078	# log to file in addition to stderr
		1079	log=+%file:%file=file=/tmp/mylog
		1080
		1081	# enable debug log messages, log warnings and above to syslog
		1082	filter=debug:log=+%warnings:%warnings=warn,syslog=LOG_LOCAL0
		1083
		1084	# log trace messages (only) from AnyEvent::Debug to file
		1085	AnyEvent::Debug=+%trace:%trace=only,trace,file=/tmp/tracelog
		1086
		1087	A context name in the log specification can be any of the following:
		1088
		1089	=over 4
		1090
		1091	=item C<collect>, C<filter>, C<log>
		1092
		1093	Correspond to the three predefined C<$AnyEvent::Log::COLLECT>,
		1094	C<AnyEvent::Log::FILTER> and C<$AnyEvent::Log::LOG> contexts.
		1095
		1096	=item C<%name>
		1097
		1098	Context names starting with a C<%> are anonymous contexts created when the
		1099	name is first mentioned. The difference to package contexts is that by
		1100	default they have no attached slaves.
		1101
		1102	=item a perl package name
		1103
		1104	Any other string references the logging context associated with the given
		1105	Perl C<package>. In the unlikely case where you want to specify a package
		1106	context that matches on of the other context name forms, you can add a
		1107	C<::> to the package name to force interpretation as a package.
		1108
		1109	=back
		1110
		1111	The configuration specifications can be any number of the following:
		1112
		1113	=over 4
		1114
		1115	=item C<stderr>
		1116
		1117	Configures the context to use Perl's C<warn> function (which typically
		1118	logs to C<STDERR>). Works like C<log_to_warn>.
		1119
		1120	=item C<file=>I<path>
		1121
		1122	Configures the context to log to a file with the given path. Works like
		1123	C<log_to_file>.
		1124
		1125	=item C<path=>I<path>
		1126
		1127	Configures the context to log to a file with the given path. Works like
		1128	C<log_to_path>.
		1129
		1130	=item C<syslog> or C<syslog=>I<expr>
		1131
		1132	Configures the context to log to syslog. If I<expr> is given, then it is
		1133	evaluated in the L<Sys::Syslog> package, so you could use:
		1134
		1135	log=syslog=LOG_LOCAL0
		1136
		1137	=item C<nolog>
		1138
		1139	Configures the context to not log anything by itself, which is the
		1140	default. Same as C<< $ctx->log_cb (undef) >>.
		1141
		1142	=item C<cap=>I<level>
		1143
		1144	Caps logging messages entering this context at the given level, i.e.
		1145	reduces the priority of messages with higher priority than this level. The
		1146	default is C<0> (or C<off>), meaning the priority will not be touched.
		1147
		1148	=item C<0> or C<off>
		1149
		1150	Sets the logging level of the context to C<0>, i.e. all messages will be
		1151	filtered out.
		1152
		1153	=item C<all>
		1154
		1155	Enables all logging levels, i.e. filtering will effectively be switched
		1156	off (the default).
		1157
		1158	=item C<only>
		1159
		1160	Disables all logging levels, and changes the interpretation of following
		1161	level specifications to enable the specified level only.
		1162
		1163	Example: only enable debug messages for a context.
		1164
		1165	context=only,debug
		1166
		1167	=item C<except>
		1168
		1169	Enables all logging levels, and changes the interpretation of following
		1170	level specifications to disable that level. Rarely used.
		1171
		1172	Example: enable all logging levels except fatal and trace (this is rather
		1173	nonsensical).
		1174
		1175	filter=exept,fatal,trace
		1176
		1177	=item C<level>
		1178
		1179	Enables all logging levels, and changes the interpretation of following
		1180	level specifications to be "that level or any higher priority
		1181	message". This is the default.
		1182
		1183	Example: log anything at or above warn level.
		1184
		1185	filter=warn
		1186
		1187	# or, more verbose
		1188	filter=only,level,warn
		1189
		1190	=item C<1>..C<9> or a logging level name (C<error>, C<debug> etc.)
		1191
		1192	A numeric loglevel or the name of a loglevel will be interpreted according
		1193	to the most recent C<only>, C<except> or C<level> directive. By default,
		1194	specifying a logging level enables that and any higher priority messages.
		1195
		1196	=item C<+>I<context>
		1197
		1198	Attaches the named context as slave to the context.
		1199
		1200	=item C<+>
		1201
		1202	A lone C<+> detaches all contexts, i.e. clears the slave list from the
		1203	context. Anonymous (C<%name>) contexts have no attached slaves by default,
		1204	but package contexts have the parent context as slave by default.
		1205
		1206	Example: log messages from My::Module to a file, do not send them to the
		1207	default log collector.
		1208
		1209	My::Module=+,file=/tmp/mymodulelog
		1210
		1211	=back
		1212
		1213	Any character can be escaped by prefixing it with a C<\> (backslash), as
		1214	usual, so to log to a file containing a comma, colon, backslash and some
		1215	spaces in the filename, you would do this:
		1216
		1217	PERL_ANYEVENT_LOG='log=file=/some\ \:file\ with\,\ \\-escapes'
		1218
		1219	Since whitespace (which includes newlines) is allowed, it is fine to
		1220	specify multiple lines in C<PERL_ANYEVENT_LOG>, e.g.:
		1221
		1222	PERL_ANYEVENT_LOG="
		1223	filter=warn
		1224	AnyEvent::Debug=+%trace
		1225	%trace=only,trace,+log
		1226	" myprog
		1227
		1228	Also, in the unlikely case when you want to concatenate specifications,
		1229	use whitespace as separator, as C<::> will be interpreted as part of a
		1230	module name, an empty spec with two separators:
		1231
		1232	PERL_ANYEVENT_LOG="$PERL_ANYEVENT_LOG MyMod=debug"
		1233
		1234	=cut
		1235
		1236	for (my $spec = $ENV{PERL_ANYEVENT_LOG}) {
		1237	my %anon;
		1238
		1239	my $pkg = sub {
		1240	$_[0] eq "log" ? $LOG
		1241	: $_[0] eq "filter" ? $FILTER
		1242	: $_[0] eq "collect" ? $COLLECT
		1243	: $_[0] =~ /^%(.+)$/ ? ($anon{$1} ||= do { my $ctx = ctx undef; $ctx->[0] = $_[0]; $ctx })
		1244	: $_[0] =~ /^(.*?)(?:::)?$/ ? ctx "$1" # egad :/
		1245	: die # never reached?
		1246	};
		1247
		1248	/\G[[:space:]]+/gc; # skip initial whitespace
		1249
		1250	while (/\G((?:[^:=[:space:]]+|::|\\.)+)=/gc) {
		1251	my $ctx = $pkg->($1);
		1252	my $level = "level";
		1253
		1254	while (/\G((?:[^,:[:space:]]+|::|\\.)+)/gc) {
		1255	for ("$1") {
		1256	if ($_ eq "stderr" ) { $ctx->log_to_warn;
		1257	} elsif (/^file=(.+)/ ) { $ctx->log_to_file ("$1");
		1258	} elsif (/^path=(.+)/ ) { $ctx->log_to_path ("$1");
		1259	} elsif (/^syslog(?:=(.*))?/ ) { require Sys::Syslog; $ctx->log_to_syslog ("$1");
		1260	} elsif ($_ eq "nolog" ) { $ctx->log_cb (undef);
		1261	} elsif (/^cap=(.+)/ ) { $ctx->cap ("$1");
		1262	} elsif (/^\+(.+)$/ ) { $ctx->attach ($pkg->("$1"));
		1263	} elsif ($_ eq "+" ) { $ctx->slaves;
		1264	} elsif ($_ eq "off" or $_ eq "0") { $ctx->level (0);
		1265	} elsif ($_ eq "all" ) { $ctx->level ("all");
		1266	} elsif ($_ eq "level" ) { $ctx->level ("all"); $level = "level";
		1267	} elsif ($_ eq "only" ) { $ctx->level ("off"); $level = "enable";
		1268	} elsif ($_ eq "except" ) { $ctx->level ("all"); $level = "disable";
		1269	} elsif (/^\d$/ ) { $ctx->$level ($_);
		1270	} elsif (exists $STR2LEVEL{$_} ) { $ctx->$level ($_);
		1271	} else { die "PERL_ANYEVENT_LOG ($spec): parse error at '$_'\n";
		1272	}
		1273	}
		1274
		1275	/\G,/gc or last;
		1276	}
		1277
		1278	/\G[:[:space:]]+/gc or last;
		1279	}
		1280
		1281	/\G[[:space:]]+/gc; # skip trailing whitespace
		1282
		1283	if (/\G(.+)/g) {
		1284	die "PERL_ANYEVENT_LOG ($spec): parse error at '$1'\n";
		1285	}
		1286	}
		1287
140	1;	1288	1;
		1289
		1290	=head1 EXAMPLES
		1291
		1292	This section shows some common configurations, both as code, and as
		1293	C<PERL_ANYEVENT_LOG> string.
		1294
		1295	=over 4
		1296
		1297	=item Setting the global logging level.
		1298
		1299	Either put C<PERL_ANYEVENT_VERBOSE=><number> into your environment before
		1300	running your program, use C<PERL_ANYEVENT_LOG> or modify the log level of
		1301	the root context at runtime:
		1302
		1303	PERL_ANYEVENT_VERBOSE=5 ./myprog
		1304
		1305	PERL_ANYEVENT_LOG=log=warn
		1306
		1307	$AnyEvent::Log::FILTER->level ("warn");
		1308
		1309	=item Append all messages to a file instead of sending them to STDERR.
		1310
		1311	This is affected by the global logging level.
		1312
		1313	$AnyEvent::Log::LOG->log_to_file ($path);
		1314
		1315	PERL_ANYEVENT_LOG=log=file=/some/path
		1316
		1317	=item Write all messages with priority C<error> and higher to a file.
		1318
		1319	This writes them only when the global logging level allows it, because
		1320	it is attached to the default context which is invoked I<after> global
		1321	filtering.
		1322
		1323	$AnyEvent::Log::FILTER->attach (
		1324	new AnyEvent::Log::Ctx log_to_file => $path);
		1325
		1326	PERL_ANYEVENT_LOG=filter=+%filelogger:%filelogger=file=/some/path
		1327
		1328	This writes them regardless of the global logging level, because it is
		1329	attached to the toplevel context, which receives all messages I<before>
		1330	the global filtering.
		1331
		1332	$AnyEvent::Log::COLLECT->attach (
		1333	new AnyEvent::Log::Ctx log_to_file => $path);
		1334
		1335	PERL_ANYEVENT_LOG=%filelogger=file=/some/path:collect=+%filelogger
		1336
		1337	In both cases, messages are still written to STDERR.
		1338
		1339	=item Additionally log all messages with C<warn> and higher priority to
		1340	C<syslog>, but cap at C<error>.
		1341
		1342	This logs all messages to the default log target, but also logs messages
		1343	with priority C<warn> or higher (and not filtered otherwise) to syslog
		1344	facility C<user>. Messages with priority higher than C<error> will be
		1345	logged with level C<error>.
		1346
		1347	$AnyEvent::Log::LOG->attach (
		1348	new AnyEvent::Log::Ctx
		1349	level => "warn",
		1350	cap => "error",
		1351	syslog => "user",
		1352	);
		1353
		1354	PERL_ANYEVENT_LOG=log=+%syslog:%syslog=warn,cap=error,syslog
		1355
		1356	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		1357
		1358	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		1359	context - this simply circumvents the global filtering for trace messages.
		1360
		1361	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		1362	$debug->attach ($AnyEvent::Log::LOG);
		1363
		1364	PERL_ANYEVENT_LOG=AnyEvent::Debug=+log
		1365
		1366	This of course works for any package, not just L<AnyEvent::Debug>, but
		1367	assumes the log level for AnyEvent::Debug hasn't been changed from the
		1368	default.
141		1369
142	=back	1370	=back
143		1371
144	=head1 AUTHOR	1372	=head1 AUTHOR
145		1373
146	Marc Lehmann <schmorp@schmorp.de>	1374	Marc Lehmann <schmorp@schmorp.de>
147	http://home.schmorp.de/	1375	http://home.schmorp.de/
148		1376
149	=cut	1377	=cut
		1378

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