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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.6 by root, Wed Aug 17 22:34:11 2011 UTC vs.
Revision 1.45 by root, Sun Oct 2 00:42:04 2011 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 alraedy 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 will be	66	Remember that the default verbosity level is C<0> (C<off>), so nothing
18	logged, ever, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number	67	will be logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number
19	before starting your program.#TODO	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
		112	the program (admins, staff), and are the only 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 single message at highest priority level
		117	(C<1>, C<fatal>), because logging a fatal message will also quit the
		118	program - so 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 in the methods they are documented for.
		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	These functions allow you to log messages. They always use the caller's
28	package as a "logging module/source". Also, The main logging function is	126	package as a "logging context". Also, the main logging function C<log> is
29	easily available as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent>	127	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is
30	module is loaded.	128	loaded.
31		129
32	=over 4	130	=over 4
33		131
34	=cut	132	=cut
35		133
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 }
42	use AnyEvent::Util ();	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, $LOG);
43		149
44	our ($now_int, $now_str1, $now_str2);	150	our ($now_int, $now_str1, $now_str2);
45		151
46	# Format Time, not public - yet?	152	# Format Time, not public - yet?
47	sub ft($) {	153	sub ft($) {
…		…
52	if $now_int != $i;	158	if $now_int != $i;
53		159
54	"$now_str1$f$now_str2"	160	"$now_str1$f$now_str2"
55	}	161	}
56		162
57	our %CTX; # all logging contexts	163	our %CTX; # all package contexts
		164
		165	# creates a default package context object for the given package
		166	sub _pkg_ctx($) {
		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	}
58		178
59	=item AnyEvent::Log::log $level, $msg[, @args]	179	=item AnyEvent::Log::log $level, $msg[, @args]
60		180
61	Requests logging of the given C<$msg> with the given log level (1..9).	181	Requests logging of the given C<$msg> with the given log level, and
62	You can also use the following strings as log level: C<fatal> (1),	182	returns true if the message was logged I<somewhere>.
63	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
64	C<info> (7), C<debug> (8), C<trace> (9).
65		183
66	For C<fatal> log levels, the program will abort.	184	For loglevel C<fatal>, the program will abort.
67		185
68	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	186	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the
69	C<$msg> is interpreted as an sprintf format string.	187	C<$msg> is interpreted as an sprintf format string.
70		188
71	The C<$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
…		…
75	supposed to return the message. It will be called only then the message	193	supposed to return the message. It will be called only then the message
76	actually gets logged, which is useful if it is costly to create the	194	actually gets logged, which is useful if it is costly to create the
77	message in the first place.	195	message in the first place.
78		196
79	Whether the given message will be logged depends on the maximum log level	197	Whether the given message will be logged depends on the maximum log level
80	and the caller's package.	198	and the caller's package. The return value can be used to ensure that
		199	messages or not "lost" - for example, when L<AnyEvent::Debug> detects a
		200	runtime error it tries to log it at C<die> level, but if that message is
		201	lost it simply uses warn.
81		202
82	Note that you can (and should) call this function as C<AnyEvent::log> or	203	Note that you can (and should) call this function as C<AnyEvent::log> or
83	C<AE::log>, without C<use>-ing this module if possible, as those functions	204	C<AE::log>, without C<use>-ing this module if possible (i.e. you don't
84	will laod the logging module on demand only.	205	need any additional functionality), as those functions will load the
		206	logging module on demand only. They are also much shorter to write.
		207
		208	Also, if you optionally generate a lot of debug messages (such as when
		209	tracing some code), you should look into using a logger callback and a
		210	boolean enabler (see C<logger>, below).
85		211
86	Example: log something at error level.	212	Example: log something at error level.
87		213
88	AE::log error => "something";	214	AE::log error => "something";
89		215
…		…
97		223
98	=cut	224	=cut
99		225
100	# also allow syslog equivalent names	226	# also allow syslog equivalent names
101	our %STR2LEVEL = (	227	our %STR2LEVEL = (
102	fatal => 1, emerg => 1,	228	fatal => 1, emerg => 1, exit => 1,
103	alert => 2,	229	alert => 2,
104	critical => 3, crit => 3,	230	critical => 3, crit => 3,
105	error => 4, err => 4,	231	error => 4, err => 4, die => 4,
106	warn => 5, warning => 5,	232	warn => 5, warning => 5,
107	note => 6, notice => 6,	233	note => 6, notice => 6,
108	info => 7,	234	info => 7,
109	debug => 8,	235	debug => 8,
110	trace => 9,	236	trace => 9,
111	);	237	);
112		238
113	sub now () { time }	239	our $TIME_EXACT;
		240
		241	sub exact_time($) {
		242	$TIME_EXACT = shift;
		243	*_ts = $AnyEvent::MODEL
		244	? $TIME_EXACT ? \&AE::now : \&AE::time
		245	: sub () { $TIME_EXACT ? do { require Time::HiRes; Time::HiRes::time () } : time };
		246	}
		247
		248	BEGIN {
		249	exact_time 0;
		250	}
		251
114	AnyEvent::post_detect {	252	AnyEvent::post_detect {
115	*now = \&AE::now;	253	exact_time $TIME_EXACT;
116	};	254	};
117		255
118	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	256	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
119		257
		258	# time, ctx, level, msg
		259	sub _format($$$$) {
		260	my $ts = ft $_[0];
		261	my $ct = " ";
		262
		263	my @res;
		264
		265	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		266	push @res, "$ts$ct$_\n";
		267	$ct = " + ";
		268	}
		269
		270	join "", @res
		271	}
		272
		273	sub fatal_exit() {
		274	exit 1;
		275	}
		276
120	sub _log {	277	sub _log {
121	my ($pkg, $targ, $msg, @args) = @_;	278	my ($ctx, $level, $format, @args) = @_;
122		279
123	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	280	$level = $level > 0 && $level <= 9
124	: $targ > 0 && $targ <= 9 ? $targ+0	281	? $level+0
125	: $STR2LEVEL{$targ} || Carp::croak "$targ: not a valid logging level, caught";	282	: $STR2LEVEL{$level} || Carp::croak "$level: not a valid logging level, caught";
126		283
127	#TODO: find actual targets, see if we even have to log	284	my $mask = 1 << $level;
128		285
129	return unless $level <= $AnyEvent::VERBOSE;	286	my ($success, %seen, @ctx, $now, @fmt);
130		287
131	$msg = $msg->() if ref $msg;	288	do
132	$msg = sprintf $msg, @args if @args;	289	{
133	$msg =~ s/\n$//;	290	# if !ref, then it's a level number
		291	if (!ref $ctx) {
		292	$level = $ctx;
		293	} elsif ($ctx->[1] & $mask and !$seen{$ctx+0}++) {
		294	# logging/recursing into this context
134		295
135	# now we have a message, log it	296	# level cap
		297	if ($ctx->[5] > $level) {
		298	push @ctx, $level; # restore level when going up in tree
		299	$level = $ctx->[5];
		300	}
136		301
137	# TODO: writers/processors/filters/formatters?	302	# log if log cb
		303	if ($ctx->[3]) {
		304	# logging target found
138		305
139	$msg = sprintf "%-5s %s: %s", $LEVEL2STR[$level], $pkg, $msg;	306	# now get raw message, unless we have it already
140	my $pfx = ft now;	307	unless ($now) {
		308	$format = $format->() if ref $format;
		309	$format = sprintf $format, @args if @args;
		310	$format =~ s/\n$//;
		311	$now = _ts;
		312	};
141		313
142	for (split /\n/, $msg) {	314	# format msg
143	printf STDERR "$pfx $_\n";	315	my $str = $ctx->[4]
144	$pfx = "\t";	316	? $ctx->[4]($now, $_[0], $level, $format)
145	}	317	: ($fmt[$level] ||= _format $now, $_[0], $level, $format);
146		318
		319	$success = 1;
		320
		321	$ctx->[3]($str)
		322	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
		323	} else {
		324	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		325	}
		326	}
		327	}
		328	while $ctx = pop @ctx;
		329
147	exit 1 if $level <= 1;	330	fatal_exit if $level <= 1;
		331
		332	$success
148	}	333	}
149		334
150	sub log($$;@) {	335	sub log($$;@) {
151	_log +(caller)[0], @_;	336	_log
		337	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		338	@_;
152	}	339	}
153
154	*AnyEvent::log = *AE::log = \&log;
155		340
156	=item $logger = AnyEvent::Log::logger $level[, \$enabled]	341	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
157		342
158	Creates a code reference that, when called, acts as if the	343	Creates a code reference that, when called, acts as if the
159	C<AnyEvent::Log::log> function was called at this point with the givne	344	C<AnyEvent::Log::log> function was called at this point with the given
160	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with	345	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
161	the C<AnyEvent::Log::log> function:	346	the C<AnyEvent::Log::log> function:
162		347
163	my $debug_log = AnyEvent::Log::logger "debug";	348	my $debug_log = AnyEvent::Log::logger "debug";
164		349
…		…
189	# and later in your program	374	# and later in your program
190	$debug_log->("yo, stuff here") if $debug;	375	$debug_log->("yo, stuff here") if $debug;
191		376
192	$debug and $debug_log->("123");	377	$debug and $debug_log->("123");
193		378
194	Note: currently the enabled var is always true - that will be fixed in a
195	future version :)
196
197	=cut	379	=cut
198		380
199	our %LOGGER;	381	our %LOGGER;
200		382
201	# re-assess logging status for all loggers	383	# re-assess logging status for all loggers
202	sub _reassess {	384	sub _reassess {
		385	local $SIG{__DIE__};
		386	my $die = sub { die };
		387
203	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {	388	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
204	my ($pkg, $level, $renabled) = @$_;	389	my ($ctx, $level, $renabled) = @$_;
205		390
206	# to detetc whether a message would be logged, we # actually	391	# to detect whether a message would be logged, we actually
207	# try to log one and die. this isn't # fast, but we can be	392	# try to log one and die. this isn't fast, but we can be
208	# sure that the logging decision is correct :)	393	# sure that the logging decision is correct :)
209		394
210	$$renabled = !eval {	395	$$renabled = !eval {
211	local $SIG{__DIE__};
212
213	_log $pkg, $level, sub { die };	396	_log $ctx, $level, $die;
214		397
215	1	398	1
216	};	399	};
217
218	$$renabled = 1; # TODO
219	}	400	}
220	}	401	}
221		402
222	sub logger($;$) {	403	sub _logger {
223	my ($level, $renabled) = @_;	404	my ($ctx, $level, $renabled) = @_;
224
225	$renabled ||= \my $enabled;
226	my $pkg = (caller)[0];
227		405
228	$$renabled = 1;	406	$$renabled = 1;
229		407
230	my $logger = [$pkg, $level, $renabled];	408	my $logger = [$ctx, $level, $renabled];
231		409
232	$LOGGER{$logger+0} = $logger;	410	$LOGGER{$logger+0} = $logger;
233		411
234	_reassess $logger+0;	412	_reassess $logger+0;
235		413
		414	require AnyEvent::Util unless $AnyEvent::Util::VERSION;
236	my $guard = AnyEvent::Util::guard {	415	my $guard = AnyEvent::Util::guard (sub {
237	# "clean up"	416	# "clean up"
238	delete $LOGGER{$logger+0};	417	delete $LOGGER{$logger+0};
239	};	418	});
240		419
241	sub {	420	sub {
242	$guard if 0; # keep guard alive, but don't cause runtime overhead	421	$guard if 0; # keep guard alive, but don't cause runtime overhead
243		422
244	_log $pkg, $level, @_	423	_log $ctx, $level, @_
245	if $$renabled;	424	if $$renabled;
246	}	425	}
247	}	426	}
248		427
249	#TODO	428	sub logger($;$) {
		429	_logger
		430	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		431	@_
		432	}
		433
		434	=item AnyEvent::Log::exact_time $on
		435
		436	By default, C<AnyEvent::Log> will use C<AE::now>, i.e. the cached
		437	eventloop time, for the log timestamps. After calling this function with a
		438	true value it will instead resort to C<AE::time>, i.e. fetch the current
		439	time on each log message. This only makes a difference for event loops
		440	that actually cache the time (such as L<EV> or L<AnyEvent::Loop>).
		441
		442	This setting can be changed at any time by calling this function.
		443
		444	Since C<AnyEvent::Log> has to work even before the L<AnyEvent> has been
		445	initialised, this switch will also decide whether to use C<CORE::time> or
		446	C<Time::HiRes::time> when logging a message before L<AnyEvent> becomes
		447	available.
250		448
251	=back	449	=back
252		450
253	=head1 CONFIGURATION FUNCTIONALITY	451	=head1 LOGGING CONTEXTS
254		452
255	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	453	This module associates every log message with a so-called I<logging
256	#TODO	454	context>, based on the package of the caller. Every perl package has its
		455	own logging context.
		456
		457	A logging context has three major responsibilities: filtering, logging and
		458	propagating the message.
		459
		460	For the first purpose, filtering, each context has a set of logging
		461	levels, called the log level mask. Messages not in the set will be ignored
		462	by this context (masked).
		463
		464	For logging, the context stores a formatting callback (which takes the
		465	timestamp, context, level and string message and formats it in the way
		466	it should be logged) and a logging callback (which is responsible for
		467	actually logging the formatted message and telling C<AnyEvent::Log>
		468	whether it has consumed the message, or whether it should be propagated).
		469
		470	For propagation, a context can have any number of attached I<slave
		471	contexts>. Any message that is neither masked by the logging mask nor
		472	masked by the logging callback returning true will be passed to all slave
		473	contexts.
		474
		475	Each call to a logging function will log the message at most once per
		476	context, so it does not matter (much) if there are cycles or if the
		477	message can arrive at the same context via multiple paths.
		478
		479	=head2 DEFAULTS
		480
		481	By default, all logging contexts have an full set of log levels ("all"), a
		482	disabled logging callback and the default formatting callback.
		483
		484	Package contexts have the package name as logging title by default.
		485
		486	They have exactly one slave - the context of the "parent" package. The
		487	parent package is simply defined to be the package name without the last
		488	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		489	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		490	exception of the rule - just like the "parent" of any single-component
		491	package name in Perl is C<main>, the default slave of any top-level
		492	package context is C<$AnyEvent::Log::COLLECT>.
		493
		494	Since perl packages form only an approximate hierarchy, this slave
		495	context can of course be removed.
		496
		497	All other (anonymous) contexts have no slaves and an empty title by
		498	default.
		499
		500	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		501	context that simply logs everything via C<warn>, without propagating
		502	anything anywhere by default. The purpose of this context is to provide
		503	a convenient place to override the global logging target or to attach
		504	additional log targets. It's not meant for filtering.
		505
		506	It then creates the C<$AnyEvent::Log::FILTER> context whose
		507	purpose is to suppress all messages with priority higher
		508	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		509	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		510	is to simply provide filtering according to some global log level.
		511
		512	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		513	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		514	leaves it at default config. Its purpose is simply to collect all log
		515	messages system-wide.
		516
		517	The hierarchy is then:
		518
		519	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		520
		521	The effect of all this is that log messages, by default, wander up to the
		522	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		523	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		524	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		525	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		526
		527	This makes it easy to set a global logging level (by modifying $FILTER),
		528	but still allow other contexts to send, for example, their debug and trace
		529	messages to the $LOG target despite the global logging level, or to attach
		530	additional log targets that log messages, regardless of the global logging
		531	level.
		532
		533	It also makes it easy to modify the default warn-logger ($LOG) to
		534	something that logs to a file, or to attach additional logging targets
		535	(such as loggign to a file) by attaching it to $FILTER.
		536
		537	=head2 CREATING/FINDING/DESTROYING CONTEXTS
257		538
258	=over 4	539	=over 4
259		540
260	=item $ctx = AnyEvent::Log::cfg [$pkg]	541	=item $ctx = AnyEvent::Log::ctx [$pkg]
261		542
262	Returns a I<config> object for the given package name (or previously	543	This function creates or returns a logging context (which is an object).
263	created package-less configuration). If no package name, or C<undef>, is	544
		545	If a package name is given, then the context for that packlage is
		546	returned. If it is called without any arguments, then the context for the
		547	callers package is returned (i.e. the same context as a C<AE::log> call
		548	would use).
		549
264	given, then it creates a new anonymous context that is not tied to any	550	If C<undef> is given, then it creates a new anonymous context that is not
265	package.	551	tied to any package and is destroyed when no longer referenced.
266		552
267	=cut	553	=cut
268		554
269	sub cfg(;$) {	555	sub ctx(;$) {
270	my $name = shift;	556	my $pkg = @_ ? shift : (caller)[0];
271		557
272	my $ctx = defined $name ? $CTX{$name} : undef;	558	ref $pkg
		559	? $pkg
		560	: defined $pkg
		561	? $CTX{$pkg} ||= AnyEvent::Log::_pkg_ctx $pkg
		562	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		563	}
273		564
274	unless ($ctx) {	565	=item AnyEvent::Log::reset
275	$ctx = bless {}, "AnyEvent::Log::Ctx";	566
276	$name = -$ctx unless defined $name;	567	Resets all package contexts and recreates the default hierarchy if
277	$ctx->{name} = $name;	568	necessary, i.e. resets the logging subsystem to defaults, as much as
278	$CTX{$name} = $ctx;	569	possible. This process keeps references to contexts held by other parts of
		570	the program intact.
		571
		572	This can be used to implement config-file (re-)loading: before loading a
		573	configuration, reset all contexts.
		574
		575	=cut
		576
		577	our $ORIG_VERBOSE = $AnyEvent::VERBOSE;
		578	$AnyEvent::VERBOSE = 9;
		579
		580	sub reset {
		581	# hard to kill complex data structures
		582	# we "recreate" all package loggers and reset the hierarchy
		583	while (my ($k, $v) = each %CTX) {
		584	@$v = ($k, (1 << 10) - 1 - 1, { });
		585
		586	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
279	}	587	}
280		588
281	$ctx	589	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		590	for $LOG, $FILTER, $COLLECT;
		591
		592	#$LOG->slaves;
		593	$LOG->title ('$AnyEvent::Log::LOG');
		594	$LOG->log_to_warn;
		595
		596	$FILTER->slaves ($LOG);
		597	$FILTER->title ('$AnyEvent::Log::FILTER');
		598	$FILTER->level ($ORIG_VERBOSE);
		599
		600	$COLLECT->slaves ($FILTER);
		601	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		602
		603	_reassess;
282	}	604	}
		605
		606	# override AE::log/logger
		607	*AnyEvent::log = *AE::log = \&log;
		608	*AnyEvent::logger = *AE::logger = \&logger;
		609
		610	# convert AnyEvent loggers to AnyEvent::Log loggers
		611	$_->[0] = ctx $_->[0] # convert "pkg" to "ctx"
		612	for values %LOGGER;
		613
		614	# create the default logger contexts
		615	$LOG = ctx undef;
		616	$FILTER = ctx undef;
		617	$COLLECT = ctx undef;
		618
		619	AnyEvent::Log::reset;
		620
		621	# hello, CPAN, please catch me
		622	package AnyEvent::Log::LOG;
		623	package AE::Log::LOG;
		624	package AnyEvent::Log::FILTER;
		625	package AE::Log::FILTER;
		626	package AnyEvent::Log::COLLECT;
		627	package AE::Log::COLLECT;
283		628
284	package AnyEvent::Log::Ctx;	629	package AnyEvent::Log::Ctx;
285		630
286	sub DESTROY {	631	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
287	# if only one member is remaining (name!) then delete this context	632
288	delete $CTX{$_[0]{name}}	633	This is a convenience constructor that makes it simpler to construct
289	if 1 == scalar keys %{ $_[0] };	634	anonymous logging contexts.
		635
		636	Each key-value pair results in an invocation of the method of the same
		637	name as the key with the value as parameter, unless the value is an
		638	arrayref, in which case it calls the method with the contents of the
		639	array. The methods are called in the same order as specified.
		640
		641	Example: create a new logging context and set both the default logging
		642	level, some slave contexts and a logging callback.
		643
		644	$ctx = new AnyEvent::Log::Ctx
		645	title => "dubious messages",
		646	level => "error",
		647	log_cb => sub { print STDOUT shift; 0 },
		648	slaves => [$ctx1, $ctx, $ctx2],
		649	;
		650
		651	=back
		652
		653	=cut
		654
		655	sub new {
		656	my $class = shift;
		657
		658	my $ctx = AnyEvent::Log::ctx undef;
		659
		660	while (@_) {
		661	my ($k, $v) = splice @_, 0, 2;
		662	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		663	}
		664
		665	bless $ctx, $class # do we really support subclassing, hmm?
		666	}
		667
		668
		669	=head2 CONFIGURING A LOG CONTEXT
		670
		671	The following methods can be used to configure the logging context.
		672
		673	=over 4
		674
		675	=item $ctx->title ([$new_title])
		676
		677	Returns the title of the logging context - this is the package name, for
		678	package contexts, and a user defined string for all others.
		679
		680	If C<$new_title> is given, then it replaces the package name or title.
		681
		682	=cut
		683
		684	sub title {
		685	$_[0][0] = $_[1] if @_ > 1;
		686	$_[0][0]
		687	}
		688
		689	=back
		690
		691	=head3 LOGGING LEVELS
		692
		693	The following methods deal with the logging level set associated with the
		694	log context.
		695
		696	The most common method to use is probably C<< $ctx->level ($level) >>,
		697	which configures the specified and any higher priority levels.
		698
		699	All functions which accept a list of levels also accept the special string
		700	C<all> which expands to all logging levels.
		701
		702	=over 4
		703
		704	=item $ctx->levels ($level[, $level...)
		705
		706	Enables logging for the given levels and disables it for all others.
		707
		708	=item $ctx->level ($level)
		709
		710	Enables logging for the given level and all lower level (higher priority)
		711	ones. In addition to normal logging levels, specifying a level of C<0> or
		712	C<off> disables all logging for this level.
		713
		714	Example: log warnings, errors and higher priority messages.
		715
		716	$ctx->level ("warn");
		717	$ctx->level (5); # same thing, just numeric
		718
		719	=item $ctx->enable ($level[, $level...])
		720
		721	Enables logging for the given levels, leaving all others unchanged.
		722
		723	=item $ctx->disable ($level[, $level...])
		724
		725	Disables logging for the given levels, leaving all others unchanged.
		726
		727	=item $ctx->cap ($level)
		728
		729	Caps the maximum priority to the given level, for all messages logged
		730	to, or passing through, this context. That is, while this doesn't affect
		731	whether a message is logged or passed on, the maximum priority of messages
		732	will be limited to the specified level - messages with a higher priority
		733	will be set to the specified priority.
		734
		735	Another way to view this is that C<< ->level >> filters out messages with
		736	a too low priority, while C<< ->cap >> modifies messages with a too high
		737	priority.
		738
		739	This is useful when different log targets have different interpretations
		740	of priority. For example, for a specific command line program, a wrong
		741	command line switch might well result in a C<fatal> log message, while the
		742	same message, logged to syslog, is likely I<not> fatal to the system or
		743	syslog facility as a whole, but more likely a mere C<error>.
		744
		745	This can be modeled by having a stderr logger that logs messages "as-is"
		746	and a syslog logger that logs messages with a level cap of, say, C<error>,
		747	or, for truly system-critical components, actually C<critical>.
		748
		749	=cut
		750
		751	sub _lvl_lst {
		752	map {
		753	$_ > 0 && $_ <= 9 ? $_+0
		754	: $_ eq "all" ? (1 .. 9)
		755	: $STR2LEVEL{$_} || Carp::croak "$_: not a valid logging level, caught"
		756	} @_
		757	}
		758
		759	sub _lvl {
		760	$_[0] =~ /^(?:0|off|none)$/ ? 0 : (_lvl_lst $_[0])[-1]
		761	}
		762
		763	our $NOP_CB = sub { 0 };
		764
		765	sub levels {
		766	my $ctx = shift;
		767	$ctx->[1] = 0;
		768	$ctx->[1] |= 1 << $_
		769	for &_lvl_lst;
		770	AnyEvent::Log::_reassess;
		771	}
		772
		773	sub level {
		774	my $ctx = shift;
		775	$ctx->[1] = ((1 << &_lvl) - 1) << 1;
		776	AnyEvent::Log::_reassess;
		777	}
		778
		779	sub enable {
		780	my $ctx = shift;
		781	$ctx->[1] |= 1 << $_
		782	for &_lvl_lst;
		783	AnyEvent::Log::_reassess;
		784	}
		785
		786	sub disable {
		787	my $ctx = shift;
		788	$ctx->[1] &= ~(1 << $_)
		789	for &_lvl_lst;
		790	AnyEvent::Log::_reassess;
		791	}
		792
		793	sub cap {
		794	my $ctx = shift;
		795	$ctx->[5] = &_lvl;
		796	}
		797
		798	=back
		799
		800	=head3 SLAVE CONTEXTS
		801
		802	The following methods attach and detach another logging context to a
		803	logging context.
		804
		805	Log messages are propagated to all slave contexts, unless the logging
		806	callback consumes the message.
		807
		808	=over 4
		809
		810	=item $ctx->attach ($ctx2[, $ctx3...])
		811
		812	Attaches the given contexts as slaves to this context. It is not an error
		813	to add a context twice (the second add will be ignored).
		814
		815	A context can be specified either as package name or as a context object.
		816
		817	=item $ctx->detach ($ctx2[, $ctx3...])
		818
		819	Removes the given slaves from this context - it's not an error to attempt
		820	to remove a context that hasn't been added.
		821
		822	A context can be specified either as package name or as a context object.
		823
		824	=item $ctx->slaves ($ctx2[, $ctx3...])
		825
		826	Replaces all slaves attached to this context by the ones given.
		827
		828	=cut
		829
		830	sub attach {
		831	my $ctx = shift;
		832
		833	$ctx->[2]{$_+0} = $_
		834	for map { AnyEvent::Log::ctx $_ } @_;
		835	}
		836
		837	sub detach {
		838	my $ctx = shift;
		839
		840	delete $ctx->[2]{$_+0}
		841	for map { AnyEvent::Log::ctx $_ } @_;
		842	}
		843
		844	sub slaves {
		845	undef $_[0][2];
		846	&attach;
		847	}
		848
		849	=back
		850
		851	=head3 LOG TARGETS
		852
		853	The following methods configure how the logging context actually does
		854	the logging (which consists of formatting the message and printing it or
		855	whatever it wants to do with it).
		856
		857	=over 4
		858
		859	=item $ctx->log_cb ($cb->($str)
		860
		861	Replaces the logging callback on the context (C<undef> disables the
		862	logging callback).
		863
		864	The logging callback is responsible for handling formatted log messages
		865	(see C<fmt_cb> below) - normally simple text strings that end with a
		866	newline (and are possibly multiline themselves).
		867
		868	It also has to return true iff it has consumed the log message, and false
		869	if it hasn't. Consuming a message means that it will not be sent to any
		870	slave context. When in doubt, return C<0> from your logging callback.
		871
		872	Example: a very simple logging callback, simply dump the message to STDOUT
		873	and do not consume it.
		874
		875	$ctx->log_cb (sub { print STDERR shift; 0 });
		876
		877	You can filter messages by having a log callback that simply returns C<1>
		878	and does not do anything with the message, but this counts as "message
		879	being logged" and might not be very efficient.
		880
		881	Example: propagate all messages except for log levels "debug" and
		882	"trace". The messages will still be generated, though, which can slow down
		883	your program.
		884
		885	$ctx->levels ("debug", "trace");
		886	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		887
		888	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		889
		890	Replaces the formatting callback on the context (C<undef> restores the
		891	default formatter).
		892
		893	The callback is passed the (possibly fractional) timestamp, the original
		894	logging context, the (numeric) logging level and the raw message string
		895	and needs to return a formatted log message. In most cases this will be a
		896	string, but it could just as well be an array reference that just stores
		897	the values.
		898
		899	If, for some reason, you want to use C<caller> to find out more baout the
		900	logger then you should walk up the call stack until you are no longer
		901	inside the C<AnyEvent::Log> package.
		902
		903	Example: format just the raw message, with numeric log level in angle
		904	brackets.
		905
		906	$ctx->fmt_cb (sub {
		907	my ($time, $ctx, $lvl, $msg) = @_;
		908
		909	"<$lvl>$msg\n"
		910	});
		911
		912	Example: return an array reference with just the log values, and use
		913	C<PApp::SQL::sql_exec> to store the emssage in a database.
		914
		915	$ctx->fmt_cb (sub { \@_ });
		916	$ctx->log_cb (sub {
		917	my ($msg) = @_;
		918
		919	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		920	$msg->[0] + 0,
		921	"$msg->[1]",
		922	$msg->[2] + 0,
		923	"$msg->[3]";
		924
		925	0
		926	});
		927
		928	=item $ctx->log_to_warn
		929
		930	Sets the C<log_cb> to simply use C<CORE::warn> to report any messages
		931	(usually this logs to STDERR).
		932
		933	=item $ctx->log_to_file ($path)
		934
		935	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		936
		937	=item $ctx->log_to_path ($path)
		938
		939	Same as C<< ->log_to_file >>, but opens the file for each message. This
		940	is much slower, but allows you to change/move/rename/delete the file at
		941	basically any time.
		942
		943	Needless(?) to say, if you do not want to be bitten by some evil person
		944	calling C<chdir>, the path should be absolute. Doesn't help with
		945	C<chroot>, but hey...
		946
		947	=item $ctx->log_to_syslog ([$facility])
		948
		949	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and
		950	all the others in the obvious way. If specified, then the C<$facility> is
		951	used as the facility (C<user>, C<auth>, C<local0> and so on). The default
		952	facility is C<user>.
		953
		954	Note that this function also sets a C<fmt_cb> - the logging part requires
		955	an array reference with [$level, $str] as input.
		956
		957	=cut
		958
		959	sub log_cb {
		960	my ($ctx, $cb) = @_;
		961
		962	$ctx->[3] = $cb;
		963	}
		964
		965	sub fmt_cb {
		966	my ($ctx, $cb) = @_;
		967
		968	$ctx->[4] = $cb;
		969	}
		970
		971	sub log_to_warn {
		972	my ($ctx, $path) = @_;
		973
		974	$ctx->log_cb (sub {
		975	warn shift;
		976	0
		977	});
		978	}
		979
		980	sub log_to_file {
		981	my ($ctx, $path) = @_;
		982
		983	open my $fh, ">>", $path
		984	or die "$path: $!";
		985
		986	$ctx->log_cb (sub {
		987	syswrite $fh, shift;
		988	0
		989	});
		990	}
		991
		992	sub log_to_path {
		993	my ($ctx, $path) = @_;
		994
		995	$ctx->log_cb (sub {
		996	open my $fh, ">>", $path
		997	or die "$path: $!";
		998
		999	syswrite $fh, shift;
		1000	0
		1001	});
		1002	}
		1003
		1004	sub log_to_syslog {
		1005	my ($ctx, $facility) = @_;
		1006
		1007	require Sys::Syslog;
		1008
		1009	$ctx->fmt_cb (sub {
		1010	my $str = $_[3];
		1011	$str =~ s/\n(?=.)/\n+ /g;
		1012
		1013	[$_[2], "($_[1][0]) $str"]
		1014	});
		1015
		1016	$facility ||= "user";
		1017
		1018	$ctx->log_cb (sub {
		1019	my $lvl = $_[0][0] < 9 ? $_[0][0] : 8;
		1020
		1021	Sys::Syslog::syslog ("$facility|" . ($lvl - 1), $_)
		1022	for split /\n/, $_[0][1];
		1023
		1024	0
		1025	});
		1026	}
		1027
		1028	=back
		1029
		1030	=head3 MESSAGE LOGGING
		1031
		1032	These methods allow you to log messages directly to a context, without
		1033	going via your package context.
		1034
		1035	=over 4
		1036
		1037	=item $ctx->log ($level, $msg[, @params])
		1038
		1039	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		1040
		1041	=item $logger = $ctx->logger ($level[, \$enabled])
		1042
		1043	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		1044	context.
		1045
		1046	=cut
		1047
		1048	*log = \&AnyEvent::Log::_log;
		1049	*logger = \&AnyEvent::Log::_logger;
		1050
		1051	=back
		1052
		1053	=cut
		1054
		1055	package AnyEvent::Log;
		1056
		1057	=head1 CONFIGURATION VIA $ENV{PERL_ANYEVENT_LOG}
		1058
		1059	Logging can also be configured by setting the environment variable
		1060	C<PERL_ANYEVENT_LOG> (or C<AE_LOG>).
		1061
		1062	The value consists of one or more logging context specifications separated
		1063	by C<:> or whitespace. Each logging specification in turn starts with a
		1064	context name, followed by C<=>, followed by zero or more comma-separated
		1065	configuration directives, here are some examples:
		1066
		1067	# set default logging level
		1068	filter=warn
		1069
		1070	# log to file instead of to stderr
		1071	log=file=/tmp/mylog
		1072
		1073	# log to file in addition to stderr
		1074	log=+%file:%file=file=/tmp/mylog
		1075
		1076	# enable debug log messages, log warnings and above to syslog
		1077	filter=debug:log=+%warnings:%warnings=warn,syslog=LOG_LOCAL0
		1078
		1079	# log trace messages (only) from AnyEvent::Debug to file
		1080	AnyEvent::Debug=+%trace:%trace=only,trace,file=/tmp/tracelog
		1081
		1082	A context name in the log specification can be any of the following:
		1083
		1084	=over 4
		1085
		1086	=item C<collect>, C<filter>, C<log>
		1087
		1088	Correspond to the three predefined C<$AnyEvent::Log::COLLECT>,
		1089	C<AnyEvent::Log::FILTER> and C<$AnyEvent::Log::LOG> contexts.
		1090
		1091	=item C<%name>
		1092
		1093	Context names starting with a C<%> are anonymous contexts created when the
		1094	name is first mentioned. The difference to package contexts is that by
		1095	default they have no attached slaves.
		1096
		1097	=item a perl package name
		1098
		1099	Any other string references the logging context associated with the given
		1100	Perl C<package>. In the unlikely case where you want to specify a package
		1101	context that matches on of the other context name forms, you can add a
		1102	C<::> to the package name to force interpretation as a package.
		1103
		1104	=back
		1105
		1106	The configuration specifications can be any number of the following:
		1107
		1108	=over 4
		1109
		1110	=item C<stderr>
		1111
		1112	Configures the context to use Perl's C<warn> function (which typically
		1113	logs to C<STDERR>). Works like C<log_to_warn>.
		1114
		1115	=item C<file=>I<path>
		1116
		1117	Configures the context to log to a file with the given path. Works like
		1118	C<log_to_file>.
		1119
		1120	=item C<path=>I<path>
		1121
		1122	Configures the context to log to a file with the given path. Works like
		1123	C<log_to_path>.
		1124
		1125	=item C<syslog> or C<syslog=>I<expr>
		1126
		1127	Configures the context to log to syslog. If I<expr> is given, then it is
		1128	evaluated in the L<Sys::Syslog> package, so you could use:
		1129
		1130	log=syslog=LOG_LOCAL0
		1131
		1132	=item C<nolog>
		1133
		1134	Configures the context to not log anything by itself, which is the
		1135	default. Same as C<< $ctx->log_cb (undef) >>.
		1136
		1137	=item C<cap=>I<level>
		1138
		1139	Caps logging messages entering this context at the given level, i.e.
		1140	reduces the priority of messages with higher priority than this level. The
		1141	default is C<0> (or C<off>), meaning the priority will not be touched.
		1142
		1143	=item C<0> or C<off>
		1144
		1145	Sets the logging level of the context to C<0>, i.e. all messages will be
		1146	filtered out.
		1147
		1148	=item C<all>
		1149
		1150	Enables all logging levels, i.e. filtering will effectively be switched
		1151	off (the default).
		1152
		1153	=item C<only>
		1154
		1155	Disables all logging levels, and changes the interpretation of following
		1156	level specifications to enable the specified level only.
		1157
		1158	Example: only enable debug messages for a context.
		1159
		1160	context=only,debug
		1161
		1162	=item C<except>
		1163
		1164	Enables all logging levels, and changes the interpretation of following
		1165	level specifications to disable that level. Rarely used.
		1166
		1167	Example: enable all logging levels except fatal and trace (this is rather
		1168	nonsensical).
		1169
		1170	filter=exept,fatal,trace
		1171
		1172	=item C<level>
		1173
		1174	Enables all logging levels, and changes the interpretation of following
		1175	level specifications to be "that level or any higher priority
		1176	message". This is the default.
		1177
		1178	Example: log anything at or above warn level.
		1179
		1180	filter=warn
		1181
		1182	# or, more verbose
		1183	filter=only,level,warn
		1184
		1185	=item C<1>..C<9> or a logging level name (C<error>, C<debug> etc.)
		1186
		1187	A numeric loglevel or the name of a loglevel will be interpreted according
		1188	to the most recent C<only>, C<except> or C<level> directive. By default,
		1189	specifying a logging level enables that and any higher priority messages.
		1190
		1191	=item C<+>I<context>
		1192
		1193	Attaches the named context as slave to the context.
		1194
		1195	=item C<+>
		1196
		1197	A line C<+> detaches all contexts, i.e. clears the slave list from the
		1198	context. Anonymous (C<%name>) contexts have no attached slaves by default,
		1199	but package contexts have the parent context as slave by default.
		1200
		1201	Example: log messages from My::Module to a file, do not send them to the
		1202	default log collector.
		1203
		1204	My::Module=+,file=/tmp/mymodulelog
		1205
		1206	=back
		1207
		1208	Any character can be escaped by prefixing it with a C<\> (backslash), as
		1209	usual, so to log to a file containing a comma, colon, backslash and some
		1210	spaces in the filename, you would do this:
		1211
		1212	PERL_ANYEVENT_LOG='log=file=/some\ \:file\ with\,\ \\-escapes'
		1213
		1214	Since whitespace (which includes newlines) is allowed, it is fine to
		1215	specify multiple lines in C<PERL_ANYEVENT_LOG>, e.g.:
		1216
		1217	PERL_ANYEVENT_LOG="
		1218	filter=warn
		1219	AnyEvent::Debug=+%trace
		1220	%trace=only,trace,+log
		1221	" myprog
		1222
		1223	Also, in the unlikely case when you want to concatenate specifications,
		1224	use whitespace as separator, as C<::> will be interpreted as part of a
		1225	module name, an empty spec with two separators:
		1226
		1227	PERL_ANYEVENT_LOG="$PERL_ANYEVENT_LOG MyMod=debug"
		1228
		1229	=cut
		1230
		1231	for (my $spec = $ENV{PERL_ANYEVENT_LOG}) {
		1232	my %anon;
		1233
		1234	my $pkg = sub {
		1235	$_[0] eq "log" ? $LOG
		1236	: $_[0] eq "filter" ? $FILTER
		1237	: $_[0] eq "collect" ? $COLLECT
		1238	: $_[0] =~ /^%(.+)$/ ? ($anon{$1} ||= do { my $ctx = ctx undef; $ctx->[0] = $_[0]; $ctx })
		1239	: $_[0] =~ /^(.*?)(?:::)?$/ ? ctx "$1" # egad :/
		1240	: die # never reached?
		1241	};
		1242
		1243	/\G[[:space:]]+/gc; # skip initial whitespace
		1244
		1245	while (/\G((?:[^:=[:space:]]+|::|\\.)+)=/gc) {
		1246	my $ctx = $pkg->($1);
		1247	my $level = "level";
		1248
		1249	while (/\G((?:[^,:[:space:]]+|::|\\.)+)/gc) {
		1250	for ("$1") {
		1251	if ($_ eq "stderr" ) { $ctx->log_to_warn;
		1252	} elsif (/^file=(.+)/ ) { $ctx->log_to_file ("$1");
		1253	} elsif (/^path=(.+)/ ) { $ctx->log_to_path ("$1");
		1254	} elsif (/^syslog(?:=(.*))?/ ) { require Sys::Syslog; $ctx->log_to_syslog ("$1");
		1255	} elsif ($_ eq "nolog" ) { $ctx->log_cb (undef);
		1256	} elsif (/^cap=(.+)/ ) { $ctx->cap ("$1");
		1257	} elsif (/^\+(.+)$/ ) { $ctx->attach ($pkg->("$1"));
		1258	} elsif ($_ eq "+" ) { $ctx->slaves;
		1259	} elsif ($_ eq "off" or $_ eq "0") { $ctx->level (0);
		1260	} elsif ($_ eq "all" ) { $ctx->level ("all");
		1261	} elsif ($_ eq "level" ) { $ctx->level ("all"); $level = "level";
		1262	} elsif ($_ eq "only" ) { $ctx->level ("off"); $level = "enable";
		1263	} elsif ($_ eq "except" ) { $ctx->level ("all"); $level = "disable";
		1264	} elsif (/^\d$/ ) { $ctx->$level ($_);
		1265	} elsif (exists $STR2LEVEL{$_} ) { $ctx->$level ($_);
		1266	} else { die "PERL_ANYEVENT_LOG ($spec): parse error at '$_'\n";
		1267	}
		1268	}
		1269
		1270	/\G,/gc or last;
		1271	}
		1272
		1273	/\G[:[:space:]]+/gc or last;
		1274	}
		1275
		1276	/\G[[:space:]]+/gc; # skip trailing whitespace
		1277
		1278	if (/\G(.+)/g) {
		1279	die "PERL_ANYEVENT_LOG ($spec): parse error at '$1'\n";
		1280	}
290	}	1281	}
291		1282
292	1;	1283	1;
		1284
		1285	=head1 EXAMPLES
		1286
		1287	This section shows some common configurations, both as code, and as
		1288	C<PERL_ANYEVENT_LOG> string.
		1289
		1290	=over 4
		1291
		1292	=item Setting the global logging level.
		1293
		1294	Either put C<PERL_ANYEVENT_VERBOSE=><number> into your environment before
		1295	running your program, use C<PERL_ANYEVENT_LOG> or modify the log level of
		1296	the root context at runtime:
		1297
		1298	PERL_ANYEVENT_VERBOSE=5 ./myprog
		1299
		1300	PERL_ANYEVENT_LOG=log=warn
		1301
		1302	$AnyEvent::Log::FILTER->level ("warn");
		1303
		1304	=item Append all messages to a file instead of sending them to STDERR.
		1305
		1306	This is affected by the global logging level.
		1307
		1308	$AnyEvent::Log::LOG->log_to_file ($path);
		1309
		1310	PERL_ANYEVENT_LOG=log=file=/some/path
		1311
		1312	=item Write all messages with priority C<error> and higher to a file.
		1313
		1314	This writes them only when the global logging level allows it, because
		1315	it is attached to the default context which is invoked I<after> global
		1316	filtering.
		1317
		1318	$AnyEvent::Log::FILTER->attach (
		1319	new AnyEvent::Log::Ctx log_to_file => $path);
		1320
		1321	PERL_ANYEVENT_LOG=filter=+%filelogger:%filelogger=file=/some/path
		1322
		1323	This writes them regardless of the global logging level, because it is
		1324	attached to the toplevel context, which receives all messages I<before>
		1325	the global filtering.
		1326
		1327	$AnyEvent::Log::COLLECT->attach (
		1328	new AnyEvent::Log::Ctx log_to_file => $path);
		1329
		1330	PERL_ANYEVENT_LOG=%filelogger=file=/some/path:collect=+%filelogger
		1331
		1332	In both cases, messages are still written to STDERR.
		1333
		1334	=item Additionally log all messages with C<warn> and higher priority to
		1335	C<syslog>, but cap at C<error>.
		1336
		1337	This logs all messages to the default log target, but also logs messages
		1338	with priority C<warn> or higher (and not filtered otherwise) to syslog
		1339	facility C<user>. Messages with priority higher than C<error> will be
		1340	logged with level C<error>.
		1341
		1342	$AnyEvent::Log::LOG->attach (
		1343	new AnyEvent::Log::Ctx
		1344	level => "warn",
		1345	cap => "error",
		1346	syslog => "user",
		1347	);
		1348
		1349	PERL_ANYEVENT_LOG=log=+%syslog:%syslog=warn,cap=error,syslog
		1350
		1351	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		1352
		1353	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		1354	context - this simply circumvents the global filtering for trace messages.
		1355
		1356	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		1357	$debug->attach ($AnyEvent::Log::LOG);
		1358
		1359	PERL_ANYEVENT_LOG=AnyEvent::Debug=+log
		1360
		1361	This of course works for any package, not just L<AnyEvent::Debug>, but
		1362	assumes the log level for AnyEvent::Debug hasn't been changed from the
		1363	default.
293		1364
294	=back	1365	=back
295		1366
296	=head1 AUTHOR	1367	=head1 AUTHOR
297		1368
298	Marc Lehmann <schmorp@schmorp.de>	1369	Marc Lehmann <schmorp@schmorp.de>
299	http://home.schmorp.de/	1370	http://home.schmorp.de/
300		1371
301	=cut	1372	=cut
		1373

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