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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.3 by root, Wed Aug 17 02:02:38 2011 UTC vs.
Revision 1.58 by root, Thu Apr 5 04:12:21 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 fatal => "No config found, cannot continue!"; # never returns
		12	AE::log alert => "The battery died!";
		13	AE::log crit => "The battery temperature is too hot!";
		14	AE::log error => "Division by zero attempted.";
		15	AE::log warn => "Couldn't delete the file.";
		16	AE::log note => "Wanted to create config, but config already exists.";
		17	AE::log info => "File soandso successfully deleted.";
		18	AE::log debug => "the function returned 3";
		19	AE::log trace => "going to call function abc";
		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	$AnyEvent::Log::COLLECT->attach (new AnyEvent::Log::Ctx
		54	level => "critical",
		55	log_to_syslog => "user",
		56	);
8		57
9	=head1 DESCRIPTION	58	=head1 DESCRIPTION
10		59
11	This module implements a relatively simple "logging framework". It doesn't	60	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	61	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	62	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	63	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	64	using it from other modules as well.
16		65
17	Remember that the default verbosity level is C<0>, so nothing	66	Remember that the default verbosity level is C<4> (C<error>), so only
18	will be logged, ever, unless you set C<$Anyvent::VERBOSE> or	67	errors and more important messages will be logged, unless you set
19	C<PERL_ANYEVENT_VERBOSE> to a higher number.	68	C<PERL_ANYEVENT_VERBOSE> to a higher number before starting your program
		69	(C<AE_VERBOSE=5> is recommended during development), or change the logging
		70	level at runtime with something like:
20		71
21	Possible future extensions are to allow custom log targets (where the	72	use AnyEvent::Log;
22	level is an object), log filtering based on package, formatting, aliasing	73	$AnyEvent::Log::FILTER->level ("info");
23	or package groups.
24		74
		75	The design goal behind this module was to keep it simple (and small),
		76	but make it powerful enough to be potentially useful for any module, and
		77	extensive enough for the most common tasks, such as logging to multiple
		78	targets, or being able to log into a database.
		79
		80	The module is also usable before AnyEvent itself is initialised, in which
		81	case some of the functionality might be reduced.
		82
		83	The amount of documentation might indicate otherwise, but the runtime part
		84	of the module is still just below 300 lines of code.
		85
		86	=head1 LOGGING LEVELS
		87
		88	Logging levels in this module range from C<1> (highest priority) to C<9>
		89	(lowest priority). Note that the lowest numerical value is the highest
		90	priority, so when this document says "higher priority" it means "lower
		91	numerical value".
		92
		93	Instead of specifying levels by name you can also specify them by aliases:
		94
		95	LVL NAME SYSLOG PERL NOTE
		96	1 fatal emerg exit system unusable, aborts program!
		97	2 alert failure in primary system
		98	3 critical crit failure in backup system
		99	4 error err die non-urgent program errors, a bug
		100	5 warn warning possible problem, not necessarily error
		101	6 note notice unusual conditions
		102	7 info normal messages, no action required
		103	8 debug debugging messages for development
		104	9 trace copious tracing output
		105
		106	As you can see, some logging levels have multiple aliases - the first one
		107	is the "official" name, the second one the "syslog" name (if it differs)
		108	and the third one the "perl" name, suggesting (only!) that you log C<die>
		109	messages at C<error> priority. The NOTE column tries to provide some
		110	rationale on how to chose a logging level.
		111
		112	As a rough guideline, levels 1..3 are primarily meant for users of the
		113	program (admins, staff), and are the only ones logged to STDERR by
		114	default. Levels 4..6 are meant for users and developers alike, while
		115	levels 7..9 are usually meant for developers.
		116
		117	You can normally only log a message once at highest priority level (C<1>,
		118	C<fatal>), because logging a fatal message will also quit the program - so
		119	use it sparingly :)
		120
		121	For example, a program that finds an unknown switch on the commandline
		122	might well use a fatal logging level to tell users about it - the "system"
		123	in this case would be the program, or module.
		124
		125	Some methods also offer some extra levels, such as C<0>, C<off>, C<none>
		126	or C<all> - these are only valid for the methods that documented them.
		127
25	=head1 LOG FUNCTIONS	128	=head1 LOGGING FUNCTIONS
26		129
27	These functions allow you to log messages. They always use the caller's	130	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	131	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>	132	C<log>, is aliased to C<AnyEvent::log> and C<AE::log> when the C<AnyEvent>
30	module is loaded.	133	module is loaded.
31		134
32	=over 4	135	=over 4
33		136
34	=cut	137	=cut
…		…
36	package AnyEvent::Log;	139	package AnyEvent::Log;
37		140
38	use Carp ();	141	use Carp ();
39	use POSIX ();	142	use POSIX ();
40		143
		144	# layout of a context
		145	# 0 1 2 3 4, 5
		146	# [$title, $level, %$slaves, &$logcb, &$fmtcb, $cap]
		147
41	use AnyEvent (); BEGIN { AnyEvent::common_sense }	148	use AnyEvent (); BEGIN { AnyEvent::common_sense }
42	use AnyEvent::Util ();	149	#use AnyEvent::Util (); need to load this in a delayed fashion, as it uses AE::log
		150
		151	our $VERSION = $AnyEvent::VERSION;
		152
		153	our ($COLLECT, $FILTER, $LOG);
43		154
44	our ($now_int, $now_str1, $now_str2);	155	our ($now_int, $now_str1, $now_str2);
45		156
46	# Format Time, not public - yet?	157	# Format Time, not public - yet?
47	sub ft($) {	158	sub ft($) {
…		…
52	if $now_int != $i;	163	if $now_int != $i;
53		164
54	"$now_str1$f$now_str2"	165	"$now_str1$f$now_str2"
55	}	166	}
56		167
57	our %CFG; #TODO	168	our %CTX; # all package contexts
		169
		170	# creates a default package context object for the given package
		171	sub _pkg_ctx($) {
		172	my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx";
		173
		174	# link "parent" package
		175	my $parent = $_[0] =~ /^(.+)::/
		176	? $CTX{$1} ||= &_pkg_ctx ("$1")
		177	: $COLLECT;
		178
		179	$ctx->[2]{$parent+0} = $parent;
		180
		181	$ctx
		182	}
58		183
59	=item AnyEvent::Log::log $level, $msg[, @args]	184	=item AnyEvent::Log::log $level, $msg[, @args]
60		185
61	Requests logging of the given C<$msg> with the given log level (1..9).	186	Requests logging of the given C<$msg> with the given log level, and
62	You can also use the following strings as log level: C<fatal> (1),	187	returns true if the message was logged I<somewhere>.
63	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
64	C<info> (7), C<debug> (8), C<trace> (9).
65		188
66	For C<fatal> log levels, the program will abort.	189	For loglevel C<fatal>, the program will abort.
67		190
68	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	191	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.	192	C<$msg> is interpreted as an sprintf format string.
70		193
71	The C<$msg> should not end with C<\n>, but may if that is convenient for	194	The C<$msg> should not end with C<\n>, but may if that is convenient for
…		…
74	Last not least, C<$msg> might be a code reference, in which case it is	197	Last not least, C<$msg> might be a code reference, in which case it is
75	supposed to return the message. It will be called only then the message	198	supposed to return the message. It will be called only then the message
76	actually gets logged, which is useful if it is costly to create the	199	actually gets logged, which is useful if it is costly to create the
77	message in the first place.	200	message in the first place.
78		201
		202	This function takes care of saving and restoring C<$!> and C<$@>, so you
		203	don't have to.
		204
79	Whether the given message will be logged depends on the maximum log level	205	Whether the given message will be logged depends on the maximum log level
80	and the caller's package.	206	and the caller's package. The return value can be used to ensure that
		207	messages or not "lost" - for example, when L<AnyEvent::Debug> detects a
		208	runtime error it tries to log it at C<die> level, but if that message is
		209	lost it simply uses warn.
81		210
82	Note that you can (and should) call this function as C<AnyEvent::log> or	211	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	212	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.	213	need any additional functionality), as those functions will load the
		214	logging module on demand only. They are also much shorter to write.
		215
		216	Also, if you optionally generate a lot of debug messages (such as when
		217	tracing some code), you should look into using a logger callback and a
		218	boolean enabler (see C<logger>, below).
85		219
86	Example: log something at error level.	220	Example: log something at error level.
87		221
88	AE::log error => "something";	222	AE::log error => "something";
89		223
…		…
97		231
98	=cut	232	=cut
99		233
100	# also allow syslog equivalent names	234	# also allow syslog equivalent names
101	our %STR2LEVEL = (	235	our %STR2LEVEL = (
102	fatal => 1, emerg => 1,	236	fatal => 1, emerg => 1, exit => 1,
103	alert => 2,	237	alert => 2,
104	critical => 3, crit => 3,	238	critical => 3, crit => 3,
105	error => 4, err => 4,	239	error => 4, err => 4, die => 4,
106	warn => 5, warning => 5,	240	warn => 5, warning => 5,
107	note => 6, notice => 6,	241	note => 6, notice => 6,
108	info => 7,	242	info => 7,
109	debug => 8,	243	debug => 8,
110	trace => 9,	244	trace => 9,
111	);	245	);
112		246
		247	our $TIME_EXACT;
		248
		249	sub exact_time($) {
		250	$TIME_EXACT = shift;
		251	*_ts = $AnyEvent::MODEL
		252	? $TIME_EXACT ? \&AE::now : \&AE::time
		253	: sub () { $TIME_EXACT ? do { require Time::HiRes; Time::HiRes::time () } : time };
		254	}
		255
		256	BEGIN {
		257	exact_time 0;
		258	}
		259
		260	AnyEvent::post_detect {
		261	exact_time $TIME_EXACT;
		262	};
		263
113	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	264	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
114		265
		266	# time, ctx, level, msg
		267	sub _format($$$$) {
		268	my $ts = ft $_[0];
		269	my $ct = " ";
		270
		271	my @res;
		272
		273	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		274	push @res, "$ts$ct$_\n";
		275	$ct = " + ";
		276	}
		277
		278	join "", @res
		279	}
		280
		281	sub fatal_exit() {
		282	exit 1;
		283	}
		284
115	sub _log {	285	sub _log {
116	my ($pkg, $targ, $msg, @args) = @_;	286	my ($ctx, $level, $format, @args) = @_;
117		287
118	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	288	$level = $level > 0 && $level <= 9
119	: $targ > 0 && $targ <= 9 ? $targ+0	289	? $level+0
120	: $STR2LEVEL{$targ} || Carp::croak "$targ: not a valid logging level, caught";	290	: $STR2LEVEL{$level} || Carp::croak "$level: not a valid logging level, caught";
121		291
122	return if $level > $AnyEvent::VERBOSE;	292	my $mask = 1 << $level;
123		293
124	$msg = $msg->() if ref $msg;	294	my ($success, %seen, @ctx, $now, @fmt);
125	$msg = sprintf $msg, @args if @args;
126	$msg =~ s/\n$//;
127		295
128	# now we have a message, log it	296	do
129	#TODO: could do LOTS of stuff here, and should, at least in some later version	297	{
		298	# if !ref, then it's a level number
		299	if (!ref $ctx) {
		300	$level = $ctx;
		301	} elsif ($ctx->[1] & $mask and !$seen{$ctx+0}++) {
		302	# logging/recursing into this context
130		303
131	$msg = sprintf "%5s %s: %s", $LEVEL2STR[$level], $pkg, $msg;	304	# level cap
132	my $pfx = ft AE::now;	305	if ($ctx->[5] > $level) {
		306	push @ctx, $level; # restore level when going up in tree
		307	$level = $ctx->[5];
		308	}
133		309
134	for (split /\n/, $msg) {	310	# log if log cb
135	printf STDERR "$pfx $_\n";	311	if ($ctx->[3]) {
136	$pfx = "\t";	312	# logging target found
137	}
138		313
		314	local ($!, $@);
		315
		316	# now get raw message, unless we have it already
		317	unless ($now) {
		318	$format = $format->() if ref $format;
		319	$format = sprintf $format, @args if @args;
		320	$format =~ s/\n$//;
		321	$now = _ts;
		322	};
		323
		324	# format msg
		325	my $str = $ctx->[4]
		326	? $ctx->[4]($now, $_[0], $level, $format)
		327	: ($fmt[$level] ||= _format $now, $_[0], $level, $format);
		328
		329	$success = 1;
		330
		331	$ctx->[3]($str)
		332	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
		333	} else {
		334	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		335	}
		336	}
		337	}
		338	while $ctx = pop @ctx;
		339
139	exit 1 if $level <= 1;	340	fatal_exit if $level <= 1;
		341
		342	$success
140	}	343	}
141		344
142	sub log($$;@) {	345	sub log($$;@) {
143	_log +(caller)[0], @_;	346	_log
		347	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		348	@_;
144	}	349	}
145
146	*AnyEvent::log = *AE::log = \&log;
147		350
148	=item $logger = AnyEvent::Log::logger $level[, \$enabled]	351	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
149		352
150	Creates a code reference that, when called, acts as if the	353	Creates a code reference that, when called, acts as if the
151	C<AnyEvent::Log::log> function was called at this point with the givne	354	C<AnyEvent::Log::log> function was called at this point with the given
152	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with	355	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
153	the C<AnyEvent::Log::log> function:	356	the C<AnyEvent::Log::log> function:
154		357
155	my $debug_log = AnyEvent::Log::logger "debug";	358	my $debug_log = AnyEvent::Log::logger "debug";
156		359
…		…
181	# and later in your program	384	# and later in your program
182	$debug_log->("yo, stuff here") if $debug;	385	$debug_log->("yo, stuff here") if $debug;
183		386
184	$debug and $debug_log->("123");	387	$debug and $debug_log->("123");
185		388
186	Note: currently the enabled var is always true - that will be fixed in a
187	future version :)
188
189	=cut	389	=cut
190		390
191	our %LOGGER;	391	our %LOGGER;
192		392
193	# re-assess logging status for all loggers	393	# re-assess logging status for all loggers
194	sub _reassess {	394	sub _reassess {
		395	local $SIG{__DIE__};
		396	my $die = sub { die };
		397
195	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {	398	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
196	my ($pkg, $level, $renabled) = @$_;	399	my ($ctx, $level, $renabled) = @$_;
197		400
198	# to detetc whether a message would be logged, we # actually	401	# to detect whether a message would be logged, we actually
199	# try to log one and die. this isn't # fast, but we can be	402	# try to log one and die. this isn't fast, but we can be
200	# sure that the logging decision is correct :)	403	# sure that the logging decision is correct :)
201		404
202	$$renabled = !eval {	405	$$renabled = !eval {
203	local $SIG{__DIE__};
204
205	_log $pkg, $level, sub { die };	406	_log $ctx, $level, $die;
206		407
207	1	408	1
208	};	409	};
209
210	$$renabled = 1; # TODO
211	}	410	}
212	}	411	}
213		412
214	sub logger($;$) {	413	sub _logger {
215	my ($level, $renabled) = @_;	414	my ($ctx, $level, $renabled) = @_;
216
217	$renabled ||= \my $enabled;
218	my $pkg = (caller)[0];
219		415
220	$$renabled = 1;	416	$$renabled = 1;
221		417
222	my $logger = [$pkg, $level, $renabled];	418	my $logger = [$ctx, $level, $renabled];
223		419
224	$LOGGER{$logger+0} = $logger;	420	$LOGGER{$logger+0} = $logger;
225		421
226	_reassess $logger+0;	422	_reassess $logger+0;
227		423
		424	require AnyEvent::Util unless $AnyEvent::Util::VERSION;
228	my $guard = AnyEvent::Util::guard {	425	my $guard = AnyEvent::Util::guard (sub {
229	# "clean up"	426	# "clean up"
230	delete $LOGGER{$logger+0};	427	delete $LOGGER{$logger+0};
231	};	428	});
232		429
233	sub {	430	sub {
234	$guard if 0; # keep guard alive, but don't cause runtime overhead	431	$guard if 0; # keep guard alive, but don't cause runtime overhead
235		432
236	_log $pkg, $level, @_	433	_log $ctx, $level, @_
237	if $$renabled;	434	if $$renabled;
238	}	435	}
239	}	436	}
240		437
241	#TODO	438	sub logger($;$) {
		439	_logger
		440	$CTX{ (caller)[0] } ||= _pkg_ctx +(caller)[0],
		441	@_
		442	}
		443
		444	=item AnyEvent::Log::exact_time $on
		445
		446	By default, C<AnyEvent::Log> will use C<AE::now>, i.e. the cached
		447	eventloop time, for the log timestamps. After calling this function with a
		448	true value it will instead resort to C<AE::time>, i.e. fetch the current
		449	time on each log message. This only makes a difference for event loops
		450	that actually cache the time (such as L<EV> or L<AnyEvent::Loop>).
		451
		452	This setting can be changed at any time by calling this function.
		453
		454	Since C<AnyEvent::Log> has to work even before the L<AnyEvent> has been
		455	initialised, this switch will also decide whether to use C<CORE::time> or
		456	C<Time::HiRes::time> when logging a message before L<AnyEvent> becomes
		457	available.
242		458
243	=back	459	=back
244		460
245	=head1 CONFIGURATION FUNCTIONALITY	461	=head1 LOGGING CONTEXTS
246		462
247	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	463	This module associates every log message with a so-called I<logging
		464	context>, based on the package of the caller. Every perl package has its
		465	own logging context.
		466
		467	A logging context has three major responsibilities: filtering, logging and
		468	propagating the message.
		469
		470	For the first purpose, filtering, each context has a set of logging
		471	levels, called the log level mask. Messages not in the set will be ignored
		472	by this context (masked).
		473
		474	For logging, the context stores a formatting callback (which takes the
		475	timestamp, context, level and string message and formats it in the way
		476	it should be logged) and a logging callback (which is responsible for
		477	actually logging the formatted message and telling C<AnyEvent::Log>
		478	whether it has consumed the message, or whether it should be propagated).
		479
		480	For propagation, a context can have any number of attached I<slave
		481	contexts>. Any message that is neither masked by the logging mask nor
		482	masked by the logging callback returning true will be passed to all slave
		483	contexts.
		484
		485	Each call to a logging function will log the message at most once per
		486	context, so it does not matter (much) if there are cycles or if the
		487	message can arrive at the same context via multiple paths.
		488
		489	=head2 DEFAULTS
		490
		491	By default, all logging contexts have an full set of log levels ("all"), a
		492	disabled logging callback and the default formatting callback.
		493
		494	Package contexts have the package name as logging title by default.
		495
		496	They have exactly one slave - the context of the "parent" package. The
		497	parent package is simply defined to be the package name without the last
		498	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		499	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		500	exception of the rule - just like the "parent" of any single-component
		501	package name in Perl is C<main>, the default slave of any top-level
		502	package context is C<$AnyEvent::Log::COLLECT>.
		503
		504	Since perl packages form only an approximate hierarchy, this slave
		505	context can of course be removed.
		506
		507	All other (anonymous) contexts have no slaves and an empty title by
		508	default.
		509
		510	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		511	context that simply logs everything via C<warn>, without propagating
		512	anything anywhere by default. The purpose of this context is to provide
		513	a convenient place to override the global logging target or to attach
		514	additional log targets. It's not meant for filtering.
		515
		516	It then creates the C<$AnyEvent::Log::FILTER> context whose
		517	purpose is to suppress all messages with priority higher
		518	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		519	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		520	is to simply provide filtering according to some global log level.
		521
		522	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		523	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		524	leaves it at default config. Its purpose is simply to collect all log
		525	messages system-wide.
		526
		527	The hierarchy is then:
		528
		529	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		530
		531	The effect of all this is that log messages, by default, wander up to the
		532	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		533	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		534	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		535	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		536
		537	This makes it easy to set a global logging level (by modifying $FILTER),
		538	but still allow other contexts to send, for example, their debug and trace
		539	messages to the $LOG target despite the global logging level, or to attach
		540	additional log targets that log messages, regardless of the global logging
		541	level.
		542
		543	It also makes it easy to modify the default warn-logger ($LOG) to
		544	something that logs to a file, or to attach additional logging targets
		545	(such as loggign to a file) by attaching it to $FILTER.
		546
		547	=head2 CREATING/FINDING/DESTROYING CONTEXTS
248		548
249	=over 4	549	=over 4
250		550
		551	=item $ctx = AnyEvent::Log::ctx [$pkg]
		552
		553	This function creates or returns a logging context (which is an object).
		554
		555	If a package name is given, then the context for that packlage is
		556	returned. If it is called without any arguments, then the context for the
		557	callers package is returned (i.e. the same context as a C<AE::log> call
		558	would use).
		559
		560	If C<undef> is given, then it creates a new anonymous context that is not
		561	tied to any package and is destroyed when no longer referenced.
		562
251	=cut	563	=cut
252		564
253	1;	565	sub ctx(;$) {
		566	my $pkg = @_ ? shift : (caller)[0];
		567
		568	ref $pkg
		569	? $pkg
		570	: defined $pkg
		571	? $CTX{$pkg} ||= AnyEvent::Log::_pkg_ctx $pkg
		572	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		573	}
		574
		575	=item AnyEvent::Log::reset
		576
		577	Resets all package contexts and recreates the default hierarchy if
		578	necessary, i.e. resets the logging subsystem to defaults, as much as
		579	possible. This process keeps references to contexts held by other parts of
		580	the program intact.
		581
		582	This can be used to implement config-file (re-)loading: before loading a
		583	configuration, reset all contexts.
		584
		585	=cut
		586
		587	our $ORIG_VERBOSE = $AnyEvent::VERBOSE;
		588	$AnyEvent::VERBOSE = 9;
		589
		590	sub reset {
		591	# hard to kill complex data structures
		592	# we "recreate" all package loggers and reset the hierarchy
		593	while (my ($k, $v) = each %CTX) {
		594	@$v = ($k, (1 << 10) - 1 - 1, { });
		595
		596	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
		597	}
		598
		599	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		600	for $LOG, $FILTER, $COLLECT;
		601
		602	#$LOG->slaves;
		603	$LOG->title ('$AnyEvent::Log::LOG');
		604	$LOG->log_to_warn;
		605
		606	$FILTER->slaves ($LOG);
		607	$FILTER->title ('$AnyEvent::Log::FILTER');
		608	$FILTER->level ($ORIG_VERBOSE);
		609
		610	$COLLECT->slaves ($FILTER);
		611	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		612
		613	_reassess;
		614	}
		615
		616	# override AE::log/logger
		617	*AnyEvent::log = *AE::log = \&log;
		618	*AnyEvent::logger = *AE::logger = \&logger;
		619
		620	# convert AnyEvent loggers to AnyEvent::Log loggers
		621	$_->[0] = ctx $_->[0] # convert "pkg" to "ctx"
		622	for values %LOGGER;
		623
		624	# create the default logger contexts
		625	$LOG = ctx undef;
		626	$FILTER = ctx undef;
		627	$COLLECT = ctx undef;
		628
		629	AnyEvent::Log::reset;
		630
		631	# hello, CPAN, please catch me
		632	package AnyEvent::Log::LOG;
		633	package AE::Log::LOG;
		634	package AnyEvent::Log::FILTER;
		635	package AE::Log::FILTER;
		636	package AnyEvent::Log::COLLECT;
		637	package AE::Log::COLLECT;
		638
		639	package AnyEvent::Log::Ctx;
		640
		641	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		642
		643	This is a convenience constructor that makes it simpler to construct
		644	anonymous logging contexts.
		645
		646	Each key-value pair results in an invocation of the method of the same
		647	name as the key with the value as parameter, unless the value is an
		648	arrayref, in which case it calls the method with the contents of the
		649	array. The methods are called in the same order as specified.
		650
		651	Example: create a new logging context and set both the default logging
		652	level, some slave contexts and a logging callback.
		653
		654	$ctx = new AnyEvent::Log::Ctx
		655	title => "dubious messages",
		656	level => "error",
		657	log_cb => sub { print STDOUT shift; 0 },
		658	slaves => [$ctx1, $ctx, $ctx2],
		659	;
254		660
255	=back	661	=back
256		662
		663	=cut
		664
		665	sub new {
		666	my $class = shift;
		667
		668	my $ctx = AnyEvent::Log::ctx undef;
		669
		670	while (@_) {
		671	my ($k, $v) = splice @_, 0, 2;
		672	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		673	}
		674
		675	bless $ctx, $class # do we really support subclassing, hmm?
		676	}
		677
		678
		679	=head2 CONFIGURING A LOG CONTEXT
		680
		681	The following methods can be used to configure the logging context.
		682
		683	=over 4
		684
		685	=item $ctx->title ([$new_title])
		686
		687	Returns the title of the logging context - this is the package name, for
		688	package contexts, and a user defined string for all others.
		689
		690	If C<$new_title> is given, then it replaces the package name or title.
		691
		692	=cut
		693
		694	sub title {
		695	$_[0][0] = $_[1] if @_ > 1;
		696	$_[0][0]
		697	}
		698
		699	=back
		700
		701	=head3 LOGGING LEVELS
		702
		703	The following methods deal with the logging level set associated with the
		704	log context.
		705
		706	The most common method to use is probably C<< $ctx->level ($level) >>,
		707	which configures the specified and any higher priority levels.
		708
		709	All functions which accept a list of levels also accept the special string
		710	C<all> which expands to all logging levels.
		711
		712	=over 4
		713
		714	=item $ctx->levels ($level[, $level...)
		715
		716	Enables logging for the given levels and disables it for all others.
		717
		718	=item $ctx->level ($level)
		719
		720	Enables logging for the given level and all lower level (higher priority)
		721	ones. In addition to normal logging levels, specifying a level of C<0> or
		722	C<off> disables all logging for this level.
		723
		724	Example: log warnings, errors and higher priority messages.
		725
		726	$ctx->level ("warn");
		727	$ctx->level (5); # same thing, just numeric
		728
		729	=item $ctx->enable ($level[, $level...])
		730
		731	Enables logging for the given levels, leaving all others unchanged.
		732
		733	=item $ctx->disable ($level[, $level...])
		734
		735	Disables logging for the given levels, leaving all others unchanged.
		736
		737	=item $ctx->cap ($level)
		738
		739	Caps the maximum priority to the given level, for all messages logged
		740	to, or passing through, this context. That is, while this doesn't affect
		741	whether a message is logged or passed on, the maximum priority of messages
		742	will be limited to the specified level - messages with a higher priority
		743	will be set to the specified priority.
		744
		745	Another way to view this is that C<< ->level >> filters out messages with
		746	a too low priority, while C<< ->cap >> modifies messages with a too high
		747	priority.
		748
		749	This is useful when different log targets have different interpretations
		750	of priority. For example, for a specific command line program, a wrong
		751	command line switch might well result in a C<fatal> log message, while the
		752	same message, logged to syslog, is likely I<not> fatal to the system or
		753	syslog facility as a whole, but more likely a mere C<error>.
		754
		755	This can be modeled by having a stderr logger that logs messages "as-is"
		756	and a syslog logger that logs messages with a level cap of, say, C<error>,
		757	or, for truly system-critical components, actually C<critical>.
		758
		759	=cut
		760
		761	sub _lvl_lst {
		762	map {
		763	$_ > 0 && $_ <= 9 ? $_+0
		764	: $_ eq "all" ? (1 .. 9)
		765	: $STR2LEVEL{$_} || Carp::croak "$_: not a valid logging level, caught"
		766	} @_
		767	}
		768
		769	sub _lvl {
		770	$_[0] =~ /^(?:0|off|none)$/ ? 0 : (_lvl_lst $_[0])[-1]
		771	}
		772
		773	our $NOP_CB = sub { 0 };
		774
		775	sub levels {
		776	my $ctx = shift;
		777	$ctx->[1] = 0;
		778	$ctx->[1] |= 1 << $_
		779	for &_lvl_lst;
		780	AnyEvent::Log::_reassess;
		781	}
		782
		783	sub level {
		784	my $ctx = shift;
		785	$ctx->[1] = ((1 << &_lvl) - 1) << 1;
		786	AnyEvent::Log::_reassess;
		787	}
		788
		789	sub enable {
		790	my $ctx = shift;
		791	$ctx->[1] |= 1 << $_
		792	for &_lvl_lst;
		793	AnyEvent::Log::_reassess;
		794	}
		795
		796	sub disable {
		797	my $ctx = shift;
		798	$ctx->[1] &= ~(1 << $_)
		799	for &_lvl_lst;
		800	AnyEvent::Log::_reassess;
		801	}
		802
		803	sub cap {
		804	my $ctx = shift;
		805	$ctx->[5] = &_lvl;
		806	}
		807
		808	=back
		809
		810	=head3 SLAVE CONTEXTS
		811
		812	The following methods attach and detach another logging context to a
		813	logging context.
		814
		815	Log messages are propagated to all slave contexts, unless the logging
		816	callback consumes the message.
		817
		818	=over 4
		819
		820	=item $ctx->attach ($ctx2[, $ctx3...])
		821
		822	Attaches the given contexts as slaves to this context. It is not an error
		823	to add a context twice (the second add will be ignored).
		824
		825	A context can be specified either as package name or as a context object.
		826
		827	=item $ctx->detach ($ctx2[, $ctx3...])
		828
		829	Removes the given slaves from this context - it's not an error to attempt
		830	to remove a context that hasn't been added.
		831
		832	A context can be specified either as package name or as a context object.
		833
		834	=item $ctx->slaves ($ctx2[, $ctx3...])
		835
		836	Replaces all slaves attached to this context by the ones given.
		837
		838	=cut
		839
		840	sub attach {
		841	my $ctx = shift;
		842
		843	$ctx->[2]{$_+0} = $_
		844	for map { AnyEvent::Log::ctx $_ } @_;
		845	}
		846
		847	sub detach {
		848	my $ctx = shift;
		849
		850	delete $ctx->[2]{$_+0}
		851	for map { AnyEvent::Log::ctx $_ } @_;
		852	}
		853
		854	sub slaves {
		855	undef $_[0][2];
		856	&attach;
		857	}
		858
		859	=back
		860
		861	=head3 LOG TARGETS
		862
		863	The following methods configure how the logging context actually does
		864	the logging (which consists of formatting the message and printing it or
		865	whatever it wants to do with it).
		866
		867	=over 4
		868
		869	=item $ctx->log_cb ($cb->($str))
		870
		871	Replaces the logging callback on the context (C<undef> disables the
		872	logging callback).
		873
		874	The logging callback is responsible for handling formatted log messages
		875	(see C<fmt_cb> below) - normally simple text strings that end with a
		876	newline (and are possibly multiline themselves).
		877
		878	It also has to return true iff it has consumed the log message, and false
		879	if it hasn't. Consuming a message means that it will not be sent to any
		880	slave context. When in doubt, return C<0> from your logging callback.
		881
		882	Example: a very simple logging callback, simply dump the message to STDOUT
		883	and do not consume it.
		884
		885	$ctx->log_cb (sub { print STDERR shift; 0 });
		886
		887	You can filter messages by having a log callback that simply returns C<1>
		888	and does not do anything with the message, but this counts as "message
		889	being logged" and might not be very efficient.
		890
		891	Example: propagate all messages except for log levels "debug" and
		892	"trace". The messages will still be generated, though, which can slow down
		893	your program.
		894
		895	$ctx->levels ("debug", "trace");
		896	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		897
		898	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		899
		900	Replaces the formatting callback on the context (C<undef> restores the
		901	default formatter).
		902
		903	The callback is passed the (possibly fractional) timestamp, the original
		904	logging context (object, not title), the (numeric) logging level and
		905	the raw message string and needs to return a formatted log message. In
		906	most cases this will be a string, but it could just as well be an array
		907	reference that just stores the values.
		908
		909	If, for some reason, you want to use C<caller> to find out more about the
		910	logger then you should walk up the call stack until you are no longer
		911	inside the C<AnyEvent::Log> package.
		912
		913	Example: format just the raw message, with numeric log level in angle
		914	brackets.
		915
		916	$ctx->fmt_cb (sub {
		917	my ($time, $ctx, $lvl, $msg) = @_;
		918
		919	"<$lvl>$msg\n"
		920	});
		921
		922	Example: return an array reference with just the log values, and use
		923	C<PApp::SQL::sql_exec> to store the message in a database.
		924
		925	$ctx->fmt_cb (sub { \@_ });
		926	$ctx->log_cb (sub {
		927	my ($msg) = @_;
		928
		929	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		930	$msg->[0] + 0,
		931	"$msg->[1]",
		932	$msg->[2] + 0,
		933	"$msg->[3]";
		934
		935	0
		936	});
		937
		938	=item $ctx->log_to_warn
		939
		940	Sets the C<log_cb> to simply use C<CORE::warn> to report any messages
		941	(usually this logs to STDERR).
		942
		943	=item $ctx->log_to_file ($path)
		944
		945	Sets the C<log_cb> to log to a file (by appending), unbuffered. The
		946	function might return before the log file has been opened or created.
		947
		948	=item $ctx->log_to_path ($path)
		949
		950	Same as C<< ->log_to_file >>, but opens the file for each message. This
		951	is much slower, but allows you to change/move/rename/delete the file at
		952	basically any time.
		953
		954	Needless(?) to say, if you do not want to be bitten by some evil person
		955	calling C<chdir>, the path should be absolute. Doesn't help with
		956	C<chroot>, but hey...
		957
		958	=item $ctx->log_to_syslog ([$facility])
		959
		960	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and
		961	all the others in the obvious way. If specified, then the C<$facility> is
		962	used as the facility (C<user>, C<auth>, C<local0> and so on). The default
		963	facility is C<user>.
		964
		965	Note that this function also sets a C<fmt_cb> - the logging part requires
		966	an array reference with [$level, $str] as input.
		967
		968	=cut
		969
		970	sub log_cb {
		971	my ($ctx, $cb) = @_;
		972
		973	$ctx->[3] = $cb;
		974	}
		975
		976	sub fmt_cb {
		977	my ($ctx, $cb) = @_;
		978
		979	$ctx->[4] = $cb;
		980	}
		981
		982	sub log_to_warn {
		983	my ($ctx, $path) = @_;
		984
		985	$ctx->log_cb (sub {
		986	warn shift;
		987	0
		988	});
		989	}
		990
		991	# this function is a good example of why threads are a must,
		992	# simply for priority inversion.
		993	sub _log_to_disk {
		994	# eval'uating this at runtime saves 220kb rss - perl has become
		995	# an insane memory waster.
		996	eval q{ # poor man's autoloading {}
		997	sub _log_to_disk {
		998	my ($ctx, $path, $keepopen) = @_;
		999
		1000	my $fh;
		1001	my @queue;
		1002	my $delay;
		1003	my $disable;
		1004
		1005	use AnyEvent::IO ();
		1006
		1007	my $kick = sub {
		1008	undef $delay;
		1009	return unless @queue;
		1010	$delay = 1;
		1011
		1012	# we pass $kick to $kick, so $kick itself doesn't keep a reference to $kick.
		1013	my $kick = shift;
		1014
		1015	# write one or more messages
		1016	my $write = sub {
		1017	# we write as many messages as have been queued
		1018	my $data = join "", @queue;
		1019	@queue = ();
		1020
		1021	AnyEvent::IO::aio_write $fh, $data, sub {
		1022	$disable = 1;
		1023	@_
		1024	? ($_[0] == length $data or AE::log 4 => "unable to write to logfile '$path': short write")
		1025	: AE::log 4 => "unable to write to logfile '$path': $!";
		1026	undef $disable;
		1027
		1028	if ($keepopen) {
		1029	$kick->($kick);
		1030	} else {
		1031	AnyEvent::IO::aio_close ($fh, sub {
		1032	undef $fh;
		1033	$kick->($kick);
		1034	});
		1035	}
		1036	};
		1037	};
		1038
		1039	if ($fh) {
		1040	$write->();
		1041	} else {
		1042	AnyEvent::IO::aio_open
		1043	$path,
		1044	AnyEvent::IO::O_CREAT | AnyEvent::IO::O_WRONLY | AnyEvent::IO::O_APPEND,
		1045	0666,
		1046	sub {
		1047	$fh = shift
		1048	or do {
		1049	$disable = 1;
		1050	AE::log 4 => "unable to open logfile '$path': $!";
		1051	undef $disable;
		1052	return;
		1053	};
		1054
		1055	$write->();
		1056	}
		1057	;
		1058	}
		1059	};
		1060
		1061	$ctx->log_cb (sub {
		1062	return if $disable;
		1063	push @queue, shift;
		1064	$kick->($kick) unless $delay;
		1065	0
		1066	});
		1067
		1068	$kick->($kick) if $keepopen; # initial open
		1069	};
		1070	};
		1071	die if $@;
		1072	&_log_to_disk
		1073	}
		1074
		1075	sub log_to_file {
		1076	my ($ctx, $path) = @_;
		1077
		1078	_log_to_disk $ctx, $path, 1;
		1079	}
		1080
		1081	sub log_to_path {
		1082	my ($ctx, $path) = @_;
		1083
		1084	_log_to_disk $ctx, $path, 0;
		1085	}
		1086
		1087	sub log_to_syslog {
		1088	my ($ctx, $facility) = @_;
		1089
		1090	require Sys::Syslog;
		1091
		1092	$ctx->fmt_cb (sub {
		1093	my $str = $_[3];
		1094	$str =~ s/\n(?=.)/\n+ /g;
		1095
		1096	[$_[2], "($_[1][0]) $str"]
		1097	});
		1098
		1099	$facility ||= "user";
		1100
		1101	$ctx->log_cb (sub {
		1102	my $lvl = $_[0][0] < 9 ? $_[0][0] : 8;
		1103
		1104	Sys::Syslog::syslog ("$facility|" . ($lvl - 1), $_)
		1105	for split /\n/, $_[0][1];
		1106
		1107	0
		1108	});
		1109	}
		1110
		1111	=back
		1112
		1113	=head3 MESSAGE LOGGING
		1114
		1115	These methods allow you to log messages directly to a context, without
		1116	going via your package context.
		1117
		1118	=over 4
		1119
		1120	=item $ctx->log ($level, $msg[, @params])
		1121
		1122	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		1123
		1124	Example: log a message in the context of another package.
		1125
		1126	(AnyEvent::Log::ctx "Other::Package")->log (warn => "heely bo");
		1127
		1128	=item $logger = $ctx->logger ($level[, \$enabled])
		1129
		1130	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		1131	context.
		1132
		1133	=cut
		1134
		1135	*log = \&AnyEvent::Log::_log;
		1136	*logger = \&AnyEvent::Log::_logger;
		1137
		1138	=back
		1139
		1140	=cut
		1141
		1142	package AnyEvent::Log;
		1143
		1144	=head1 CONFIGURATION VIA $ENV{PERL_ANYEVENT_LOG}
		1145
		1146	Logging can also be configured by setting the environment variable
		1147	C<PERL_ANYEVENT_LOG> (or C<AE_LOG>).
		1148
		1149	The value consists of one or more logging context specifications separated
		1150	by C<:> or whitespace. Each logging specification in turn starts with a
		1151	context name, followed by C<=>, followed by zero or more comma-separated
		1152	configuration directives, here are some examples:
		1153
		1154	# set default logging level
		1155	filter=warn
		1156
		1157	# log to file instead of to stderr
		1158	log=file=/tmp/mylog
		1159
		1160	# log to file in addition to stderr
		1161	log=+%file:%file=file=/tmp/mylog
		1162
		1163	# enable debug log messages, log warnings and above to syslog
		1164	filter=debug:log=+%warnings:%warnings=warn,syslog=LOG_LOCAL0
		1165
		1166	# log trace messages (only) from AnyEvent::Debug to file
		1167	AnyEvent::Debug=+%trace:%trace=only,trace,file=/tmp/tracelog
		1168
		1169	A context name in the log specification can be any of the following:
		1170
		1171	=over 4
		1172
		1173	=item C<collect>, C<filter>, C<log>
		1174
		1175	Correspond to the three predefined C<$AnyEvent::Log::COLLECT>,
		1176	C<AnyEvent::Log::FILTER> and C<$AnyEvent::Log::LOG> contexts.
		1177
		1178	=item C<%name>
		1179
		1180	Context names starting with a C<%> are anonymous contexts created when the
		1181	name is first mentioned. The difference to package contexts is that by
		1182	default they have no attached slaves.
		1183
		1184	=item a perl package name
		1185
		1186	Any other string references the logging context associated with the given
		1187	Perl C<package>. In the unlikely case where you want to specify a package
		1188	context that matches on of the other context name forms, you can add a
		1189	C<::> to the package name to force interpretation as a package.
		1190
		1191	=back
		1192
		1193	The configuration specifications can be any number of the following:
		1194
		1195	=over 4
		1196
		1197	=item C<stderr>
		1198
		1199	Configures the context to use Perl's C<warn> function (which typically
		1200	logs to C<STDERR>). Works like C<log_to_warn>.
		1201
		1202	=item C<file=>I<path>
		1203
		1204	Configures the context to log to a file with the given path. Works like
		1205	C<log_to_file>.
		1206
		1207	=item C<path=>I<path>
		1208
		1209	Configures the context to log to a file with the given path. Works like
		1210	C<log_to_path>.
		1211
		1212	=item C<syslog> or C<syslog=>I<expr>
		1213
		1214	Configures the context to log to syslog. If I<expr> is given, then it is
		1215	evaluated in the L<Sys::Syslog> package, so you could use:
		1216
		1217	log=syslog=LOG_LOCAL0
		1218
		1219	=item C<nolog>
		1220
		1221	Configures the context to not log anything by itself, which is the
		1222	default. Same as C<< $ctx->log_cb (undef) >>.
		1223
		1224	=item C<cap=>I<level>
		1225
		1226	Caps logging messages entering this context at the given level, i.e.
		1227	reduces the priority of messages with higher priority than this level. The
		1228	default is C<0> (or C<off>), meaning the priority will not be touched.
		1229
		1230	=item C<0> or C<off>
		1231
		1232	Sets the logging level of the context to C<0>, i.e. all messages will be
		1233	filtered out.
		1234
		1235	=item C<all>
		1236
		1237	Enables all logging levels, i.e. filtering will effectively be switched
		1238	off (the default).
		1239
		1240	=item C<only>
		1241
		1242	Disables all logging levels, and changes the interpretation of following
		1243	level specifications to enable the specified level only.
		1244
		1245	Example: only enable debug messages for a context.
		1246
		1247	context=only,debug
		1248
		1249	=item C<except>
		1250
		1251	Enables all logging levels, and changes the interpretation of following
		1252	level specifications to disable that level. Rarely used.
		1253
		1254	Example: enable all logging levels except fatal and trace (this is rather
		1255	nonsensical).
		1256
		1257	filter=exept,fatal,trace
		1258
		1259	=item C<level>
		1260
		1261	Enables all logging levels, and changes the interpretation of following
		1262	level specifications to be "that level or any higher priority
		1263	message". This is the default.
		1264
		1265	Example: log anything at or above warn level.
		1266
		1267	filter=warn
		1268
		1269	# or, more verbose
		1270	filter=only,level,warn
		1271
		1272	=item C<1>..C<9> or a logging level name (C<error>, C<debug> etc.)
		1273
		1274	A numeric loglevel or the name of a loglevel will be interpreted according
		1275	to the most recent C<only>, C<except> or C<level> directive. By default,
		1276	specifying a logging level enables that and any higher priority messages.
		1277
		1278	=item C<+>I<context>
		1279
		1280	Attaches the named context as slave to the context.
		1281
		1282	=item C<+>
		1283
		1284	A lone C<+> detaches all contexts, i.e. clears the slave list from the
		1285	context. Anonymous (C<%name>) contexts have no attached slaves by default,
		1286	but package contexts have the parent context as slave by default.
		1287
		1288	Example: log messages from My::Module to a file, do not send them to the
		1289	default log collector.
		1290
		1291	My::Module=+,file=/tmp/mymodulelog
		1292
		1293	=back
		1294
		1295	Any character can be escaped by prefixing it with a C<\> (backslash), as
		1296	usual, so to log to a file containing a comma, colon, backslash and some
		1297	spaces in the filename, you would do this:
		1298
		1299	PERL_ANYEVENT_LOG='log=file=/some\ \:file\ with\,\ \\-escapes'
		1300
		1301	Since whitespace (which includes newlines) is allowed, it is fine to
		1302	specify multiple lines in C<PERL_ANYEVENT_LOG>, e.g.:
		1303
		1304	PERL_ANYEVENT_LOG="
		1305	filter=warn
		1306	AnyEvent::Debug=+%trace
		1307	%trace=only,trace,+log
		1308	" myprog
		1309
		1310	Also, in the unlikely case when you want to concatenate specifications,
		1311	use whitespace as separator, as C<::> will be interpreted as part of a
		1312	module name, an empty spec with two separators:
		1313
		1314	PERL_ANYEVENT_LOG="$PERL_ANYEVENT_LOG MyMod=debug"
		1315
		1316	=cut
		1317
		1318	for (my $spec = $ENV{PERL_ANYEVENT_LOG}) {
		1319	my %anon;
		1320
		1321	my $pkg = sub {
		1322	$_[0] eq "log" ? $LOG
		1323	: $_[0] eq "filter" ? $FILTER
		1324	: $_[0] eq "collect" ? $COLLECT
		1325	: $_[0] =~ /^%(.+)$/ ? ($anon{$1} ||= do { my $ctx = ctx undef; $ctx->[0] = $_[0]; $ctx })
		1326	: $_[0] =~ /^(.*?)(?:::)?$/ ? ctx "$1" # egad :/
		1327	: die # never reached?
		1328	};
		1329
		1330	/\G[[:space:]]+/gc; # skip initial whitespace
		1331
		1332	while (/\G((?:[^:=[:space:]]+|::|\\.)+)=/gc) {
		1333	my $ctx = $pkg->($1);
		1334	my $level = "level";
		1335
		1336	while (/\G((?:[^,:[:space:]]+|::|\\.)+)/gc) {
		1337	for ("$1") {
		1338	if ($_ eq "stderr" ) { $ctx->log_to_warn;
		1339	} elsif (/^file=(.+)/ ) { $ctx->log_to_file ("$1");
		1340	} elsif (/^path=(.+)/ ) { $ctx->log_to_path ("$1");
		1341	} elsif (/^syslog(?:=(.*))?/ ) { require Sys::Syslog; $ctx->log_to_syslog ("$1");
		1342	} elsif ($_ eq "nolog" ) { $ctx->log_cb (undef);
		1343	} elsif (/^cap=(.+)/ ) { $ctx->cap ("$1");
		1344	} elsif (/^\+(.+)$/ ) { $ctx->attach ($pkg->("$1"));
		1345	} elsif ($_ eq "+" ) { $ctx->slaves;
		1346	} elsif ($_ eq "off" or $_ eq "0") { $ctx->level (0);
		1347	} elsif ($_ eq "all" ) { $ctx->level ("all");
		1348	} elsif ($_ eq "level" ) { $ctx->level ("all"); $level = "level";
		1349	} elsif ($_ eq "only" ) { $ctx->level ("off"); $level = "enable";
		1350	} elsif ($_ eq "except" ) { $ctx->level ("all"); $level = "disable";
		1351	} elsif (/^\d$/ ) { $ctx->$level ($_);
		1352	} elsif (exists $STR2LEVEL{$_} ) { $ctx->$level ($_);
		1353	} else { die "PERL_ANYEVENT_LOG ($spec): parse error at '$_'\n";
		1354	}
		1355	}
		1356
		1357	/\G,/gc or last;
		1358	}
		1359
		1360	/\G[:[:space:]]+/gc or last;
		1361	}
		1362
		1363	/\G[[:space:]]+/gc; # skip trailing whitespace
		1364
		1365	if (/\G(.+)/g) {
		1366	die "PERL_ANYEVENT_LOG ($spec): parse error at '$1'\n";
		1367	}
		1368	}
		1369
		1370	=head1 EXAMPLES
		1371
		1372	This section shows some common configurations, both as code, and as
		1373	C<PERL_ANYEVENT_LOG> string.
		1374
		1375	=over 4
		1376
		1377	=item Setting the global logging level.
		1378
		1379	Either put C<PERL_ANYEVENT_VERBOSE=><number> into your environment before
		1380	running your program, use C<PERL_ANYEVENT_LOG> or modify the log level of
		1381	the root context at runtime:
		1382
		1383	PERL_ANYEVENT_VERBOSE=5 ./myprog
		1384
		1385	PERL_ANYEVENT_LOG=log=warn
		1386
		1387	$AnyEvent::Log::FILTER->level ("warn");
		1388
		1389	=item Append all messages to a file instead of sending them to STDERR.
		1390
		1391	This is affected by the global logging level.
		1392
		1393	$AnyEvent::Log::LOG->log_to_file ($path);
		1394
		1395	PERL_ANYEVENT_LOG=log=file=/some/path
		1396
		1397	=item Write all messages with priority C<error> and higher to a file.
		1398
		1399	This writes them only when the global logging level allows it, because
		1400	it is attached to the default context which is invoked I<after> global
		1401	filtering.
		1402
		1403	$AnyEvent::Log::FILTER->attach (
		1404	new AnyEvent::Log::Ctx log_to_file => $path);
		1405
		1406	PERL_ANYEVENT_LOG=filter=+%filelogger:%filelogger=file=/some/path
		1407
		1408	This writes them regardless of the global logging level, because it is
		1409	attached to the toplevel context, which receives all messages I<before>
		1410	the global filtering.
		1411
		1412	$AnyEvent::Log::COLLECT->attach (
		1413	new AnyEvent::Log::Ctx log_to_file => $path);
		1414
		1415	PERL_ANYEVENT_LOG=%filelogger=file=/some/path:collect=+%filelogger
		1416
		1417	In both cases, messages are still written to STDERR.
		1418
		1419	=item Additionally log all messages with C<warn> and higher priority to
		1420	C<syslog>, but cap at C<error>.
		1421
		1422	This logs all messages to the default log target, but also logs messages
		1423	with priority C<warn> or higher (and not filtered otherwise) to syslog
		1424	facility C<user>. Messages with priority higher than C<error> will be
		1425	logged with level C<error>.
		1426
		1427	$AnyEvent::Log::LOG->attach (
		1428	new AnyEvent::Log::Ctx
		1429	level => "warn",
		1430	cap => "error",
		1431	syslog => "user",
		1432	);
		1433
		1434	PERL_ANYEVENT_LOG=log=+%syslog:%syslog=warn,cap=error,syslog
		1435
		1436	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		1437
		1438	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		1439	context - this simply circumvents the global filtering for trace messages.
		1440
		1441	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		1442	$debug->attach ($AnyEvent::Log::LOG);
		1443
		1444	PERL_ANYEVENT_LOG=AnyEvent::Debug=+log
		1445
		1446	This of course works for any package, not just L<AnyEvent::Debug>, but
		1447	assumes the log level for AnyEvent::Debug hasn't been changed from the
		1448	default.
		1449
		1450	=back
		1451
257	=head1 AUTHOR	1452	=head1 AUTHOR
258		1453
259	Marc Lehmann <schmorp@schmorp.de>	1454	Marc Lehmann <schmorp@schmorp.de>
260	http://home.schmorp.de/	1455	http://software.schmorp.de/pkg/AnyEvent.html
261		1456
262	=cut	1457	=cut
		1458
		1459	1
		1460

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