[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent/Log.pm

Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.2 by root, Tue Aug 16 14:47:27 2011 UTC vs.
Revision 1.18 by root, Sat Aug 20 15:57:35 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 use
		8	use AnyEvent;
		9
		10	AE::log debug => "hit my knee";
		11	AE::log warn => "it's a bit too hot";
		12	AE::log error => "the flag was false!";
		13	AE::log fatal => "the bit toggled! run!";
		14
		15	# "complex" use
7	use AnyEvent::Log;	16	use AnyEvent::Log;
		17
		18	my $tracer = AnyEvent::Log::logger trace => \$my $trace;
		19
		20	$tracer->("i am here") if $trace;
		21	$tracer->(sub { "lots of data: " . Dumper $self }) if $trace;
		22
		23	# configuration
		24
		25	# set logging for the current package to errors and higher only
		26	AnyEvent::Log::ctx->level ("error");
		27
		28	# set logging globally to anything below debug
		29	$AnyEvent::Log::FILTER->level ("notice");
		30
		31	# see also EXAMPLES, below
8		32
9	=head1 DESCRIPTION	33	=head1 DESCRIPTION
10		34
11	This module implements a relatively simple "logging framework". It doesn't	35	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	36	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	37	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	38	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	39	using it from other modules as well.
16		40
17	Remember that the default verbosity level is C<0>, so nothing	41	Remember that the default verbosity level is C<0>, so nothing will be
18	will be logged, ever, unless you set C<$Anyvent::VERBOSE> or	42	logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number before
19	C<PERL_ANYEVENT_VERBOSE> to a higher number.	43	starting your program, or change the logging level at runtime with
		44	something like:
20		45
21	Possible future extensions are to allow custom log targets (where the	46	use AnyEvent::Log;
22	level is an object), log filtering based on package, formatting, aliasing	47	AnyEvent::Log::FILTER->level ("info");
23	or package groups.
24		48
		49	The design goal behind this module was to keep it simple (and small),
		50	but make it powerful enough to be potentially useful for any module, and
		51	extensive enough for the most common tasks, such as logging to multiple
		52	targets, or being able to log into a database.
		53
		54	The amount of documentation might indicate otherwise, but the module is
		55	still just below 300 lines of code.
		56
		57	=head1 LOGGING LEVELS
		58
		59	Logging levels in this module range from C<1> (highest priority) to C<9>
		60	(lowest priority). Note that the lowest numerical value is the highest
		61	priority, so when this document says "higher priority" it means "lower
		62	numerical value".
		63
		64	Instead of specifying levels by name you can also specify them by aliases:
		65
		66	LVL NAME SYSLOG PERL NOTE
		67	1 fatal emerg exit aborts program!
		68	2 alert
		69	3 critical crit
		70	4 error err die
		71	5 warn warning
		72	6 note notice
		73	7 info
		74	8 debug
		75	9 trace
		76
		77	As you can see, some logging levels have multiple aliases - the first one
		78	is the "official" name, the second one the "syslog" name (if it differs)
		79	and the third one the "perl" name, suggesting that you log C<die> messages
		80	at C<error> priority.
		81
		82	You can normally only log a single message at highest priority level
		83	(C<1>, C<fatal>), because logging a fatal message will also quit the
		84	program - so use it sparingly :)
		85
		86	Some methods also offer some extra levels, such as C<0>, C<off>, C<none>
		87	or C<all> - these are only valid in the methods they are documented for.
		88
25	=head1 LOG FUNCTIONS	89	=head1 LOGGING FUNCTIONS
26		90
27	These functions allow you to log messages. They always use the caller's	91	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	92	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>	93	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is
30	module is loaded.	94	loaded.
31		95
32	=over 4	96	=over 4
33		97
34	=cut	98	=cut
35		99
…		…
37		101
38	use Carp ();	102	use Carp ();
39	use POSIX ();	103	use POSIX ();
40		104
41	use AnyEvent (); BEGIN { AnyEvent::common_sense }	105	use AnyEvent (); BEGIN { AnyEvent::common_sense }
		106	use AnyEvent::Util ();
		107
		108	our $VERSION = $AnyEvent::VERSION;
		109
		110	our ($COLLECT, $FILTER, $LOG);
42		111
43	our ($now_int, $now_str1, $now_str2);	112	our ($now_int, $now_str1, $now_str2);
44		113
45	# Format Time, not public - yet?	114	# Format Time, not public - yet?
46	sub ft($) {	115	sub ft($) {
…		…
51	if $now_int != $i;	120	if $now_int != $i;
52		121
53	"$now_str1$f$now_str2"	122	"$now_str1$f$now_str2"
54	}	123	}
55		124
		125	our %CTX; # all package contexts
		126
		127	# creates a default package context object for the given package
		128	sub _pkg_ctx($) {
		129	my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx";
		130
		131	# link "parent" package
		132	my $parent = $_[0] =~ /^(.+)::/
		133	? $CTX{$1} \|\|= &_pkg_ctx ("$1")
		134	: $COLLECT;
		135
		136	$ctx->[2]{$parent+0} = $parent;
		137
		138	$ctx
		139	}
		140
56	=item AnyEvent::Log::log $level, $msg[, @args]	141	=item AnyEvent::Log::log $level, $msg[, @args]
57		142
58	Requests logging of the given C<$msg> with the given log level (1..9).	143	Requests logging of the given C<$msg> with the given log level.
59	You can also use the following strings as log level: C<fatal> (1),
60	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
61	C<info> (7), C<debug> (8), C<trace> (9).
62		144
63	For C<fatal> log levels, the program will abort.	145	For C<fatal> log levels, the program will abort.
64		146
65	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	147	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the
66	C<$msg> is interpreted as an sprintf format string.	148	C<$msg> is interpreted as an sprintf format string.
67		149
68	The C<$msg> should not end with C<\n>, but may if that is convenient for	150	The C<$msg> should not end with C<\n>, but may if that is convenient for
69	you. Also, multiline messages are handled properly.	151	you. Also, multiline messages are handled properly.
70		152
71	In addition, for possible future expansion, C<$msg> must not start with an	153	Last not least, C<$msg> might be a code reference, in which case it is
72	angle bracket (C<< < >>).	154	supposed to return the message. It will be called only then the message
		155	actually gets logged, which is useful if it is costly to create the
		156	message in the first place.
73		157
74	Whether the given message will be logged depends on the maximum log level	158	Whether the given message will be logged depends on the maximum log level
75	and the caller's package.	159	and the caller's package.
76		160
77	Note that you can (and should) call this function as C<AnyEvent::log> or	161	Note that you can (and should) call this function as C<AnyEvent::log> or
78	C<AE::log>, without C<use>-ing this module if possible, as those functions	162	C<AE::log>, without C<use>-ing this module if possible (i.e. you don't
79	will laod the logging module on demand only.	163	need any additional functionality), as those functions will load the
		164	logging module on demand only. They are also much shorter to write.
		165
		166	Also, if you optionally generate a lot of debug messages (such as when
		167	tracing some code), you should look into using a logger callback and a
		168	boolean enabler (see C<logger>, below).
		169
		170	Example: log something at error level.
		171
		172	AE::log error => "something";
		173
		174	Example: use printf-formatting.
		175
		176	AE::log info => "%5d %-10.10s %s", $index, $category, $msg;
		177
		178	Example: only generate a costly dump when the message is actually being logged.
		179
		180	AE::log debug => sub { require Data::Dump; Data::Dump::dump \%cache };
80		181
81	=cut	182	=cut
82		183
83	# also allow syslog equivalent names	184	# also allow syslog equivalent names
84	our %STR2LEVEL = (	185	our %STR2LEVEL = (
85	fatal => 1, emerg => 1,	186	fatal => 1, emerg => 1, exit => 1,
86	alert => 2,	187	alert => 2,
87	critical => 3, crit => 3,	188	critical => 3, crit => 3,
88	error => 4, err => 4,	189	error => 4, err => 4, die => 4,
89	warn => 5, warning => 5,	190	warn => 5, warning => 5,
90	note => 6, notice => 6,	191	note => 6, notice => 6,
91	info => 7,	192	info => 7,
92	debug => 8,	193	debug => 8,
93	trace => 9,	194	trace => 9,
94	);	195	);
95		196
		197	sub now () { time }
		198
		199	AnyEvent::post_detect {
		200	*now = \&AE::now;
		201	};
		202
96	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	203	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
97		204
		205	# time, ctx, level, msg
		206	sub _format($$$$) {
		207	my $ts = ft $_[0];
		208	my $ct = " ";
		209
		210	my @res;
		211
		212	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		213	push @res, "$ts$ct$_\n";
		214	$ct = " + ";
		215	}
		216
		217	join "", @res
		218	}
		219
		220	sub _log {
		221	my ($ctx, $level, $format, @args) = @_;
		222
		223	$level = $level > 0 && $level <= 9
		224	? $level+0
		225	: $STR2LEVEL{$level} \|\| Carp::croak "$level: not a valid logging level, caught";
		226
		227	my $mask = 1 << $level;
		228
		229	my (%seen, @ctx, $now, $fmt);
		230
		231	do
		232	{
		233	# skip if masked
		234	if ($ctx->[1] & $mask && !$seen{$ctx+0}++) {
		235	if ($ctx->[3]) {
		236	# logging target found
		237
		238	# now get raw message, unless we have it already
		239	unless ($now) {
		240	$format = $format->() if ref $format;
		241	$format = sprintf $format, @args if @args;
		242	$format =~ s/\n$//;
		243	$now = AE::now;
		244	};
		245
		246	# format msg
		247	my $str = $ctx->[4]
		248	? $ctx->[4]($now, $_[0], $level, $format)
		249	: $fmt \|\|= _format $now, $_[0], $level, $format;
		250
		251	$ctx->[3]($str)
		252	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
		253	} else {
		254	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		255	}
		256	}
		257	}
		258	while $ctx = pop @ctx;
		259
		260	exit 1 if $level <= 1;
		261	}
		262
98	sub log($$;@) {	263	sub log($$;@) {
99	my ($targ, $msg, @args) = @_;	264	_log
		265	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		266	@_;
		267	}
100		268
101	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	269	AnyEvent::log = AE::log = \&log;
102	: $targ > 0 && $targ <= 9 ? $targ+0
103	: $STR2LEVEL{$targ} \|\| Carp::croak "$targ: not a valid logging level, caught";
104		270
105	return if $level > $AnyEvent::VERBOSE;	271	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
106		272
107	my $pkg = (caller)[0];	273	Creates a code reference that, when called, acts as if the
		274	C<AnyEvent::Log::log> function was called at this point with the givne
		275	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
		276	the C<AnyEvent::Log::log> function:
108		277
109	$msg = sprintf $msg, @args if @args;	278	my $debug_log = AnyEvent::Log::logger "debug";
110	$msg =~ s/\n$//;
111		279
112	# now we have a message, log it	280	$debug_log->("debug here");
113	#TODO: could do LOTS of stuff here, and should, at least in some later version	281	$debug_log->("%06d emails processed", 12345);
		282	$debug_log->(sub { $obj->as_string });
114		283
115	$msg = sprintf "%5s (%s) %s", $LEVEL2STR[$level], $pkg, $msg;	284	The idea behind this function is to decide whether to log before actually
116	my $pfx = ft AE::now;	285	logging - when the C<logger> function is called once, but the returned
		286	logger callback often, then this can be a tremendous speed win.
117		287
118	for (split /\n/, $msg) {	288	Despite this speed advantage, changes in logging configuration will
119	printf STDERR "$pfx $_\n";	289	still be reflected by the logger callback, even if configuration changes
120	$pfx = "\t";	290	I<after> it was created.
		291
		292	To further speed up logging, you can bind a scalar variable to the logger,
		293	which contains true if the logger should be called or not - if it is
		294	false, calling the logger can be safely skipped. This variable will be
		295	updated as long as C<$logger> is alive.
		296
		297	Full example:
		298
		299	# near the init section
		300	use AnyEvent::Log;
		301
		302	my $debug_log = AnyEvent:Log::logger debug => \my $debug;
		303
		304	# and later in your program
		305	$debug_log->("yo, stuff here") if $debug;
		306
		307	$debug and $debug_log->("123");
		308
		309	=cut
		310
		311	our %LOGGER;
		312
		313	# re-assess logging status for all loggers
		314	sub _reassess {
		315	local $SIG{__DIE__};
		316	my $die = sub { die };
		317
		318	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
		319	my ($ctx, $level, $renabled) = @$_;
		320
		321	# to detect whether a message would be logged, we actually
		322	# try to log one and die. this isn't fast, but we can be
		323	# sure that the logging decision is correct :)
		324
		325	$$renabled = !eval {
		326	_log $ctx, $level, $die;
		327
		328	1
		329	};
121	}	330	}
122
123	exit 1 if $level <= 1;
124	}	331	}
125		332
126	AnyEvent::log = AE::log = \&log;	333	sub _logger {
		334	my ($ctx, $level, $renabled) = @_;
127		335
128	#TODO	336	$$renabled = 1;
		337
		338	my $logger = [$ctx, $level, $renabled];
		339
		340	$LOGGER{$logger+0} = $logger;
		341
		342	_reassess $logger+0;
		343
		344	my $guard = AnyEvent::Util::guard {
		345	# "clean up"
		346	delete $LOGGER{$logger+0};
		347	};
		348
		349	sub {
		350	$guard if 0; # keep guard alive, but don't cause runtime overhead
		351
		352	_log $ctx, $level, @_
		353	if $$renabled;
		354	}
		355	}
		356
		357	sub logger($;$) {
		358	_logger
		359	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		360	@_
		361	}
129		362
130	=back	363	=back
131		364
132	=head1 CONFIGURATION FUNCTIONALITY	365	=head1 LOGGING CONTEXTS
133		366
134	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	367	This module associates every log message with a so-called I<logging
		368	context>, based on the package of the caller. Every perl package has its
		369	own logging context.
		370
		371	A logging context has three major responsibilities: filtering, logging and
		372	propagating the message.
		373
		374	For the first purpose, filtering, each context has a set of logging
		375	levels, called the log level mask. Messages not in the set will be ignored
		376	by this context (masked).
		377
		378	For logging, the context stores a formatting callback (which takes the
		379	timestamp, context, level and string message and formats it in the way
		380	it should be logged) and a logging callback (which is responsible for
		381	actually logging the formatted message and telling C<AnyEvent::Log>
		382	whether it has consumed the message, or whether it should be propagated).
		383
		384	For propagation, a context can have any number of attached I<slave
		385	contexts>. Any message that is neither masked by the logging mask nor
		386	masked by the logging callback returning true will be passed to all slave
		387	contexts.
		388
		389	Each call to a logging function will log the message at most once per
		390	context, so it does not matter (much) if there are cycles or if the
		391	message can arrive at the same context via multiple paths.
		392
		393	=head2 DEFAULTS
		394
		395	By default, all logging contexts have an full set of log levels ("all"), a
		396	disabled logging callback and the default formatting callback.
		397
		398	Package contexts have the package name as logging title by default.
		399
		400	They have exactly one slave - the context of the "parent" package. The
		401	parent package is simply defined to be the package name without the last
		402	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		403	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		404	exception of the rule - just like the "parent" of any single-component
		405	package name in Perl is C<main>, the default slave of any top-level
		406	package context is C<$AnyEvent::Log::COLLECT>.
		407
		408	Since perl packages form only an approximate hierarchy, this slave
		409	context can of course be removed.
		410
		411	All other (anonymous) contexts have no slaves and an empty title by
		412	default.
		413
		414	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		415	context that simply logs everything via C<warn>, without propagating
		416	anything anywhere by default. The purpose of this context is to provide
		417	a convenient place to override the global logging target or to attach
		418	additional log targets. It's not meant for filtering.
		419
		420	It then creates the C<$AnyEvent::Log::FILTER> context whose
		421	purpose is to suppress all messages with priority higher
		422	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		423	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		424	is to simply provide filtering according to some global log level.
		425
		426	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		427	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		428	leaves it at default config. Its purpose is simply to collect all log
		429	messages system-wide.
		430
		431	The hierarchy is then:
		432
		433	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		434
		435	The effect of all this is that log messages, by default, wander up to the
		436	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		437	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		438	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		439	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		440
		441	This makes it easy to set a global logging level (by modifying $FILTER),
		442	but still allow other contexts to send, for example, their debug and trace
		443	messages to the $LOG target despite the global logging level, or to attach
		444	additional log targets that log messages, regardless of the global logging
		445	level.
		446
		447	It also makes it easy to modify the default warn-logger ($LOG) to
		448	something that logs to a file, or to attach additional logging targets
		449	(such as loggign to a file) by attaching it to $FILTER.
		450
		451	=head2 CREATING/FINDING/DESTROYING CONTEXTS
135		452
136	=over 4	453	=over 4
137		454
		455	=item $ctx = AnyEvent::Log::ctx [$pkg]
		456
		457	This function creates or returns a logging context (which is an object).
		458
		459	If a package name is given, then the context for that packlage is
		460	returned. If it is called without any arguments, then the context for the
		461	callers package is returned (i.e. the same context as a C<AE::log> call
		462	would use).
		463
		464	If C<undef> is given, then it creates a new anonymous context that is not
		465	tied to any package and is destroyed when no longer referenced.
		466
138	=cut	467	=cut
		468
		469	sub ctx(;$) {
		470	my $pkg = @_ ? shift : (caller)[0];
		471
		472	ref $pkg
		473	? $pkg
		474	: defined $pkg
		475	? $CTX{$pkg} \|\|= AnyEvent::Log::_pkg_ctx $pkg
		476	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		477	}
		478
		479	=item AnyEvent::Log::reset
		480
		481	Resets all package contexts and recreates the default hierarchy if
		482	necessary, i.e. resets the logging subsystem to defaults, as much as
		483	possible. This process keeps references to contexts held by other parts of
		484	the program intact.
		485
		486	This can be used to implement config-file (re-)loading: before loading a
		487	configuration, reset all contexts.
		488
		489	=cut
		490
		491	sub reset {
		492	# hard to kill complex data structures
		493	# we recreate all package loggers and reset the hierarchy
		494	while (my ($k, $v) = each %CTX) {
		495	@$v = ($k, (1 << 10) - 1 - 1, { });
		496
		497	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log);
		498	}
		499
		500	$LOG->slaves;
		501	$LOG->title ('$AnyEvent::Log::LOG');
		502	$LOG->log_cb (sub {
		503	warn shift;
		504	0
		505	});
		506
		507	$FILTER->slaves ($LOG);
		508	$FILTER->title ('$AnyEvent::Log::FILTER');
		509	$FILTER->level ($AnyEvent::VERBOSE);
		510
		511	$COLLECT->slaves ($FILTER);
		512	$COLLECT->title ('$AnyEvent::Log::FILTER');
		513
		514	_reassess;
		515	}
		516
		517	# create the default logger contexts
		518	$LOG = ctx undef;
		519	$FILTER = ctx undef;
		520	$COLLECT = ctx undef;
		521
		522	AnyEvent::Log::reset;
		523
		524	# hello, CPAN, please catch me
		525	package AnyEvent::Log::LOG;
		526	package AE::Log::LOG;
		527	package AnyEvent::Log::FILTER;
		528	package AE::Log::FILTER;
		529	package AnyEvent::Log::COLLECT;
		530	package AE::Log::COLLECT;
		531
		532	package AnyEvent::Log::Ctx;
		533
		534	# 0 1 2 3 4
		535	# [$title, $level, %$slaves, &$logcb, &$fmtcb]
		536
		537	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		538
		539	This is a convenience constructor that makes it simpler to construct
		540	anonymous logging contexts.
		541
		542	Each key-value pair results in an invocation of the method of the same
		543	name as the key with the value as parameter, unless the value is an
		544	arrayref, in which case it calls the method with the contents of the
		545	array. The methods are called in the same order as specified.
		546
		547	Example: create a new logging context and set both the default logging
		548	level, some slave contexts and a logging callback.
		549
		550	$ctx = new AnyEvent::Log::Ctx
		551	title => "dubious messages",
		552	level => "error",
		553	log_cb => sub { print STDOUT shift; 0 },
		554	slaves => [$ctx1, $ctx, $ctx2],
		555	;
		556
		557	=back
		558
		559	=cut
		560
		561	sub new {
		562	my $class = shift;
		563
		564	my $ctx = AnyEvent::Log::ctx undef;
		565
		566	while (@_) {
		567	my ($k, $v) = splice @_, 0, 2;
		568	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		569	}
		570
		571	bless $ctx, $class # do we really support subclassing, hmm?
		572	}
		573
		574
		575	=head2 CONFIGURING A LOG CONTEXT
		576
		577	The following methods can be used to configure the logging context.
		578
		579	=over 4
		580
		581	=item $ctx->title ([$new_title])
		582
		583	Returns the title of the logging context - this is the package name, for
		584	package contexts, and a user defined string for all others.
		585
		586	If C<$new_title> is given, then it replaces the package name or title.
		587
		588	=cut
		589
		590	sub title {
		591	$_[0][0] = $_[1] if @_ > 1;
		592	$_[0][0]
		593	}
		594
		595	=back
		596
		597	=head3 LOGGING LEVELS
		598
		599	The following methods deal with the logging level set associated with the
		600	log context.
		601
		602	The most common method to use is probably C<< $ctx->level ($level) >>,
		603	which configures the specified and any higher priority levels.
		604
		605	All functions which accept a list of levels also accept the special string
		606	C<all> which expands to all logging levels.
		607
		608	=over 4
		609
		610	=item $ctx->levels ($level[, $level...)
		611
		612	Enables logging for the given levels and disables it for all others.
		613
		614	=item $ctx->level ($level)
		615
		616	Enables logging for the given level and all lower level (higher priority)
		617	ones. In addition to normal logging levels, specifying a level of C<0> or
		618	C<off> disables all logging for this level.
		619
		620	Example: log warnings, errors and higher priority messages.
		621
		622	$ctx->level ("warn");
		623	$ctx->level (5); # same thing, just numeric
		624
		625	=item $ctx->enable ($level[, $level...])
		626
		627	Enables logging for the given levels, leaving all others unchanged.
		628
		629	=item $ctx->disable ($level[, $level...])
		630
		631	Disables logging for the given levels, leaving all others unchanged.
		632
		633	=cut
		634
		635	sub _lvl_lst {
		636	map {
		637	$_ > 0 && $_ <= 9 ? $_+0
		638	: $_ eq "all" ? (1 .. 9)
		639	: $STR2LEVEL{$_} \|\| Carp::croak "$_: not a valid logging level, caught"
		640	} @_
		641	}
		642
		643	our $NOP_CB = sub { 0 };
		644
		645	sub levels {
		646	my $ctx = shift;
		647	$ctx->[1] = 0;
		648	$ctx->[1] \|= 1 << $_
		649	for &_lvl_lst;
		650	AnyEvent::Log::_reassess;
		651	}
		652
		653	sub level {
		654	my $ctx = shift;
		655	my $lvl = $_[0] =~ /^(?:0\|off\|none)$/ ? 0 : (_lvl_lst $_[0])[-1];
		656
		657	$ctx->[1] = ((1 << $lvl) - 1) << 1;
		658	AnyEvent::Log::_reassess;
		659	}
		660
		661	sub enable {
		662	my $ctx = shift;
		663	$ctx->[1] \|= 1 << $_
		664	for &_lvl_lst;
		665	AnyEvent::Log::_reassess;
		666	}
		667
		668	sub disable {
		669	my $ctx = shift;
		670	$ctx->[1] &= ~(1 << $_)
		671	for &_lvl_lst;
		672	AnyEvent::Log::_reassess;
		673	}
		674
		675	=back
		676
		677	=head3 SLAVE CONTEXTS
		678
		679	The following methods attach and detach another logging context to a
		680	logging context.
		681
		682	Log messages are propagated to all slave contexts, unless the logging
		683	callback consumes the message.
		684
		685	=over 4
		686
		687	=item $ctx->attach ($ctx2[, $ctx3...])
		688
		689	Attaches the given contexts as slaves to this context. It is not an error
		690	to add a context twice (the second add will be ignored).
		691
		692	A context can be specified either as package name or as a context object.
		693
		694	=item $ctx->detach ($ctx2[, $ctx3...])
		695
		696	Removes the given slaves from this context - it's not an error to attempt
		697	to remove a context that hasn't been added.
		698
		699	A context can be specified either as package name or as a context object.
		700
		701	=item $ctx->slaves ($ctx2[, $ctx3...])
		702
		703	Replaces all slaves attached to this context by the ones given.
		704
		705	=cut
		706
		707	sub attach {
		708	my $ctx = shift;
		709
		710	$ctx->[2]{$_+0} = $_
		711	for map { AnyEvent::Log::ctx $_ } @_;
		712	}
		713
		714	sub detach {
		715	my $ctx = shift;
		716
		717	delete $ctx->[2]{$_+0}
		718	for map { AnyEvent::Log::ctx $_ } @_;
		719	}
		720
		721	sub slaves {
		722	undef $_[0][2];
		723	&attach;
		724	}
		725
		726	=back
		727
		728	=head3 LOG TARGETS
		729
		730	The following methods configure how the logging context actually does
		731	the logging (which consists of formatting the message and printing it or
		732	whatever it wants to do with it).
		733
		734	=over 4
		735
		736	=item $ctx->log_cb ($cb->($str))
		737
		738	Replaces the logging callback on the context (C<undef> disables the
		739	logging callback).
		740
		741	The logging callback is responsible for handling formatted log messages
		742	(see C<fmt_cb> below) - normally simple text strings that end with a
		743	newline (and are possibly multiline themselves).
		744
		745	It also has to return true iff it has consumed the log message, and false
		746	if it hasn't. Consuming a message means that it will not be sent to any
		747	slave context. When in doubt, return C<0> from your logging callback.
		748
		749	Example: a very simple logging callback, simply dump the message to STDOUT
		750	and do not consume it.
		751
		752	$ctx->log_cb (sub { print STDERR shift; 0 });
		753
		754	You can filter messages by having a log callback that simply returns C<1>
		755	and does not do anything with the message, but this counts as "message
		756	being logged" and might not be very efficient.
		757
		758	Example: propagate all messages except for log levels "debug" and
		759	"trace". The messages will still be generated, though, which can slow down
		760	your program.
		761
		762	$ctx->levels ("debug", "trace");
		763	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		764
		765	=item $ctx->log_to_file ($path)
		766
		767	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		768
		769	=item $ctx->log_to_path ($path)
		770
		771	Same as C<< ->log_to_file >>, but opens the file for each message. This
		772	is much slower, but allows you to change/move/rename/delete the file at
		773	basically any time.
		774
		775	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $ctx, $level, $message))
		776
		777	Replaces the formatting callback on the context (C<undef> restores the
		778	default formatter).
		779
		780	The callback is passed the (possibly fractional) timestamp, the original
		781	logging context, the (numeric) logging level and the raw message string
		782	and needs to return a formatted log message. In most cases this will be a
		783	string, but it could just as well be an array reference that just stores
		784	the values.
		785
		786	If, for some reaosn, you want to use C<caller> to find out more baout the
		787	logger then you should walk up the call stack until you are no longer
		788	inside the C<AnyEvent::Log> package.
		789
		790	Example: format just the raw message, with numeric log level in angle
		791	brackets.
		792
		793	$ctx->fmt_cb (sub {
		794	my ($time, $ctx, $lvl, $msg) = @_;
		795
		796	"<$lvl>$msg\n"
		797	});
		798
		799	Example: return an array reference with just the log values, and use
		800	C<PApp::SQL::sql_exec> to store the emssage in a database.
		801
		802	$ctx->fmt_cb (sub { \@_ });
		803	$ctx->log_cb (sub {
		804	my ($msg) = @_;
		805
		806	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		807	$msg->[0] + 0,
		808	"$msg->[1]",
		809	$msg->[2] + 0,
		810	"$msg->[3]";
		811
		812	0
		813	});
		814
		815	=cut
		816
		817	sub log_cb {
		818	my ($ctx, $cb) = @_;
		819
		820	$ctx->[3] = $cb;
		821	}
		822
		823	sub fmt_cb {
		824	my ($ctx, $cb) = @_;
		825
		826	$ctx->[4] = $cb;
		827	}
		828
		829	sub log_to_file {
		830	my ($ctx, $path) = @_;
		831
		832	open my $fh, ">>", $path
		833	or die "$path: $!";
		834
		835	$ctx->log_cb (sub {
		836	syswrite $fh, shift;
		837	0
		838	});
		839	}
		840
		841	sub log_to_file {
		842	my ($ctx, $path) = @_;
		843
		844	$ctx->log_cb (sub {
		845	open my $fh, ">>", $path
		846	or die "$path: $!";
		847
		848	syswrite $fh, shift;
		849	0
		850	});
		851	}
		852
		853	=back
		854
		855	=head3 MESSAGE LOGGING
		856
		857	These methods allow you to log messages directly to a context, without
		858	going via your package context.
		859
		860	=over 4
		861
		862	=item $ctx->log ($level, $msg[, @params])
		863
		864	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		865
		866	=item $logger = $ctx->logger ($level[, \$enabled])
		867
		868	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		869	context.
		870
		871	=cut
		872
		873	*log = \&AnyEvent::Log::_log;
		874	*logger = \&AnyEvent::Log::_logger;
139		875
140	1;	876	1;
		877
		878	=back
		879
		880	=head1 EXAMPLES
		881
		882	This section shows some common configurations.
		883
		884	=over 4
		885
		886	=item Setting the global logging level.
		887
		888	Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before
		889	running your program, or modify the log level of the root context:
		890
		891	PERL_ANYEVENT_VERBOSE=5 ./myprog
		892
		893	$AnyEvent::Log::FILTER->level ("warn");
		894
		895	=item Append all messages to a file instead of sending them to STDERR.
		896
		897	This is affected by the global logging level.
		898
		899	$AnyEvent::Log::LOG->log_to_file ($path); (sub {
		900
		901	=item Write all messages with priority C<error> and higher to a file.
		902
		903	This writes them only when the global logging level allows it, because
		904	it is attached to the default context which is invoked I<after> global
		905	filtering.
		906
		907	$AnyEvent::Log::FILTER->attach
		908	new AnyEvent::Log::Ctx log_to_file => $path);
		909
		910	This writes them regardless of the global logging level, because it is
		911	attached to the toplevel context, which receives all messages I<before>
		912	the global filtering.
		913
		914	$AnyEvent::Log::COLLECT->attach (
		915	new AnyEvent::Log::Ctx log_to_file => $path);
		916
		917	In both cases, messages are still written to STDERR.
		918
		919	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		920
		921	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		922	context - this simply circumvents the global filtering for trace messages.
		923
		924	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		925	$debug->attach ($AnyEvent::Log::LOG);
		926
		927	This of course works for any package, not just L<AnyEvent::Debug>, but
		928	assumes the log level for AnyEvent::Debug hasn't been changed from the
		929	default.
141		930
142	=back	931	=back
143		932
144	=head1 AUTHOR	933	=head1 AUTHOR
145		934

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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents): Revision 1.2 by root, Tue Aug 16 14:47:27 2011 UTC vs. Revision 1.18 by root, Sat Aug 20 15:57:35 2011 UTC

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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.2 by root, Tue Aug 16 14:47:27 2011 UTC vs.
Revision 1.18 by root, Sat Aug 20 15:57:35 2011 UTC