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

Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.6 by root, Wed Aug 17 22:34:11 2011 UTC vs.
Revision 1.12 by root, Sat Aug 20 01:33:10 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 this package to maximum
		26	AnyEvent::Log::ctx->level ("all");
		27
		28	# set logging globally to anything below debug
		29	(AnyEvent::Log::ctx "")->level ("notice");
		30
		31	# see also EXAMPLES, below
		32
		33	# disable logging for package "AnyEvent" and all packages below it
		34	AnyEvent->AnyEvent::Log::ctx->level (0);
		35
		36	# log everything below debug to a file, for the whole program
		37	my $ctx = AnyEvent::Log::ctx;
		38	$ctx->log_cb (sub { print FILE shift; 0 });
		39	(AnyEvent::Log::ctx "")->add ($ctx);
8		40
9	=head1 DESCRIPTION	41	=head1 DESCRIPTION
10		42
11	This module implements a relatively simple "logging framework". It doesn't	43	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	44	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	45	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	46	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	47	using it from other modules as well.
16		48
17	Remember that the default verbosity level is C<0>, so nothing will be	49	Remember that the default verbosity level is C<0>, so nothing will be
18	logged, ever, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number	50	logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number before
19	before starting your program.#TODO	51	starting your program, or change the logging level at runtime with
		52	something like:
20		53
21	Possible future extensions are to allow custom log targets (where the	54	use AnyEvent;
22	level is an object), log filtering based on package, formatting, aliasing	55	(AnyEvent::Log::ctx "")->level ("info");
23	or package groups.
24		56
		57	The design goal behind this module was to keep it simple (and small),
		58	but make it powerful enough to be potentially useful for any module, and
		59	extensive enough for the most common tasks, such as logging to multiple
		60	targets, or being able to log into a database.
		61
25	=head1 LOG FUNCTIONS	62	=head1 LOGGING FUNCTIONS
26		63
27	These functions allow you to log messages. They always use the caller's	64	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	65	package as a "logging module/source". Also, the main logging function is
29	easily available as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent>	66	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is
30	module is loaded.	67	loaded.
31		68
32	=over 4	69	=over 4
33		70
34	=cut	71	=cut
35		72
…		…
54	"$now_str1$f$now_str2"	91	"$now_str1$f$now_str2"
55	}	92	}
56		93
57	our %CTX; # all logging contexts	94	our %CTX; # all logging contexts
58		95
		96	# creates a default package context object for the given package
		97	sub _pkg_ctx($) {
		98	my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx";
		99
		100	# link "parent" package
		101	my $pkg = $_[0] =~ /^(.+)::/ ? $1 : "AE::Log::Top";
		102
		103	$pkg = $CTX{$pkg} \|\|= &_pkg_ctx ($pkg);
		104	$ctx->[2]{$pkg+0} = $pkg;
		105
		106	$ctx
		107	}
		108
59	=item AnyEvent::Log::log $level, $msg[, @args]	109	=item AnyEvent::Log::log $level, $msg[, @args]
60		110
61	Requests logging of the given C<$msg> with the given log level (1..9).	111	Requests logging of the given C<$msg> with the given log level (1..9).
62	You can also use the following strings as log level: C<fatal> (1),	112	You can also use the following strings as log level: C<fatal> (1),
63	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),	113	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
…		…
78		128
79	Whether the given message will be logged depends on the maximum log level	129	Whether the given message will be logged depends on the maximum log level
80	and the caller's package.	130	and the caller's package.
81		131
82	Note that you can (and should) call this function as C<AnyEvent::log> or	132	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	133	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.	134	need any additional functionality), as those functions will load the
		135	logging module on demand only. They are also much shorter to write.
		136
		137	Also, if you optionally generate a lot of debug messages (such as when
		138	tracing some code), you should look into using a logger callback and a
		139	boolean enabler (see C<logger>, below).
85		140
86	Example: log something at error level.	141	Example: log something at error level.
87		142
88	AE::log error => "something";	143	AE::log error => "something";
89		144
…		…
109	debug => 8,	164	debug => 8,
110	trace => 9,	165	trace => 9,
111	);	166	);
112		167
113	sub now () { time }	168	sub now () { time }
		169
114	AnyEvent::post_detect {	170	AnyEvent::post_detect {
115	*now = \&AE::now;	171	*now = \&AE::now;
116	};	172	};
117		173
118	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	174	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
119		175
		176	# time, ctx, level, msg
		177	sub _format($$$$) {
		178	my $ts = ft $_[0];
		179	my $ct = " ";
		180
		181	my @res;
		182
		183	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		184	push @res, "$ts$ct$_\n";
		185	$ct = " + ";
		186	}
		187
		188	join "", @res
		189	}
		190
120	sub _log {	191	sub _log {
121	my ($pkg, $targ, $msg, @args) = @_;	192	my ($ctx, $level, $format, @args) = @_;
122		193
123	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	194	$level = $level > 0 && $level <= 9
124	: $targ > 0 && $targ <= 9 ? $targ+0	195	? $level+0
125	: $STR2LEVEL{$targ} \|\| Carp::croak "$targ: not a valid logging level, caught";	196	: $STR2LEVEL{$level} \|\| Carp::croak "$level: not a valid logging level, caught";
126		197
127	#TODO: find actual targets, see if we even have to log	198	my $mask = 1 << $level;
128		199
129	return unless $level <= $AnyEvent::VERBOSE;	200	my (%seen, @ctx, $now, $fmt);
130		201
131	$msg = $msg->() if ref $msg;	202	do
132	$msg = sprintf $msg, @args if @args;	203	{
133	$msg =~ s/\n$//;	204	# skip if masked
		205	if ($ctx->[1] & $mask && !$seen{$ctx+0}++) {
		206	if ($ctx->[3]) {
		207	# logging target found
134		208
135	# now we have a message, log it	209	# now get raw message, unless we have it already
		210	unless ($now) {
		211	$format = $format->() if ref $format;
		212	$format = sprintf $format, @args if @args;
		213	$format =~ s/\n$//;
		214	$now = AE::now;
		215	};
136		216
137	# TODO: writers/processors/filters/formatters?	217	# format msg
		218	my $str = $ctx->[4]
		219	? $ctx->[4]($now, $_[0], $level, $format)
		220	: $fmt \|\|= _format $now, $_[0], $level, $format;
138		221
139	$msg = sprintf "%-5s %s: %s", $LEVEL2STR[$level], $pkg, $msg;	222	$ctx->[3]($str);
140	my $pfx = ft now;	223	}
141		224
142	for (split /\n/, $msg) {	225	# not masked, not consumed - propagate to parent contexts
143	printf STDERR "$pfx $_\n";	226	push @ctx, values %{ $ctx->[2] };
144	$pfx = "\t";	227	}
145	}	228	}
		229	while $ctx = pop @ctx;
146		230
147	exit 1 if $level <= 1;	231	exit 1 if $level <= 1;
148	}	232	}
149		233
150	sub log($$;@) {	234	sub log($$;@) {
151	_log +(caller)[0], @_;	235	_log
		236	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		237	@_;
152	}	238	}
153		239
154	AnyEvent::log = AE::log = \&log;	240	AnyEvent::log = AE::log = \&log;
155		241
156	=item $logger = AnyEvent::Log::logger $level[, \$enabled]	242	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
…		…
199	our %LOGGER;	285	our %LOGGER;
200		286
201	# re-assess logging status for all loggers	287	# re-assess logging status for all loggers
202	sub _reassess {	288	sub _reassess {
203	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {	289	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
204	my ($pkg, $level, $renabled) = @$_;	290	my ($ctx, $level, $renabled) = @$_;
205		291
206	# to detetc whether a message would be logged, we # actually	292	# to detect whether a message would be logged, we # actually
207	# try to log one and die. this isn't # fast, but we can be	293	# try to log one and die. this isn't fast, but we can be
208	# sure that the logging decision is correct :)	294	# sure that the logging decision is correct :)
209		295
210	$$renabled = !eval {	296	$$renabled = !eval {
211	local $SIG{__DIE__};	297	local $SIG{__DIE__};
212		298
213	_log $pkg, $level, sub { die };	299	_log $ctx, $level, sub { die };
214		300
215	1	301	1
216	};	302	};
217		303
218	$$renabled = 1; # TODO	304	$$renabled = 1; # TODO
219	}	305	}
220	}	306	}
221		307
222	sub logger($;$) {	308	sub _logger($;$) {
223	my ($level, $renabled) = @_;	309	my ($ctx, $level, $renabled) = @_;
224		310
225	$renabled \|\|= \my $enabled;	311	$renabled \|\|= \my $enabled;
226	my $pkg = (caller)[0];
227		312
228	$$renabled = 1;	313	$$renabled = 1;
229		314
230	my $logger = [$pkg, $level, $renabled];	315	my $logger = [$ctx, $level, $renabled];
231		316
232	$LOGGER{$logger+0} = $logger;	317	$LOGGER{$logger+0} = $logger;
233		318
234	_reassess $logger+0;	319	_reassess $logger+0;
235		320
…		…
239	};	324	};
240		325
241	sub {	326	sub {
242	$guard if 0; # keep guard alive, but don't cause runtime overhead	327	$guard if 0; # keep guard alive, but don't cause runtime overhead
243		328
244	_log $pkg, $level, @_	329	_log $ctx, $level, @_
245	if $$renabled;	330	if $$renabled;
246	}	331	}
247	}	332	}
248		333
249	#TODO	334	sub logger($;$) {
		335	_logger
		336	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		337	@_
		338	}
250		339
251	=back	340	=back
252		341
253	=head1 CONFIGURATION FUNCTIONALITY	342	=head1 LOGGING CONTEXTS
254		343
255	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	344	This module associates every log message with a so-called I<logging
256	#TODO	345	context>, based on the package of the caller. Every perl package has its
		346	own logging context.
		347
		348	A logging context has three major responsibilities: filtering, logging and
		349	propagating the message.
		350
		351	For the first purpose, filtering, each context has a set of logging
		352	levels, called the log level mask. Messages not in the set will be ignored
		353	by this context (masked).
		354
		355	For logging, the context stores a formatting callback (which takes the
		356	timestamp, context, level and string message and formats it in the way
		357	it should be logged) and a logging callback (which is responsible for
		358	actually logging the formatted message and telling C<AnyEvent::Log>
		359	whether it has consumed the message, or whether it should be propagated).
		360
		361	For propagation, a context can have any number of attached I<parent
		362	contexts>. Any message that is neither masked by the logging mask nor
		363	masked by the logging callback returning true will be passed to all parent
		364	contexts.
		365
		366	Each call to a logging function will log the message at most once per
		367	context, so it does not matter (much) if there are cycles or if the
		368	message can arrive at the same context via multiple paths.
		369
		370	=head2 DEFAULTS
		371
		372	By default, all logging contexts have an full set of log levels ("all"), a
		373	disabled logging callback and the default formatting callback.
		374
		375	Package contexts have the package name as logging title by default.
		376
		377	They have exactly one parent - the context of the "parent" package. The
		378	parent package is simply defined to be the package name without the last
		379	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		380	and C<AnyEvent> becomes ... C<AnyEvent::Log::Top> which is the
		381	exception of the rule - just like the parent of any package name in
		382	Perl is C<main>, the default parent of any top-level package context is
		383	C<AnyEvent::Log::Top>.
		384
		385	Since perl packages form only an approximate hierarchy, this parent
		386	context can of course be removed.
		387
		388	All other (anonymous) contexts have no parents and an empty title by
		389	default.
		390
		391	When the module is loaded it creates the default context called
		392	C<AnyEvent::Log::Default> (also stored in C<$AnyEvent::Log::Default>),
		393	which simply logs everything to STDERR and doesn't propagate anything
		394	anywhere by default. The purpose of the default context is to provide
		395	a convenient place to override the global logging target or to attach
		396	additional log targets. It's not meant for filtering.
		397
		398	It then creates the root context called C<AnyEvent::Log::Root> (also
		399	stored in C<$AnyEvent::Log::Root>) and sets its log level set to all
		400	levels up to the one specified by C<$ENV{PERL_ANYEVENT_VERBOSE}>. It
		401	then attached the default logging context to it. The purpose of the root
		402	context is to simply provide filtering according to some global log level.
		403
		404	Finally it creates the top-level package context called
		405	C<AnyEvent::Log::Top> (also stored in, you might have guessed,
		406	C<$AnyEvent::Log::Top>) and attached the root context but otherwise leaves
		407	it at default config. It's purpose is simply to collect all log messages
		408	system-wide.
		409
		410	These three special contexts can also be referred to by the
		411	package/context names C<AE::Log::Default>, C<AE::Log::Root> and
		412	C<AE::Log::Top>.
		413
		414	The effect of all this is that log messages, by default, wander up
		415	to the root context where log messages with lower priority then
		416	C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered away and then to the
		417	AnyEvent::Log::Default context to be logged to STDERR.
		418
		419	Splitting the top level context into three contexts makes it easy to set
		420	a global logging level (by modifying the root context), but still allow
		421	other contexts to log, for example, their debug and trace messages to the
		422	default target despite the global logging level, or to attach additional
		423	log targets that log messages, regardless of the global logging level.
		424
		425	It also makes it easy to replace the default STDERR-logger by something
		426	that logs to a file, or to attach additional logging targets.
		427
		428	=head2 CREATING/FINDING/DESTROYING CONTEXTS
257		429
258	=over 4	430	=over 4
259		431
260	=item $ctx = AnyEvent::Log::cfg [$pkg]	432	=item $ctx = AnyEvent::Log::ctx [$pkg]
261		433
262	Returns a I<config> object for the given package name (or previously	434	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	435
		436	If a package name is given, then the context for that packlage is
		437	returned. If it is called without any arguments, then the context for the
		438	callers package is returned (i.e. the same context as a C<AE::log> call
		439	would use).
		440
264	given, then it creates a new anonymous context that is not tied to any	441	If C<undef> is given, then it creates a new anonymous context that is not
265	package.	442	tied to any package and is destroyed when no longer referenced.
266		443
267	=cut	444	=cut
268		445
269	sub cfg(;$) {	446	sub ctx(;$) {
		447	my $pkg = @_ ? shift : (caller)[0];
		448
		449	ref $pkg
		450	? $pkg
		451	: defined $pkg
		452	? $CTX{$pkg} \|\|= AnyEvent::Log::_pkg_ctx $pkg
		453	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		454	}
		455
		456	=item AnyEvent::Log::reset
		457
		458	Deletes all contexts and recreates the default hierarchy, i.e. resets the
		459	logging subsystem to defaults.
		460
		461	This can be used to implement config-file (re-)loading: before loading a
		462	configuration, reset all contexts.
		463
		464	=cut
		465
		466	sub reset {
		467	@$_ = () for values %CTX; # just to be sure - to kill circular logging dependencies
		468	%CTX = ();
		469
		470	my $default = ctx undef;
		471	$default->title ("AnyEvent::Log::Default");
		472	$default->log_cb (sub {
		473	print STDERR shift;
		474	0
		475	});
		476	$AnyEvent::Log::Default = $CTX{"AnyEvent::Log::Default"} = $CTX{"AE::Log::Default"} = $default;
		477
		478	my $root = ctx undef;
		479	$root->title ("AnyEvent::Log::Root");
		480	$root->level ($AnyEvent::VERBOSE);
		481	$root->attach ($default);
		482	$AnyEvent::Log::Root = $CTX{"AnyEvent::Log::Root"} = $CTX{"AE::Log::Root"} = $root;
		483
		484	my $top = ctx undef;
		485	$top->title ("AnyEvent::Log::Top");
		486	$top->attach ($root);
		487	$AnyEvent::Log::Top = $CTX{"AnyEvent::Log::Top"} = $CTX{"AE::Log::Top"} = $top;
		488	}
		489
		490	AnyEvent::Log::reset;
		491
		492	# hello, CPAN, please catch me
		493	package AnyEvent::Log::Default;
		494	package AE::Log::Default;
		495	package AnyEvent::Log::Root;
		496	package AE::Log::Root;
		497	package AnyEvent::Log::Top;
		498	package AE::Log::Top;
		499
		500	package AnyEvent::Log::Ctx;
		501
		502	# 0 1 2 3 4
		503	# [$title, $level, %$parents, &$logcb, &$fmtcb]
		504
		505	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		506
		507	This is a convenience constructor that makes it simpler to construct
		508	anonymous logging contexts.
		509
		510	Each key-value pair results in an invocation of the method of the same
		511	name as the key with the value as parameter, unless the value is an
		512	arrayref, in which case it calls the method with the contents of the
		513	array. The methods are called in the same order as specified.
		514
		515	Example: create a new logging context and set both the default logging
		516	level, some parent contexts and a logging callback.
		517
		518	$ctx = new AnyEvent::Log::Ctx
		519	title => "dubious messages",
		520	level => "error",
		521	log_cb => sub { print STDOUT shift; 0 },
		522	parents => [$ctx1, $ctx, $ctx2],
		523	;
		524
		525	=back
		526
		527	=cut
		528
		529	sub new {
270	my $name = shift;	530	my $class = shift;
271		531
272	my $ctx = defined $name ? $CTX{$name} : undef;	532	my $ctx = AnyEvent::Log::ctx undef;
273		533
274	unless ($ctx) {	534	while (@_) {
275	$ctx = bless {}, "AnyEvent::Log::Ctx";	535	my ($k, $v) = splice @_, 0, 2;
276	$name = -$ctx unless defined $name;	536	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
277	$ctx->{name} = $name;
278	$CTX{$name} = $ctx;
279	}	537	}
280		538
281	$ctx	539	bless $ctx, $class # do we really support subclassing, hmm?
282	}	540	}
283		541
284	package AnyEvent::Log::Ctx;
285		542
286	sub DESTROY {	543	=head2 CONFIGURING A LOG CONTEXT
287	# if only one member is remaining (name!) then delete this context	544
288	delete $CTX{$_[0]{name}}	545	The following methods can be used to configure the logging context.
289	if 1 == scalar keys %{ $_[0] };	546
		547	=over 4
		548
		549	=item $ctx->title ([$new_title])
		550
		551	Returns the title of the logging context - this is the package name, for
		552	package contexts, and a user defined string for all others.
		553
		554	If C<$new_title> is given, then it replaces the package name or title.
		555
		556	=cut
		557
		558	sub title {
		559	$_[0][0] = $_[1] if @_ > 1;
		560	$_[0][0]
290	}	561	}
		562
		563	=back
		564
		565	=head3 LOGGING LEVELS
		566
		567	The following methods deal with the logging level set associated with the
		568	log context.
		569
		570	The most common method to use is probably C<< $ctx->level ($level) >>,
		571	which configures the specified and any higher priority levels.
		572
		573	All functions which accept a list of levels also accept the special string
		574	C<all> which expands to all logging levels.
		575
		576	=over 4
		577
		578	=item $ctx->levels ($level[, $level...)
		579
		580	Enables logging for the given levels and disables it for all others.
		581
		582	=item $ctx->level ($level)
		583
		584	Enables logging for the given level and all lower level (higher priority)
		585	ones. In addition to normal logging levels, specifying a level of C<0> or
		586	C<off> disables all logging for this level.
		587
		588	Example: log warnings, errors and higher priority messages.
		589
		590	$ctx->level ("warn");
		591	$ctx->level (5); # same thing, just numeric
		592
		593	=item $ctx->enable ($level[, $level...])
		594
		595	Enables logging for the given levels, leaving all others unchanged.
		596
		597	=item $ctx->disable ($level[, $level...])
		598
		599	Disables logging for the given levels, leaving all others unchanged.
		600
		601	=cut
		602
		603	sub _lvl_lst {
		604	map {
		605	$_ > 0 && $_ <= 9 ? $_+0
		606	: $_ eq "all" ? (1 .. 9)
		607	: $STR2LEVEL{$_} \|\| Carp::croak "$_: not a valid logging level, caught"
		608	} @_
		609	}
		610
		611	our $NOP_CB = sub { 0 };
		612
		613	sub levels {
		614	my $ctx = shift;
		615	$ctx->[1] = 0;
		616	$ctx->[1] \|= 1 << $_
		617	for &_lvl_lst;
		618	AnyEvent::Log::_reassess;
		619	}
		620
		621	sub level {
		622	my $ctx = shift;
		623	my $lvl = $_[0] =~ /^(?:0\|off\|none)$/ ? 0 : (_lvl_lst $_[0])[-1];
		624
		625	$ctx->[1] = ((1 << $lvl) - 1) << 1;
		626	AnyEvent::Log::_reassess;
		627	}
		628
		629	sub enable {
		630	my $ctx = shift;
		631	$ctx->[1] \|= 1 << $_
		632	for &_lvl_lst;
		633	AnyEvent::Log::_reassess;
		634	}
		635
		636	sub disable {
		637	my $ctx = shift;
		638	$ctx->[1] &= ~(1 << $_)
		639	for &_lvl_lst;
		640	AnyEvent::Log::_reassess;
		641	}
		642
		643	=back
		644
		645	=head3 PARENT CONTEXTS
		646
		647	The following methods attach and detach another logging context to a
		648	logging context.
		649
		650	Log messages are propagated to all parent contexts, unless the logging
		651	callback consumes the message.
		652
		653	=over 4
		654
		655	=item $ctx->attach ($ctx2[, $ctx3...])
		656
		657	Attaches the given contexts as parents to this context. It is not an error
		658	to add a context twice (the second add will be ignored).
		659
		660	A context can be specified either as package name or as a context object.
		661
		662	=item $ctx->detach ($ctx2[, $ctx3...])
		663
		664	Removes the given parents from this context - it's not an error to attempt
		665	to remove a context that hasn't been added.
		666
		667	A context can be specified either as package name or as a context object.
		668
		669	=item $ctx->parents ($ctx2[, $ctx3...])
		670
		671	Replaces all parents attached to this context by the ones given.
		672
		673	=cut
		674
		675	sub attach {
		676	my $ctx = shift;
		677
		678	$ctx->[2]{$_+0} = $_
		679	for map { AnyEvent::Log::ctx $_ } @_;
		680	}
		681
		682	sub detach {
		683	my $ctx = shift;
		684
		685	delete $ctx->[2]{$_+0}
		686	for map { AnyEvent::Log::ctx $_ } @_;
		687	}
		688
		689	sub parents {
		690	undef $_[0][2];
		691	&attach;
		692	}
		693
		694	=back
		695
		696	=head3 MESSAGE LOGGING
		697
		698	The following methods configure how the logging context actually does
		699	the logging (which consists of formatting the message and printing it or
		700	whatever it wants to do with it) and also allows you to log messages
		701	directly to a context, without going via your package context.
		702
		703	=over 4
		704
		705	=item $ctx->log_cb ($cb->($str))
		706
		707	Replaces the logging callback on the context (C<undef> disables the
		708	logging callback).
		709
		710	The logging callback is responsible for handling formatted log messages
		711	(see C<fmt_cb> below) - normally simple text strings that end with a
		712	newline (and are possibly multiline themselves).
		713
		714	It also has to return true iff it has consumed the log message, and false
		715	if it hasn't. Consuming a message means that it will not be sent to any
		716	parent context. When in doubt, return C<0> from your logging callback.
		717
		718	Example: a very simple logging callback, simply dump the message to STDOUT
		719	and do not consume it.
		720
		721	$ctx->log_cb (sub { print STDERR shift; 0 });
		722
		723	You can filter messages by having a log callback that simply returns C<1>
		724	and does not do anything with the message, but this counts as "message
		725	being logged" and might not be very efficient.
		726
		727	Example: propagate all messages except for log levels "debug" and
		728	"trace". The messages will still be generated, though, which can slow down
		729	your program.
		730
		731	$ctx->levels ("debug", "trace");
		732	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		733
		734	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $ctx, $level, $message))
		735
		736	Replaces the formatting callback on the context (C<undef> restores the
		737	default formatter).
		738
		739	The callback is passed the (possibly fractional) timestamp, the original
		740	logging context, the (numeric) logging level and the raw message string and needs to
		741	return a formatted log message. In most cases this will be a string, but
		742	it could just as well be an array reference that just stores the values.
		743
		744	Example: format just the raw message, with numeric log level in angle
		745	brackets.
		746
		747	$ctx->fmt_cb (sub {
		748	my ($time, $ctx, $lvl, $msg) = @_;
		749
		750	"<$lvl>$msg\n"
		751	});
		752
		753	Example: return an array reference with just the log values, and use
		754	C<PApp::SQL::sql_exec> to store the emssage in a database.
		755
		756	$ctx->fmt_cb (sub { \@_ });
		757	$ctx->log_cb (sub {
		758	my ($msg) = @_;
		759
		760	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		761	$msg->[0] + 0,
		762	"$msg->[1]",
		763	$msg->[2] + 0,
		764	"$msg->[3]";
		765
		766	0
		767	});
		768
		769	=cut
		770
		771	sub log_cb {
		772	my ($ctx, $cb) = @_;
		773
		774	$ctx->[3] = $cb;
		775	}
		776
		777	sub fmt_cb {
		778	my ($ctx, $cb) = @_;
		779
		780	$ctx->[4] = $cb;
		781	}
		782
		783	=item $ctx->log ($level, $msg[, @params])
		784
		785	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		786
		787	=item $logger = $ctx->logger ($level[, \$enabled])
		788
		789	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		790	context.
		791
		792	=cut
		793
		794	*log = \&AnyEvent::Log::_log;
		795	*logger = \&AnyEvent::Log::_logger;
291		796
292	1;	797	1;
		798
		799	=back
		800
		801	=head1 EXAMPLES
		802
		803	This section shows some common configurations.
		804
		805	=over 4
		806
		807	=item Setting the global logging level.
		808
		809	Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before
		810	running your program, or modify the log level of the root context:
		811
		812	PERL_ANYEVENT_VERBOSE=5 ./myprog
		813
		814	$AnyEvent::Log::Root->level ("warn");
		815
		816	=item Append all messages to a file instead of sending them to STDERR.
		817
		818	This is affected by the global logging level.
		819
		820	open my $fh, ">>", $path
		821	or die "$path: $!";
		822
		823	$AnyEvent::Log::Default->log_cb (sub {
		824	syswrite $fh, shift;
		825	0
		826	});
		827
		828	=item Write all messages with priority C<error> and higher to a file.
		829
		830	This writes them only when the global logging level allows it, because
		831	it is attached to the default context which is invoked I<after> global
		832	filtering.
		833
		834	open my $fh, ">>", $path
		835	or die "$path: $!";
		836
		837	$AnyEvent::Log::Default->attach (new AnyEvent::Log::Ctx
		838	log_cb => sub { syswrite $fh, shift; 0 });
		839
		840	This writes them regardless of the global logging level, because it is
		841	attached to the toplevel context, which receives all messages I<before>
		842	the global filtering.
		843
		844	$AnyEvent::Log::Top->attach (new AnyEvent::Log::Ctx
		845	log_cb => sub { syswrite $fh, shift; 0 });
		846
		847	In both cases, messages are still written to STDOUT.
		848
		849	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		850
		851	Attach the CyAnyEvent::Log::Default> context to the C<AnyEvent::Debug>
		852	context and increase the C<AnyEvent::Debug> logging level - this simply
		853	circumvents the global filtering for trace messages.
		854
		855	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		856	$debug->attach ($AnyEvent::Log::Default);
		857	$debug->levels ("trace"); # not "level"!
293		858
294	=back	859	=back
295		860
296	=head1 AUTHOR	861	=head1 AUTHOR
297		862

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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 1.12 by root, Sat Aug 20 01:33:10 2011 UTC

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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 1.12 by root, Sat Aug 20 01:33:10 2011 UTC