[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 1.22 by root, Sun Aug 21 02:19:30 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	$AnyEvent::Log::FILTER->level ("notice");
		30
		31	# see also EXAMPLES, below
8		32
9	=head1 DESCRIPTION	33	=head1 DESCRIPTION
10		34
11	This module implements a relatively simple "logging framework". It doesn't	35	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	36	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	37	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	38	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	39	using it from other modules as well.
16		40
17	Remember that the default verbosity level is C<0>, so nothing	41	Remember that the default verbosity level is C<0> (C<off>), so nothing
18	will be logged, ever, unless you set C<$Anyvent::VERBOSE> or	42	will be logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number
19	C<PERL_ANYEVENT_VERBOSE> to a higher number.	43	before 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<$msg> with the given log level, and
59	You can also use the following strings as log level: C<fatal> (1),	144	returns true if the message was logged I<somewhere>.
60	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
61	C<info> (7), C<debug> (8), C<trace> (9).
62		145
63	For C<fatal> log levels, the program will abort.	146	For C<fatal> log levels, the program will abort.
64		147
65	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	148	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.	149	C<$msg> is interpreted as an sprintf format string.
67		150
68	The C<$msg> should not end with C<\n>, but may if that is convenient for	151	The C<$msg> should not end with C<\n>, but may if that is convenient for
69	you. Also, multiline messages are handled properly.	152	you. Also, multiline messages are handled properly.
70		153
71	In addition, for possible future expansion, C<$msg> must not start with an	154	Last not least, C<$msg> might be a code reference, in which case it is
72	angle bracket (C<< < >>).	155	supposed to return the message. It will be called only then the message
		156	actually gets logged, which is useful if it is costly to create the
		157	message in the first place.
73		158
74	Whether the given message will be logged depends on the maximum log level	159	Whether the given message will be logged depends on the maximum log level
75	and the caller's package.	160	and the caller's package. The return value can be used to ensure that
		161	messages or not "lost" - for example, when L<AnyEvent::Debug> detects a
		162	runtime error it tries to log it at C<die> level, but if that message is
		163	lost it simply uses warn.
76		164
77	Note that you can (and should) call this function as C<AnyEvent::log> or	165	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	166	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.	167	need any additional functionality), as those functions will load the
		168	logging module on demand only. They are also much shorter to write.
		169
		170	Also, if you optionally generate a lot of debug messages (such as when
		171	tracing some code), you should look into using a logger callback and a
		172	boolean enabler (see C<logger>, below).
		173
		174	Example: log something at error level.
		175
		176	AE::log error => "something";
		177
		178	Example: use printf-formatting.
		179
		180	AE::log info => "%5d %-10.10s %s", $index, $category, $msg;
		181
		182	Example: only generate a costly dump when the message is actually being logged.
		183
		184	AE::log debug => sub { require Data::Dump; Data::Dump::dump \%cache };
80		185
81	=cut	186	=cut
82		187
83	# also allow syslog equivalent names	188	# also allow syslog equivalent names
84	our %STR2LEVEL = (	189	our %STR2LEVEL = (
85	fatal => 1, emerg => 1,	190	fatal => 1, emerg => 1, exit => 1,
86	alert => 2,	191	alert => 2,
87	critical => 3, crit => 3,	192	critical => 3, crit => 3,
88	error => 4, err => 4,	193	error => 4, err => 4, die => 4,
89	warn => 5, warning => 5,	194	warn => 5, warning => 5,
90	note => 6, notice => 6,	195	note => 6, notice => 6,
91	info => 7,	196	info => 7,
92	debug => 8,	197	debug => 8,
93	trace => 9,	198	trace => 9,
94	);	199	);
95		200
		201	sub now () { time }
		202
		203	AnyEvent::post_detect {
		204	*now = \&AE::now;
		205	};
		206
96	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	207	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
97		208
		209	# time, ctx, level, msg
		210	sub _format($$$$) {
		211	my $ts = ft $_[0];
		212	my $ct = " ";
		213
		214	my @res;
		215
		216	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		217	push @res, "$ts$ct$_\n";
		218	$ct = " + ";
		219	}
		220
		221	join "", @res
		222	}
		223
		224	sub _log {
		225	my ($ctx, $level, $format, @args) = @_;
		226
		227	$level = $level > 0 && $level <= 9
		228	? $level+0
		229	: $STR2LEVEL{$level} \|\| Carp::croak "$level: not a valid logging level, caught";
		230
		231	my $mask = 1 << $level;
		232
		233	my ($success, %seen, @ctx, $now, $fmt);
		234
		235	do
		236	{
		237	# skip if masked
		238	if ($ctx->[1] & $mask && !$seen{$ctx+0}++) {
		239	if ($ctx->[3]) {
		240	# logging target found
		241
		242	# now get raw message, unless we have it already
		243	unless ($now) {
		244	$format = $format->() if ref $format;
		245	$format = sprintf $format, @args if @args;
		246	$format =~ s/\n$//;
		247	$now = AE::now;
		248	};
		249
		250	# format msg
		251	my $str = $ctx->[4]
		252	? $ctx->[4]($now, $_[0], $level, $format)
		253	: ($fmt \|\|= _format $now, $_[0], $level, $format);
		254
		255	$success = 1;
		256
		257	$ctx->[3]($str)
		258	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
		259	} else {
		260	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		261	}
		262	}
		263	}
		264	while $ctx = pop @ctx;
		265
		266	exit 1 if $level <= 1;
		267
		268	$success
		269	}
		270
98	sub log($$;@) {	271	sub log($$;@) {
99	my ($targ, $msg, @args) = @_;	272	_log
		273	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		274	@_;
		275	}
100		276
101	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	277	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		278
105	return if $level > $AnyEvent::VERBOSE;	279	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
106		280
107	my $pkg = (caller)[0];	281	Creates a code reference that, when called, acts as if the
		282	C<AnyEvent::Log::log> function was called at this point with the given
		283	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
		284	the C<AnyEvent::Log::log> function:
108		285
109	$msg = sprintf $msg, @args if @args;	286	my $debug_log = AnyEvent::Log::logger "debug";
110	$msg =~ s/\n$//;
111		287
112	# now we have a message, log it	288	$debug_log->("debug here");
113	#TODO: could do LOTS of stuff here, and should, at least in some later version	289	$debug_log->("%06d emails processed", 12345);
		290	$debug_log->(sub { $obj->as_string });
114		291
115	$msg = sprintf "%5s (%s) %s", $LEVEL2STR[$level], $pkg, $msg;	292	The idea behind this function is to decide whether to log before actually
116	my $pfx = ft AE::now;	293	logging - when the C<logger> function is called once, but the returned
		294	logger callback often, then this can be a tremendous speed win.
117		295
118	for (split /\n/, $msg) {	296	Despite this speed advantage, changes in logging configuration will
119	printf STDERR "$pfx $_\n";	297	still be reflected by the logger callback, even if configuration changes
120	$pfx = "\t";	298	I<after> it was created.
		299
		300	To further speed up logging, you can bind a scalar variable to the logger,
		301	which contains true if the logger should be called or not - if it is
		302	false, calling the logger can be safely skipped. This variable will be
		303	updated as long as C<$logger> is alive.
		304
		305	Full example:
		306
		307	# near the init section
		308	use AnyEvent::Log;
		309
		310	my $debug_log = AnyEvent:Log::logger debug => \my $debug;
		311
		312	# and later in your program
		313	$debug_log->("yo, stuff here") if $debug;
		314
		315	$debug and $debug_log->("123");
		316
		317	=cut
		318
		319	our %LOGGER;
		320
		321	# re-assess logging status for all loggers
		322	sub _reassess {
		323	local $SIG{__DIE__};
		324	my $die = sub { die };
		325
		326	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
		327	my ($ctx, $level, $renabled) = @$_;
		328
		329	# to detect whether a message would be logged, we actually
		330	# try to log one and die. this isn't fast, but we can be
		331	# sure that the logging decision is correct :)
		332
		333	$$renabled = !eval {
		334	_log $ctx, $level, $die;
		335
		336	1
		337	};
121	}	338	}
122
123	exit 1 if $level <= 1;
124	}	339	}
125		340
126	AnyEvent::log = AE::log = \&log;	341	sub _logger {
		342	my ($ctx, $level, $renabled) = @_;
127		343
128	#TODO	344	$$renabled = 1;
		345
		346	my $logger = [$ctx, $level, $renabled];
		347
		348	$LOGGER{$logger+0} = $logger;
		349
		350	_reassess $logger+0;
		351
		352	my $guard = AnyEvent::Util::guard {
		353	# "clean up"
		354	delete $LOGGER{$logger+0};
		355	};
		356
		357	sub {
		358	$guard if 0; # keep guard alive, but don't cause runtime overhead
		359
		360	_log $ctx, $level, @_
		361	if $$renabled;
		362	}
		363	}
		364
		365	sub logger($;$) {
		366	_logger
		367	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		368	@_
		369	}
129		370
130	=back	371	=back
131		372
132	=head1 CONFIGURATION FUNCTIONALITY	373	=head1 LOGGING CONTEXTS
133		374
134	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	375	This module associates every log message with a so-called I<logging
		376	context>, based on the package of the caller. Every perl package has its
		377	own logging context.
		378
		379	A logging context has three major responsibilities: filtering, logging and
		380	propagating the message.
		381
		382	For the first purpose, filtering, each context has a set of logging
		383	levels, called the log level mask. Messages not in the set will be ignored
		384	by this context (masked).
		385
		386	For logging, the context stores a formatting callback (which takes the
		387	timestamp, context, level and string message and formats it in the way
		388	it should be logged) and a logging callback (which is responsible for
		389	actually logging the formatted message and telling C<AnyEvent::Log>
		390	whether it has consumed the message, or whether it should be propagated).
		391
		392	For propagation, a context can have any number of attached I<slave
		393	contexts>. Any message that is neither masked by the logging mask nor
		394	masked by the logging callback returning true will be passed to all slave
		395	contexts.
		396
		397	Each call to a logging function will log the message at most once per
		398	context, so it does not matter (much) if there are cycles or if the
		399	message can arrive at the same context via multiple paths.
		400
		401	=head2 DEFAULTS
		402
		403	By default, all logging contexts have an full set of log levels ("all"), a
		404	disabled logging callback and the default formatting callback.
		405
		406	Package contexts have the package name as logging title by default.
		407
		408	They have exactly one slave - the context of the "parent" package. The
		409	parent package is simply defined to be the package name without the last
		410	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		411	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		412	exception of the rule - just like the "parent" of any single-component
		413	package name in Perl is C<main>, the default slave of any top-level
		414	package context is C<$AnyEvent::Log::COLLECT>.
		415
		416	Since perl packages form only an approximate hierarchy, this slave
		417	context can of course be removed.
		418
		419	All other (anonymous) contexts have no slaves and an empty title by
		420	default.
		421
		422	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		423	context that simply logs everything via C<warn>, without propagating
		424	anything anywhere by default. The purpose of this context is to provide
		425	a convenient place to override the global logging target or to attach
		426	additional log targets. It's not meant for filtering.
		427
		428	It then creates the C<$AnyEvent::Log::FILTER> context whose
		429	purpose is to suppress all messages with priority higher
		430	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		431	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		432	is to simply provide filtering according to some global log level.
		433
		434	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		435	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		436	leaves it at default config. Its purpose is simply to collect all log
		437	messages system-wide.
		438
		439	The hierarchy is then:
		440
		441	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		442
		443	The effect of all this is that log messages, by default, wander up to the
		444	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		445	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		446	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		447	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		448
		449	This makes it easy to set a global logging level (by modifying $FILTER),
		450	but still allow other contexts to send, for example, their debug and trace
		451	messages to the $LOG target despite the global logging level, or to attach
		452	additional log targets that log messages, regardless of the global logging
		453	level.
		454
		455	It also makes it easy to modify the default warn-logger ($LOG) to
		456	something that logs to a file, or to attach additional logging targets
		457	(such as loggign to a file) by attaching it to $FILTER.
		458
		459	=head2 CREATING/FINDING/DESTROYING CONTEXTS
135		460
136	=over 4	461	=over 4
137		462
		463	=item $ctx = AnyEvent::Log::ctx [$pkg]
		464
		465	This function creates or returns a logging context (which is an object).
		466
		467	If a package name is given, then the context for that packlage is
		468	returned. If it is called without any arguments, then the context for the
		469	callers package is returned (i.e. the same context as a C<AE::log> call
		470	would use).
		471
		472	If C<undef> is given, then it creates a new anonymous context that is not
		473	tied to any package and is destroyed when no longer referenced.
		474
138	=cut	475	=cut
		476
		477	sub ctx(;$) {
		478	my $pkg = @_ ? shift : (caller)[0];
		479
		480	ref $pkg
		481	? $pkg
		482	: defined $pkg
		483	? $CTX{$pkg} \|\|= AnyEvent::Log::_pkg_ctx $pkg
		484	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		485	}
		486
		487	=item AnyEvent::Log::reset
		488
		489	Resets all package contexts and recreates the default hierarchy if
		490	necessary, i.e. resets the logging subsystem to defaults, as much as
		491	possible. This process keeps references to contexts held by other parts of
		492	the program intact.
		493
		494	This can be used to implement config-file (re-)loading: before loading a
		495	configuration, reset all contexts.
		496
		497	=cut
		498
		499	sub reset {
		500	# hard to kill complex data structures
		501	# we "recreate" all package loggers and reset the hierarchy
		502	while (my ($k, $v) = each %CTX) {
		503	@$v = ($k, (1 << 10) - 1 - 1, { });
		504
		505	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
		506	}
		507
		508	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		509	for $LOG, $FILTER, $COLLECT;
		510
		511	$LOG->slaves;
		512	$LOG->title ('$AnyEvent::Log::LOG');
		513	$LOG->log_cb (sub {
		514	warn shift;
		515	0
		516	});
		517
		518	$FILTER->slaves ($LOG);
		519	$FILTER->title ('$AnyEvent::Log::FILTER');
		520	$FILTER->level ($AnyEvent::VERBOSE);
		521
		522	$COLLECT->slaves ($FILTER);
		523	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		524
		525	_reassess;
		526	}
		527
		528	# create the default logger contexts
		529	$LOG = ctx undef;
		530	$FILTER = ctx undef;
		531	$COLLECT = ctx undef;
		532
		533	AnyEvent::Log::reset;
		534
		535	# hello, CPAN, please catch me
		536	package AnyEvent::Log::LOG;
		537	package AE::Log::LOG;
		538	package AnyEvent::Log::FILTER;
		539	package AE::Log::FILTER;
		540	package AnyEvent::Log::COLLECT;
		541	package AE::Log::COLLECT;
		542
		543	package AnyEvent::Log::Ctx;
		544
		545	# 0 1 2 3 4
		546	# [$title, $level, %$slaves, &$logcb, &$fmtcb]
		547
		548	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		549
		550	This is a convenience constructor that makes it simpler to construct
		551	anonymous logging contexts.
		552
		553	Each key-value pair results in an invocation of the method of the same
		554	name as the key with the value as parameter, unless the value is an
		555	arrayref, in which case it calls the method with the contents of the
		556	array. The methods are called in the same order as specified.
		557
		558	Example: create a new logging context and set both the default logging
		559	level, some slave contexts and a logging callback.
		560
		561	$ctx = new AnyEvent::Log::Ctx
		562	title => "dubious messages",
		563	level => "error",
		564	log_cb => sub { print STDOUT shift; 0 },
		565	slaves => [$ctx1, $ctx, $ctx2],
		566	;
		567
		568	=back
		569
		570	=cut
		571
		572	sub new {
		573	my $class = shift;
		574
		575	my $ctx = AnyEvent::Log::ctx undef;
		576
		577	while (@_) {
		578	my ($k, $v) = splice @_, 0, 2;
		579	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		580	}
		581
		582	bless $ctx, $class # do we really support subclassing, hmm?
		583	}
		584
		585
		586	=head2 CONFIGURING A LOG CONTEXT
		587
		588	The following methods can be used to configure the logging context.
		589
		590	=over 4
		591
		592	=item $ctx->title ([$new_title])
		593
		594	Returns the title of the logging context - this is the package name, for
		595	package contexts, and a user defined string for all others.
		596
		597	If C<$new_title> is given, then it replaces the package name or title.
		598
		599	=cut
		600
		601	sub title {
		602	$_[0][0] = $_[1] if @_ > 1;
		603	$_[0][0]
		604	}
		605
		606	=back
		607
		608	=head3 LOGGING LEVELS
		609
		610	The following methods deal with the logging level set associated with the
		611	log context.
		612
		613	The most common method to use is probably C<< $ctx->level ($level) >>,
		614	which configures the specified and any higher priority levels.
		615
		616	All functions which accept a list of levels also accept the special string
		617	C<all> which expands to all logging levels.
		618
		619	=over 4
		620
		621	=item $ctx->levels ($level[, $level...)
		622
		623	Enables logging for the given levels and disables it for all others.
		624
		625	=item $ctx->level ($level)
		626
		627	Enables logging for the given level and all lower level (higher priority)
		628	ones. In addition to normal logging levels, specifying a level of C<0> or
		629	C<off> disables all logging for this level.
		630
		631	Example: log warnings, errors and higher priority messages.
		632
		633	$ctx->level ("warn");
		634	$ctx->level (5); # same thing, just numeric
		635
		636	=item $ctx->enable ($level[, $level...])
		637
		638	Enables logging for the given levels, leaving all others unchanged.
		639
		640	=item $ctx->disable ($level[, $level...])
		641
		642	Disables logging for the given levels, leaving all others unchanged.
		643
		644	=cut
		645
		646	sub _lvl_lst {
		647	map {
		648	$_ > 0 && $_ <= 9 ? $_+0
		649	: $_ eq "all" ? (1 .. 9)
		650	: $STR2LEVEL{$_} \|\| Carp::croak "$_: not a valid logging level, caught"
		651	} @_
		652	}
		653
		654	our $NOP_CB = sub { 0 };
		655
		656	sub levels {
		657	my $ctx = shift;
		658	$ctx->[1] = 0;
		659	$ctx->[1] \|= 1 << $_
		660	for &_lvl_lst;
		661	AnyEvent::Log::_reassess;
		662	}
		663
		664	sub level {
		665	my $ctx = shift;
		666	my $lvl = $_[0] =~ /^(?:0\|off\|none)$/ ? 0 : (_lvl_lst $_[0])[-1];
		667
		668	$ctx->[1] = ((1 << $lvl) - 1) << 1;
		669	AnyEvent::Log::_reassess;
		670	}
		671
		672	sub enable {
		673	my $ctx = shift;
		674	$ctx->[1] \|= 1 << $_
		675	for &_lvl_lst;
		676	AnyEvent::Log::_reassess;
		677	}
		678
		679	sub disable {
		680	my $ctx = shift;
		681	$ctx->[1] &= ~(1 << $_)
		682	for &_lvl_lst;
		683	AnyEvent::Log::_reassess;
		684	}
		685
		686	=back
		687
		688	=head3 SLAVE CONTEXTS
		689
		690	The following methods attach and detach another logging context to a
		691	logging context.
		692
		693	Log messages are propagated to all slave contexts, unless the logging
		694	callback consumes the message.
		695
		696	=over 4
		697
		698	=item $ctx->attach ($ctx2[, $ctx3...])
		699
		700	Attaches the given contexts as slaves to this context. It is not an error
		701	to add a context twice (the second add will be ignored).
		702
		703	A context can be specified either as package name or as a context object.
		704
		705	=item $ctx->detach ($ctx2[, $ctx3...])
		706
		707	Removes the given slaves from this context - it's not an error to attempt
		708	to remove a context that hasn't been added.
		709
		710	A context can be specified either as package name or as a context object.
		711
		712	=item $ctx->slaves ($ctx2[, $ctx3...])
		713
		714	Replaces all slaves attached to this context by the ones given.
		715
		716	=cut
		717
		718	sub attach {
		719	my $ctx = shift;
		720
		721	$ctx->[2]{$_+0} = $_
		722	for map { AnyEvent::Log::ctx $_ } @_;
		723	}
		724
		725	sub detach {
		726	my $ctx = shift;
		727
		728	delete $ctx->[2]{$_+0}
		729	for map { AnyEvent::Log::ctx $_ } @_;
		730	}
		731
		732	sub slaves {
		733	undef $_[0][2];
		734	&attach;
		735	}
		736
		737	=back
		738
		739	=head3 LOG TARGETS
		740
		741	The following methods configure how the logging context actually does
		742	the logging (which consists of formatting the message and printing it or
		743	whatever it wants to do with it).
		744
		745	=over 4
		746
		747	=item $ctx->log_cb ($cb->($str)
		748
		749	Replaces the logging callback on the context (C<undef> disables the
		750	logging callback).
		751
		752	The logging callback is responsible for handling formatted log messages
		753	(see C<fmt_cb> below) - normally simple text strings that end with a
		754	newline (and are possibly multiline themselves).
		755
		756	It also has to return true iff it has consumed the log message, and false
		757	if it hasn't. Consuming a message means that it will not be sent to any
		758	slave context. When in doubt, return C<0> from your logging callback.
		759
		760	Example: a very simple logging callback, simply dump the message to STDOUT
		761	and do not consume it.
		762
		763	$ctx->log_cb (sub { print STDERR shift; 0 });
		764
		765	You can filter messages by having a log callback that simply returns C<1>
		766	and does not do anything with the message, but this counts as "message
		767	being logged" and might not be very efficient.
		768
		769	Example: propagate all messages except for log levels "debug" and
		770	"trace". The messages will still be generated, though, which can slow down
		771	your program.
		772
		773	$ctx->levels ("debug", "trace");
		774	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		775
		776	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		777
		778	Replaces the formatting callback on the context (C<undef> restores the
		779	default formatter).
		780
		781	The callback is passed the (possibly fractional) timestamp, the original
		782	logging context, the (numeric) logging level and the raw message string
		783	and needs to return a formatted log message. In most cases this will be a
		784	string, but it could just as well be an array reference that just stores
		785	the values.
		786
		787	If, for some reaosn, you want to use C<caller> to find out more baout the
		788	logger then you should walk up the call stack until you are no longer
		789	inside the C<AnyEvent::Log> package.
		790
		791	Example: format just the raw message, with numeric log level in angle
		792	brackets.
		793
		794	$ctx->fmt_cb (sub {
		795	my ($time, $ctx, $lvl, $msg) = @_;
		796
		797	"<$lvl>$msg\n"
		798	});
		799
		800	Example: return an array reference with just the log values, and use
		801	C<PApp::SQL::sql_exec> to store the emssage in a database.
		802
		803	$ctx->fmt_cb (sub { \@_ });
		804	$ctx->log_cb (sub {
		805	my ($msg) = @_;
		806
		807	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		808	$msg->[0] + 0,
		809	"$msg->[1]",
		810	$msg->[2] + 0,
		811	"$msg->[3]";
		812
		813	0
		814	});
		815
		816	=item $ctx->log_to_file ($path)
		817
		818	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		819
		820	=item $ctx->log_to_path ($path)
		821
		822	Same as C<< ->log_to_file >>, but opens the file for each message. This
		823	is much slower, but allows you to change/move/rename/delete the file at
		824	basically any time.
		825
		826	=item $ctx->log_to_syslog ([$log_flags])
		827
		828	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and all
		829	the others in the obvious way. If specified, then the C<$log_flags> are
		830	simply or'ed onto the priority argument and can contain any C<LOG_xxx>
		831	flags valid for Sys::Syslog::syslog, except for the priority levels.
		832
		833	Note that this function also sets a C<fmt_cb> - the logging part requires
		834	an array reference with [$level, $str] as input.
		835
		836	=cut
		837
		838	sub log_cb {
		839	my ($ctx, $cb) = @_;
		840
		841	$ctx->[3] = $cb;
		842	}
		843
		844	sub fmt_cb {
		845	my ($ctx, $cb) = @_;
		846
		847	$ctx->[4] = $cb;
		848	}
		849
		850	sub log_to_file {
		851	my ($ctx, $path) = @_;
		852
		853	open my $fh, ">>", $path
		854	or die "$path: $!";
		855
		856	$ctx->log_cb (sub {
		857	syswrite $fh, shift;
		858	0
		859	});
		860	}
		861
		862	sub log_to_file {
		863	my ($ctx, $path) = @_;
		864
		865	$ctx->log_cb (sub {
		866	open my $fh, ">>", $path
		867	or die "$path: $!";
		868
		869	syswrite $fh, shift;
		870	0
		871	});
		872	}
		873
		874	sub log_to_syslog {
		875	my ($ctx, $flags) = @_;
		876
		877	require Sys::Syslog;
		878
		879	$ctx->fmt_cb (sub {
		880	my $str = $_[3];
		881	$str =~ s/\n(?=.)/\n+ /g;
		882
		883	[$_[2], "($_[1][0]) $str"]
		884	});
		885
		886	$ctx->log_cb (sub {
		887	my $lvl = $_[0][0] < 9 ? $_[0][0] : 8;
		888
		889	Sys::Syslog::syslog ($flags \| ($lvl - 1), $_)
		890	for split /\n/, $_[0][1];
		891
		892	0
		893	});
		894	}
		895
		896	=back
		897
		898	=head3 MESSAGE LOGGING
		899
		900	These methods allow you to log messages directly to a context, without
		901	going via your package context.
		902
		903	=over 4
		904
		905	=item $ctx->log ($level, $msg[, @params])
		906
		907	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		908
		909	=item $logger = $ctx->logger ($level[, \$enabled])
		910
		911	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		912	context.
		913
		914	=cut
		915
		916	*log = \&AnyEvent::Log::_log;
		917	*logger = \&AnyEvent::Log::_logger;
139		918
140	1;	919	1;
		920
		921	=back
		922
		923	=head1 EXAMPLES
		924
		925	This section shows some common configurations.
		926
		927	=over 4
		928
		929	=item Setting the global logging level.
		930
		931	Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before
		932	running your program, or modify the log level of the root context:
		933
		934	PERL_ANYEVENT_VERBOSE=5 ./myprog
		935
		936	$AnyEvent::Log::FILTER->level ("warn");
		937
		938	=item Append all messages to a file instead of sending them to STDERR.
		939
		940	This is affected by the global logging level.
		941
		942	$AnyEvent::Log::LOG->log_to_file ($path); (sub {
		943
		944	=item Write all messages with priority C<error> and higher to a file.
		945
		946	This writes them only when the global logging level allows it, because
		947	it is attached to the default context which is invoked I<after> global
		948	filtering.
		949
		950	$AnyEvent::Log::FILTER->attach
		951	new AnyEvent::Log::Ctx log_to_file => $path);
		952
		953	This writes them regardless of the global logging level, because it is
		954	attached to the toplevel context, which receives all messages I<before>
		955	the global filtering.
		956
		957	$AnyEvent::Log::COLLECT->attach (
		958	new AnyEvent::Log::Ctx log_to_file => $path);
		959
		960	In both cases, messages are still written to STDERR.
		961
		962	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		963
		964	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		965	context - this simply circumvents the global filtering for trace messages.
		966
		967	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		968	$debug->attach ($AnyEvent::Log::LOG);
		969
		970	This of course works for any package, not just L<AnyEvent::Debug>, but
		971	assumes the log level for AnyEvent::Debug hasn't been changed from the
		972	default.
141		973
142	=back	974	=back
143		975
144	=head1 AUTHOR	976	=head1 AUTHOR
145		977

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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 1.22 by root, Sun Aug 21 02:19:30 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 1.22 by root, Sun Aug 21 02:19:30 2011 UTC