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

Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.7 by root, Thu Aug 18 18:02:11 2011 UTC vs.
Revision 1.20 by root, Sat Aug 20 22:27:07 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 will be	41	Remember that the default verbosity level is C<0> (C<off>), so nothing
18	logged, ever, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number	42	will be logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number
19	before starting your program.#TODO	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	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is	93	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is
30	loaded.	94	loaded.
31		95
32	=over 4	96	=over 4
33		97
…		…
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 }
42	use AnyEvent::Util ();	106	use AnyEvent::Util ();
		107
		108	our $VERSION = $AnyEvent::VERSION;
		109
		110	our ($COLLECT, $FILTER, $LOG);
43		111
44	our ($now_int, $now_str1, $now_str2);	112	our ($now_int, $now_str1, $now_str2);
45		113
46	# Format Time, not public - yet?	114	# Format Time, not public - yet?
47	sub ft($) {	115	sub ft($) {
…		…
52	if $now_int != $i;	120	if $now_int != $i;
53		121
54	"$now_str1$f$now_str2"	122	"$now_str1$f$now_str2"
55	}	123	}
56		124
57	our %CTX; # all logging contexts	125	our %CTX; # all package contexts
		126
		127	# creates a default package context object for the given package
		128	sub _pkg_ctx($) {
		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	}
58		140
59	=item AnyEvent::Log::log $level, $msg[, @args]	141	=item AnyEvent::Log::log $level, $msg[, @args]
60		142
61	Requests logging of the given C<$msg> with the given log level (1..9).	143	Requests logging of the given C<$msg> with the given log level.
62	You can also use the following strings as log level: C<fatal> (1),
63	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
64	C<info> (7), C<debug> (8), C<trace> (9).
65		144
66	For C<fatal> log levels, the program will abort.	145	For C<fatal> log levels, the program will abort.
67		146
68	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	147	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the
69	C<$msg> is interpreted as an sprintf format string.	148	C<$msg> is interpreted as an sprintf format string.
…		…
78		157
79	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
80	and the caller's package.	159	and the caller's package.
81		160
82	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
83	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
84	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).
85		169
86	Example: log something at error level.	170	Example: log something at error level.
87		171
88	AE::log error => "something";	172	AE::log error => "something";
89		173
…		…
97		181
98	=cut	182	=cut
99		183
100	# also allow syslog equivalent names	184	# also allow syslog equivalent names
101	our %STR2LEVEL = (	185	our %STR2LEVEL = (
102	fatal => 1, emerg => 1,	186	fatal => 1, emerg => 1, exit => 1,
103	alert => 2,	187	alert => 2,
104	critical => 3, crit => 3,	188	critical => 3, crit => 3,
105	error => 4, err => 4,	189	error => 4, err => 4, die => 4,
106	warn => 5, warning => 5,	190	warn => 5, warning => 5,
107	note => 6, notice => 6,	191	note => 6, notice => 6,
108	info => 7,	192	info => 7,
109	debug => 8,	193	debug => 8,
110	trace => 9,	194	trace => 9,
111	);	195	);
112		196
113	sub now () { time }	197	sub now () { time }
		198
114	AnyEvent::post_detect {	199	AnyEvent::post_detect {
115	*now = \&AE::now;	200	*now = \&AE::now;
116	};	201	};
117		202
118	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);
119		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
120	sub _log {	220	sub _log {
121	my ($pkg, $targ, $msg, @args) = @_;	221	my ($ctx, $level, $format, @args) = @_;
122		222
123	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	223	$level = $level > 0 && $level <= 9
124	: $targ > 0 && $targ <= 9 ? $targ+0	224	? $level+0
125	: $STR2LEVEL{$targ} \|\| Carp::croak "$targ: not a valid logging level, caught";	225	: $STR2LEVEL{$level} \|\| Carp::croak "$level: not a valid logging level, caught";
126		226
127	#TODO: find actual targets, see if we even have to log	227	my $mask = 1 << $level;
128		228
129	return unless $level <= $AnyEvent::VERBOSE;	229	my (%seen, @ctx, $now, $fmt);
130		230
131	$msg = $msg->() if ref $msg;	231	do
132	$msg = sprintf $msg, @args if @args;	232	{
133	$msg =~ s/\n$//;	233	# skip if masked
		234	if ($ctx->[1] & $mask && !$seen{$ctx+0}++) {
		235	if ($ctx->[3]) {
		236	# logging target found
134		237
135	# now we have a message, log it	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	};
136		245
137	# TODO: writers/processors/filters/formatters?	246	# format msg
		247	my $str = $ctx->[4]
		248	? $ctx->[4]($now, $_[0], $level, $format)
		249	: ($fmt \|\|= _format $now, $_[0], $level, $format);
138		250
139	$msg = sprintf "%-5s %s: %s", $LEVEL2STR[$level], $pkg, $msg;	251	$ctx->[3]($str, $_[0], $level)
140	my $pfx = ft now;	252	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
141		253	} else {
142	for (split /\n/, $msg) {	254	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
143	printf STDERR "$pfx $_\n";	255	}
144	$pfx = "\t";	256	}
145	}	257	}
		258	while $ctx = pop @ctx;
146		259
147	exit 1 if $level <= 1;	260	exit 1 if $level <= 1;
148	}	261	}
149		262
150	sub log($$;@) {	263	sub log($$;@) {
151	_log +(caller)[0], @_;	264	_log
		265	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		266	@_;
152	}	267	}
153		268
154	AnyEvent::log = AE::log = \&log;	269	AnyEvent::log = AE::log = \&log;
155		270
156	=item $logger = AnyEvent::Log::logger $level[, \$enabled]	271	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
…		…
189	# and later in your program	304	# and later in your program
190	$debug_log->("yo, stuff here") if $debug;	305	$debug_log->("yo, stuff here") if $debug;
191		306
192	$debug and $debug_log->("123");	307	$debug and $debug_log->("123");
193		308
194	Note: currently the enabled var is always true - that will be fixed in a
195	future version :)
196
197	=cut	309	=cut
198		310
199	our %LOGGER;	311	our %LOGGER;
200		312
201	# re-assess logging status for all loggers	313	# re-assess logging status for all loggers
202	sub _reassess {	314	sub _reassess {
		315	local $SIG{__DIE__};
		316	my $die = sub { die };
		317
203	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {	318	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
204	my ($pkg, $level, $renabled) = @$_;	319	my ($ctx, $level, $renabled) = @$_;
205		320
206	# to detetc whether a message would be logged, we # actually	321	# to detect whether a message would be logged, we actually
207	# try to log one and die. this isn't # fast, but we can be	322	# try to log one and die. this isn't fast, but we can be
208	# sure that the logging decision is correct :)	323	# sure that the logging decision is correct :)
209		324
210	$$renabled = !eval {	325	$$renabled = !eval {
211	local $SIG{__DIE__};
212
213	_log $pkg, $level, sub { die };	326	_log $ctx, $level, $die;
214		327
215	1	328	1
216	};	329	};
217
218	$$renabled = 1; # TODO
219	}	330	}
220	}	331	}
221		332
222	sub logger($;$) {	333	sub _logger {
223	my ($level, $renabled) = @_;	334	my ($ctx, $level, $renabled) = @_;
224
225	$renabled \|\|= \my $enabled;
226	my $pkg = (caller)[0];
227		335
228	$$renabled = 1;	336	$$renabled = 1;
229		337
230	my $logger = [$pkg, $level, $renabled];	338	my $logger = [$ctx, $level, $renabled];
231		339
232	$LOGGER{$logger+0} = $logger;	340	$LOGGER{$logger+0} = $logger;
233		341
234	_reassess $logger+0;	342	_reassess $logger+0;
235		343
…		…
239	};	347	};
240		348
241	sub {	349	sub {
242	$guard if 0; # keep guard alive, but don't cause runtime overhead	350	$guard if 0; # keep guard alive, but don't cause runtime overhead
243		351
244	_log $pkg, $level, @_	352	_log $ctx, $level, @_
245	if $$renabled;	353	if $$renabled;
246	}	354	}
247	}	355	}
248		356
249	#TODO	357	sub logger($;$) {
		358	_logger
		359	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		360	@_
		361	}
250		362
251	=back	363	=back
252		364
253	=head1 CONFIGURATION FUNCTIONALITY	365	=head1 LOGGING CONTEXTS
254		366
255	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
256	#TODO	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
257		452
258	=over 4	453	=over 4
259		454
260	=item $ctx = AnyEvent::Log::cfg [$pkg]	455	=item $ctx = AnyEvent::Log::ctx [$pkg]
261		456
262	Returns a I<config> object for the given package name (or previously	457	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	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
264	given, then it creates a new anonymous context that is not tied to any	464	If C<undef> is given, then it creates a new anonymous context that is not
265	package.	465	tied to any package and is destroyed when no longer referenced.
266		466
267	=cut	467	=cut
268		468
269	sub cfg(;$) {	469	sub ctx(;$) {
270	my $name = shift;	470	my $pkg = @_ ? shift : (caller)[0];
271		471
272	my $ctx = defined $name ? $CTX{$name} : undef;	472	ref $pkg
		473	? $pkg
		474	: defined $pkg
		475	? $CTX{$pkg} \|\|= AnyEvent::Log::_pkg_ctx $pkg
		476	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		477	}
273		478
274	unless ($ctx) {	479	=item AnyEvent::Log::reset
275	$ctx = bless {}, "AnyEvent::Log::Ctx";	480
276	$name = -$ctx unless defined $name;	481	Resets all package contexts and recreates the default hierarchy if
277	$ctx->{name} = $name;	482	necessary, i.e. resets the logging subsystem to defaults, as much as
278	$CTX{$name} = $ctx;	483	possible. This process keeps references to contexts held by other parts of
		484	the program intact.
		485
		486	This can be used to implement config-file (re-)loading: before loading a
		487	configuration, reset all contexts.
		488
		489	=cut
		490
		491	sub reset {
		492	# hard to kill complex data structures
		493	# we "recreate" all package loggers and reset the hierarchy
		494	while (my ($k, $v) = each %CTX) {
		495	@$v = ($k, (1 << 10) - 1 - 1, { });
		496
		497	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
279	}	498	}
280		499
281	$ctx	500	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		501	for $LOG, $FILTER, $COLLECT;
		502
		503	$LOG->slaves;
		504	$LOG->title ('$AnyEvent::Log::LOG');
		505	$LOG->log_cb (sub {
		506	warn shift;
		507	0
		508	});
		509
		510	$FILTER->slaves ($LOG);
		511	$FILTER->title ('$AnyEvent::Log::FILTER');
		512	$FILTER->level ($AnyEvent::VERBOSE);
		513
		514	$COLLECT->slaves ($FILTER);
		515	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		516
		517	_reassess;
282	}	518	}
		519
		520	# create the default logger contexts
		521	$LOG = ctx undef;
		522	$FILTER = ctx undef;
		523	$COLLECT = ctx undef;
		524
		525	AnyEvent::Log::reset;
		526
		527	# hello, CPAN, please catch me
		528	package AnyEvent::Log::LOG;
		529	package AE::Log::LOG;
		530	package AnyEvent::Log::FILTER;
		531	package AE::Log::FILTER;
		532	package AnyEvent::Log::COLLECT;
		533	package AE::Log::COLLECT;
283		534
284	package AnyEvent::Log::Ctx;	535	package AnyEvent::Log::Ctx;
285		536
286	sub DESTROY {	537	# 0 1 2 3 4
287	# if only one member is remaining (name!) then delete this context	538	# [$title, $level, %$slaves, &$logcb, &$fmtcb]
288	delete $CTX{$_[0]{name}}	539
289	if 1 == scalar keys %{ $_[0] };	540	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		541
		542	This is a convenience constructor that makes it simpler to construct
		543	anonymous logging contexts.
		544
		545	Each key-value pair results in an invocation of the method of the same
		546	name as the key with the value as parameter, unless the value is an
		547	arrayref, in which case it calls the method with the contents of the
		548	array. The methods are called in the same order as specified.
		549
		550	Example: create a new logging context and set both the default logging
		551	level, some slave contexts and a logging callback.
		552
		553	$ctx = new AnyEvent::Log::Ctx
		554	title => "dubious messages",
		555	level => "error",
		556	log_cb => sub { print STDOUT shift; 0 },
		557	slaves => [$ctx1, $ctx, $ctx2],
		558	;
		559
		560	=back
		561
		562	=cut
		563
		564	sub new {
		565	my $class = shift;
		566
		567	my $ctx = AnyEvent::Log::ctx undef;
		568
		569	while (@_) {
		570	my ($k, $v) = splice @_, 0, 2;
		571	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		572	}
		573
		574	bless $ctx, $class # do we really support subclassing, hmm?
290	}	575	}
		576
		577
		578	=head2 CONFIGURING A LOG CONTEXT
		579
		580	The following methods can be used to configure the logging context.
		581
		582	=over 4
		583
		584	=item $ctx->title ([$new_title])
		585
		586	Returns the title of the logging context - this is the package name, for
		587	package contexts, and a user defined string for all others.
		588
		589	If C<$new_title> is given, then it replaces the package name or title.
		590
		591	=cut
		592
		593	sub title {
		594	$_[0][0] = $_[1] if @_ > 1;
		595	$_[0][0]
		596	}
		597
		598	=back
		599
		600	=head3 LOGGING LEVELS
		601
		602	The following methods deal with the logging level set associated with the
		603	log context.
		604
		605	The most common method to use is probably C<< $ctx->level ($level) >>,
		606	which configures the specified and any higher priority levels.
		607
		608	All functions which accept a list of levels also accept the special string
		609	C<all> which expands to all logging levels.
		610
		611	=over 4
		612
		613	=item $ctx->levels ($level[, $level...)
		614
		615	Enables logging for the given levels and disables it for all others.
		616
		617	=item $ctx->level ($level)
		618
		619	Enables logging for the given level and all lower level (higher priority)
		620	ones. In addition to normal logging levels, specifying a level of C<0> or
		621	C<off> disables all logging for this level.
		622
		623	Example: log warnings, errors and higher priority messages.
		624
		625	$ctx->level ("warn");
		626	$ctx->level (5); # same thing, just numeric
		627
		628	=item $ctx->enable ($level[, $level...])
		629
		630	Enables logging for the given levels, leaving all others unchanged.
		631
		632	=item $ctx->disable ($level[, $level...])
		633
		634	Disables logging for the given levels, leaving all others unchanged.
		635
		636	=cut
		637
		638	sub _lvl_lst {
		639	map {
		640	$_ > 0 && $_ <= 9 ? $_+0
		641	: $_ eq "all" ? (1 .. 9)
		642	: $STR2LEVEL{$_} \|\| Carp::croak "$_: not a valid logging level, caught"
		643	} @_
		644	}
		645
		646	our $NOP_CB = sub { 0 };
		647
		648	sub levels {
		649	my $ctx = shift;
		650	$ctx->[1] = 0;
		651	$ctx->[1] \|= 1 << $_
		652	for &_lvl_lst;
		653	AnyEvent::Log::_reassess;
		654	}
		655
		656	sub level {
		657	my $ctx = shift;
		658	my $lvl = $_[0] =~ /^(?:0\|off\|none)$/ ? 0 : (_lvl_lst $_[0])[-1];
		659
		660	$ctx->[1] = ((1 << $lvl) - 1) << 1;
		661	AnyEvent::Log::_reassess;
		662	}
		663
		664	sub enable {
		665	my $ctx = shift;
		666	$ctx->[1] \|= 1 << $_
		667	for &_lvl_lst;
		668	AnyEvent::Log::_reassess;
		669	}
		670
		671	sub disable {
		672	my $ctx = shift;
		673	$ctx->[1] &= ~(1 << $_)
		674	for &_lvl_lst;
		675	AnyEvent::Log::_reassess;
		676	}
		677
		678	=back
		679
		680	=head3 SLAVE CONTEXTS
		681
		682	The following methods attach and detach another logging context to a
		683	logging context.
		684
		685	Log messages are propagated to all slave contexts, unless the logging
		686	callback consumes the message.
		687
		688	=over 4
		689
		690	=item $ctx->attach ($ctx2[, $ctx3...])
		691
		692	Attaches the given contexts as slaves to this context. It is not an error
		693	to add a context twice (the second add will be ignored).
		694
		695	A context can be specified either as package name or as a context object.
		696
		697	=item $ctx->detach ($ctx2[, $ctx3...])
		698
		699	Removes the given slaves from this context - it's not an error to attempt
		700	to remove a context that hasn't been added.
		701
		702	A context can be specified either as package name or as a context object.
		703
		704	=item $ctx->slaves ($ctx2[, $ctx3...])
		705
		706	Replaces all slaves attached to this context by the ones given.
		707
		708	=cut
		709
		710	sub attach {
		711	my $ctx = shift;
		712
		713	$ctx->[2]{$_+0} = $_
		714	for map { AnyEvent::Log::ctx $_ } @_;
		715	}
		716
		717	sub detach {
		718	my $ctx = shift;
		719
		720	delete $ctx->[2]{$_+0}
		721	for map { AnyEvent::Log::ctx $_ } @_;
		722	}
		723
		724	sub slaves {
		725	undef $_[0][2];
		726	&attach;
		727	}
		728
		729	=back
		730
		731	=head3 LOG TARGETS
		732
		733	The following methods configure how the logging context actually does
		734	the logging (which consists of formatting the message and printing it or
		735	whatever it wants to do with it).
		736
		737	=over 4
		738
		739	=item $ctx->log_cb ($cb->($str, $orig_ctx, $level))
		740
		741	Replaces the logging callback on the context (C<undef> disables the
		742	logging callback).
		743
		744	The logging callback is responsible for handling formatted log messages
		745	(see C<fmt_cb> below) - normally simple text strings that end with a
		746	newline (and are possibly multiline themselves). In addition to the
		747	message, which is often the only argument you need to look at, it is
		748	passed the numeric log level and originating context.
		749
		750	It also has to return true iff it has consumed the log message, and false
		751	if it hasn't. Consuming a message means that it will not be sent to any
		752	slave context. When in doubt, return C<0> from your logging callback.
		753
		754	Example: a very simple logging callback, simply dump the message to STDOUT
		755	and do not consume it.
		756
		757	$ctx->log_cb (sub { print STDERR shift; 0 });
		758
		759	You can filter messages by having a log callback that simply returns C<1>
		760	and does not do anything with the message, but this counts as "message
		761	being logged" and might not be very efficient.
		762
		763	Example: propagate all messages except for log levels "debug" and
		764	"trace". The messages will still be generated, though, which can slow down
		765	your program.
		766
		767	$ctx->levels ("debug", "trace");
		768	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		769
		770	=item $ctx->log_to_file ($path)
		771
		772	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		773
		774	=item $ctx->log_to_path ($path)
		775
		776	Same as C<< ->log_to_file >>, but opens the file for each message. This
		777	is much slower, but allows you to change/move/rename/delete the file at
		778	basically any time.
		779
		780	=item $ctx->log_to_syslog ([$log_flags])
		781
		782	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and all
		783	the others in the obvious way. If specified, then the C<$log_flags> are
		784	simply or'ed onto the priority argument and can contain any C<LOG_xxx>
		785	flags valid for Sys::Syslog::syslog, except for the priority levels.
		786
		787	Note that the default logging format includes a verbose timestamp, which
		788	is not so suited for syslog, so a simpler C<fmt_cb> might be useful:
		789
		790	$ctx->log_to_syslog;
		791	$ctx->fmt_cb (sub { "($_[1][0]) $_[3]" });
		792
		793	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		794
		795	Replaces the formatting callback on the context (C<undef> restores the
		796	default formatter).
		797
		798	The callback is passed the (possibly fractional) timestamp, the original
		799	logging context, the (numeric) logging level and the raw message string
		800	and needs to return a formatted log message. In most cases this will be a
		801	string, but it could just as well be an array reference that just stores
		802	the values.
		803
		804	If, for some reaosn, you want to use C<caller> to find out more baout the
		805	logger then you should walk up the call stack until you are no longer
		806	inside the C<AnyEvent::Log> package.
		807
		808	Example: format just the raw message, with numeric log level in angle
		809	brackets.
		810
		811	$ctx->fmt_cb (sub {
		812	my ($time, $ctx, $lvl, $msg) = @_;
		813
		814	"<$lvl>$msg\n"
		815	});
		816
		817	Example: return an array reference with just the log values, and use
		818	C<PApp::SQL::sql_exec> to store the emssage in a database.
		819
		820	$ctx->fmt_cb (sub { \@_ });
		821	$ctx->log_cb (sub {
		822	my ($msg) = @_;
		823
		824	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		825	$msg->[0] + 0,
		826	"$msg->[1]",
		827	$msg->[2] + 0,
		828	"$msg->[3]";
		829
		830	0
		831	});
		832
		833	=cut
		834
		835	sub log_cb {
		836	my ($ctx, $cb) = @_;
		837
		838	$ctx->[3] = $cb;
		839	}
		840
		841	sub fmt_cb {
		842	my ($ctx, $cb) = @_;
		843
		844	$ctx->[4] = $cb;
		845	}
		846
		847	sub log_to_file {
		848	my ($ctx, $path) = @_;
		849
		850	open my $fh, ">>", $path
		851	or die "$path: $!";
		852
		853	$ctx->log_cb (sub {
		854	syswrite $fh, shift;
		855	0
		856	});
		857	}
		858
		859	sub log_to_file {
		860	my ($ctx, $path) = @_;
		861
		862	$ctx->log_cb (sub {
		863	open my $fh, ">>", $path
		864	or die "$path: $!";
		865
		866	syswrite $fh, shift;
		867	0
		868	});
		869	}
		870
		871	sub log_to_syslog {
		872	my ($ctx, $flags) = @_;
		873
		874	require Sys::Syslog;
		875
		876	$ctx->log_cb (sub {
		877	my $lvl = $_[2] < 9 ? $_[2] : 8;
		878
		879	Sys::Syslog::syslog ($flags \| ($lvl - 1), $_)
		880	for split /\n/, shift;
		881
		882	0
		883	});
		884	}
		885
		886	=back
		887
		888	=head3 MESSAGE LOGGING
		889
		890	These methods allow you to log messages directly to a context, without
		891	going via your package context.
		892
		893	=over 4
		894
		895	=item $ctx->log ($level, $msg[, @params])
		896
		897	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		898
		899	=item $logger = $ctx->logger ($level[, \$enabled])
		900
		901	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		902	context.
		903
		904	=cut
		905
		906	*log = \&AnyEvent::Log::_log;
		907	*logger = \&AnyEvent::Log::_logger;
291		908
292	1;	909	1;
		910
		911	=back
		912
		913	=head1 EXAMPLES
		914
		915	This section shows some common configurations.
		916
		917	=over 4
		918
		919	=item Setting the global logging level.
		920
		921	Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before
		922	running your program, or modify the log level of the root context:
		923
		924	PERL_ANYEVENT_VERBOSE=5 ./myprog
		925
		926	$AnyEvent::Log::FILTER->level ("warn");
		927
		928	=item Append all messages to a file instead of sending them to STDERR.
		929
		930	This is affected by the global logging level.
		931
		932	$AnyEvent::Log::LOG->log_to_file ($path); (sub {
		933
		934	=item Write all messages with priority C<error> and higher to a file.
		935
		936	This writes them only when the global logging level allows it, because
		937	it is attached to the default context which is invoked I<after> global
		938	filtering.
		939
		940	$AnyEvent::Log::FILTER->attach
		941	new AnyEvent::Log::Ctx log_to_file => $path);
		942
		943	This writes them regardless of the global logging level, because it is
		944	attached to the toplevel context, which receives all messages I<before>
		945	the global filtering.
		946
		947	$AnyEvent::Log::COLLECT->attach (
		948	new AnyEvent::Log::Ctx log_to_file => $path);
		949
		950	In both cases, messages are still written to STDERR.
		951
		952	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		953
		954	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		955	context - this simply circumvents the global filtering for trace messages.
		956
		957	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		958	$debug->attach ($AnyEvent::Log::LOG);
		959
		960	This of course works for any package, not just L<AnyEvent::Debug>, but
		961	assumes the log level for AnyEvent::Debug hasn't been changed from the
		962	default.
293		963
294	=back	964	=back
295		965
296	=head1 AUTHOR	966	=head1 AUTHOR
297		967

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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents): Revision 1.7 by root, Thu Aug 18 18:02:11 2011 UTC vs. Revision 1.20 by root, Sat Aug 20 22:27:07 2011 UTC

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Comparing AnyEvent/lib/AnyEvent/Log.pm (file contents):
Revision 1.7 by root, Thu Aug 18 18:02:11 2011 UTC vs.
Revision 1.20 by root, Sat Aug 20 22:27:07 2011 UTC