[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 1.26 by root, Sun Aug 21 03:29:19 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 uses:
		8
		9	use AnyEvent;
		10
		11	AE::log debug => "hit my knee";
		12	AE::log warn => "it's a bit too hot";
		13	AE::log error => "the flag was false!";
		14	AE::log fatal => "the bit toggled! run!"; # never returns
		15
		16	"Complex" uses (for speed sensitive code):
		17
7	use AnyEvent::Log;	18	use AnyEvent::Log;
		19
		20	my $tracer = AnyEvent::Log::logger trace => \$my $trace;
		21
		22	$tracer->("i am here") if $trace;
		23	$tracer->(sub { "lots of data: " . Dumper $self }) if $trace;
		24
		25	Configuration (also look at the EXAMPLES section):
		26
		27	# set logging for the current package to errors and higher only
		28	AnyEvent::Log::ctx->level ("error");
		29
		30	# set logging level to suppress anything below "notice"
		31	$AnyEvent::Log::FILTER->level ("notice");
		32
		33	# send all critical and higher priority messages to syslog,
		34	# regardless of (most) other settings
		35	$AnyEvent::Log::COLLECT->attach (new AnyEvent::Log::Ctx
		36	level => "critical",
		37	log_to_syslog => 0,
		38	);
8		39
9	=head1 DESCRIPTION	40	=head1 DESCRIPTION
10		41
11	This module implements a relatively simple "logging framework". It doesn't	42	This module implements a relatively simple "logging framework". It doesn't
12	attempt to be "the" logging solution or even "a" logging solution for	43	attempt to be "the" logging solution or even "a" logging solution for
13	AnyEvent - AnyEvent simply creates logging messages internally, and this	44	AnyEvent - AnyEvent simply creates logging messages internally, and this
14	module more or less exposes the mechanism, with some extra spiff to allow	45	module more or less exposes the mechanism, with some extra spiff to allow
15	using it from other modules as well.	46	using it from other modules as well.
16		47
17	Remember that the default verbosity level is C<0>, so nothing will be	48	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	49	will be logged, unless you set C<PERL_ANYEVENT_VERBOSE> to a higher number
19	before starting your program.#TODO	50	before starting your program, or change the logging level at runtime with
		51	something like:
20		52
21	Possible future extensions are to allow custom log targets (where the	53	use AnyEvent::Log;
22	level is an object), log filtering based on package, formatting, aliasing	54	AnyEvent::Log::FILTER->level ("info");
23	or package groups.
24		55
		56	The design goal behind this module was to keep it simple (and small),
		57	but make it powerful enough to be potentially useful for any module, and
		58	extensive enough for the most common tasks, such as logging to multiple
		59	targets, or being able to log into a database.
		60
		61	The amount of documentation might indicate otherwise, but the module is
		62	still just below 300 lines of code.
		63
		64	=head1 LOGGING LEVELS
		65
		66	Logging levels in this module range from C<1> (highest priority) to C<9>
		67	(lowest priority). Note that the lowest numerical value is the highest
		68	priority, so when this document says "higher priority" it means "lower
		69	numerical value".
		70
		71	Instead of specifying levels by name you can also specify them by aliases:
		72
		73	LVL NAME SYSLOG PERL NOTE
		74	1 fatal emerg exit aborts program!
		75	2 alert
		76	3 critical crit
		77	4 error err die
		78	5 warn warning
		79	6 note notice
		80	7 info
		81	8 debug
		82	9 trace
		83
		84	As you can see, some logging levels have multiple aliases - the first one
		85	is the "official" name, the second one the "syslog" name (if it differs)
		86	and the third one the "perl" name, suggesting that you log C<die> messages
		87	at C<error> priority.
		88
		89	You can normally only log a single message at highest priority level
		90	(C<1>, C<fatal>), because logging a fatal message will also quit the
		91	program - so use it sparingly :)
		92
		93	Some methods also offer some extra levels, such as C<0>, C<off>, C<none>
		94	or C<all> - these are only valid in the methods they are documented for.
		95
25	=head1 LOG FUNCTIONS	96	=head1 LOGGING FUNCTIONS
26		97
27	These functions allow you to log messages. They always use the caller's	98	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	99	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>	100	callable as C<AnyEvent::log> or C<AE::log> when the C<AnyEvent> module is
30	module is loaded.	101	loaded.
31		102
32	=over 4	103	=over 4
33		104
34	=cut	105	=cut
35		106
…		…
38	use Carp ();	109	use Carp ();
39	use POSIX ();	110	use POSIX ();
40		111
41	use AnyEvent (); BEGIN { AnyEvent::common_sense }	112	use AnyEvent (); BEGIN { AnyEvent::common_sense }
42	use AnyEvent::Util ();	113	use AnyEvent::Util ();
		114
		115	our $VERSION = $AnyEvent::VERSION;
		116
		117	our ($COLLECT, $FILTER, $LOG);
43		118
44	our ($now_int, $now_str1, $now_str2);	119	our ($now_int, $now_str1, $now_str2);
45		120
46	# Format Time, not public - yet?	121	# Format Time, not public - yet?
47	sub ft($) {	122	sub ft($) {
…		…
52	if $now_int != $i;	127	if $now_int != $i;
53		128
54	"$now_str1$f$now_str2"	129	"$now_str1$f$now_str2"
55	}	130	}
56		131
57	our %CTX; # all logging contexts	132	our %CTX; # all package contexts
		133
		134	# creates a default package context object for the given package
		135	sub _pkg_ctx($) {
		136	my $ctx = bless [$_[0], (1 << 10) - 1 - 1, {}], "AnyEvent::Log::Ctx";
		137
		138	# link "parent" package
		139	my $parent = $_[0] =~ /^(.+)::/
		140	? $CTX{$1} \|\|= &_pkg_ctx ("$1")
		141	: $COLLECT;
		142
		143	$ctx->[2]{$parent+0} = $parent;
		144
		145	$ctx
		146	}
58		147
59	=item AnyEvent::Log::log $level, $msg[, @args]	148	=item AnyEvent::Log::log $level, $msg[, @args]
60		149
61	Requests logging of the given C<$msg> with the given log level (1..9).	150	Requests logging of the given C<$msg> with the given log level, and
62	You can also use the following strings as log level: C<fatal> (1),	151	returns true if the message was logged I<somewhere>.
63	C<alert> (2), C<critical> (3), C<error> (4), C<warn> (5), C<note> (6),
64	C<info> (7), C<debug> (8), C<trace> (9).
65		152
66	For C<fatal> log levels, the program will abort.	153	For C<fatal> log levels, the program will abort.
67		154
68	If only a C<$msg> is given, it is logged as-is. With extra C<@args>, the	155	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.	156	C<$msg> is interpreted as an sprintf format string.
…		…
75	supposed to return the message. It will be called only then the message	162	supposed to return the message. It will be called only then the message
76	actually gets logged, which is useful if it is costly to create the	163	actually gets logged, which is useful if it is costly to create the
77	message in the first place.	164	message in the first place.
78		165
79	Whether the given message will be logged depends on the maximum log level	166	Whether the given message will be logged depends on the maximum log level
80	and the caller's package.	167	and the caller's package. The return value can be used to ensure that
		168	messages or not "lost" - for example, when L<AnyEvent::Debug> detects a
		169	runtime error it tries to log it at C<die> level, but if that message is
		170	lost it simply uses warn.
81		171
82	Note that you can (and should) call this function as C<AnyEvent::log> or	172	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	173	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.	174	need any additional functionality), as those functions will load the
		175	logging module on demand only. They are also much shorter to write.
		176
		177	Also, if you optionally generate a lot of debug messages (such as when
		178	tracing some code), you should look into using a logger callback and a
		179	boolean enabler (see C<logger>, below).
85		180
86	Example: log something at error level.	181	Example: log something at error level.
87		182
88	AE::log error => "something";	183	AE::log error => "something";
89		184
…		…
97		192
98	=cut	193	=cut
99		194
100	# also allow syslog equivalent names	195	# also allow syslog equivalent names
101	our %STR2LEVEL = (	196	our %STR2LEVEL = (
102	fatal => 1, emerg => 1,	197	fatal => 1, emerg => 1, exit => 1,
103	alert => 2,	198	alert => 2,
104	critical => 3, crit => 3,	199	critical => 3, crit => 3,
105	error => 4, err => 4,	200	error => 4, err => 4, die => 4,
106	warn => 5, warning => 5,	201	warn => 5, warning => 5,
107	note => 6, notice => 6,	202	note => 6, notice => 6,
108	info => 7,	203	info => 7,
109	debug => 8,	204	debug => 8,
110	trace => 9,	205	trace => 9,
111	);	206	);
112		207
113	sub now () { time }	208	sub now () { time }
		209
114	AnyEvent::post_detect {	210	AnyEvent::post_detect {
115	*now = \&AE::now;	211	*now = \&AE::now;
116	};	212	};
117		213
118	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);	214	our @LEVEL2STR = qw(0 fatal alert crit error warn note info debug trace);
119		215
		216	# time, ctx, level, msg
		217	sub _format($$$$) {
		218	my $ts = ft $_[0];
		219	my $ct = " ";
		220
		221	my @res;
		222
		223	for (split /\n/, sprintf "%-5s %s: %s", $LEVEL2STR[$_[2]], $_[1][0], $_[3]) {
		224	push @res, "$ts$ct$_\n";
		225	$ct = " + ";
		226	}
		227
		228	join "", @res
		229	}
		230
120	sub _log {	231	sub _log {
121	my ($pkg, $targ, $msg, @args) = @_;	232	my ($ctx, $level, $format, @args) = @_;
122		233
123	my $level = ref $targ ? die "Can't use reference as logging level (yet)"	234	$level = $level > 0 && $level <= 9
124	: $targ > 0 && $targ <= 9 ? $targ+0	235	? $level+0
125	: $STR2LEVEL{$targ} \|\| Carp::croak "$targ: not a valid logging level, caught";	236	: $STR2LEVEL{$level} \|\| Carp::croak "$level: not a valid logging level, caught";
126		237
127	#TODO: find actual targets, see if we even have to log	238	my $mask = 1 << $level;
128		239
129	return unless $level <= $AnyEvent::VERBOSE;	240	my ($success, %seen, @ctx, $now, $fmt);
130		241
131	$msg = $msg->() if ref $msg;	242	do
132	$msg = sprintf $msg, @args if @args;	243	{
133	$msg =~ s/\n$//;	244	# skip if masked
		245	if ($ctx->[1] & $mask && !$seen{$ctx+0}++) {
		246	if ($ctx->[3]) {
		247	# logging target found
134		248
135	# now we have a message, log it	249	# now get raw message, unless we have it already
		250	unless ($now) {
		251	$format = $format->() if ref $format;
		252	$format = sprintf $format, @args if @args;
		253	$format =~ s/\n$//;
		254	$now = AE::now;
		255	};
136		256
137	# TODO: writers/processors/filters/formatters?	257	# format msg
		258	my $str = $ctx->[4]
		259	? $ctx->[4]($now, $_[0], $level, $format)
		260	: ($fmt \|\|= _format $now, $_[0], $level, $format);
138		261
139	$msg = sprintf "%-5s %s: %s", $LEVEL2STR[$level], $pkg, $msg;	262	$success = 1;
140	my $pfx = ft now;
141		263
142	for (split /\n/, $msg) {	264	$ctx->[3]($str)
143	printf STDERR "$pfx $_\n";	265	or push @ctx, values %{ $ctx->[2] }; # not consumed - propagate
144	$pfx = "\t";	266	} else {
145	}	267	push @ctx, values %{ $ctx->[2] }; # not masked - propagate
		268	}
		269	}
		270	}
		271	while $ctx = pop @ctx;
146		272
147	exit 1 if $level <= 1;	273	exit 1 if $level <= 1;
		274
		275	$success
148	}	276	}
149		277
150	sub log($$;@) {	278	sub log($$;@) {
151	_log +(caller)[0], @_;	279	_log
		280	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		281	@_;
152	}	282	}
153		283
154	AnyEvent::log = AE::log = \&log;	284	AnyEvent::log = AE::log = \&log;
155		285
156	=item $logger = AnyEvent::Log::logger $level[, \$enabled]	286	=item $logger = AnyEvent::Log::logger $level[, \$enabled]
157		287
158	Creates a code reference that, when called, acts as if the	288	Creates a code reference that, when called, acts as if the
159	C<AnyEvent::Log::log> function was called at this point with the givne	289	C<AnyEvent::Log::log> function was called at this point with the given
160	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with	290	level. C<$logger> is passed a C<$msg> and optional C<@args>, just as with
161	the C<AnyEvent::Log::log> function:	291	the C<AnyEvent::Log::log> function:
162		292
163	my $debug_log = AnyEvent::Log::logger "debug";	293	my $debug_log = AnyEvent::Log::logger "debug";
164		294
…		…
189	# and later in your program	319	# and later in your program
190	$debug_log->("yo, stuff here") if $debug;	320	$debug_log->("yo, stuff here") if $debug;
191		321
192	$debug and $debug_log->("123");	322	$debug and $debug_log->("123");
193		323
194	Note: currently the enabled var is always true - that will be fixed in a
195	future version :)
196
197	=cut	324	=cut
198		325
199	our %LOGGER;	326	our %LOGGER;
200		327
201	# re-assess logging status for all loggers	328	# re-assess logging status for all loggers
202	sub _reassess {	329	sub _reassess {
		330	local $SIG{__DIE__};
		331	my $die = sub { die };
		332
203	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {	333	for (@_ ? $LOGGER{$_[0]} : values %LOGGER) {
204	my ($pkg, $level, $renabled) = @$_;	334	my ($ctx, $level, $renabled) = @$_;
205		335
206	# to detetc whether a message would be logged, we # actually	336	# 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	337	# try to log one and die. this isn't fast, but we can be
208	# sure that the logging decision is correct :)	338	# sure that the logging decision is correct :)
209		339
210	$$renabled = !eval {	340	$$renabled = !eval {
211	local $SIG{__DIE__};
212
213	_log $pkg, $level, sub { die };	341	_log $ctx, $level, $die;
214		342
215	1	343	1
216	};	344	};
217
218	$$renabled = 1; # TODO
219	}	345	}
220	}	346	}
221		347
222	sub logger($;$) {	348	sub _logger {
223	my ($level, $renabled) = @_;	349	my ($ctx, $level, $renabled) = @_;
224
225	$renabled \|\|= \my $enabled;
226	my $pkg = (caller)[0];
227		350
228	$$renabled = 1;	351	$$renabled = 1;
229		352
230	my $logger = [$pkg, $level, $renabled];	353	my $logger = [$ctx, $level, $renabled];
231		354
232	$LOGGER{$logger+0} = $logger;	355	$LOGGER{$logger+0} = $logger;
233		356
234	_reassess $logger+0;	357	_reassess $logger+0;
235		358
…		…
239	};	362	};
240		363
241	sub {	364	sub {
242	$guard if 0; # keep guard alive, but don't cause runtime overhead	365	$guard if 0; # keep guard alive, but don't cause runtime overhead
243		366
244	_log $pkg, $level, @_	367	_log $ctx, $level, @_
245	if $$renabled;	368	if $$renabled;
246	}	369	}
247	}	370	}
248		371
249	#TODO	372	sub logger($;$) {
		373	_logger
		374	$CTX{ (caller)[0] } \|\|= _pkg_ctx +(caller)[0],
		375	@_
		376	}
250		377
251	=back	378	=back
252		379
253	=head1 CONFIGURATION FUNCTIONALITY	380	=head1 LOGGING CONTEXTS
254		381
255	None, yet, except for C<PERL_ANYEVENT_VERBOSE>, described in the L<AnyEvent> manpage.	382	This module associates every log message with a so-called I<logging
256	#TODO	383	context>, based on the package of the caller. Every perl package has its
		384	own logging context.
		385
		386	A logging context has three major responsibilities: filtering, logging and
		387	propagating the message.
		388
		389	For the first purpose, filtering, each context has a set of logging
		390	levels, called the log level mask. Messages not in the set will be ignored
		391	by this context (masked).
		392
		393	For logging, the context stores a formatting callback (which takes the
		394	timestamp, context, level and string message and formats it in the way
		395	it should be logged) and a logging callback (which is responsible for
		396	actually logging the formatted message and telling C<AnyEvent::Log>
		397	whether it has consumed the message, or whether it should be propagated).
		398
		399	For propagation, a context can have any number of attached I<slave
		400	contexts>. Any message that is neither masked by the logging mask nor
		401	masked by the logging callback returning true will be passed to all slave
		402	contexts.
		403
		404	Each call to a logging function will log the message at most once per
		405	context, so it does not matter (much) if there are cycles or if the
		406	message can arrive at the same context via multiple paths.
		407
		408	=head2 DEFAULTS
		409
		410	By default, all logging contexts have an full set of log levels ("all"), a
		411	disabled logging callback and the default formatting callback.
		412
		413	Package contexts have the package name as logging title by default.
		414
		415	They have exactly one slave - the context of the "parent" package. The
		416	parent package is simply defined to be the package name without the last
		417	component, i.e. C<AnyEvent::Debug::Wrapped> becomes C<AnyEvent::Debug>,
		418	and C<AnyEvent> becomes ... C<$AnyEvent::Log::COLLECT> which is the
		419	exception of the rule - just like the "parent" of any single-component
		420	package name in Perl is C<main>, the default slave of any top-level
		421	package context is C<$AnyEvent::Log::COLLECT>.
		422
		423	Since perl packages form only an approximate hierarchy, this slave
		424	context can of course be removed.
		425
		426	All other (anonymous) contexts have no slaves and an empty title by
		427	default.
		428
		429	When the module is loaded it creates the C<$AnyEvent::Log::LOG> logging
		430	context that simply logs everything via C<warn>, without propagating
		431	anything anywhere by default. The purpose of this context is to provide
		432	a convenient place to override the global logging target or to attach
		433	additional log targets. It's not meant for filtering.
		434
		435	It then creates the C<$AnyEvent::Log::FILTER> context whose
		436	purpose is to suppress all messages with priority higher
		437	than C<$ENV{PERL_ANYEVENT_VERBOSE}>. It then attached the
		438	C<$AnyEvent::Log::LOG> context to it. The purpose of the filter context
		439	is to simply provide filtering according to some global log level.
		440
		441	Finally it creates the top-level package context C<$AnyEvent::Log::COLLECT>
		442	and attaches the C<$AnyEvent::Log::FILTER> context to it, but otherwise
		443	leaves it at default config. Its purpose is simply to collect all log
		444	messages system-wide.
		445
		446	The hierarchy is then:
		447
		448	any package, eventually -> $COLLECT -> $FILTER -> $LOG
		449
		450	The effect of all this is that log messages, by default, wander up to the
		451	C<$AnyEvent::Log::COLLECT> context where all messages normally end up,
		452	from there to C<$AnyEvent::Log::FILTER> where log messages with lower
		453	priority then C<$ENV{PERL_ANYEVENT_VERBOSE}> will be filtered out and then
		454	to the C<$AnyEvent::Log::LOG> context to be passed to C<warn>.
		455
		456	This makes it easy to set a global logging level (by modifying $FILTER),
		457	but still allow other contexts to send, for example, their debug and trace
		458	messages to the $LOG target despite the global logging level, or to attach
		459	additional log targets that log messages, regardless of the global logging
		460	level.
		461
		462	It also makes it easy to modify the default warn-logger ($LOG) to
		463	something that logs to a file, or to attach additional logging targets
		464	(such as loggign to a file) by attaching it to $FILTER.
		465
		466	=head2 CREATING/FINDING/DESTROYING CONTEXTS
257		467
258	=over 4	468	=over 4
259		469
260	=item $ctx = AnyEvent::Log::cfg [$pkg]	470	=item $ctx = AnyEvent::Log::ctx [$pkg]
261		471
262	Returns a I<config> object for the given package name (or previously	472	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	473
		474	If a package name is given, then the context for that packlage is
		475	returned. If it is called without any arguments, then the context for the
		476	callers package is returned (i.e. the same context as a C<AE::log> call
		477	would use).
		478
264	given, then it creates a new anonymous context that is not tied to any	479	If C<undef> is given, then it creates a new anonymous context that is not
265	package.	480	tied to any package and is destroyed when no longer referenced.
266		481
267	=cut	482	=cut
268		483
269	sub cfg(;$) {	484	sub ctx(;$) {
270	my $name = shift;	485	my $pkg = @_ ? shift : (caller)[0];
271		486
272	my $ctx = defined $name ? $CTX{$name} : undef;	487	ref $pkg
		488	? $pkg
		489	: defined $pkg
		490	? $CTX{$pkg} \|\|= AnyEvent::Log::_pkg_ctx $pkg
		491	: bless [undef, (1 << 10) - 1 - 1], "AnyEvent::Log::Ctx"
		492	}
273		493
274	unless ($ctx) {	494	=item AnyEvent::Log::reset
275	$ctx = bless {}, "AnyEvent::Log::Ctx";	495
276	$name = -$ctx unless defined $name;	496	Resets all package contexts and recreates the default hierarchy if
277	$ctx->{name} = $name;	497	necessary, i.e. resets the logging subsystem to defaults, as much as
278	$CTX{$name} = $ctx;	498	possible. This process keeps references to contexts held by other parts of
		499	the program intact.
		500
		501	This can be used to implement config-file (re-)loading: before loading a
		502	configuration, reset all contexts.
		503
		504	=cut
		505
		506	sub reset {
		507	# hard to kill complex data structures
		508	# we "recreate" all package loggers and reset the hierarchy
		509	while (my ($k, $v) = each %CTX) {
		510	@$v = ($k, (1 << 10) - 1 - 1, { });
		511
		512	$v->attach ($k =~ /^(.+)::/ ? $CTX{$1} : $AnyEvent::Log::COLLECT);
279	}	513	}
280		514
281	$ctx	515	@$_ = ($_->[0], (1 << 10) - 1 - 1)
		516	for $LOG, $FILTER, $COLLECT;
		517
		518	$LOG->slaves;
		519	$LOG->title ('$AnyEvent::Log::LOG');
		520	$LOG->log_cb (sub {
		521	warn shift;
		522	0
		523	});
		524
		525	$FILTER->slaves ($LOG);
		526	$FILTER->title ('$AnyEvent::Log::FILTER');
		527	$FILTER->level ($AnyEvent::VERBOSE);
		528
		529	$COLLECT->slaves ($FILTER);
		530	$COLLECT->title ('$AnyEvent::Log::COLLECT');
		531
		532	_reassess;
282	}	533	}
		534
		535	# create the default logger contexts
		536	$LOG = ctx undef;
		537	$FILTER = ctx undef;
		538	$COLLECT = ctx undef;
		539
		540	AnyEvent::Log::reset;
		541
		542	# hello, CPAN, please catch me
		543	package AnyEvent::Log::LOG;
		544	package AE::Log::LOG;
		545	package AnyEvent::Log::FILTER;
		546	package AE::Log::FILTER;
		547	package AnyEvent::Log::COLLECT;
		548	package AE::Log::COLLECT;
283		549
284	package AnyEvent::Log::Ctx;	550	package AnyEvent::Log::Ctx;
285		551
286	sub DESTROY {	552	# 0 1 2 3 4
287	# if only one member is remaining (name!) then delete this context	553	# [$title, $level, %$slaves, &$logcb, &$fmtcb]
288	delete $CTX{$_[0]{name}}	554
289	if 1 == scalar keys %{ $_[0] };	555	=item $ctx = new AnyEvent::Log::Ctx methodname => param...
		556
		557	This is a convenience constructor that makes it simpler to construct
		558	anonymous logging contexts.
		559
		560	Each key-value pair results in an invocation of the method of the same
		561	name as the key with the value as parameter, unless the value is an
		562	arrayref, in which case it calls the method with the contents of the
		563	array. The methods are called in the same order as specified.
		564
		565	Example: create a new logging context and set both the default logging
		566	level, some slave contexts and a logging callback.
		567
		568	$ctx = new AnyEvent::Log::Ctx
		569	title => "dubious messages",
		570	level => "error",
		571	log_cb => sub { print STDOUT shift; 0 },
		572	slaves => [$ctx1, $ctx, $ctx2],
		573	;
		574
		575	=back
		576
		577	=cut
		578
		579	sub new {
		580	my $class = shift;
		581
		582	my $ctx = AnyEvent::Log::ctx undef;
		583
		584	while (@_) {
		585	my ($k, $v) = splice @_, 0, 2;
		586	$ctx->$k (ref $v eq "ARRAY" ? @$v : $v);
		587	}
		588
		589	bless $ctx, $class # do we really support subclassing, hmm?
290	}	590	}
		591
		592
		593	=head2 CONFIGURING A LOG CONTEXT
		594
		595	The following methods can be used to configure the logging context.
		596
		597	=over 4
		598
		599	=item $ctx->title ([$new_title])
		600
		601	Returns the title of the logging context - this is the package name, for
		602	package contexts, and a user defined string for all others.
		603
		604	If C<$new_title> is given, then it replaces the package name or title.
		605
		606	=cut
		607
		608	sub title {
		609	$_[0][0] = $_[1] if @_ > 1;
		610	$_[0][0]
		611	}
		612
		613	=back
		614
		615	=head3 LOGGING LEVELS
		616
		617	The following methods deal with the logging level set associated with the
		618	log context.
		619
		620	The most common method to use is probably C<< $ctx->level ($level) >>,
		621	which configures the specified and any higher priority levels.
		622
		623	All functions which accept a list of levels also accept the special string
		624	C<all> which expands to all logging levels.
		625
		626	=over 4
		627
		628	=item $ctx->levels ($level[, $level...)
		629
		630	Enables logging for the given levels and disables it for all others.
		631
		632	=item $ctx->level ($level)
		633
		634	Enables logging for the given level and all lower level (higher priority)
		635	ones. In addition to normal logging levels, specifying a level of C<0> or
		636	C<off> disables all logging for this level.
		637
		638	Example: log warnings, errors and higher priority messages.
		639
		640	$ctx->level ("warn");
		641	$ctx->level (5); # same thing, just numeric
		642
		643	=item $ctx->enable ($level[, $level...])
		644
		645	Enables logging for the given levels, leaving all others unchanged.
		646
		647	=item $ctx->disable ($level[, $level...])
		648
		649	Disables logging for the given levels, leaving all others unchanged.
		650
		651	=cut
		652
		653	sub _lvl_lst {
		654	map {
		655	$_ > 0 && $_ <= 9 ? $_+0
		656	: $_ eq "all" ? (1 .. 9)
		657	: $STR2LEVEL{$_} \|\| Carp::croak "$_: not a valid logging level, caught"
		658	} @_
		659	}
		660
		661	our $NOP_CB = sub { 0 };
		662
		663	sub levels {
		664	my $ctx = shift;
		665	$ctx->[1] = 0;
		666	$ctx->[1] \|= 1 << $_
		667	for &_lvl_lst;
		668	AnyEvent::Log::_reassess;
		669	}
		670
		671	sub level {
		672	my $ctx = shift;
		673	my $lvl = $_[0] =~ /^(?:0\|off\|none)$/ ? 0 : (_lvl_lst $_[0])[-1];
		674
		675	$ctx->[1] = ((1 << $lvl) - 1) << 1;
		676	AnyEvent::Log::_reassess;
		677	}
		678
		679	sub enable {
		680	my $ctx = shift;
		681	$ctx->[1] \|= 1 << $_
		682	for &_lvl_lst;
		683	AnyEvent::Log::_reassess;
		684	}
		685
		686	sub disable {
		687	my $ctx = shift;
		688	$ctx->[1] &= ~(1 << $_)
		689	for &_lvl_lst;
		690	AnyEvent::Log::_reassess;
		691	}
		692
		693	=back
		694
		695	=head3 SLAVE CONTEXTS
		696
		697	The following methods attach and detach another logging context to a
		698	logging context.
		699
		700	Log messages are propagated to all slave contexts, unless the logging
		701	callback consumes the message.
		702
		703	=over 4
		704
		705	=item $ctx->attach ($ctx2[, $ctx3...])
		706
		707	Attaches the given contexts as slaves to this context. It is not an error
		708	to add a context twice (the second add will be ignored).
		709
		710	A context can be specified either as package name or as a context object.
		711
		712	=item $ctx->detach ($ctx2[, $ctx3...])
		713
		714	Removes the given slaves from this context - it's not an error to attempt
		715	to remove a context that hasn't been added.
		716
		717	A context can be specified either as package name or as a context object.
		718
		719	=item $ctx->slaves ($ctx2[, $ctx3...])
		720
		721	Replaces all slaves attached to this context by the ones given.
		722
		723	=cut
		724
		725	sub attach {
		726	my $ctx = shift;
		727
		728	$ctx->[2]{$_+0} = $_
		729	for map { AnyEvent::Log::ctx $_ } @_;
		730	}
		731
		732	sub detach {
		733	my $ctx = shift;
		734
		735	delete $ctx->[2]{$_+0}
		736	for map { AnyEvent::Log::ctx $_ } @_;
		737	}
		738
		739	sub slaves {
		740	undef $_[0][2];
		741	&attach;
		742	}
		743
		744	=back
		745
		746	=head3 LOG TARGETS
		747
		748	The following methods configure how the logging context actually does
		749	the logging (which consists of formatting the message and printing it or
		750	whatever it wants to do with it).
		751
		752	=over 4
		753
		754	=item $ctx->log_cb ($cb->($str)
		755
		756	Replaces the logging callback on the context (C<undef> disables the
		757	logging callback).
		758
		759	The logging callback is responsible for handling formatted log messages
		760	(see C<fmt_cb> below) - normally simple text strings that end with a
		761	newline (and are possibly multiline themselves).
		762
		763	It also has to return true iff it has consumed the log message, and false
		764	if it hasn't. Consuming a message means that it will not be sent to any
		765	slave context. When in doubt, return C<0> from your logging callback.
		766
		767	Example: a very simple logging callback, simply dump the message to STDOUT
		768	and do not consume it.
		769
		770	$ctx->log_cb (sub { print STDERR shift; 0 });
		771
		772	You can filter messages by having a log callback that simply returns C<1>
		773	and does not do anything with the message, but this counts as "message
		774	being logged" and might not be very efficient.
		775
		776	Example: propagate all messages except for log levels "debug" and
		777	"trace". The messages will still be generated, though, which can slow down
		778	your program.
		779
		780	$ctx->levels ("debug", "trace");
		781	$ctx->log_cb (sub { 1 }); # do not log, but eat debug and trace messages
		782
		783	=item $ctx->fmt_cb ($fmt_cb->($timestamp, $orig_ctx, $level, $message))
		784
		785	Replaces the formatting callback on the context (C<undef> restores the
		786	default formatter).
		787
		788	The callback is passed the (possibly fractional) timestamp, the original
		789	logging context, the (numeric) logging level and the raw message string
		790	and needs to return a formatted log message. In most cases this will be a
		791	string, but it could just as well be an array reference that just stores
		792	the values.
		793
		794	If, for some reason, you want to use C<caller> to find out more baout the
		795	logger then you should walk up the call stack until you are no longer
		796	inside the C<AnyEvent::Log> package.
		797
		798	Example: format just the raw message, with numeric log level in angle
		799	brackets.
		800
		801	$ctx->fmt_cb (sub {
		802	my ($time, $ctx, $lvl, $msg) = @_;
		803
		804	"<$lvl>$msg\n"
		805	});
		806
		807	Example: return an array reference with just the log values, and use
		808	C<PApp::SQL::sql_exec> to store the emssage in a database.
		809
		810	$ctx->fmt_cb (sub { \@_ });
		811	$ctx->log_cb (sub {
		812	my ($msg) = @_;
		813
		814	sql_exec "insert into log (when, subsys, prio, msg) values (?, ?, ?, ?)",
		815	$msg->[0] + 0,
		816	"$msg->[1]",
		817	$msg->[2] + 0,
		818	"$msg->[3]";
		819
		820	0
		821	});
		822
		823	=item $ctx->log_to_file ($path)
		824
		825	Sets the C<log_cb> to log to a file (by appending), unbuffered.
		826
		827	=item $ctx->log_to_path ($path)
		828
		829	Same as C<< ->log_to_file >>, but opens the file for each message. This
		830	is much slower, but allows you to change/move/rename/delete the file at
		831	basically any time.
		832
		833	=item $ctx->log_to_syslog ([$log_flags])
		834
		835	Logs all messages via L<Sys::Syslog>, mapping C<trace> to C<debug> and all
		836	the others in the obvious way. If specified, then the C<$log_flags> are
		837	simply or'ed onto the priority argument and can contain any C<LOG_xxx>
		838	flags valid for Sys::Syslog::syslog, except for the priority levels.
		839
		840	Note that this function also sets a C<fmt_cb> - the logging part requires
		841	an array reference with [$level, $str] as input.
		842
		843	=cut
		844
		845	sub log_cb {
		846	my ($ctx, $cb) = @_;
		847
		848	$ctx->[3] = $cb;
		849	}
		850
		851	sub fmt_cb {
		852	my ($ctx, $cb) = @_;
		853
		854	$ctx->[4] = $cb;
		855	}
		856
		857	sub log_to_file {
		858	my ($ctx, $path) = @_;
		859
		860	open my $fh, ">>", $path
		861	or die "$path: $!";
		862
		863	$ctx->log_cb (sub {
		864	syswrite $fh, shift;
		865	0
		866	});
		867	}
		868
		869	sub log_to_file {
		870	my ($ctx, $path) = @_;
		871
		872	$ctx->log_cb (sub {
		873	open my $fh, ">>", $path
		874	or die "$path: $!";
		875
		876	syswrite $fh, shift;
		877	0
		878	});
		879	}
		880
		881	sub log_to_syslog {
		882	my ($ctx, $flags) = @_;
		883
		884	require Sys::Syslog;
		885
		886	$ctx->fmt_cb (sub {
		887	my $str = $_[3];
		888	$str =~ s/\n(?=.)/\n+ /g;
		889
		890	[$_[2], "($_[1][0]) $str"]
		891	});
		892
		893	$ctx->log_cb (sub {
		894	my $lvl = $_[0][0] < 9 ? $_[0][0] : 8;
		895
		896	Sys::Syslog::syslog ($flags \| ($lvl - 1), $_)
		897	for split /\n/, $_[0][1];
		898
		899	0
		900	});
		901	}
		902
		903	=back
		904
		905	=head3 MESSAGE LOGGING
		906
		907	These methods allow you to log messages directly to a context, without
		908	going via your package context.
		909
		910	=over 4
		911
		912	=item $ctx->log ($level, $msg[, @params])
		913
		914	Same as C<AnyEvent::Log::log>, but uses the given context as log context.
		915
		916	=item $logger = $ctx->logger ($level[, \$enabled])
		917
		918	Same as C<AnyEvent::Log::logger>, but uses the given context as log
		919	context.
		920
		921	=cut
		922
		923	*log = \&AnyEvent::Log::_log;
		924	*logger = \&AnyEvent::Log::_logger;
291		925
292	1;	926	1;
		927
		928	=back
		929
		930	=head1 EXAMPLES
		931
		932	This section shows some common configurations.
		933
		934	=over 4
		935
		936	=item Setting the global logging level.
		937
		938	Either put PERL_ANYEVENT_VERBOSE=<number> into your environment before
		939	running your program, or modify the log level of the root context:
		940
		941	PERL_ANYEVENT_VERBOSE=5 ./myprog
		942
		943	$AnyEvent::Log::FILTER->level ("warn");
		944
		945	=item Append all messages to a file instead of sending them to STDERR.
		946
		947	This is affected by the global logging level.
		948
		949	$AnyEvent::Log::LOG->log_to_file ($path); (sub {
		950
		951	=item Write all messages with priority C<error> and higher to a file.
		952
		953	This writes them only when the global logging level allows it, because
		954	it is attached to the default context which is invoked I<after> global
		955	filtering.
		956
		957	$AnyEvent::Log::FILTER->attach
		958	new AnyEvent::Log::Ctx log_to_file => $path);
		959
		960	This writes them regardless of the global logging level, because it is
		961	attached to the toplevel context, which receives all messages I<before>
		962	the global filtering.
		963
		964	$AnyEvent::Log::COLLECT->attach (
		965	new AnyEvent::Log::Ctx log_to_file => $path);
		966
		967	In both cases, messages are still written to STDERR.
		968
		969	=item Write trace messages (only) from L<AnyEvent::Debug> to the default logging target(s).
		970
		971	Attach the C<$AnyEvent::Log::LOG> context to the C<AnyEvent::Debug>
		972	context - this simply circumvents the global filtering for trace messages.
		973
		974	my $debug = AnyEvent::Debug->AnyEvent::Log::ctx;
		975	$debug->attach ($AnyEvent::Log::LOG);
		976
		977	This of course works for any package, not just L<AnyEvent::Debug>, but
		978	assumes the log level for AnyEvent::Debug hasn't been changed from the
		979	default.
293		980
294	=back	981	=back
295		982
296	=head1 AUTHOR	983	=head1 AUTHOR
297		984

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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 1.26 by root, Sun Aug 21 03:29:19 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 1.26 by root, Sun Aug 21 03:29:19 2011 UTC