File: FileRotate.pm

package info (click to toggle)
liblog-dispatch-filerotate-perl 1.19-1
  • links: PTS
  • area: main
  • in suites: jessie, jessie-kfreebsd, squeeze, stretch, wheezy
  • size: 104 kB
  • ctags: 19
  • sloc: perl: 532; makefile: 45
file content (926 lines) | stat: -rw-r--r-- 26,070 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
package Log::Dispatch::FileRotate;

require 5.005;
use strict;

use Log::Dispatch::Output;

use base qw( Log::Dispatch::Output );

use Log::Dispatch::File;   # We are a wrapper around Log::Dispatch::File

use Date::Manip;  # For time based recurring rotations
use File::Spec;   # For file-names

use Params::Validate qw(validate SCALAR BOOLEAN);
Params::Validate::validation_options( allow_extra => 1 );

use vars qw[ $VERSION ];

$VERSION = sprintf "%d.%02d", q$Revision: 1.19 $ =~ /: (\d+)\.(\d+)/;

sub new
{
    my $proto = shift;
    my $class = ref $proto || $proto;

    my %p = @_;

    my $self = bless {}, $class;

	$self->{'debug'} = 0;
    $self->_basic_init(%p);
    $self->{'LDF'} =  Log::Dispatch::File->new(%p);  # Our log
	$self->{'timer'} = sub { time() } unless defined $self->{'timer'};

	# Keep a copy of interesting stuff as well
	$self->{params} = \%p;

	# Turn ON/OFF debugging as required
	$p{'DEBUG'} ? $self->debug(1) : $self->debug(0);
	
	# Size defaults to 10meg in all failure modes, hopefully
	my $ten_meg = 1024*1024*10;
	my $two_gig = 1024*1024*1024*2;
	my $size = $ten_meg;
	$size = $p{size} if defined $p{size};
	$size = $ten_meg unless $size =~ /^\d+$/ && $size < $two_gig && $size > 0;
	$self->{size} = $size;

	# Max number of files defaults to 1. No limit enforced here. Only
	# positive whole numbers allowed
	$self->{max}  = $p{max};
	$self->{max}  = 1 unless defined $self->{max} && $self->{max} =~ /^\d+$/ && $self->{max} > 0 ;

	# Get a name for our Lock file
	my $name = $self->{params}->{filename};
	my ($vol, $dir, $f) = File::Spec->splitpath($name);
	$dir = '.' unless $dir;
	$f = $name unless $f;

	my $lockfile = File::Spec->catpath($vol, $dir, ".".$f.".LCK");
	warn "Lock file is $lockfile\n" if $self->{'debug'};
	$self->{'lf'} = $lockfile;

	# Have we been called with a time based rotation pattern then setup
	# timebased stuff. TZ is important and must match current TZ or all
	# bets are off!
	if(defined $p{'TZ'})
	{
		Date_Init("TZ=".$p{'TZ'});  # EADT or EAST when not in daylight savings
	}
	if(defined $p{'DatePattern'})
	{
		$self->setDatePattern($p{'DatePattern'});
	}

	# Flag this as first creation point
	$self->{'new'} = 1;

    return $self;
}


###########################################################################
#
# Subroutine setDatePattern
#       
#       Args: a single string or ArrayRef of strings
#
#       Rtns: Nothing
#
# Description:
#     Set a recurrance for file rotation. We accept Date::Manip
#     recurrances and the log4j/DailyRollingFileAppender patterns
#       
#     Date:Manip =>              
#			0:0:0:0:5:30:0       every 5 hours and 30 minutes
#			0:0:0:2*12:30:0      every 2 days at 12:30 (each day)
#			3*1:0:2:12:0:0       every 3 years on Jan 2 at noon
#
#	  DailyRollingFileAppender =>
#			yyyy-MM
#			yyyy-ww
#			yyyy-MM-dd
#			yyyy-MM-dd-a
#			yyyy-MM-dd-HH
#			yyyy-MM-dd-HH-MM
#
# To specify multiple recurances in a single string seperate them with a
# comma: yyyy-MM-dd,0:0:0:2*12:30:0
#
sub setDatePattern
{
    my $self = shift;        # My object
    my($arg) = shift;

	local($_);               # Don't crap on $_
	my @pats = ();

	my %lookup = (
		#					 Y:M:W:D:H:M:S
		'yyyy-mm'		=> 	'0:1*0:1:0:0:0',  # Every Month
		'yyyy-ww'		=> 	'0:0:1*0:0:0:0',  # Every week
		'yyyy-dd'		=> 	'0:0:0:1*0:0:0',  # Every day 
		'yyyy-mm-dd'	=> 	'0:0:0:1*0:0:0',  # Every day 
		'yyyy-dd-a'		=> 	'0:0:0:1*12:0:0', # Every day 12noon
		'yyyy-mm-dd-a'	=> 	'0:0:0:1*12:0:0', # Every day 12noon
		'yyyy-dd-hh'	=> 	'0:0:0:0:1*0:0',  # Every hour
		'yyyy-mm-dd-hh'	=> 	'0:0:0:0:1*0:0',  # Every hour
		'yyyy-dd-hh-mm'	=> 	'0:0:0:0:0:1*0',  # Every minute
		'yyyy-mm-dd-hh-mm'	=> 	'0:0:0:0:0:1*0',  # Every minute
	);

	# Convert arg to array
	if( ref($arg) eq 'ARRAY' )
	{
		@pats = @$arg;
	}
	elsif( !ref($arg) )
	{
		$arg =~ s/\s+//go;
		@pats = split(/;/,$arg);
	}
	else
	{
		die "Bad reference type argument ".ref($arg);
	}

	# Handle (possibly multiple) recurrances
	foreach my $pat (@pats)
	{
		# Convert any log4j patterns across
		if($pat =~ /^yyyy/i) # Then log4j style
		{
			$pat = lc($pat); # Use lowercase lookup
			# Default to daily on bad pattern
			unless(grep($pat eq $_,keys %lookup))
			{
				warn "Bad Rotation pattern ($pat) using yyyy-dd\n";
				$pat = 'yyyy-dd';
			}
			$pat = $lookup{$pat};
		}

		my $abs = $self->_get_next_occurance($pat);
		warn "Adding [dates,pat] =>[$abs,$pat]\n" if $self->{debug};
		my $ref = [$abs, $pat];
		push(@{$self->{'recurrance'}}, $ref);

	}

}


sub log_message
{
    my $self = shift;
    my %p = @_;

	my $max_size = $self->{size};
	my $numfiles = $self->{max};
	my $name     = $self->{params}->{filename};
	my $fh       = $self->{LDF}->{fh};

	# Prime our time based data outside the critical code area
	my ($in_time_mode,$time_to_rotate) = $self->time_to_rotate();

	# Handle critical code for logging. No changes if someone else is in
	if( !$self->lfhlock_test() )
	{
		warn "$$ waiting on lock\n" if $self->{debug};
		unless($self->lfhlock())
		{
			warn "$$ failed to get lock. returning\n" if $self->{debug};
			return;
		}
		warn "$$ got lock after wait\n" if $self->{debug};
	}

	my $size   = (stat($fh))[7];   # Stat the handle to get real size
	my $inode  = (stat($fh))[1];   # get real inode
	my $finode = (stat($name))[1]; # Stat the name for comparision
	warn localtime()." $$  s=$size, i=$inode, f=".
			(defined $finode ? $finode : "undef") .
			 ", n=$name\n" if $self->{debug};

	# If finode and inode are the same then nobody has done a rename
	# under us and we can continue. Otherwise just close and reopen.
	# Time mode overrides Size mode
	if(!defined($finode) || $inode != $finode)
	{
		# Oops someone moved things on us. So just reopen our log
		delete $self->{LDF};  # Should get rid of current LDF
		$self->{LDF} =  Log::Dispatch::File->new(%{$self->{params}});  # Our log

		warn localtime()." $$ Someone else rotated: normal log\n" if $self->{debug};
		$self->logit($p{message});
	}
	elsif($in_time_mode && !$time_to_rotate)
	{
		warn localtime()." $$ In time mode: normal log\n" if $self->{debug};
		$self->logit($p{message});
	}
	elsif(!$in_time_mode && defined($size) && $size < $max_size )
	{
		warn localtime()." $$ In size mode: normal log\n" if $self->{debug};
		$self->logit($p{message});
	}
	# Need to rotate
	elsif(($in_time_mode && $time_to_rotate) || 
	      (!$in_time_mode && $size)
		 )
	{
		# Shut down the log
		delete $self->{LDF};  # Should get rid of current LDF

		my $idx = $numfiles -1;

		warn localtime() . " $$ Rotating\n" if $self->{debug};
		while($idx >= 0)
		{
			if($idx <= 0)
			{
				warn "$$ rename $name $name.1\n" if $self->{debug};
				rename($name, "$name.1");
			}
			else
			{
				warn "$$ rename $name.$idx $name.".($idx+1)."\n" if $self->{debug};
				rename("$name.$idx", "$name.".($idx+1));
			}

			$idx--;
		}
		warn localtime() . " $$ Rotating Done\n" if $self->{debug}; 

		# reopen the logfile for writing.
		$self->{LDF} =  Log::Dispatch::File->new(%{$self->{params}});  # Our log

		# Write it out
		warn localtime()." $$ rotated: normal log\n" if $self->{debug};
		$self->logit($p{message});
	}
	#else size is zero :-} just don't do anything!

	$self->lfhunlock();
}

sub DESTROY
{
    my $self = shift;

    if ( $self->{LDF} )
    {
		delete $self->{LDF};  # Should get rid of current LDF
    }

	# Clean up locks
	close $self->{lfh} if $self->{lfh};
 	unlink $self->{lf} if -f $self->{lf};
}

sub logit
{
	my $self = $_[0];

	$self->lock();
	$self->{LDF}->log_message(message => $_[1]);
	$self->unlock();
	return;
}


###########################################################################
#
# Subroutine time_to_rotate
#       
#       Args: none
#
#       Rtns: (1,n)  if we are in time mode and its time to rotate
#                    n defines the number of timers that expired
#             (1,0)  if we are in time mode but not ready to rotate
#             (0,0)  otherwise
#
# Description:
#     time_to_rotate - update internal clocks and return status as
#     defined above
#
# If we have just been created then the first recurrance is an indication
# to check against the log file.
#       
#       
#	my ($in_time_mode,$time_to_rotate) = $self->time_to_rotate();
sub time_to_rotate
{
    my $self   = shift;        # My object
	my $mode   = defined($self->{'recurrance'});
	my $rotate = 0;

	if($mode)
	{
		# Then do some checking and update ourselves if we think we need
		# to rotate. Wether we rotate or not is up to our caller. We
		# assume they know what they are doing!

		# Only stat the log file here if we are in our first invocation.
		my $ftime = 0;
		if($self->{'new'})
		{
			# Last time the log file was changed
			$ftime   = (stat($self->{LDF}{fh}))[9];

			# In Date::Manip format
			# $ftime   = ParseDate(scalar(localtime($ftime)));
		}

		# Check need for rotation. Loop through our recurrances looking
		# for expiration times. Any we find that have expired we update.
		my $tm    = $self->{timer}->();
		my @recur = @{$self->{'recurrance'}};
		@{$self->{'recurrance'}} = ();
		for my $rec (@recur)
		{
			my ($abs,$pat) = @$rec;

			# Extra checking
			unless(defined $abs && $abs)
			{
				warn "Bad time found for recurrance pattern $pat: $abs\n";
				next;
			}
			my $dorotate = 0;

			# If this is first time through
			if($self->{'new'})
			{
				# If it needs a rotate then flag it
				if($ftime <= $abs)
				{
					# Then we need to rotate
					warn "Need rotate file($ftime) <= $abs\n" if $self->{debug};
					$rotate++;
					$dorotate++;  # Just for debugging
				}

				# Move to next occurance regardless
				warn "Dropping initial occurance($abs)\n" if $self->{debug};
				$abs = $self->_get_next_occurance($pat);
				unless(defined $abs && $abs)
				{
					warn "Next occurance is null for $pat\n";
					$abs = 0;
				}
			}
			# Elsif it is time to rotate
			#elsif(Date_Cmp($abs,$tm) <= 0)
			elsif($abs <= $tm)
			{
				# Then we need to rotate
				warn "Need rotate $abs <= $tm\n" if $self->{debug};
				$abs = $self->_get_next_occurance($pat);
				unless(defined $abs && $abs)
				{
					warn "Next occurance is null for $pat\n";
					$abs = 0;
				}
				$rotate++;
				$dorotate++;  # Just for debugging
			}
			push(@{$self->{'recurrance'}},[$abs,$pat]) if $abs;
			warn "time_to_rotate(mode,rotate,next) => ($mode,$dorotate,$abs)\n" if $self->{debug};
		}
		
	}

	$self->{'new'} = 0;  # No longer brand-spankers

	warn "time_to_rotate(mode,rotate) => ($mode,$rotate)\n" if $self->{debug};
	return wantarray ? ($mode,$rotate) : $rotate;
}

###########################################################################
#
# Subroutine _gen_occurance
#       
#       Args: Date::Manip occurance pattern
#
#       Rtns: array of dates for next few events
#
#  If asked we will return an inital occurance that is before the current
#  time. This can be used to see if we need to rotate on start up. We are
#  often called by CGI (short lived) proggies :-(
#
sub _gen_occurance
{
    my $self = shift;        # My object
    my $pat  = shift;

	# Do we return an initial occurance before the current time?
	my $initial = shift || 0;

	my $range = '';
	my $base  = 'now'; # default to calcs based on the current time

	if($pat =~ /^0:0:0:0:0/) # Small recurrance less than 1 hour
	{
		$range = "4 hours later";
		$base  = "1 hours ago" if $initial;
	}
	elsif($pat =~ /^0:0:0:0/) # recurrance less than 1 day
	{
		$range = "4 days later";
		$base  = "1 days ago" if $initial;
	}
	elsif($pat =~ /^0:0:0:/) #  recurrance less than 1 week
	{
		$range = "4 weeks later";
		$base  = "1 weeks ago" if $initial;
	}
	elsif($pat =~ /^0:0:/) #  recurrance less than 1 month
	{
		$range = "4 months later";
		$base  = "1 months ago" if $initial;
	}
	elsif($pat =~ /^0:/) #  recurrance less than 1 year
	{
		$range = "24 months later";
		$base  = "24 months ago" if $initial;
	}
	else # years
	{
		my($yrs) = $pat =~ m/^(\d+):/;
		$yrs = 1 unless $yrs;
		my $months = $yrs * 4 * 12;

		$range = "$months months later";
		$base  = "$months months ago" if $initial;
	}

	# The next date must start at least 1 second away from now other wise
	# we may rotate for every message we recieve with in this second :-(
	my $start = DateCalc($base,"+ 1 second");

	warn "ParseRecur($pat,$base,$start,$range);\n" if $self->{debug};
	my @dates = ParseRecur($pat,$base,$start,$range);

	# Just in case we have a bad parse or our assumptions are wrong.
	# We default to days
	unless(scalar @dates >= 2)
	{
		warn "Failed to parse ($pat). Going daily\n";
		@dates = ParseRecur('0:0:0:1*0:0:0',"now","now","1 months later");
		if($initial)
		{
			@dates = ParseRecur('0:0:0:1*0:0:0',"2 days ago","2 days ago","1 months later");
		}
	}

	# Convert the dates to seconds since the epoch so we can use
	# numerical comparision instead of textual
	my @epochs = ();
	my @a = ('%Y','%m','%d','%H','%M','%S');
	foreach(@dates)
	{
		my($y,$m,$d,$h,$mn,$s) = Date::Manip::UnixDate($_, @a);
		my $e = Date_SecsSince1970GMT($m,$d,$y,$h,$mn,$s);
		if( $self->{debug} )
		{
			warn "Date to epochs ($_) => ($e)\n";
		}
		push @epochs, $e;
	}

	# Clean out all but the one previous to now if we are doing an
	# initial occurance
	my $now = time();
	if($initial)
	{
		my $before = '';
		while(@epochs && ( $epochs[0] <= $now) )
		{
			$before = shift(@epochs);
			#warn "Shifting $before\n";
		}
		#warn "Unshifting $before\n";
		unshift(@epochs,$before) if $before;
	}
	else
	{
		# Clean out dates that occur before now, being careful not to loop
		# forever (thanks James).
		shift(@epochs) while @epochs && ( $epochs[0] <= $now);
	}

	if($self->{debug})
	{
		warn "Recurrances are at: ".join("\n\t", @dates),"\n";
	}
	warn "No recurrances found! Probably a timezone issue!\n" unless @dates;

	return @epochs;
}

###########################################################################
#
# Subroutine _get_next_occurance
#       
#       Args: Date::Manip occurance pattern
#
#       Rtns: date
#
# We don't want to call Date::Manip::ParseRecur too often as it is very
# expensive. So, we cache what is returned from _gen_occurance().
sub _get_next_occurance
{
    my $self = shift;        # My object
    my $pat  = shift;

	# (ms) Throw out expired occurances
	my $now = $self->{timer}->();
	if(defined $self->{'dates'}{$pat})
	{
		while( @{$self->{'dates'}{$pat}} )
		{
			last if $self->{'dates'}{$pat}->[0] >= $now;
			shift @{$self->{'dates'}{$pat}};
		}
	}

	# If this is first time then generate some new ones including one
	# before our time to test against the log file
	if(!defined $self->{'dates'}{$pat})
	{
		@{$self->{'dates'}{$pat}} = $self->_gen_occurance($pat,1);
	}
	# Elsif close to the end of what we have
	elsif( scalar(@{$self->{'dates'}{$pat}}) < 2)
	{
		@{$self->{'dates'}{$pat}} = $self->_gen_occurance($pat);
	}
	
	return( shift(@{$self->{'dates'}{$pat}}) );
}


# Lock and unlock routines. For when we need to write a message.
use Fcntl ':flock'; # import LOCK_* constants

sub lock 
{
	my $self = shift;

	flock($self->{LDF}->{fh},LOCK_EX);

	# Make sure we are at the EOF
	seek($self->{LDF}->{fh}, 0, 2);

	warn localtime() ." $$ Locked\n" if $self->{debug};
	return;
}

sub unlock 
{
	my $self = shift;
	flock($self->{LDF}->{fh},LOCK_UN);
	warn localtime() . " $$ unLocked\n" if $self->{debug};
}

# Lock and unlock routines. For when we need to roll the logs.
#
# Note: On May 1, Dan Waldheim's good news was:
# I discovered something interesting about forked processes and locking.
# If the parent "open"s the filehandle and then forks, exclusive locks
# don't work properly between the parent and children.  Anyone can grab a
# lock while someone else thinks they have it.  To work properly the
# "open" has to be done within each process.
#
# Thanks Dan
sub lfhlock_test 
{
	my $self = shift;

	if (open(LFH, ">>$self->{lf}"))
	{
		$self->{lfh} = *LFH;
		if (flock($self->{lfh}, LOCK_EX | LOCK_NB))
		{
			warn "$$ got lock on Lock File ".$self->{lfh}."\n" if $self->{debug};
			return 1;
		}
	}
	else
	{
		$self->{lfh} = 0;
		warn "$$ couldn't get lock on Lock File\n" if $self->{debug};
		return 0;
	}
}

sub lfhlock
{
	my $self = shift;

	if (!$self->{lfh})
	{
		if (!open(LFH, ">>$self->{lf}"))
		{
			return 0;
		}
		$self->{lfh} = *LFH;
	}

	flock($self->{lfh},LOCK_EX);
}

sub lfhunlock 
{
	my $self = shift;

	if($self->{lfh})
	{
		flock($self->{lfh},LOCK_UN);
		close $self->{lfh};
		$self->{lfh} = 0;
	}
}

sub debug
{
	$_[0]->{'debug'} = $_[1];
}

__END__

=head1 NAME

Log::Dispatch::FileRotate - Log to files that archive/rotate themselves

=head1 SYNOPSIS

  use Log::Dispatch::FileRotate;

  my $file = Log::Dispatch::FileRotate->new( name      => 'file1',
                                       min_level => 'info',
                                       filename  => 'Somefile.log',
                                       mode      => 'append' ,
                                       size      => 10,
                                       max       => 6,
                                      );
  # or for a time based rotation

  my $file = Log::Dispatch::FileRotate->new( name      => 'file1',
                                       min_level => 'info',
                                       filename  => 'Somefile.log',
                                       mode      => 'append' ,
                                       TZ        => 'AEDT',
                                       DatePattern => 'yyyy-dd-HH',
                                      );

  $file->log( level => 'info', message => "your comment\n" );

=head1 DESCRIPTION

This module provides a simple object for logging to files under the
Log::Dispatch::* system, and automatically rotating them according to
different constraints. This is basically a Log::Dispatch::File wrapper
with additions. To that end the arguments

	name, min_level, filename and  mode

behave the same as Log::Dispatch::File. So see its man page 
(perldoc Log::Dispatch::File)

The arguments size and max specify the maximum size and maximum
number of log files created. The size defaults to 10M and the max number
of files defaults to 1. If DatePattern is not defined then we default to
working in size mode. That is, use size values for deciding when to rotate.

Once DatePattern is defined FileRotate will move into time mode. Once
this happens file rotation ignores size constraints and uses the defined
date pattern constraints.

If you setup a config file using Log::Log4perl::init_and_watch() or the
like, you can switch between modes just by commenting out the DatePattern
line.

When using DatePattern make sure TZ is defined correctly and that the TZ
you use is understood by Date::Manip. We use Date::Manip to generate our
recurrences. Bad TZ equals bad recurrences equals surprises! Read the
Date::Manip man page for more details on TZ.

DatePattern will default to a daily rotate if your entered pattern is
incorrect. You will also get a warning message.

If you have multiple writers that were started at different times you
will find each writer will try to rotate the log file at a recurrence
calculated from its start time. To sync all the writers just use a config
file and update it after starting your last writer. This will cause
Log::Dispatch::FileRotate->new() to be called by each of the writers
close to the same time, and if your recurrences aren't too close together
all should sync up just nicely.

I initially aasumed a long runinng process but it seems people are using
this module as part of short running CGI programs. So, now we look at the
last modified time stamp of the log file and compare it to a previous
occurance of a DatePattern, on startup only. If the file stat shows
the mtime to be earlier than the previous recurrance then I rotate the
log file.

We handle multiple writers using flock().

=head1 DatePattern

As I said earlier we use Date::Manip for generating our recurrence
events. This means we can understand Date::Manip's recurrence patterns
and the normal log4j DatePatterns. We don't use DatePattern to define the
extension of the log file though.

DatePattern can therefore take forms like:

	
      Date::Manip style
            0:0:0:0:5:30:0       every 5 hours and 30 minutes
            0:0:0:2*12:30:0      every 2 days at 12:30 (each day)
            3*1:0:2:12:0:0       every 3 years on Jan 2 at noon

      DailyRollingFileAppender log4j style
            yyyy-MM              every month
            yyyy-ww              every week
            yyyy-MM-dd           every day
            yyyy-MM-dd-a         every day at noon
            yyyy-MM-dd-HH        every hour
            yyyy-MM-dd-HH-MM     every minute

To specify multiple recurrences in a single string separate them with a
semicolon:
        yyyy-MM-dd; 0:0:0:2*12:30:0

This says we want to rotate every day AND every 2 days at 12:30. Put in
as many as you like.

A complete description of Date::Manip recurrences is beyond us here
except to quote (from the man page):

           A recur description is a string of the format
           Y:M:W:D:H:MN:S .  Exactly one of the colons may
           optionally be replaced by an asterisk, or an asterisk
           may be prepended to the string.

           Any value "N" to the left of the asterisk refers to
           the "Nth" one.  Any value to the right of the asterisk
           refers to a value as it appears on a calendar/clock.
           Values to the right can be listed a single values,
           ranges (2 numbers separated by a dash "-"), or a comma
           separated list of values or ranges.  In a few cases,
           negative values are appropriate.

           This is best illustrated by example.

             0:0:2:1:0:0:0        every 2 weeks and 1 day
             0:0:0:0:5:30:0       every 5 hours and 30 minutes
             0:0:0:2*12:30:0      every 2 days at 12:30 (each day)
             3*1:0:2:12:0:0       every 3 years on Jan 2 at noon
             0:1*0:2:12,14:0:0    2nd of every month at 12:00 and 14:00
             1:0:0*45:0:0:0       45th day of every year
             0:1*4:2:0:0:0        4th tuesday (day 2) of every month
             0:1*-1:2:0:0:0       last tuesday of every month
             0:1:0*-2:0:0:0       2nd to last day of every month



=head1 METHODS

=over 4

=item * new(%p)

This method takes a hash of parameters.  The following options are
valid:

=item -- name ($)

The name of the object (not the filename!).  Required.

=item -- size ($)

The maxium (or close to) size the log file can grow too.

=item -- max ($)

The maxium number of log files to create.


=item -- TZ ($)

The TimeZone time based calculations should be done in. This should match
Date::Manip's concept of timezones and of course your machines timezone.

=item -- DatePattern ($)

The DatePattern as defined above.

=item -- min_level ($)

The minimum logging level this object will accept.  See the
Log::Dispatch documentation for more information.  Required.

=item -- max_level ($)

The maximum logging level this obejct will accept.  See the
Log::Dispatch documentation for more information.  This is not
required.  By default the maximum is the highest possible level (which
means functionally that the object has no maximum).

=item -- filename ($)

The filename to be opened for writing. This is the base name. Rotated log
files will be renamed filename.1 thru to filename.C<max>. Where max is the
paramater defined above.

=item -- mode ($)

The mode the file should be opened with.  Valid options are 'write',
'>', 'append', '>>', or the relevant constants from Fcntl.  The
default is 'write'.

=item -- autoflush ($)

Whether or not the file should be autoflushed.  This defaults to true.

=item -- callbacks( \& or [ \&, \&, ... ] )

This parameter may be a single subroutine reference or an array
reference of subroutine references.  These callbacks will be called in
the order they are given and passed a hash containing the following keys:

 ( message => $log_message, level => $log_level )

The callbacks are expected to modify the message and then return a
single scalar containing that modified message.  These callbacks will
be called when either the C<log> or C<log_to> methods are called and
will only be applied to a given message once.

=item -- DEBUG ($)

Turn on lots of warning messages to STDERR about what this module is
doing if set to 1. Really only useful to me.

=item * log_message( message => $ )

Sends a message to the appropriate output.  Generally this shouldn't
be called directly but should be called through the C<log()> method
(in Log::Dispatch::Output).

=item * setDatePattern( $ or [ $, $, ... ] )

Set a new suite of recurrances for file rotation. You can pass in a
single string or a reference to an array of strings. Multiple recurrences
can also be define within a single string by seperating them with a
semi-colon (;)

See the discussion above regarding the setDatePattern paramater for more
details.

=back

=head1 TODO

compression, signal based rotates, proper test suite

Could possibly use Logfile::Rotate as well/instead.

=head1 AUTHOR

Mark Pfeiffer, <markpf at mlp-consulting dot com dot au> inspired by
Dave Rolsky's, <autarch at urth dot org>, code :-)

Kevin Goess <cpan at goess dot org> suggested multiple writers should be
supported. He also conned me into doing the time based stuff.
Thanks Kevin! :-)

Thanks also to Dan Waldheim for helping with some of the
locking issues in a forked environment.

And thanks to Stephen Gordon for his more portable code on lockfile
naming.

=cut

=head1 Copyright

Copyright 2005-2006, Mark Pfeiffer

This code may be copied only under the terms of the Artistic License, or
GPL License which may be found in the Perl 5 source kit.

Use 'perldoc perlartistic' to see the Artistic License.
Use 'perldoc perlgpl' to see the GNU General Public License.

Complete documentation for Perl, including FAQ lists, should be found on
this system using `man perl' or `perldoc perl'.  If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

=cut