1Config::Watch(3)      User Contributed Perl Documentation     Config::Watch(3)
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NAME

6       Log::Log4perl::Config::Watch - Detect file changes
7

SYNOPSIS

9           use Log::Log4perl::Config::Watch;
10
11           my $watcher = Log::Log4perl::Config::Watch->new(
12                                 file            => "/data/my.conf",
13                                 check_interval  => 30,
14                         );
15
16           while(1) {
17               if($watcher->change_detected()) {
18                   print "Change detected!\n";
19               }
20               sleep(1);
21           }
22

DESCRIPTION

24       This module helps detecting changes in files. Although it comes with
25       the "Log::Log4perl" distribution, it can be used independly.
26
27       The constructor defines the file to be watched and the check interval
28       in seconds. Subsequent calls to "change_detected()" will
29
30       ·   return a false value immediately without doing physical file checks
31           if "check_interval" hasn't elapsed.
32
33       ·   perform a physical test on the specified file if the number of sec‐
34           onds specified in "check_interval" have elapsed since the last
35           physical check. If the file's modification date has changed since
36           the last physical check, it will return a true value, otherwise a
37           false value is returned.
38
39       Bottom line: "check_interval" allows you to call the function
40       "change_detected()" as often as you like, without paying the performing
41       a significant performance penalty because file system operations are
42       being performed (however, you pay the price of not knowing about file
43       changes until "check_interval" seconds have elapsed).
44
45       The module clearly distinguishes system time from file system time.  If
46       your (e.g. NFS mounted) file system is off by a constant amount of time
47       compared to the executing computer's clock, it'll just work fine.
48
49       To disable the resource-saving delay feature, just set "check_interval"
50       to 0 and "change_detected()" will run a physical file test on every
51       call.
52
53       If you already have the current time available, you can pass it on to
54       "change_detected()" as an optional parameter, like in
55
56           change_detected($time)
57
58       which then won't trigger a call to "time()", but use the value pro‐
59       vided.
60
61       SIGNAL MODE
62
63       Instead of polling time and file changes, "new()" can be instructed to
64       set up a signal handler. If you call the constructor like
65
66           my $watcher = Log::Log4perl::Config::Watch->new(
67                                 file    => "/data/my.conf",
68                                 signal  => 'HUP'
69                         );
70
71       then a signal handler will be installed, setting the object's variable
72       "$self->{signal_caught}" to a true value when the signal arrives. Comes
73       with all the problems that signal handlers go along with.
74

SEE ALSO

AUTHOR
77           Mike Schilli, <log4perl@perlmeister.com>
78

80       Copyright 2003 by Mike Schilli <m@perlmeister.com> and Kevin Goess
81       <cpan@goess.org>.
82
83       This library is free software; you can redistribute it and/or modify it
84       under the same terms as Perl itself.
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88perl v5.8.8                       2002-07-10                  Config::Watch(3)



        

    


            
        

        

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