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1 | package FileCache; |
2 | |
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3 | our $VERSION = '1.01'; |
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4 | |
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5 | =head1 NAME |
6 | |
7 | FileCache - keep more files open than the system permits |
8 | |
9 | =head1 SYNOPSIS |
10 | |
11 | cacheout $path; |
12 | print $path @data; |
13 | |
14 | =head1 DESCRIPTION |
15 | |
16 | The C<cacheout> function will make sure that there's a filehandle open |
17 | for writing available as the pathname you give it. It automatically |
18 | closes and re-opens files if you exceed your system file descriptor |
19 | maximum. |
20 | |
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21 | =head1 CAVEATS |
22 | |
23 | If the argument passed to cacheout does not begin with a valid mode |
24 | (>, +>, <, +<, >>, |) then the file will be clobbered the first time |
25 | it is opened. |
26 | |
27 | cacheout '>>' . $path; |
28 | print $path @data; |
29 | |
30 | If $path includes the filemode the filehandle will not be accessible |
31 | as $path. |
32 | |
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33 | =head1 BUGS |
34 | |
35 | F<sys/param.h> lies with its C<NOFILE> define on some systems, |
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36 | so you may have to set $FileCache::cacheout_maxopen yourself. |
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37 | |
38 | =cut |
39 | |
40 | require 5.000; |
41 | use Carp; |
42 | use Exporter; |
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43 | use strict; |
44 | use vars qw(@ISA @EXPORT %saw $cacheout_maxopen); |
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45 | |
46 | @ISA = qw(Exporter); |
47 | @EXPORT = qw( |
48 | cacheout |
49 | ); |
50 | |
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51 | my %isopen; |
52 | my $cacheout_seq = 0; |
53 | |
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54 | # Open in their package. |
55 | |
56 | sub cacheout_open { |
57 | my $pack = caller(1); |
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58 | no strict 'refs'; |
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59 | open(*{$pack . '::' . $_[0]}, $_[1]); |
60 | } |
61 | |
62 | sub cacheout_close { |
63 | my $pack = caller(1); |
64 | close(*{$pack . '::' . $_[0]}); |
65 | } |
66 | |
67 | # But only this sub name is visible to them. |
68 | |
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69 | sub cacheout { |
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70 | my($file) = @_; |
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71 | unless (defined $cacheout_maxopen) { |
72 | if (open(PARAM,'/usr/include/sys/param.h')) { |
7adad424 |
73 | local ($_, $.); |
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74 | while (<PARAM>) { |
75 | $cacheout_maxopen = $1 - 4 |
76 | if /^\s*#\s*define\s+NOFILE\s+(\d+)/; |
77 | } |
78 | close PARAM; |
79 | } |
80 | $cacheout_maxopen = 16 unless $cacheout_maxopen; |
81 | } |
82 | if (!$isopen{$file}) { |
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83 | if ( scalar keys(%isopen) + 1 > $cacheout_maxopen) { |
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84 | my @lru = sort {$isopen{$a} <=> $isopen{$b};} keys(%isopen); |
85 | splice(@lru, $cacheout_maxopen / 3); |
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86 | for (@lru) { &cacheout_close($_); delete $isopen{$_}; } |
87 | } |
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88 | my $symbol = $file; |
89 | unless( $symbol =~ s/^(\s?(?:>>)|(?:\+?>)|(?:\+?<)|\|)// ){ |
90 | $file = ($saw{$file}++ ? '>>' : '>') . $file; |
91 | } |
92 | cacheout_open($symbol, $file) |
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93 | or croak("Can't create $file: $!"); |
94 | } |
95 | $isopen{$file} = ++$cacheout_seq; |
96 | } |
97 | |
98 | 1; |