Revision 10724,
1.6 KB
checked in by ghudson, 27 years ago
(diff) |
This commit was generated by cvs2svn to compensate for changes in r10723,
which included commits to RCS files with non-trunk default branches.
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1 | package FileCache; |
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2 | |
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3 | =head1 NAME |
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4 | |
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5 | FileCache - keep more files open than the system permits |
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6 | |
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7 | =head1 SYNOPSIS |
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8 | |
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9 | cacheout $path; |
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10 | print $path @data; |
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11 | |
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12 | =head1 DESCRIPTION |
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13 | |
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14 | The C<cacheout> function will make sure that there's a filehandle open |
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15 | for writing available as the pathname you give it. It automatically |
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16 | closes and re-opens files if you exceed your system file descriptor |
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17 | maximum. |
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18 | |
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19 | =head1 BUGS |
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20 | |
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21 | F<sys/param.h> lies with its C<NOFILE> define on some systems, |
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22 | so you may have to set $FileCache::cacheout_maxopen yourself. |
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23 | |
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24 | =cut |
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25 | |
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26 | require 5.000; |
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27 | use Carp; |
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28 | use Exporter; |
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29 | |
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30 | @ISA = qw(Exporter); |
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31 | @EXPORT = qw( |
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32 | cacheout |
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33 | ); |
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34 | |
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35 | # Open in their package. |
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36 | |
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37 | sub cacheout_open { |
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38 | my $pack = caller(1); |
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39 | open(*{$pack . '::' . $_[0]}, $_[1]); |
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40 | } |
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41 | |
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42 | sub cacheout_close { |
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43 | my $pack = caller(1); |
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44 | close(*{$pack . '::' . $_[0]}); |
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45 | } |
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46 | |
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47 | # But only this sub name is visible to them. |
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48 | |
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49 | $cacheout_seq = 0; |
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50 | $cacheout_numopen = 0; |
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51 | |
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52 | sub cacheout { |
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53 | ($file) = @_; |
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54 | unless (defined $cacheout_maxopen) { |
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55 | if (open(PARAM,'/usr/include/sys/param.h')) { |
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56 | local ($_, $.); |
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57 | while (<PARAM>) { |
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58 | $cacheout_maxopen = $1 - 4 |
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59 | if /^\s*#\s*define\s+NOFILE\s+(\d+)/; |
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60 | } |
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61 | close PARAM; |
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62 | } |
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63 | $cacheout_maxopen = 16 unless $cacheout_maxopen; |
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64 | } |
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65 | if (!$isopen{$file}) { |
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66 | if (++$cacheout_numopen > $cacheout_maxopen) { |
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67 | my @lru = sort {$isopen{$a} <=> $isopen{$b};} keys(%isopen); |
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68 | splice(@lru, $cacheout_maxopen / 3); |
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69 | $cacheout_numopen -= @lru; |
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70 | for (@lru) { &cacheout_close($_); delete $isopen{$_}; } |
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71 | } |
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72 | cacheout_open($file, ($saw{$file}++ ? '>>' : '>') . $file) |
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73 | or croak("Can't create $file: $!"); |
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74 | } |
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75 | $isopen{$file} = ++$cacheout_seq; |
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76 | } |
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77 | |
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78 | 1; |
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