Commit | Line | Data |
c07a80fd |
1 | package FileCache; |
2 | |
045cad98 |
3 | our $VERSION = '1.08'; |
b75c8c73 |
4 | |
c07a80fd |
5 | =head1 NAME |
6 | |
7 | FileCache - keep more files open than the system permits |
8 | |
9 | =head1 SYNOPSIS |
10 | |
46f1a616 |
11 | no strict 'refs'; |
12 | |
c14fc35a |
13 | use FileCache; |
14 | # or |
15 | use FileCache maxopen => 16; |
16 | |
ba1df86b |
17 | cacheout $mode, $path; |
18 | # or |
c07a80fd |
19 | cacheout $path; |
20 | print $path @data; |
21 | |
ba1df86b |
22 | $fh = cacheout $mode, $path; |
23 | # or |
24 | $fh = cacheout $path; |
25 | print $fh @data; |
c14fc35a |
26 | |
c07a80fd |
27 | =head1 DESCRIPTION |
28 | |
29 | The C<cacheout> function will make sure that there's a filehandle open |
c14fc35a |
30 | for reading or writing available as the pathname you give it. It |
ba1df86b |
31 | automatically closes and re-opens files if you exceed your system's |
32 | maximum number of file descriptors, or the suggested maximum I<maxopen>. |
c07a80fd |
33 | |
c14fc35a |
34 | =over |
7c21b9ea |
35 | |
c14fc35a |
36 | =item cacheout EXPR |
7c21b9ea |
37 | |
c14fc35a |
38 | The 1-argument form of cacheout will open a file for writing (C<< '>' >>) |
39 | on it's first use, and appending (C<<< '>>' >>>) thereafter. |
40 | |
ba1df86b |
41 | Returns EXPR on success for convenience. You may neglect the |
42 | return value and manipulate EXPR as the filehandle directly if you prefer. |
43 | |
c14fc35a |
44 | =item cacheout MODE, EXPR |
45 | |
46 | The 2-argument form of cacheout will use the supplied mode for the initial |
47 | and subsequent openings. Most valid modes for 3-argument C<open> are supported |
48 | namely; C<< '>' >>, C<< '+>' >>, C<< '<' >>, C<< '<+' >>, C<<< '>>' >>>, |
49 | C< '|-' > and C< '-|' > |
50 | |
841bcc4d |
51 | To pass supplemental arguments to a program opened with C< '|-' > or C< '-|' > |
52 | append them to the command string as you would system EXPR. |
53 | |
ba1df86b |
54 | Returns EXPR on success for convenience. You may neglect the |
55 | return value and manipulate EXPR as the filehandle directly if you prefer. |
7c21b9ea |
56 | |
00baac8f |
57 | =back |
58 | |
ba1df86b |
59 | =head1 CAVEATS |
7c21b9ea |
60 | |
dfe3554a |
61 | While it is permissible to C<close> a FileCache managed file, |
62 | do not do so if you are calling C<FileCache::cacheout> from a package other |
63 | than which it was imported, or with another module which overrides C<close>. |
64 | If you must, use C<FileCache::cacheout_close>. |
65 | |
533968fe |
66 | Although FileCache can be used with piped opens ('-|' or '|-') doing so is |
67 | strongly discouraged. If FileCache finds it necessary to close and then reopen |
68 | a pipe, the command at the far end of the pipe will be reexecuted - the results |
69 | of performing IO on FileCache'd pipes is unlikely to be what you expect. The |
70 | ability to use FileCache on pipes may be removed in a future release. |
71 | |
72 | FileCache does not store the current file offset if it finds it necessary to |
73 | close a file. When the file is reopened, the offset will be as specified by the |
74 | original C<open> file mode. This could be construed to be a bug. |
75 | |
46f1a616 |
76 | The module functionality relies on symbolic references, so things will break |
77 | under 'use strict' unless 'no strict "refs"' is also specified. |
78 | |
c07a80fd |
79 | =head1 BUGS |
80 | |
81 | F<sys/param.h> lies with its C<NOFILE> define on some systems, |
ba1df86b |
82 | so you may have to set I<maxopen> yourself. |
83 | |
c07a80fd |
84 | =cut |
85 | |
dfe3554a |
86 | require 5.006; |
c07a80fd |
87 | use Carp; |
7c21b9ea |
88 | use strict; |
c14fc35a |
89 | no strict 'refs'; |
c9463f45 |
90 | |
c14fc35a |
91 | # These are not C<my> for legacy reasons. |
92 | # Previous versions requested the user set $cacheout_maxopen by hand. |
93 | # Some authors fiddled with %saw to overcome the clobber on initial open. |
c9463f45 |
94 | use vars qw(%saw $cacheout_maxopen); |
95 | $cacheout_maxopen = 16; |
96 | |
97 | use base 'Exporter'; |
98 | our @EXPORT = qw[cacheout cacheout_close]; |
99 | |
100 | |
7c21b9ea |
101 | my %isopen; |
102 | my $cacheout_seq = 0; |
103 | |
c14fc35a |
104 | sub import { |
105 | my ($pkg,%args) = @_; |
02c473a9 |
106 | |
02c473a9 |
107 | # Use Exporter. %args are for us, not Exporter. |
108 | # Make sure to up export_to_level, or we will import into ourselves, |
109 | # rather than our calling package; |
02c473a9 |
110 | |
111 | __PACKAGE__->export_to_level(1); |
112 | Exporter::import( $pkg ); |
ba1df86b |
113 | |
c14fc35a |
114 | # Truth is okay here because setting maxopen to 0 would be bad |
ba1df86b |
115 | return $cacheout_maxopen = $args{maxopen} if $args{maxopen}; |
c9463f45 |
116 | |
117 | # XXX This code is crazy. Why is it a one element foreach loop? |
118 | # Why is it using $param both as a filename and filehandle? |
ba1df86b |
119 | foreach my $param ( '/usr/include/sys/param.h' ){ |
120 | if (open($param, '<', $param)) { |
121 | local ($_, $.); |
122 | while (<$param>) { |
123 | if( /^\s*#\s*define\s+NOFILE\s+(\d+)/ ){ |
124 | $cacheout_maxopen = $1 - 4; |
125 | close($param); |
126 | last; |
127 | } |
128 | } |
129 | close $param; |
c14fc35a |
130 | } |
c14fc35a |
131 | } |
132 | $cacheout_maxopen ||= 16; |
133 | } |
134 | |
c07a80fd |
135 | # Open in their package. |
c07a80fd |
136 | sub cacheout_open { |
ba1df86b |
137 | return open(*{caller(1) . '::' . $_[1]}, $_[0], $_[1]) && $_[1]; |
c07a80fd |
138 | } |
139 | |
c14fc35a |
140 | # Close in their package. |
c07a80fd |
141 | sub cacheout_close { |
ba1df86b |
142 | # Short-circuit in case the filehandle disappeared |
143 | my $pkg = caller($_[1]||0); |
414ef3ea |
144 | defined fileno(*{$pkg . '::' . $_[0]}) && |
ba1df86b |
145 | CORE::close(*{$pkg . '::' . $_[0]}); |
146 | delete $isopen{$_[0]}; |
c07a80fd |
147 | } |
148 | |
149 | # But only this sub name is visible to them. |
c07a80fd |
150 | sub cacheout { |
ba1df86b |
151 | my($mode, $file, $class, $ret, $ref, $narg); |
152 | croak "Not enough arguments for cacheout" unless $narg = scalar @_; |
153 | croak "Too many arguments for cacheout" if $narg > 2; |
c14fc35a |
154 | |
ba1df86b |
155 | ($mode, $file) = @_; |
156 | ($file, $mode) = ($mode, $file) if $narg == 1; |
157 | croak "Invalid mode for cacheout" if $mode && |
158 | ( $mode !~ /^\s*(?:>>|\+?>|\+?<|\|\-|)|\-\|\s*$/ ); |
841bcc4d |
159 | |
ba1df86b |
160 | # Mode changed? |
8ac28360 |
161 | if( $isopen{$file} && ($mode||'>') ne $isopen{$file}->[1] ){ |
ba1df86b |
162 | &cacheout_close($file, 1); |
163 | } |
c9463f45 |
164 | |
ba1df86b |
165 | if( $isopen{$file}) { |
166 | $ret = $file; |
167 | $isopen{$file}->[0]++; |
168 | } |
169 | else{ |
c14fc35a |
170 | if( scalar keys(%isopen) > $cacheout_maxopen -1 ) { |
ba1df86b |
171 | my @lru = sort{ $isopen{$a}->[0] <=> $isopen{$b}->[0] } keys(%isopen); |
172 | $cacheout_seq = 0; |
173 | $isopen{$_}->[0] = $cacheout_seq++ for |
174 | splice(@lru, int($cacheout_maxopen / 3)||$cacheout_maxopen); |
175 | &cacheout_close($_, 1) for @lru; |
c14fc35a |
176 | } |
ba1df86b |
177 | |
178 | unless( $ref ){ |
179 | $mode ||= $saw{$file} ? '>>' : ($saw{$file}=1, '>'); |
180 | } |
181 | #XXX should we just return the value from cacheout_open, no croak? |
182 | $ret = cacheout_open($mode, $file) or croak("Can't create $file: $!"); |
c9463f45 |
183 | |
ba1df86b |
184 | $isopen{$file} = [++$cacheout_seq, $mode]; |
c07a80fd |
185 | } |
ba1df86b |
186 | return $ret; |
c07a80fd |
187 | } |
c07a80fd |
188 | 1; |