3 our $VERSION = '1.04_01';
7 FileCache - keep more files open than the system permits
13 use FileCache maxopen => 16;
15 cacheout $mode, $path;
20 $fh = cacheout $mode, $path;
27 The C<cacheout> function will make sure that there's a filehandle open
28 for reading or writing available as the pathname you give it. It
29 automatically closes and re-opens files if you exceed your system's
30 maximum number of file descriptors, or the suggested maximum I<maxopen>.
36 The 1-argument form of cacheout will open a file for writing (C<< '>' >>)
37 on it's first use, and appending (C<<< '>>' >>>) thereafter.
39 Returns EXPR on success for convenience. You may neglect the
40 return value and manipulate EXPR as the filehandle directly if you prefer.
42 =item cacheout MODE, EXPR
44 The 2-argument form of cacheout will use the supplied mode for the initial
45 and subsequent openings. Most valid modes for 3-argument C<open> are supported
46 namely; C<< '>' >>, C<< '+>' >>, C<< '<' >>, C<< '<+' >>, C<<< '>>' >>>,
47 C< '|-' > and C< '-|' >
49 To pass supplemental arguments to a program opened with C< '|-' > or C< '-|' >
50 append them to the command string as you would system EXPR.
52 Returns EXPR on success for convenience. You may neglect the
53 return value and manipulate EXPR as the filehandle directly if you prefer.
57 While it is permissible to C<close> a FileCache managed file,
58 do not do so if you are calling C<FileCache::cacheout> from a package other
59 than which it was imported, or with another module which overrides C<close>.
60 If you must, use C<FileCache::cacheout_close>.
62 Although FileCache can be used with piped opens ('-|' or '|-') doing so is
63 strongly discouraged. If FileCache finds it necessary to close and then reopen
64 a pipe, the command at the far end of the pipe will be reexecuted - the results
65 of performing IO on FileCache'd pipes is unlikely to be what you expect. The
66 ability to use FileCache on pipes may be removed in a future release.
68 FileCache does not store the current file offset if it finds it necessary to
69 close a file. When the file is reopened, the offset will be as specified by the
70 original C<open> file mode. This could be construed to be a bug.
74 F<sys/param.h> lies with its C<NOFILE> define on some systems,
75 so you may have to set I<maxopen> yourself.
84 # These are not C<my> for legacy reasons.
85 # Previous versions requested the user set $cacheout_maxopen by hand.
86 # Some authors fiddled with %saw to overcome the clobber on initial open.
87 use vars qw(%saw $cacheout_maxopen @EXPORT);
94 # Not using Exporter is naughty.
95 # Also, using caller(1) is just wrong.
97 #*{$pkg.'::cacheout'} = \&cacheout;
98 #*{$pkg.'::close'} = \&cacheout_close;
100 # Use Exporter. %args are for us, not Exporter.
101 # Make sure to up export_to_level, or we will import into ourselves,
102 # rather than our calling package;
104 @EXPORT = qw[cacheout cacheout_close];
106 __PACKAGE__->export_to_level(1);
107 Exporter::import( $pkg );
109 # Truth is okay here because setting maxopen to 0 would be bad
110 return $cacheout_maxopen = $args{maxopen} if $args{maxopen};
111 foreach my $param ( '/usr/include/sys/param.h' ){
112 if (open($param, '<', $param)) {
115 if( /^\s*#\s*define\s+NOFILE\s+(\d+)/ ){
116 $cacheout_maxopen = $1 - 4;
124 $cacheout_maxopen ||= 16;
127 # Open in their package.
129 return open(*{caller(1) . '::' . $_[1]}, $_[0], $_[1]) && $_[1];
132 # Close in their package.
134 # Short-circuit in case the filehandle disappeared
135 my $pkg = caller($_[1]||0);
136 fileno(*{$pkg . '::' . $_[0]}) &&
137 CORE::close(*{$pkg . '::' . $_[0]});
138 delete $isopen{$_[0]};
141 # But only this sub name is visible to them.
143 my($mode, $file, $class, $ret, $ref, $narg);
144 croak "Not enough arguments for cacheout" unless $narg = scalar @_;
145 croak "Too many arguments for cacheout" if $narg > 2;
148 ($file, $mode) = ($mode, $file) if $narg == 1;
149 croak "Invalid mode for cacheout" if $mode &&
150 ( $mode !~ /^\s*(?:>>|\+?>|\+?<|\|\-|)|\-\|\s*$/ );
153 if( $isopen{$file} && ($mode||'>') ne $isopen{$file}->[1] ){
154 &cacheout_close($file, 1);
157 if( $isopen{$file}) {
159 $isopen{$file}->[0]++;
162 if( scalar keys(%isopen) > $cacheout_maxopen -1 ) {
163 my @lru = sort{ $isopen{$a}->[0] <=> $isopen{$b}->[0] } keys(%isopen);
165 $isopen{$_}->[0] = $cacheout_seq++ for
166 splice(@lru, int($cacheout_maxopen / 3)||$cacheout_maxopen);
167 &cacheout_close($_, 1) for @lru;
171 $mode ||= $saw{$file} ? '>>' : ($saw{$file}=1, '>');
173 #XXX should we just return the value from cacheout_open, no croak?
174 $ret = cacheout_open($mode, $file) or croak("Can't create $file: $!");
176 $isopen{$file} = [++$cacheout_seq, $mode];