2640 lines
76 KiB
Perl
2640 lines
76 KiB
Perl
package Tie::File;
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require 5.005;
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use strict;
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use warnings;
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use Carp ':DEFAULT', 'confess';
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use POSIX 'SEEK_SET';
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use Fcntl 'O_CREAT', 'O_RDWR', 'LOCK_EX', 'LOCK_SH', 'O_WRONLY', 'O_RDONLY';
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sub O_ACCMODE () { O_RDONLY | O_RDWR | O_WRONLY }
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our $VERSION = "1.06";
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my $DEFAULT_MEMORY_SIZE = 1<<21; # 2 megabytes
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my $DEFAULT_AUTODEFER_THRESHHOLD = 3; # 3 records
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my $DEFAULT_AUTODEFER_FILELEN_THRESHHOLD = 65536; # 16 disk blocksful
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my %good_opt = map {$_ => 1, "-$_" => 1}
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qw(memory dw_size mode recsep discipline
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autodefer autochomp autodefer_threshhold concurrent);
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our $DIAGNOSTIC = 0;
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our @OFF; # used as a temporary alias in some subroutines.
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our @H; # used as a temporary alias in _annotate_ad_history
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sub TIEARRAY {
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if (@_ % 2 != 0) {
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croak "usage: tie \@array, $_[0], filename, [option => value]...";
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}
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my ($pack, $file, %opts) = @_;
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# transform '-foo' keys into 'foo' keys
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for my $key (keys %opts) {
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unless ($good_opt{$key}) {
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croak("$pack: Unrecognized option '$key'\n");
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}
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my $okey = $key;
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if ($key =~ s/^-+//) {
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$opts{$key} = delete $opts{$okey};
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}
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}
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if ($opts{concurrent}) {
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croak("$pack: concurrent access not supported yet\n");
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}
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unless (defined $opts{memory}) {
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# default is the larger of the default cache size and the
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# deferred-write buffer size (if specified)
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$opts{memory} = $DEFAULT_MEMORY_SIZE;
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$opts{memory} = $opts{dw_size}
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if defined $opts{dw_size} && $opts{dw_size} > $DEFAULT_MEMORY_SIZE;
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# Dora Winifred Read
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}
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$opts{dw_size} = $opts{memory} unless defined $opts{dw_size};
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if ($opts{dw_size} > $opts{memory}) {
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croak("$pack: dw_size may not be larger than total memory allocation\n");
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}
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# are we in deferred-write mode?
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$opts{defer} = 0 unless defined $opts{defer};
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$opts{deferred} = {}; # no records are presently deferred
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$opts{deferred_s} = 0; # count of total bytes in ->{deferred}
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$opts{deferred_max} = -1; # empty
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# What's a good way to arrange that this class can be overridden?
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$opts{cache} = Tie::File::Cache->new($opts{memory});
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# autodeferment is enabled by default
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$opts{autodefer} = 1 unless defined $opts{autodefer};
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$opts{autodeferring} = 0; # but is not initially active
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$opts{ad_history} = [];
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$opts{autodefer_threshhold} = $DEFAULT_AUTODEFER_THRESHHOLD
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unless defined $opts{autodefer_threshhold};
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$opts{autodefer_filelen_threshhold} = $DEFAULT_AUTODEFER_FILELEN_THRESHHOLD
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unless defined $opts{autodefer_filelen_threshhold};
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$opts{offsets} = [0];
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$opts{filename} = $file;
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unless (defined $opts{recsep}) {
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$opts{recsep} = _default_recsep();
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}
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$opts{recseplen} = length($opts{recsep});
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if ($opts{recseplen} == 0) {
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croak "Empty record separator not supported by $pack";
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}
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$opts{autochomp} = 1 unless defined $opts{autochomp};
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$opts{mode} = O_CREAT|O_RDWR unless defined $opts{mode};
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$opts{rdonly} = (($opts{mode} & O_ACCMODE) == O_RDONLY);
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$opts{sawlastrec} = undef;
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my $fh;
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if (UNIVERSAL::isa($file, 'GLOB')) {
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# We use 1 here on the theory that some systems
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# may not indicate failure if we use 0.
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# MSWin32 does not indicate failure with 0, but I don't know if
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# it will indicate failure with 1 or not.
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unless (seek $file, 1, SEEK_SET) {
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croak "$pack: your filehandle does not appear to be seekable";
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}
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seek $file, 0, SEEK_SET; # put it back
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$fh = $file; # setting binmode is the user's problem
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} elsif (ref $file) {
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croak "usage: tie \@array, $pack, filename, [option => value]...";
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} else {
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# $fh = \do { local *FH }; # XXX this is buggy
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if ($] < 5.006) {
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# perl 5.005 and earlier don't autovivify filehandles
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require Symbol;
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$fh = Symbol::gensym();
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}
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sysopen $fh, $file, $opts{mode}, 0666 or return;
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binmode $fh;
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++$opts{ourfh};
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}
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{ my $ofh = select $fh; $| = 1; select $ofh } # autoflush on write
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if (defined $opts{discipline} && $] >= 5.006) {
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# This avoids a compile-time warning under 5.005
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eval 'binmode($fh, $opts{discipline})';
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croak $@ if $@ =~ /unknown discipline/i;
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die if $@;
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}
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$opts{fh} = $fh;
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bless \%opts => $pack;
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}
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sub FETCH {
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my ($self, $n) = @_;
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my $rec;
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# check the defer buffer
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$rec = $self->{deferred}{$n} if exists $self->{deferred}{$n};
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$rec = $self->_fetch($n) unless defined $rec;
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# inlined _chomp1
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substr($rec, - $self->{recseplen}) = ""
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if defined $rec && $self->{autochomp};
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$rec;
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}
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# Chomp many records in-place; return nothing useful
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sub _chomp {
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my $self = shift;
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return unless $self->{autochomp};
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if ($self->{autochomp}) {
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for (@_) {
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next unless defined;
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substr($_, - $self->{recseplen}) = "";
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}
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}
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}
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# Chomp one record in-place; return modified record
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sub _chomp1 {
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my ($self, $rec) = @_;
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return $rec unless $self->{autochomp};
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return unless defined $rec;
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substr($rec, - $self->{recseplen}) = "";
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$rec;
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}
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sub _fetch {
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my ($self, $n) = @_;
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# check the record cache
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{ my $cached = $self->{cache}->lookup($n);
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return $cached if defined $cached;
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}
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if ($#{$self->{offsets}} < $n) {
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return if $self->{eof}; # request for record beyond end of file
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my $o = $self->_fill_offsets_to($n);
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# If it's still undefined, there is no such record, so return 'undef'
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return unless defined $o;
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}
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my $fh = $self->{FH};
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$self->_seek($n); # we can do this now that offsets is populated
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my $rec = $self->_read_record;
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# If we happen to have just read the first record, check to see if
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# the length of the record matches what 'tell' says. If not, Tie::File
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# won't work, and should drop dead.
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#
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# if ($n == 0 && defined($rec) && tell($self->{fh}) != length($rec)) {
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# if (defined $self->{discipline}) {
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# croak "I/O discipline $self->{discipline} not supported";
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# } else {
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# croak "File encoding not supported";
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# }
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# }
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$self->{cache}->insert($n, $rec) if defined $rec && not $self->{flushing};
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$rec;
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}
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sub STORE {
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my ($self, $n, $rec) = @_;
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die "STORE called from _check_integrity!" if $DIAGNOSTIC;
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$self->_fixrecs($rec);
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if ($self->{autodefer}) {
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$self->_annotate_ad_history($n);
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}
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return $self->_store_deferred($n, $rec) if $self->_is_deferring;
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# We need this to decide whether the new record will fit
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# It incidentally populates the offsets table
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# Note we have to do this before we alter the cache
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# 20020324 Wait, but this DOES alter the cache. TODO BUG?
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my $oldrec = $self->_fetch($n);
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if (not defined $oldrec) {
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# We're storing a record beyond the end of the file
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$self->_extend_file_to($n+1);
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$oldrec = $self->{recsep};
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}
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# return if $oldrec eq $rec; # don't bother
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my $len_diff = length($rec) - length($oldrec);
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# length($oldrec) here is not consistent with text mode TODO XXX BUG
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$self->_mtwrite($rec, $self->{offsets}[$n], length($oldrec));
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$self->_oadjust([$n, 1, $rec]);
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$self->{cache}->update($n, $rec);
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}
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sub _store_deferred {
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my ($self, $n, $rec) = @_;
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$self->{cache}->remove($n);
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my $old_deferred = $self->{deferred}{$n};
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if (defined $self->{deferred_max} && $n > $self->{deferred_max}) {
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$self->{deferred_max} = $n;
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}
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$self->{deferred}{$n} = $rec;
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my $len_diff = length($rec);
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$len_diff -= length($old_deferred) if defined $old_deferred;
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$self->{deferred_s} += $len_diff;
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$self->{cache}->adj_limit(-$len_diff);
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if ($self->{deferred_s} > $self->{dw_size}) {
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$self->_flush;
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} elsif ($self->_cache_too_full) {
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$self->_cache_flush;
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}
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}
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# Remove a single record from the deferred-write buffer without writing it
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# The record need not be present
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sub _delete_deferred {
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my ($self, $n) = @_;
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my $rec = delete $self->{deferred}{$n};
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return unless defined $rec;
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if (defined $self->{deferred_max}
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&& $n == $self->{deferred_max}) {
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undef $self->{deferred_max};
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}
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$self->{deferred_s} -= length $rec;
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$self->{cache}->adj_limit(length $rec);
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}
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sub FETCHSIZE {
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my $self = shift;
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my $n = $self->{eof} ? $#{$self->{offsets}} : $self->_fill_offsets;
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my $top_deferred = $self->_defer_max;
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$n = $top_deferred+1 if defined $top_deferred && $n < $top_deferred+1;
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$n;
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}
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sub STORESIZE {
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my ($self, $len) = @_;
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if ($self->{autodefer}) {
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$self->_annotate_ad_history('STORESIZE');
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}
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my $olen = $self->FETCHSIZE;
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return if $len == $olen; # Woo-hoo!
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# file gets longer
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if ($len > $olen) {
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if ($self->_is_deferring) {
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for ($olen .. $len-1) {
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$self->_store_deferred($_, $self->{recsep});
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}
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} else {
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$self->_extend_file_to($len);
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}
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return;
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}
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# file gets shorter
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if ($self->_is_deferring) {
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# TODO maybe replace this with map-plus-assignment?
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for (grep $_ >= $len, keys %{$self->{deferred}}) {
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$self->_delete_deferred($_);
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}
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$self->{deferred_max} = $len-1;
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}
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$self->_seek($len);
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$self->_chop_file;
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$#{$self->{offsets}} = $len;
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# $self->{offsets}[0] = 0; # in case we just chopped this
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$self->{cache}->remove(grep $_ >= $len, $self->{cache}->ckeys);
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}
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### OPTIMIZE ME
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### It should not be necessary to do FETCHSIZE
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### Just seek to the end of the file.
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sub PUSH {
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my $self = shift;
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$self->SPLICE($self->FETCHSIZE, scalar(@_), @_);
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# No need to return:
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# $self->FETCHSIZE; # because av.c takes care of this for me
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}
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sub POP {
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my $self = shift;
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my $size = $self->FETCHSIZE;
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return if $size == 0;
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# print STDERR "# POPPITY POP POP POP\n";
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scalar $self->SPLICE($size-1, 1);
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}
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sub SHIFT {
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my $self = shift;
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scalar $self->SPLICE(0, 1);
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}
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sub UNSHIFT {
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my $self = shift;
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$self->SPLICE(0, 0, @_);
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# $self->FETCHSIZE; # av.c takes care of this for me
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}
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sub CLEAR {
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my $self = shift;
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if ($self->{autodefer}) {
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$self->_annotate_ad_history('CLEAR');
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}
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$self->_seekb(0);
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$self->_chop_file;
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$self->{cache}->set_limit($self->{memory});
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$self->{cache}->empty;
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@{$self->{offsets}} = (0);
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%{$self->{deferred}}= ();
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$self->{deferred_s} = 0;
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$self->{deferred_max} = -1;
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}
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sub EXTEND {
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my ($self, $n) = @_;
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# No need to pre-extend anything in this case
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return if $self->_is_deferring;
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$self->_fill_offsets_to($n);
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$self->_extend_file_to($n);
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}
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sub DELETE {
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my ($self, $n) = @_;
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if ($self->{autodefer}) {
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$self->_annotate_ad_history('DELETE');
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}
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my $lastrec = $self->FETCHSIZE-1;
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my $rec = $self->FETCH($n);
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$self->_delete_deferred($n) if $self->_is_deferring;
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if ($n == $lastrec) {
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$self->_seek($n);
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$self->_chop_file;
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$#{$self->{offsets}}--;
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$self->{cache}->remove($n);
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# perhaps in this case I should also remove trailing null records?
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# 20020316
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# Note that delete @a[-3..-1] deletes the records in the wrong order,
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# so we only chop the very last one out of the file. We could repair this
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# by tracking deleted records inside the object.
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} elsif ($n < $lastrec) {
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$self->STORE($n, "");
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}
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$rec;
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}
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sub EXISTS {
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my ($self, $n) = @_;
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return 1 if exists $self->{deferred}{$n};
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$n < $self->FETCHSIZE;
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}
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sub SPLICE {
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my $self = shift;
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if ($self->{autodefer}) {
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$self->_annotate_ad_history('SPLICE');
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}
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$self->_flush if $self->_is_deferring; # move this up?
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if (wantarray) {
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$self->_chomp(my @a = $self->_splice(@_));
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@a;
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} else {
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$self->_chomp1(scalar $self->_splice(@_));
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}
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}
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sub DESTROY {
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my $self = shift;
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$self->flush if $self->_is_deferring;
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$self->{cache}->delink if defined $self->{cache}; # break circular link
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if ($self->{fh} and $self->{ourfh}) {
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delete $self->{ourfh};
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close delete $self->{fh};
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}
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}
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sub _splice {
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my ($self, $pos, $nrecs, @data) = @_;
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my @result;
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$pos = 0 unless defined $pos;
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# Deal with negative and other out-of-range positions
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# Also set default for $nrecs
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{
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my $oldsize = $self->FETCHSIZE;
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$nrecs = $oldsize unless defined $nrecs;
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my $oldpos = $pos;
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if ($pos < 0) {
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$pos += $oldsize;
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if ($pos < 0) {
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croak "Modification of non-creatable array value attempted, " .
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"subscript $oldpos";
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}
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}
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if ($pos > $oldsize) {
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return unless @data;
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$pos = $oldsize; # This is what perl does for normal arrays
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}
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# The manual is very unclear here
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if ($nrecs < 0) {
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$nrecs = $oldsize - $pos + $nrecs;
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$nrecs = 0 if $nrecs < 0;
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}
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# nrecs is too big---it really means "until the end"
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# 20030507
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if ($nrecs + $pos > $oldsize) {
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$nrecs = $oldsize - $pos;
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}
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}
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$self->_fixrecs(@data);
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my $data = join '', @data;
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my $datalen = length $data;
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my $oldlen = 0;
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# compute length of data being removed
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for ($pos .. $pos+$nrecs-1) {
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last unless defined $self->_fill_offsets_to($_);
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my $rec = $self->_fetch($_);
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last unless defined $rec;
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push @result, $rec;
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# Why don't we just use length($rec) here?
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# Because that record might have come from the cache. _splice
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# might have been called to flush out the deferred-write records,
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# and in this case length($rec) is the length of the record to be
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# *written*, not the length of the actual record in the file. But
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# the offsets are still true. 20020322
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$oldlen += $self->{offsets}[$_+1] - $self->{offsets}[$_]
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if defined $self->{offsets}[$_+1];
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}
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$self->_fill_offsets_to($pos+$nrecs);
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# Modify the file
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$self->_mtwrite($data, $self->{offsets}[$pos], $oldlen);
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# Adjust the offsets table
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$self->_oadjust([$pos, $nrecs, @data]);
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{ # Take this read cache stuff out into a separate function
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# You made a half-attempt to put it into _oadjust.
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# Finish something like that up eventually.
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|
# STORE also needs to do something similarish
|
|
|
|
# update the read cache, part 1
|
|
# modified records
|
|
for ($pos .. $pos+$nrecs-1) {
|
|
my $new = $data[$_-$pos];
|
|
if (defined $new) {
|
|
$self->{cache}->update($_, $new);
|
|
} else {
|
|
$self->{cache}->remove($_);
|
|
}
|
|
}
|
|
|
|
# update the read cache, part 2
|
|
# moved records - records past the site of the change
|
|
# need to be renumbered
|
|
# Maybe merge this with the previous block?
|
|
{
|
|
my @oldkeys = grep $_ >= $pos + $nrecs, $self->{cache}->ckeys;
|
|
my @newkeys = map $_-$nrecs+@data, @oldkeys;
|
|
$self->{cache}->rekey(\@oldkeys, \@newkeys);
|
|
}
|
|
|
|
# Now there might be too much data in the cache, if we spliced out
|
|
# some short records and spliced in some long ones. If so, flush
|
|
# the cache.
|
|
$self->_cache_flush;
|
|
}
|
|
|
|
# Yes, the return value of 'splice' *is* actually this complicated
|
|
wantarray ? @result : @result ? $result[-1] : undef;
|
|
}
|
|
|
|
|
|
# write data into the file
|
|
# $data is the data to be written.
|
|
# it should be written at position $pos, and should overwrite
|
|
# exactly $len of the following bytes.
|
|
# Note that if length($data) > $len, the subsequent bytes will have to
|
|
# be moved up, and if length($data) < $len, they will have to
|
|
# be moved down
|
|
sub _twrite {
|
|
my ($self, $data, $pos, $len) = @_;
|
|
|
|
unless (defined $pos) {
|
|
die "\$pos was undefined in _twrite";
|
|
}
|
|
|
|
my $len_diff = length($data) - $len;
|
|
|
|
if ($len_diff == 0) { # Woo-hoo!
|
|
my $fh = $self->{fh};
|
|
$self->_seekb($pos);
|
|
$self->_write_record($data);
|
|
return; # well, that was easy.
|
|
}
|
|
|
|
# the two records are of different lengths
|
|
# our strategy here: rewrite the tail of the file,
|
|
# reading ahead one buffer at a time
|
|
# $bufsize is required to be at least as large as the data we're overwriting
|
|
my $bufsize = _bufsize($len_diff);
|
|
my ($writepos, $readpos) = ($pos, $pos+$len);
|
|
my $next_block;
|
|
my $more_data;
|
|
|
|
# Seems like there ought to be a way to avoid the repeated code
|
|
# and the special case here. The read(1) is also a little weird.
|
|
# Think about this.
|
|
do {
|
|
$self->_seekb($readpos);
|
|
my $br = read $self->{fh}, $next_block, $bufsize;
|
|
$more_data = read $self->{fh}, my($dummy), 1;
|
|
$self->_seekb($writepos);
|
|
$self->_write_record($data);
|
|
$readpos += $br;
|
|
$writepos += length $data;
|
|
$data = $next_block;
|
|
} while $more_data;
|
|
$self->_seekb($writepos);
|
|
$self->_write_record($next_block);
|
|
|
|
# There might be leftover data at the end of the file
|
|
$self->_chop_file if $len_diff < 0;
|
|
}
|
|
|
|
# _iwrite(D, S, E)
|
|
# Insert text D at position S.
|
|
# Let C = E-S-|D|. If C < 0; die.
|
|
# Data in [S,S+C) is copied to [S+D,S+D+C) = [S+D,E).
|
|
# Data in [S+C = E-D, E) is returned. Data in [E, oo) is untouched.
|
|
#
|
|
# In a later version, don't read the entire intervening area into
|
|
# memory at once; do the copying block by block.
|
|
sub _iwrite {
|
|
my $self = shift;
|
|
my ($D, $s, $e) = @_;
|
|
my $d = length $D;
|
|
my $c = $e-$s-$d;
|
|
local *FH = $self->{fh};
|
|
confess "Not enough space to insert $d bytes between $s and $e"
|
|
if $c < 0;
|
|
confess "[$s,$e) is an invalid insertion range" if $e < $s;
|
|
|
|
$self->_seekb($s);
|
|
read FH, my $buf, $e-$s;
|
|
|
|
$D .= substr($buf, 0, $c, "");
|
|
|
|
$self->_seekb($s);
|
|
$self->_write_record($D);
|
|
|
|
return $buf;
|
|
}
|
|
|
|
# Like _twrite, but the data-pos-len triple may be repeated; you may
|
|
# write several chunks. All the writing will be done in
|
|
# one pass. Chunks SHALL be in ascending order and SHALL NOT overlap.
|
|
sub _mtwrite {
|
|
my $self = shift;
|
|
my $unwritten = "";
|
|
my $delta = 0;
|
|
|
|
@_ % 3 == 0
|
|
or die "Arguments to _mtwrite did not come in groups of three";
|
|
|
|
while (@_) {
|
|
my ($data, $pos, $len) = splice @_, 0, 3;
|
|
my $end = $pos + $len; # The OLD end of the segment to be replaced
|
|
$data = $unwritten . $data;
|
|
$delta -= length($unwritten);
|
|
$unwritten = "";
|
|
$pos += $delta; # This is where the data goes now
|
|
my $dlen = length $data;
|
|
$self->_seekb($pos);
|
|
if ($len >= $dlen) { # the data will fit
|
|
$self->_write_record($data);
|
|
$delta += ($dlen - $len); # everything following moves down by this much
|
|
$data = ""; # All the data in the buffer has been written
|
|
} else { # won't fit
|
|
my $writable = substr($data, 0, $len - $delta, "");
|
|
$self->_write_record($writable);
|
|
$delta += ($dlen - $len); # everything following moves down by this much
|
|
}
|
|
|
|
# At this point we've written some but maybe not all of the data.
|
|
# There might be a gap to close up, or $data might still contain a
|
|
# bunch of unwritten data that didn't fit.
|
|
my $ndlen = length $data;
|
|
if ($delta == 0) {
|
|
$self->_write_record($data);
|
|
} elsif ($delta < 0) {
|
|
# upcopy (close up gap)
|
|
if (@_) {
|
|
$self->_upcopy($end, $end + $delta, $_[1] - $end);
|
|
} else {
|
|
$self->_upcopy($end, $end + $delta);
|
|
}
|
|
} else {
|
|
# downcopy (insert data that didn't fit; replace this data in memory
|
|
# with _later_ data that doesn't fit)
|
|
if (@_) {
|
|
$unwritten = $self->_downcopy($data, $end, $_[1] - $end);
|
|
} else {
|
|
# Make the file longer to accommodate the last segment that doesn't
|
|
$unwritten = $self->_downcopy($data, $end);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
# Copy block of data of length $len from position $spos to position $dpos
|
|
# $dpos must be <= $spos
|
|
#
|
|
# If $len is undefined, go all the way to the end of the file
|
|
# and then truncate it ($spos - $dpos bytes will be removed)
|
|
sub _upcopy {
|
|
my $blocksize = 8192;
|
|
my ($self, $spos, $dpos, $len) = @_;
|
|
if ($dpos > $spos) {
|
|
die "source ($spos) was upstream of destination ($dpos) in _upcopy";
|
|
} elsif ($dpos == $spos) {
|
|
return;
|
|
}
|
|
|
|
while (! defined ($len) || $len > 0) {
|
|
my $readsize = ! defined($len) ? $blocksize
|
|
: $len > $blocksize ? $blocksize
|
|
: $len;
|
|
|
|
my $fh = $self->{fh};
|
|
$self->_seekb($spos);
|
|
my $bytes_read = read $fh, my($data), $readsize;
|
|
$self->_seekb($dpos);
|
|
if ($data eq "") {
|
|
$self->_chop_file;
|
|
last;
|
|
}
|
|
$self->_write_record($data);
|
|
$spos += $bytes_read;
|
|
$dpos += $bytes_read;
|
|
$len -= $bytes_read if defined $len;
|
|
}
|
|
}
|
|
|
|
# Write $data into a block of length $len at position $pos,
|
|
# moving everything in the block forwards to make room.
|
|
# Instead of writing the last length($data) bytes from the block
|
|
# (because there isn't room for them any longer) return them.
|
|
#
|
|
# Undefined $len means 'until the end of the file'
|
|
sub _downcopy {
|
|
my $blocksize = 8192;
|
|
my ($self, $data, $pos, $len) = @_;
|
|
my $fh = $self->{fh};
|
|
|
|
while (! defined $len || $len > 0) {
|
|
my $readsize = ! defined($len) ? $blocksize
|
|
: $len > $blocksize? $blocksize : $len;
|
|
$self->_seekb($pos);
|
|
read $fh, my($old), $readsize;
|
|
my $last_read_was_short = length($old) < $readsize;
|
|
$data .= $old;
|
|
my $writable;
|
|
if ($last_read_was_short) {
|
|
# If last read was short, then $data now contains the entire rest
|
|
# of the file, so there's no need to write only one block of it
|
|
$writable = $data;
|
|
$data = "";
|
|
} else {
|
|
$writable = substr($data, 0, $readsize, "");
|
|
}
|
|
last if $writable eq "";
|
|
$self->_seekb($pos);
|
|
$self->_write_record($writable);
|
|
last if $last_read_was_short && $data eq "";
|
|
$len -= $readsize if defined $len;
|
|
$pos += $readsize;
|
|
}
|
|
return $data;
|
|
}
|
|
|
|
# Adjust the object data structures following an '_mtwrite'
|
|
# Arguments are
|
|
# [$pos, $nrecs, @length] items
|
|
# indicating that $nrecs records were removed at $recpos (a record offset)
|
|
# and replaced with records of length @length...
|
|
# Arguments guarantee that $recpos is strictly increasing.
|
|
# No return value
|
|
sub _oadjust {
|
|
my $self = shift;
|
|
my $delta = 0;
|
|
my $delta_recs = 0;
|
|
my $prev_end = -1;
|
|
|
|
for (@_) {
|
|
my ($pos, $nrecs, @data) = @$_;
|
|
$pos += $delta_recs;
|
|
|
|
# Adjust the offsets of the records after the previous batch up
|
|
# to the first new one of this batch
|
|
for my $i ($prev_end+2 .. $pos - 1) {
|
|
$self->{offsets}[$i] += $delta;
|
|
}
|
|
|
|
$prev_end = $pos + @data - 1; # last record moved on this pass
|
|
|
|
# Remove the offsets for the removed records;
|
|
# replace with the offsets for the inserted records
|
|
my @newoff = ($self->{offsets}[$pos] + $delta);
|
|
for my $i (0 .. $#data) {
|
|
my $newlen = length $data[$i];
|
|
push @newoff, $newoff[$i] + $newlen;
|
|
$delta += $newlen;
|
|
}
|
|
|
|
for my $i ($pos .. $pos+$nrecs-1) {
|
|
last if $i+1 > $#{$self->{offsets}};
|
|
my $oldlen = $self->{offsets}[$i+1] - $self->{offsets}[$i];
|
|
$delta -= $oldlen;
|
|
}
|
|
|
|
# replace old offsets with new
|
|
splice @{$self->{offsets}}, $pos, $nrecs+1, @newoff;
|
|
# What if we just spliced out the end of the offsets table?
|
|
# shouldn't we clear $self->{eof}? Test for this XXX BUG TODO
|
|
|
|
$delta_recs += @data - $nrecs; # net change in total number of records
|
|
}
|
|
|
|
# The trailing records at the very end of the file
|
|
if ($delta) {
|
|
for my $i ($prev_end+2 .. $#{$self->{offsets}}) {
|
|
$self->{offsets}[$i] += $delta;
|
|
}
|
|
}
|
|
|
|
# If we scrubbed out all known offsets, regenerate the trivial table
|
|
# that knows that the file does indeed start at 0.
|
|
$self->{offsets}[0] = 0 unless @{$self->{offsets}};
|
|
# If the file got longer, the offsets table is no longer complete
|
|
# $self->{eof} = 0 if $delta_recs > 0;
|
|
|
|
# Now there might be too much data in the cache, if we spliced out
|
|
# some short records and spliced in some long ones. If so, flush
|
|
# the cache.
|
|
$self->_cache_flush;
|
|
}
|
|
|
|
# If a record does not already end with the appropriate terminator
|
|
# string, append one.
|
|
sub _fixrecs {
|
|
my $self = shift;
|
|
for (@_) {
|
|
$_ = "" unless defined $_;
|
|
$_ .= $self->{recsep}
|
|
unless substr($_, - $self->{recseplen}) eq $self->{recsep};
|
|
}
|
|
}
|
|
|
|
|
|
################################################################
|
|
#
|
|
# Basic read, write, and seek
|
|
#
|
|
|
|
# seek to the beginning of record #$n
|
|
# Assumes that the offsets table is already correctly populated
|
|
#
|
|
# Note that $n=-1 has a special meaning here: It means the start of
|
|
# the last known record; this may or may not be the very last record
|
|
# in the file, depending on whether the offsets table is fully populated.
|
|
#
|
|
sub _seek {
|
|
my ($self, $n) = @_;
|
|
my $o = $self->{offsets}[$n];
|
|
defined($o)
|
|
or confess("logic error: undefined offset for record $n");
|
|
seek $self->{fh}, $o, SEEK_SET
|
|
or confess "Couldn't seek filehandle: $!"; # "Should never happen."
|
|
}
|
|
|
|
# seek to byte $b in the file
|
|
sub _seekb {
|
|
my ($self, $b) = @_;
|
|
seek $self->{fh}, $b, SEEK_SET
|
|
or die "Couldn't seek filehandle: $!"; # "Should never happen."
|
|
}
|
|
|
|
# populate the offsets table up to the beginning of record $n
|
|
# return the offset of record $n
|
|
sub _fill_offsets_to {
|
|
my ($self, $n) = @_;
|
|
|
|
return $self->{offsets}[$n] if $self->{eof};
|
|
|
|
my $fh = $self->{fh};
|
|
local *OFF = $self->{offsets};
|
|
my $rec;
|
|
|
|
until ($#OFF >= $n) {
|
|
$self->_seek(-1); # tricky -- see comment at _seek
|
|
$rec = $self->_read_record;
|
|
if (defined $rec) {
|
|
push @OFF, int(tell $fh); # Tels says that int() saves memory here
|
|
} else {
|
|
$self->{eof} = 1;
|
|
return; # It turns out there is no such record
|
|
}
|
|
}
|
|
|
|
# we have now read all the records up to record n-1,
|
|
# so we can return the offset of record n
|
|
$OFF[$n];
|
|
}
|
|
|
|
sub _fill_offsets {
|
|
my ($self) = @_;
|
|
|
|
my $fh = $self->{fh};
|
|
local *OFF = $self->{offsets};
|
|
|
|
$self->_seek(-1); # tricky -- see comment at _seek
|
|
|
|
# Tels says that inlining read_record() would make this loop
|
|
# five times faster. 20030508
|
|
while ( defined $self->_read_record()) {
|
|
# int() saves us memory here
|
|
push @OFF, int(tell $fh);
|
|
}
|
|
|
|
$self->{eof} = 1;
|
|
$#OFF;
|
|
}
|
|
|
|
# assumes that $rec is already suitably terminated
|
|
sub _write_record {
|
|
my ($self, $rec) = @_;
|
|
my $fh = $self->{fh};
|
|
local $\ = "";
|
|
print $fh $rec
|
|
or die "Couldn't write record: $!"; # "Should never happen."
|
|
# $self->{_written} += length($rec);
|
|
}
|
|
|
|
sub _read_record {
|
|
my $self = shift;
|
|
my $rec;
|
|
{ local $/ = $self->{recsep};
|
|
my $fh = $self->{fh};
|
|
$rec = <$fh>;
|
|
}
|
|
return unless defined $rec;
|
|
if (substr($rec, -$self->{recseplen}) ne $self->{recsep}) {
|
|
# improperly terminated final record --- quietly fix it.
|
|
# my $ac = substr($rec, -$self->{recseplen});
|
|
# $ac =~ s/\n/\\n/g;
|
|
$self->{sawlastrec} = 1;
|
|
unless ($self->{rdonly}) {
|
|
local $\ = "";
|
|
my $fh = $self->{fh};
|
|
print $fh $self->{recsep};
|
|
}
|
|
$rec .= $self->{recsep};
|
|
}
|
|
# $self->{_read} += length($rec) if defined $rec;
|
|
$rec;
|
|
}
|
|
|
|
sub _rw_stats {
|
|
my $self = shift;
|
|
@{$self}{'_read', '_written'};
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Read cache management
|
|
|
|
sub _cache_flush {
|
|
my ($self) = @_;
|
|
$self->{cache}->reduce_size_to($self->{memory} - $self->{deferred_s});
|
|
}
|
|
|
|
sub _cache_too_full {
|
|
my $self = shift;
|
|
$self->{cache}->bytes + $self->{deferred_s} >= $self->{memory};
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# File custodial services
|
|
#
|
|
|
|
|
|
# We have read to the end of the file and have the offsets table
|
|
# entirely populated. Now we need to write a new record beyond
|
|
# the end of the file. We prepare for this by writing
|
|
# empty records into the file up to the position we want
|
|
#
|
|
# assumes that the offsets table already contains the offset of record $n,
|
|
# if it exists, and extends to the end of the file if not.
|
|
sub _extend_file_to {
|
|
my ($self, $n) = @_;
|
|
$self->_seek(-1); # position after the end of the last record
|
|
my $pos = $self->{offsets}[-1];
|
|
|
|
# the offsets table has one entry more than the total number of records
|
|
my $extras = $n - $#{$self->{offsets}};
|
|
|
|
# Todo : just use $self->{recsep} x $extras here?
|
|
while ($extras-- > 0) {
|
|
$self->_write_record($self->{recsep});
|
|
push @{$self->{offsets}}, int(tell $self->{fh});
|
|
}
|
|
}
|
|
|
|
# Truncate the file at the current position
|
|
sub _chop_file {
|
|
my $self = shift;
|
|
truncate $self->{fh}, tell($self->{fh});
|
|
}
|
|
|
|
|
|
# compute the size of a buffer suitable for moving
|
|
# all the data in a file forward $n bytes
|
|
# ($n may be negative)
|
|
# The result should be at least $n.
|
|
sub _bufsize {
|
|
my $n = shift;
|
|
return 8192 if $n <= 0;
|
|
my $b = $n & ~8191;
|
|
$b += 8192 if $n & 8191;
|
|
$b;
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Miscellaneous public methods
|
|
#
|
|
|
|
# Lock the file
|
|
sub flock {
|
|
my ($self, $op) = @_;
|
|
unless (@_ <= 3) {
|
|
my $pack = ref $self;
|
|
croak "Usage: $pack\->flock([OPERATION])";
|
|
}
|
|
my $fh = $self->{fh};
|
|
$op = LOCK_EX unless defined $op;
|
|
my $locked = flock $fh, $op;
|
|
|
|
if ($locked && ($op & (LOCK_EX | LOCK_SH))) {
|
|
# If you're locking the file, then presumably it's because
|
|
# there might have been a write access by another process.
|
|
# In that case, the read cache contents and the offsets table
|
|
# might be invalid, so discard them. 20030508
|
|
$self->{offsets} = [0];
|
|
$self->{cache}->empty;
|
|
}
|
|
|
|
$locked;
|
|
}
|
|
|
|
# Get/set autochomp option
|
|
sub autochomp {
|
|
my $self = shift;
|
|
if (@_) {
|
|
my $old = $self->{autochomp};
|
|
$self->{autochomp} = shift;
|
|
$old;
|
|
} else {
|
|
$self->{autochomp};
|
|
}
|
|
}
|
|
|
|
# Get offset table entries; returns offset of nth record
|
|
sub offset {
|
|
my ($self, $n) = @_;
|
|
|
|
if ($#{$self->{offsets}} < $n) {
|
|
return if $self->{eof}; # request for record beyond the end of file
|
|
my $o = $self->_fill_offsets_to($n);
|
|
# If it's still undefined, there is no such record, so return 'undef'
|
|
return unless defined $o;
|
|
}
|
|
|
|
$self->{offsets}[$n];
|
|
}
|
|
|
|
sub discard_offsets {
|
|
my $self = shift;
|
|
$self->{offsets} = [0];
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Matters related to deferred writing
|
|
#
|
|
|
|
# Defer writes
|
|
sub defer {
|
|
my $self = shift;
|
|
$self->_stop_autodeferring;
|
|
@{$self->{ad_history}} = ();
|
|
$self->{defer} = 1;
|
|
}
|
|
|
|
# Flush deferred writes
|
|
#
|
|
# This could be better optimized to write the file in one pass, instead
|
|
# of one pass per block of records. But that will require modifications
|
|
# to _twrite, so I should have a good _twrite test suite first.
|
|
sub flush {
|
|
my $self = shift;
|
|
|
|
$self->_flush;
|
|
$self->{defer} = 0;
|
|
}
|
|
|
|
sub _old_flush {
|
|
my $self = shift;
|
|
my @writable = sort {$a<=>$b} (keys %{$self->{deferred}});
|
|
|
|
while (@writable) {
|
|
# gather all consecutive records from the front of @writable
|
|
my $first_rec = shift @writable;
|
|
my $last_rec = $first_rec+1;
|
|
++$last_rec, shift @writable while @writable && $last_rec == $writable[0];
|
|
--$last_rec;
|
|
$self->_fill_offsets_to($last_rec);
|
|
$self->_extend_file_to($last_rec);
|
|
$self->_splice($first_rec, $last_rec-$first_rec+1,
|
|
@{$self->{deferred}}{$first_rec .. $last_rec});
|
|
}
|
|
|
|
$self->_discard; # clear out defered-write-cache
|
|
}
|
|
|
|
sub _flush {
|
|
my $self = shift;
|
|
my @writable = sort {$a<=>$b} (keys %{$self->{deferred}});
|
|
my @args;
|
|
my @adjust;
|
|
|
|
while (@writable) {
|
|
# gather all consecutive records from the front of @writable
|
|
my $first_rec = shift @writable;
|
|
my $last_rec = $first_rec+1;
|
|
++$last_rec, shift @writable while @writable && $last_rec == $writable[0];
|
|
--$last_rec;
|
|
my $end = $self->_fill_offsets_to($last_rec+1);
|
|
if (not defined $end) {
|
|
$self->_extend_file_to($last_rec);
|
|
$end = $self->{offsets}[$last_rec];
|
|
}
|
|
my ($start) = $self->{offsets}[$first_rec];
|
|
push @args,
|
|
join("", @{$self->{deferred}}{$first_rec .. $last_rec}), # data
|
|
$start, # position
|
|
$end-$start; # length
|
|
push @adjust, [$first_rec, # starting at this position...
|
|
$last_rec-$first_rec+1, # this many records...
|
|
# are replaced with these...
|
|
@{$self->{deferred}}{$first_rec .. $last_rec},
|
|
];
|
|
}
|
|
|
|
$self->_mtwrite(@args); # write multiple record groups
|
|
$self->_discard; # clear out defered-write-cache
|
|
$self->_oadjust(@adjust);
|
|
}
|
|
|
|
# Discard deferred writes and disable future deferred writes
|
|
sub discard {
|
|
my $self = shift;
|
|
$self->_discard;
|
|
$self->{defer} = 0;
|
|
}
|
|
|
|
# Discard deferred writes, but retain old deferred writing mode
|
|
sub _discard {
|
|
my $self = shift;
|
|
%{$self->{deferred}} = ();
|
|
$self->{deferred_s} = 0;
|
|
$self->{deferred_max} = -1;
|
|
$self->{cache}->set_limit($self->{memory});
|
|
}
|
|
|
|
# Deferred writing is enabled, either explicitly ($self->{defer})
|
|
# or automatically ($self->{autodeferring})
|
|
sub _is_deferring {
|
|
my $self = shift;
|
|
$self->{defer} || $self->{autodeferring};
|
|
}
|
|
|
|
# The largest record number of any deferred record
|
|
sub _defer_max {
|
|
my $self = shift;
|
|
return $self->{deferred_max} if defined $self->{deferred_max};
|
|
my $max = -1;
|
|
for my $key (keys %{$self->{deferred}}) {
|
|
$max = $key if $key > $max;
|
|
}
|
|
$self->{deferred_max} = $max;
|
|
$max;
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Matters related to autodeferment
|
|
#
|
|
|
|
# Get/set autodefer option
|
|
sub autodefer {
|
|
my $self = shift;
|
|
if (@_) {
|
|
my $old = $self->{autodefer};
|
|
$self->{autodefer} = shift;
|
|
if ($old) {
|
|
$self->_stop_autodeferring;
|
|
@{$self->{ad_history}} = ();
|
|
}
|
|
$old;
|
|
} else {
|
|
$self->{autodefer};
|
|
}
|
|
}
|
|
|
|
# The user is trying to store record #$n Record that in the history,
|
|
# and then enable (or disable) autodeferment if that seems useful.
|
|
# Note that it's OK for $n to be a non-number, as long as the function
|
|
# is prepared to deal with that. Nobody else looks at the ad_history.
|
|
#
|
|
# Now, what does the ad_history mean, and what is this function doing?
|
|
# Essentially, the idea is to enable autodeferring when we see that the
|
|
# user has made three consecutive STORE calls to three consecutive records.
|
|
# ("Three" is actually ->{autodefer_threshhold}.)
|
|
# A STORE call for record #$n inserts $n into the autodefer history,
|
|
# and if the history contains three consecutive records, we enable
|
|
# autodeferment. An ad_history of [X, Y] means that the most recent
|
|
# STOREs were for records X, X+1, ..., Y, in that order.
|
|
#
|
|
# Inserting a nonconsecutive number erases the history and starts over.
|
|
#
|
|
# Performing a special operation like SPLICE erases the history.
|
|
#
|
|
# There's one special case: CLEAR means that CLEAR was just called.
|
|
# In this case, we prime the history with [-2, -1] so that if the next
|
|
# write is for record 0, autodeferring goes on immediately. This is for
|
|
# the common special case of "@a = (...)".
|
|
#
|
|
sub _annotate_ad_history {
|
|
my ($self, $n) = @_;
|
|
return unless $self->{autodefer}; # feature is disabled
|
|
return if $self->{defer}; # already in explicit defer mode
|
|
return unless $self->{offsets}[-1] >= $self->{autodefer_filelen_threshhold};
|
|
|
|
local *H = $self->{ad_history};
|
|
if ($n eq 'CLEAR') {
|
|
@H = (-2, -1); # prime the history with fake records
|
|
$self->_stop_autodeferring;
|
|
} elsif ($n =~ /^\d+$/) {
|
|
if (@H == 0) {
|
|
@H = ($n, $n);
|
|
} else { # @H == 2
|
|
if ($H[1] == $n-1) { # another consecutive record
|
|
$H[1]++;
|
|
if ($H[1] - $H[0] + 1 >= $self->{autodefer_threshhold}) {
|
|
$self->{autodeferring} = 1;
|
|
}
|
|
} else { # nonconsecutive- erase and start over
|
|
@H = ($n, $n);
|
|
$self->_stop_autodeferring;
|
|
}
|
|
}
|
|
} else { # SPLICE or STORESIZE or some such
|
|
@H = ();
|
|
$self->_stop_autodeferring;
|
|
}
|
|
}
|
|
|
|
# If autodeferring was enabled, cut it out and discard the history
|
|
sub _stop_autodeferring {
|
|
my $self = shift;
|
|
if ($self->{autodeferring}) {
|
|
$self->_flush;
|
|
}
|
|
$self->{autodeferring} = 0;
|
|
}
|
|
|
|
################################################################
|
|
|
|
|
|
# This is NOT a method. It is here for two reasons:
|
|
# 1. To factor a fairly complicated block out of the constructor
|
|
# 2. To provide access for the test suite, which need to be sure
|
|
# files are being written properly.
|
|
sub _default_recsep {
|
|
my $recsep = $/;
|
|
if ($^O eq 'MSWin32') { # Dos too?
|
|
# Windows users expect files to be terminated with \r\n
|
|
# But $/ is set to \n instead
|
|
# Note that this also transforms \n\n into \r\n\r\n.
|
|
# That is a feature.
|
|
$recsep =~ s/\n/\r\n/g;
|
|
}
|
|
$recsep;
|
|
}
|
|
|
|
# Utility function for _check_integrity
|
|
sub _ci_warn {
|
|
my $msg = shift;
|
|
$msg =~ s/\n/\\n/g;
|
|
$msg =~ s/\r/\\r/g;
|
|
print "# $msg\n";
|
|
}
|
|
|
|
# Given a file, make sure the cache is consistent with the
|
|
# file contents and the internal data structures are consistent with
|
|
# each other. Returns true if everything checks out, false if not
|
|
#
|
|
# The $file argument is no longer used. It is retained for compatibility
|
|
# with the existing test suite.
|
|
sub _check_integrity {
|
|
my ($self, $file, $warn) = @_;
|
|
my $rsl = $self->{recseplen};
|
|
my $rs = $self->{recsep};
|
|
my $good = 1;
|
|
local *_; # local $_ does not work here
|
|
local $DIAGNOSTIC = 1;
|
|
|
|
if (not defined $rs) {
|
|
_ci_warn("recsep is undef!");
|
|
$good = 0;
|
|
} elsif ($rs eq "") {
|
|
_ci_warn("recsep is empty!");
|
|
$good = 0;
|
|
} elsif ($rsl != length $rs) {
|
|
my $ln = length $rs;
|
|
_ci_warn("recsep <$rs> has length $ln, should be $rsl");
|
|
$good = 0;
|
|
}
|
|
|
|
if (not defined $self->{offsets}[0]) {
|
|
_ci_warn("offset 0 is missing!");
|
|
$good = 0;
|
|
|
|
} elsif ($self->{offsets}[0] != 0) {
|
|
_ci_warn("rec 0: offset <$self->{offsets}[0]> s/b 0!");
|
|
$good = 0;
|
|
}
|
|
|
|
my $cached = 0;
|
|
{
|
|
local *F = $self->{fh};
|
|
seek F, 0, SEEK_SET;
|
|
local $. = 0;
|
|
local $/ = $rs;
|
|
|
|
while (<F>) {
|
|
my $n = $. - 1;
|
|
my $cached = $self->{cache}->_produce($n);
|
|
my $offset = $self->{offsets}[$.];
|
|
my $ao = tell F;
|
|
if (defined $offset && $offset != $ao) {
|
|
_ci_warn("rec $n: offset <$offset> actual <$ao>");
|
|
$good = 0;
|
|
}
|
|
if (defined $cached && $_ ne $cached && ! $self->{deferred}{$n}) {
|
|
$good = 0;
|
|
_ci_warn("rec $n: cached <$cached> actual <$_>");
|
|
}
|
|
if (defined $cached && substr($cached, -$rsl) ne $rs) {
|
|
$good = 0;
|
|
_ci_warn("rec $n in the cache is missing the record separator");
|
|
}
|
|
if (! defined $offset && $self->{eof}) {
|
|
$good = 0;
|
|
_ci_warn("The offset table was marked complete, but it is missing " .
|
|
"element $.");
|
|
}
|
|
}
|
|
if (@{$self->{offsets}} > $.+1) {
|
|
$good = 0;
|
|
my $n = @{$self->{offsets}};
|
|
_ci_warn("The offset table has $n items, but the file has only $.");
|
|
}
|
|
|
|
my $deferring = $self->_is_deferring;
|
|
for my $n ($self->{cache}->ckeys) {
|
|
my $r = $self->{cache}->_produce($n);
|
|
$cached += length($r);
|
|
next if $n+1 <= $.; # checked this already
|
|
_ci_warn("spurious caching of record $n");
|
|
$good = 0;
|
|
}
|
|
my $b = $self->{cache}->bytes;
|
|
if ($cached != $b) {
|
|
_ci_warn("cache size is $b, should be $cached");
|
|
$good = 0;
|
|
}
|
|
}
|
|
|
|
# That cache has its own set of tests
|
|
$good = 0 unless $self->{cache}->_check_integrity;
|
|
|
|
# Now let's check the deferbuffer
|
|
# Unless deferred writing is enabled, it should be empty
|
|
if (! $self->_is_deferring && %{$self->{deferred}}) {
|
|
_ci_warn("deferred writing disabled, but deferbuffer nonempty");
|
|
$good = 0;
|
|
}
|
|
|
|
# Any record in the deferbuffer should *not* be present in the readcache
|
|
my $deferred_s = 0;
|
|
while (my ($n, $r) = each %{$self->{deferred}}) {
|
|
$deferred_s += length($r);
|
|
if (defined $self->{cache}->_produce($n)) {
|
|
_ci_warn("record $n is in the deferbuffer *and* the readcache");
|
|
$good = 0;
|
|
}
|
|
if (substr($r, -$rsl) ne $rs) {
|
|
_ci_warn("rec $n in the deferbuffer is missing the record separator");
|
|
$good = 0;
|
|
}
|
|
}
|
|
|
|
# Total size of deferbuffer should match internal total
|
|
if ($deferred_s != $self->{deferred_s}) {
|
|
_ci_warn("buffer size is $self->{deferred_s}, should be $deferred_s");
|
|
$good = 0;
|
|
}
|
|
|
|
# Total size of deferbuffer should not exceed the specified limit
|
|
if ($deferred_s > $self->{dw_size}) {
|
|
_ci_warn("buffer size is $self->{deferred_s} which exceeds the limit " .
|
|
"of $self->{dw_size}");
|
|
$good = 0;
|
|
}
|
|
|
|
# Total size of cached data should not exceed the specified limit
|
|
if ($deferred_s + $cached > $self->{memory}) {
|
|
my $total = $deferred_s + $cached;
|
|
_ci_warn("total stored data size is $total which exceeds the limit " .
|
|
"of $self->{memory}");
|
|
$good = 0;
|
|
}
|
|
|
|
# Stuff related to autodeferment
|
|
if (!$self->{autodefer} && @{$self->{ad_history}}) {
|
|
_ci_warn("autodefer is disabled, but ad_history is nonempty");
|
|
$good = 0;
|
|
}
|
|
if ($self->{autodeferring} && $self->{defer}) {
|
|
_ci_warn("both autodeferring and explicit deferring are active");
|
|
$good = 0;
|
|
}
|
|
if (@{$self->{ad_history}} == 0) {
|
|
# That's OK, no additional tests required
|
|
} elsif (@{$self->{ad_history}} == 2) {
|
|
my @non_number = grep !/^-?\d+$/, @{$self->{ad_history}};
|
|
if (@non_number) {
|
|
my $msg;
|
|
{ local $" = ')(';
|
|
$msg = "ad_history contains non-numbers (@{$self->{ad_history}})";
|
|
}
|
|
_ci_warn($msg);
|
|
$good = 0;
|
|
} elsif ($self->{ad_history}[1] < $self->{ad_history}[0]) {
|
|
_ci_warn("ad_history has nonsensical values @{$self->{ad_history}}");
|
|
$good = 0;
|
|
}
|
|
} else {
|
|
_ci_warn("ad_history has bad length <@{$self->{ad_history}}>");
|
|
$good = 0;
|
|
}
|
|
|
|
$good;
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Tie::File::Cache
|
|
#
|
|
# Read cache
|
|
|
|
package Tie::File::Cache;
|
|
$Tie::File::Cache::VERSION = $Tie::File::VERSION;
|
|
use Carp ':DEFAULT', 'confess';
|
|
|
|
sub HEAP () { 0 }
|
|
sub HASH () { 1 }
|
|
sub MAX () { 2 }
|
|
sub BYTES() { 3 }
|
|
#sub STAT () { 4 } # Array with request statistics for each record
|
|
#sub MISS () { 5 } # Total number of cache misses
|
|
#sub REQ () { 6 } # Total number of cache requests
|
|
use strict 'vars';
|
|
|
|
sub new {
|
|
my ($pack, $max) = @_;
|
|
local *_;
|
|
croak "missing argument to ->new" unless defined $max;
|
|
my $self = [];
|
|
bless $self => $pack;
|
|
@$self = (Tie::File::Heap->new($self), {}, $max, 0);
|
|
$self;
|
|
}
|
|
|
|
sub adj_limit {
|
|
my ($self, $n) = @_;
|
|
$self->[MAX] += $n;
|
|
}
|
|
|
|
sub set_limit {
|
|
my ($self, $n) = @_;
|
|
$self->[MAX] = $n;
|
|
}
|
|
|
|
# For internal use only
|
|
# Will be called by the heap structure to notify us that a certain
|
|
# piece of data has moved from one heap element to another.
|
|
# $k is the hash key of the item
|
|
# $n is the new index into the heap at which it is stored
|
|
# If $n is undefined, the item has been removed from the heap.
|
|
sub _heap_move {
|
|
my ($self, $k, $n) = @_;
|
|
if (defined $n) {
|
|
$self->[HASH]{$k} = $n;
|
|
} else {
|
|
delete $self->[HASH]{$k};
|
|
}
|
|
}
|
|
|
|
sub insert {
|
|
my ($self, $key, $val) = @_;
|
|
local *_;
|
|
croak "missing argument to ->insert" unless defined $key;
|
|
unless (defined $self->[MAX]) {
|
|
confess "undefined max" ;
|
|
}
|
|
confess "undefined val" unless defined $val;
|
|
return if length($val) > $self->[MAX];
|
|
|
|
# if ($self->[STAT]) {
|
|
# $self->[STAT][$key] = 1;
|
|
# return;
|
|
# }
|
|
|
|
my $oldnode = $self->[HASH]{$key};
|
|
if (defined $oldnode) {
|
|
my $oldval = $self->[HEAP]->set_val($oldnode, $val);
|
|
$self->[BYTES] -= length($oldval);
|
|
} else {
|
|
$self->[HEAP]->insert($key, $val);
|
|
}
|
|
$self->[BYTES] += length($val);
|
|
$self->flush if $self->[BYTES] > $self->[MAX];
|
|
}
|
|
|
|
sub expire {
|
|
my $self = shift;
|
|
my $old_data = $self->[HEAP]->popheap;
|
|
return unless defined $old_data;
|
|
$self->[BYTES] -= length $old_data;
|
|
$old_data;
|
|
}
|
|
|
|
sub remove {
|
|
my ($self, @keys) = @_;
|
|
my @result;
|
|
|
|
# if ($self->[STAT]) {
|
|
# for my $key (@keys) {
|
|
# $self->[STAT][$key] = 0;
|
|
# }
|
|
# return;
|
|
# }
|
|
|
|
for my $key (@keys) {
|
|
next unless exists $self->[HASH]{$key};
|
|
my $old_data = $self->[HEAP]->remove($self->[HASH]{$key});
|
|
$self->[BYTES] -= length $old_data;
|
|
push @result, $old_data;
|
|
}
|
|
@result;
|
|
}
|
|
|
|
sub lookup {
|
|
my ($self, $key) = @_;
|
|
local *_;
|
|
croak "missing argument to ->lookup" unless defined $key;
|
|
|
|
# if ($self->[STAT]) {
|
|
# $self->[MISS]++ if $self->[STAT][$key]++ == 0;
|
|
# $self->[REQ]++;
|
|
# my $hit_rate = 1 - $self->[MISS] / $self->[REQ];
|
|
# # Do some testing to determine this threshhold
|
|
# $#$self = STAT - 1 if $hit_rate > 0.20;
|
|
# }
|
|
|
|
if (exists $self->[HASH]{$key}) {
|
|
$self->[HEAP]->lookup($self->[HASH]{$key});
|
|
} else {
|
|
return;
|
|
}
|
|
}
|
|
|
|
# For internal use only
|
|
sub _produce {
|
|
my ($self, $key) = @_;
|
|
my $loc = $self->[HASH]{$key};
|
|
return unless defined $loc;
|
|
$self->[HEAP][$loc][2];
|
|
}
|
|
|
|
# For internal use only
|
|
sub _promote {
|
|
my ($self, $key) = @_;
|
|
$self->[HEAP]->promote($self->[HASH]{$key});
|
|
}
|
|
|
|
sub empty {
|
|
my ($self) = @_;
|
|
%{$self->[HASH]} = ();
|
|
$self->[BYTES] = 0;
|
|
$self->[HEAP]->empty;
|
|
# @{$self->[STAT]} = ();
|
|
# $self->[MISS] = 0;
|
|
# $self->[REQ] = 0;
|
|
}
|
|
|
|
sub is_empty {
|
|
my ($self) = @_;
|
|
keys %{$self->[HASH]} == 0;
|
|
}
|
|
|
|
sub update {
|
|
my ($self, $key, $val) = @_;
|
|
local *_;
|
|
croak "missing argument to ->update" unless defined $key;
|
|
if (length($val) > $self->[MAX]) {
|
|
my ($oldval) = $self->remove($key);
|
|
$self->[BYTES] -= length($oldval) if defined $oldval;
|
|
} elsif (exists $self->[HASH]{$key}) {
|
|
my $oldval = $self->[HEAP]->set_val($self->[HASH]{$key}, $val);
|
|
$self->[BYTES] += length($val);
|
|
$self->[BYTES] -= length($oldval) if defined $oldval;
|
|
} else {
|
|
$self->[HEAP]->insert($key, $val);
|
|
$self->[BYTES] += length($val);
|
|
}
|
|
$self->flush;
|
|
}
|
|
|
|
sub rekey {
|
|
my ($self, $okeys, $nkeys) = @_;
|
|
local *_;
|
|
my %map;
|
|
@map{@$okeys} = @$nkeys;
|
|
croak "missing argument to ->rekey" unless defined $nkeys;
|
|
croak "length mismatch in ->rekey arguments" unless @$nkeys == @$okeys;
|
|
my %adjusted; # map new keys to heap indices
|
|
# You should be able to cut this to one loop TODO XXX
|
|
for (0 .. $#$okeys) {
|
|
$adjusted{$nkeys->[$_]} = delete $self->[HASH]{$okeys->[$_]};
|
|
}
|
|
while (my ($nk, $ix) = each %adjusted) {
|
|
# @{$self->[HASH]}{keys %adjusted} = values %adjusted;
|
|
$self->[HEAP]->rekey($ix, $nk);
|
|
$self->[HASH]{$nk} = $ix;
|
|
}
|
|
}
|
|
|
|
sub ckeys {
|
|
my $self = shift;
|
|
my @a = keys %{$self->[HASH]};
|
|
@a;
|
|
}
|
|
|
|
# Return total amount of cached data
|
|
sub bytes {
|
|
my $self = shift;
|
|
$self->[BYTES];
|
|
}
|
|
|
|
# Expire oldest item from cache until cache size is smaller than $max
|
|
sub reduce_size_to {
|
|
my ($self, $max) = @_;
|
|
until ($self->[BYTES] <= $max) {
|
|
# Note that Tie::File::Cache::expire has been inlined here
|
|
my $old_data = $self->[HEAP]->popheap;
|
|
return unless defined $old_data;
|
|
$self->[BYTES] -= length $old_data;
|
|
}
|
|
}
|
|
|
|
# Why not just $self->reduce_size_to($self->[MAX])?
|
|
# Try this when things stabilize TODO XXX
|
|
# If the cache is too full, expire the oldest records
|
|
sub flush {
|
|
my $self = shift;
|
|
$self->reduce_size_to($self->[MAX]) if $self->[BYTES] > $self->[MAX];
|
|
}
|
|
|
|
# For internal use only
|
|
sub _produce_lru {
|
|
my $self = shift;
|
|
$self->[HEAP]->expire_order;
|
|
}
|
|
|
|
BEGIN { *_ci_warn = \&Tie::File::_ci_warn }
|
|
|
|
sub _check_integrity { # For CACHE
|
|
my $self = shift;
|
|
my $good = 1;
|
|
|
|
# Test HEAP
|
|
$self->[HEAP]->_check_integrity or $good = 0;
|
|
|
|
# Test HASH
|
|
my $bytes = 0;
|
|
for my $k (keys %{$self->[HASH]}) {
|
|
if ($k ne '0' && $k !~ /^[1-9][0-9]*$/) {
|
|
$good = 0;
|
|
_ci_warn "Cache hash key <$k> is non-numeric";
|
|
}
|
|
|
|
my $h = $self->[HASH]{$k};
|
|
if (! defined $h) {
|
|
$good = 0;
|
|
_ci_warn "Heap index number for key $k is undefined";
|
|
} elsif ($h == 0) {
|
|
$good = 0;
|
|
_ci_warn "Heap index number for key $k is zero";
|
|
} else {
|
|
my $j = $self->[HEAP][$h];
|
|
if (! defined $j) {
|
|
$good = 0;
|
|
_ci_warn "Heap contents key $k (=> $h) are undefined";
|
|
} else {
|
|
$bytes += length($j->[2]);
|
|
if ($k ne $j->[1]) {
|
|
$good = 0;
|
|
_ci_warn "Heap contents key $k (=> $h) is $j->[1], should be $k";
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
# Test BYTES
|
|
if ($bytes != $self->[BYTES]) {
|
|
$good = 0;
|
|
_ci_warn "Total data in cache is $bytes, expected $self->[BYTES]";
|
|
}
|
|
|
|
# Test MAX
|
|
if ($bytes > $self->[MAX]) {
|
|
$good = 0;
|
|
_ci_warn "Total data in cache is $bytes, exceeds maximum $self->[MAX]";
|
|
}
|
|
|
|
return $good;
|
|
}
|
|
|
|
sub delink {
|
|
my $self = shift;
|
|
$self->[HEAP] = undef; # Bye bye heap
|
|
}
|
|
|
|
################################################################
|
|
#
|
|
# Tie::File::Heap
|
|
#
|
|
# Heap data structure for use by cache LRU routines
|
|
|
|
package Tie::File::Heap;
|
|
use Carp ':DEFAULT', 'confess';
|
|
$Tie::File::Heap::VERSION = $Tie::File::Cache::VERSION;
|
|
sub SEQ () { 0 };
|
|
sub KEY () { 1 };
|
|
sub DAT () { 2 };
|
|
|
|
sub new {
|
|
my ($pack, $cache) = @_;
|
|
die "$pack: Parent cache object $cache does not support _heap_move method"
|
|
unless eval { $cache->can('_heap_move') };
|
|
my $self = [[0,$cache,0]];
|
|
bless $self => $pack;
|
|
}
|
|
|
|
# Allocate a new sequence number, larger than all previously allocated numbers
|
|
sub _nseq {
|
|
my $self = shift;
|
|
$self->[0][0]++;
|
|
}
|
|
|
|
sub _cache {
|
|
my $self = shift;
|
|
$self->[0][1];
|
|
}
|
|
|
|
sub _nelts {
|
|
my $self = shift;
|
|
$self->[0][2];
|
|
}
|
|
|
|
sub _nelts_inc {
|
|
my $self = shift;
|
|
++$self->[0][2];
|
|
}
|
|
|
|
sub _nelts_dec {
|
|
my $self = shift;
|
|
--$self->[0][2];
|
|
}
|
|
|
|
sub is_empty {
|
|
my $self = shift;
|
|
$self->_nelts == 0;
|
|
}
|
|
|
|
sub empty {
|
|
my $self = shift;
|
|
$#$self = 0;
|
|
$self->[0][2] = 0;
|
|
$self->[0][0] = 0; # might as well reset the sequence numbers
|
|
}
|
|
|
|
# notify the parent cache object that we moved something
|
|
sub _heap_move {
|
|
my $self = shift;
|
|
$self->_cache->_heap_move(@_);
|
|
}
|
|
|
|
# Insert a piece of data into the heap with the indicated sequence number.
|
|
# The item with the smallest sequence number is always at the top.
|
|
# If no sequence number is specified, allocate a new one and insert the
|
|
# item at the bottom.
|
|
sub insert {
|
|
my ($self, $key, $data, $seq) = @_;
|
|
$seq = $self->_nseq unless defined $seq;
|
|
$self->_insert_new([$seq, $key, $data]);
|
|
}
|
|
|
|
# Insert a new, fresh item at the bottom of the heap
|
|
sub _insert_new {
|
|
my ($self, $item) = @_;
|
|
my $i = @$self;
|
|
$i = int($i/2) until defined $self->[$i/2];
|
|
$self->[$i] = $item;
|
|
$self->[0][1]->_heap_move($self->[$i][KEY], $i);
|
|
$self->_nelts_inc;
|
|
}
|
|
|
|
# Insert [$data, $seq] pair at or below item $i in the heap.
|
|
# If $i is omitted, default to 1 (the top element.)
|
|
sub _insert {
|
|
my ($self, $item, $i) = @_;
|
|
# $self->_check_loc($i) if defined $i;
|
|
$i = 1 unless defined $i;
|
|
until (! defined $self->[$i]) {
|
|
if ($self->[$i][SEQ] > $item->[SEQ]) { # inserted item is older
|
|
($self->[$i], $item) = ($item, $self->[$i]);
|
|
$self->[0][1]->_heap_move($self->[$i][KEY], $i);
|
|
}
|
|
# If either is undefined, go that way. Otherwise, choose at random
|
|
my $dir;
|
|
$dir = 0 if !defined $self->[2*$i];
|
|
$dir = 1 if !defined $self->[2*$i+1];
|
|
$dir = int(rand(2)) unless defined $dir;
|
|
$i = 2*$i + $dir;
|
|
}
|
|
$self->[$i] = $item;
|
|
$self->[0][1]->_heap_move($self->[$i][KEY], $i);
|
|
$self->_nelts_inc;
|
|
}
|
|
|
|
# Remove the item at node $i from the heap, moving child items upwards.
|
|
# The item with the smallest sequence number is always at the top.
|
|
# Moving items upwards maintains this condition.
|
|
# Return the removed item. Return undef if there was no item at node $i.
|
|
sub remove {
|
|
my ($self, $i) = @_;
|
|
$i = 1 unless defined $i;
|
|
my $top = $self->[$i];
|
|
return unless defined $top;
|
|
while (1) {
|
|
my $ii;
|
|
my ($L, $R) = (2*$i, 2*$i+1);
|
|
|
|
# If either is undefined, go the other way.
|
|
# Otherwise, go towards the smallest.
|
|
last unless defined $self->[$L] || defined $self->[$R];
|
|
$ii = $R if not defined $self->[$L];
|
|
$ii = $L if not defined $self->[$R];
|
|
unless (defined $ii) {
|
|
$ii = $self->[$L][SEQ] < $self->[$R][SEQ] ? $L : $R;
|
|
}
|
|
|
|
$self->[$i] = $self->[$ii]; # Promote child to fill vacated spot
|
|
$self->[0][1]->_heap_move($self->[$i][KEY], $i);
|
|
$i = $ii; # Fill new vacated spot
|
|
}
|
|
$self->[0][1]->_heap_move($top->[KEY], undef);
|
|
undef $self->[$i];
|
|
$self->_nelts_dec;
|
|
return $top->[DAT];
|
|
}
|
|
|
|
sub popheap {
|
|
my $self = shift;
|
|
$self->remove(1);
|
|
}
|
|
|
|
# set the sequence number of the indicated item to a higher number
|
|
# than any other item in the heap, and bubble the item down to the
|
|
# bottom.
|
|
sub promote {
|
|
my ($self, $n) = @_;
|
|
# $self->_check_loc($n);
|
|
$self->[$n][SEQ] = $self->_nseq;
|
|
my $i = $n;
|
|
while (1) {
|
|
my ($L, $R) = (2*$i, 2*$i+1);
|
|
my $dir;
|
|
last unless defined $self->[$L] || defined $self->[$R];
|
|
$dir = $R unless defined $self->[$L];
|
|
$dir = $L unless defined $self->[$R];
|
|
unless (defined $dir) {
|
|
$dir = $self->[$L][SEQ] < $self->[$R][SEQ] ? $L : $R;
|
|
}
|
|
@{$self}[$i, $dir] = @{$self}[$dir, $i];
|
|
for ($i, $dir) {
|
|
$self->[0][1]->_heap_move($self->[$_][KEY], $_) if defined $self->[$_];
|
|
}
|
|
$i = $dir;
|
|
}
|
|
}
|
|
|
|
# Return item $n from the heap, promoting its LRU status
|
|
sub lookup {
|
|
my ($self, $n) = @_;
|
|
# $self->_check_loc($n);
|
|
my $val = $self->[$n];
|
|
$self->promote($n);
|
|
$val->[DAT];
|
|
}
|
|
|
|
|
|
# Assign a new value for node $n, promoting it to the bottom of the heap
|
|
sub set_val {
|
|
my ($self, $n, $val) = @_;
|
|
# $self->_check_loc($n);
|
|
my $oval = $self->[$n][DAT];
|
|
$self->[$n][DAT] = $val;
|
|
$self->promote($n);
|
|
return $oval;
|
|
}
|
|
|
|
# The hash key has changed for an item;
|
|
# alter the heap's record of the hash key
|
|
sub rekey {
|
|
my ($self, $n, $new_key) = @_;
|
|
# $self->_check_loc($n);
|
|
$self->[$n][KEY] = $new_key;
|
|
}
|
|
|
|
sub _check_loc {
|
|
my ($self, $n) = @_;
|
|
unless (1 || defined $self->[$n]) {
|
|
confess "_check_loc($n) failed";
|
|
}
|
|
}
|
|
|
|
BEGIN { *_ci_warn = \&Tie::File::_ci_warn }
|
|
|
|
sub _check_integrity {
|
|
my $self = shift;
|
|
my $good = 1;
|
|
my %seq;
|
|
|
|
unless (eval {$self->[0][1]->isa("Tie::File::Cache")}) {
|
|
_ci_warn "Element 0 of heap corrupt";
|
|
$good = 0;
|
|
}
|
|
$good = 0 unless $self->_satisfies_heap_condition(1);
|
|
for my $i (2 .. $#{$self}) {
|
|
my $p = int($i/2); # index of parent node
|
|
if (defined $self->[$i] && ! defined $self->[$p]) {
|
|
_ci_warn "Element $i of heap defined, but parent $p isn't";
|
|
$good = 0;
|
|
}
|
|
|
|
if (defined $self->[$i]) {
|
|
if ($seq{$self->[$i][SEQ]}) {
|
|
my $seq = $self->[$i][SEQ];
|
|
_ci_warn "Nodes $i and $seq{$seq} both have SEQ=$seq";
|
|
$good = 0;
|
|
} else {
|
|
$seq{$self->[$i][SEQ]} = $i;
|
|
}
|
|
}
|
|
}
|
|
|
|
return $good;
|
|
}
|
|
|
|
sub _satisfies_heap_condition {
|
|
my $self = shift;
|
|
my $n = shift || 1;
|
|
my $good = 1;
|
|
for (0, 1) {
|
|
my $c = $n*2 + $_;
|
|
next unless defined $self->[$c];
|
|
if ($self->[$n][SEQ] >= $self->[$c]) {
|
|
_ci_warn "Node $n of heap does not predate node $c";
|
|
$good = 0 ;
|
|
}
|
|
$good = 0 unless $self->_satisfies_heap_condition($c);
|
|
}
|
|
return $good;
|
|
}
|
|
|
|
# Return a list of all the values, sorted by expiration order
|
|
sub expire_order {
|
|
my $self = shift;
|
|
my @nodes = sort {$a->[SEQ] <=> $b->[SEQ]} $self->_nodes;
|
|
map { $_->[KEY] } @nodes;
|
|
}
|
|
|
|
sub _nodes {
|
|
my $self = shift;
|
|
my $i = shift || 1;
|
|
return unless defined $self->[$i];
|
|
($self->[$i], $self->_nodes($i*2), $self->_nodes($i*2+1));
|
|
}
|
|
|
|
1;
|
|
|
|
__END__
|
|
|
|
=head1 NAME
|
|
|
|
Tie::File - Access the lines of a disk file via a Perl array
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
use Tie::File;
|
|
|
|
tie @array, 'Tie::File', filename or die ...;
|
|
|
|
$array[0] = 'blah'; # first line of the file is now 'blah'
|
|
# (line numbering starts at 0)
|
|
print $array[42]; # display line 43 of the file
|
|
|
|
$n_recs = @array; # how many records are in the file?
|
|
$#array -= 2; # chop two records off the end
|
|
|
|
|
|
for (@array) {
|
|
s/PERL/Perl/g; # Replace PERL with Perl everywhere in the file
|
|
}
|
|
|
|
# These are just like regular push, pop, unshift, shift, and splice
|
|
# Except that they modify the file in the way you would expect
|
|
|
|
push @array, new recs...;
|
|
my $r1 = pop @array;
|
|
unshift @array, new recs...;
|
|
my $r2 = shift @array;
|
|
@old_recs = splice @array, 3, 7, new recs...;
|
|
|
|
untie @array; # all finished
|
|
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
C<Tie::File> represents a regular text file as a Perl array. Each
|
|
element in the array corresponds to a record in the file. The first
|
|
line of the file is element 0 of the array; the second line is element
|
|
1, and so on.
|
|
|
|
The file is I<not> loaded into memory, so this will work even for
|
|
gigantic files.
|
|
|
|
Changes to the array are reflected in the file immediately.
|
|
|
|
Lazy people and beginners may now stop reading the manual.
|
|
|
|
=head2 C<recsep>
|
|
|
|
What is a 'record'? By default, the meaning is the same as for the
|
|
C<E<lt>...E<gt>> operator: It's a string terminated by C<$/>, which is
|
|
probably C<"\n">. (Minor exception: on DOS and Win32 systems, a
|
|
'record' is a string terminated by C<"\r\n">.) You may change the
|
|
definition of "record" by supplying the C<recsep> option in the C<tie>
|
|
call:
|
|
|
|
tie @array, 'Tie::File', $file, recsep => 'es';
|
|
|
|
This says that records are delimited by the string C<es>. If the file
|
|
contained the following data:
|
|
|
|
Curse these pesky flies!\n
|
|
|
|
then the C<@array> would appear to have four elements:
|
|
|
|
"Curse th"
|
|
"e p"
|
|
"ky fli"
|
|
"!\n"
|
|
|
|
An undefined value is not permitted as a record separator. Perl's
|
|
special "paragraph mode" semantics (E<agrave> la C<$/ = "">) are not
|
|
emulated.
|
|
|
|
Records read from the tied array do not have the record separator
|
|
string on the end; this is to allow
|
|
|
|
$array[17] .= "extra";
|
|
|
|
to work as expected.
|
|
|
|
(See L<"autochomp">, below.) Records stored into the array will have
|
|
the record separator string appended before they are written to the
|
|
file, if they don't have one already. For example, if the record
|
|
separator string is C<"\n">, then the following two lines do exactly
|
|
the same thing:
|
|
|
|
$array[17] = "Cherry pie";
|
|
$array[17] = "Cherry pie\n";
|
|
|
|
The result is that the contents of line 17 of the file will be
|
|
replaced with "Cherry pie"; a newline character will separate line 17
|
|
from line 18. This means that this code will do nothing:
|
|
|
|
chomp $array[17];
|
|
|
|
Because the C<chomp>ed value will have the separator reattached when
|
|
it is written back to the file. There is no way to create a file
|
|
whose trailing record separator string is missing.
|
|
|
|
Inserting records that I<contain> the record separator string is not
|
|
supported by this module. It will probably produce a reasonable
|
|
result, but what this result will be may change in a future version.
|
|
Use 'splice' to insert records or to replace one record with several.
|
|
|
|
=head2 C<autochomp>
|
|
|
|
Normally, array elements have the record separator removed, so that if
|
|
the file contains the text
|
|
|
|
Gold
|
|
Frankincense
|
|
Myrrh
|
|
|
|
the tied array will appear to contain C<("Gold", "Frankincense",
|
|
"Myrrh")>. If you set C<autochomp> to a false value, the record
|
|
separator will not be removed. If the file above was tied with
|
|
|
|
tie @gifts, "Tie::File", $gifts, autochomp => 0;
|
|
|
|
then the array C<@gifts> would appear to contain C<("Gold\n",
|
|
"Frankincense\n", "Myrrh\n")>, or (on Win32 systems) C<("Gold\r\n",
|
|
"Frankincense\r\n", "Myrrh\r\n")>.
|
|
|
|
=head2 C<mode>
|
|
|
|
Normally, the specified file will be opened for read and write access,
|
|
and will be created if it does not exist. (That is, the flags
|
|
C<O_RDWR | O_CREAT> are supplied in the C<open> call.) If you want to
|
|
change this, you may supply alternative flags in the C<mode> option.
|
|
See L<Fcntl> for a listing of available flags.
|
|
For example:
|
|
|
|
# open the file if it exists, but fail if it does not exist
|
|
use Fcntl 'O_RDWR';
|
|
tie @array, 'Tie::File', $file, mode => O_RDWR;
|
|
|
|
# create the file if it does not exist
|
|
use Fcntl 'O_RDWR', 'O_CREAT';
|
|
tie @array, 'Tie::File', $file, mode => O_RDWR | O_CREAT;
|
|
|
|
# open an existing file in read-only mode
|
|
use Fcntl 'O_RDONLY';
|
|
tie @array, 'Tie::File', $file, mode => O_RDONLY;
|
|
|
|
Opening the data file in write-only or append mode is not supported.
|
|
|
|
=head2 C<memory>
|
|
|
|
This is an upper limit on the amount of memory that C<Tie::File> will
|
|
consume at any time while managing the file. This is used for two
|
|
things: managing the I<read cache> and managing the I<deferred write
|
|
buffer>.
|
|
|
|
Records read in from the file are cached, to avoid having to re-read
|
|
them repeatedly. If you read the same record twice, the first time it
|
|
will be stored in memory, and the second time it will be fetched from
|
|
the I<read cache>. The amount of data in the read cache will not
|
|
exceed the value you specified for C<memory>. If C<Tie::File> wants
|
|
to cache a new record, but the read cache is full, it will make room
|
|
by expiring the least-recently visited records from the read cache.
|
|
|
|
The default memory limit is 2Mib. You can adjust the maximum read
|
|
cache size by supplying the C<memory> option. The argument is the
|
|
desired cache size, in bytes.
|
|
|
|
# I have a lot of memory, so use a large cache to speed up access
|
|
tie @array, 'Tie::File', $file, memory => 20_000_000;
|
|
|
|
Setting the memory limit to 0 will inhibit caching; records will be
|
|
fetched from disk every time you examine them.
|
|
|
|
The C<memory> value is not an absolute or exact limit on the memory
|
|
used. C<Tie::File> objects contains some structures besides the read
|
|
cache and the deferred write buffer, whose sizes are not charged
|
|
against C<memory>.
|
|
|
|
The cache itself consumes about 310 bytes per cached record, so if
|
|
your file has many short records, you may want to decrease the cache
|
|
memory limit, or else the cache overhead may exceed the size of the
|
|
cached data.
|
|
|
|
|
|
=head2 C<dw_size>
|
|
|
|
(This is an advanced feature. Skip this section on first reading.)
|
|
|
|
If you use deferred writing (See L<"Deferred Writing">, below) then
|
|
data you write into the array will not be written directly to the
|
|
file; instead, it will be saved in the I<deferred write buffer> to be
|
|
written out later. Data in the deferred write buffer is also charged
|
|
against the memory limit you set with the C<memory> option.
|
|
|
|
You may set the C<dw_size> option to limit the amount of data that can
|
|
be saved in the deferred write buffer. This limit may not exceed the
|
|
total memory limit. For example, if you set C<dw_size> to 1000 and
|
|
C<memory> to 2500, that means that no more than 1000 bytes of deferred
|
|
writes will be saved up. The space available for the read cache will
|
|
vary, but it will always be at least 1500 bytes (if the deferred write
|
|
buffer is full) and it could grow as large as 2500 bytes (if the
|
|
deferred write buffer is empty.)
|
|
|
|
If you don't specify a C<dw_size>, it defaults to the entire memory
|
|
limit.
|
|
|
|
=head2 Option Format
|
|
|
|
C<-mode> is a synonym for C<mode>. C<-recsep> is a synonym for
|
|
C<recsep>. C<-memory> is a synonym for C<memory>. You get the
|
|
idea.
|
|
|
|
=head1 Public Methods
|
|
|
|
The C<tie> call returns an object, say C<$o>. You may call
|
|
|
|
$rec = $o->FETCH($n);
|
|
$o->STORE($n, $rec);
|
|
|
|
to fetch or store the record at line C<$n>, respectively; similarly
|
|
the other tied array methods. (See L<perltie> for details.) You may
|
|
also call the following methods on this object:
|
|
|
|
=head2 C<flock>
|
|
|
|
$o->flock(MODE)
|
|
|
|
will lock the tied file. C<MODE> has the same meaning as the second
|
|
argument to the Perl built-in C<flock> function; for example
|
|
C<LOCK_SH> or C<LOCK_EX | LOCK_NB>. (These constants are provided by
|
|
the C<use Fcntl ':flock'> declaration.)
|
|
|
|
C<MODE> is optional; the default is C<LOCK_EX>.
|
|
|
|
C<Tie::File> maintains an internal table of the byte offset of each
|
|
record it has seen in the file.
|
|
|
|
When you use C<flock> to lock the file, C<Tie::File> assumes that the
|
|
read cache is no longer trustworthy, because another process might
|
|
have modified the file since the last time it was read. Therefore, a
|
|
successful call to C<flock> discards the contents of the read cache
|
|
and the internal record offset table.
|
|
|
|
C<Tie::File> promises that the following sequence of operations will
|
|
be safe:
|
|
|
|
my $o = tie @array, "Tie::File", $filename;
|
|
$o->flock;
|
|
|
|
In particular, C<Tie::File> will I<not> read or write the file during
|
|
the C<tie> call. (Exception: Using C<mode =E<gt> O_TRUNC> will, of
|
|
course, erase the file during the C<tie> call. If you want to do this
|
|
safely, then open the file without C<O_TRUNC>, lock the file, and use
|
|
C<@array = ()>.)
|
|
|
|
The best way to unlock a file is to discard the object and untie the
|
|
array. It is probably unsafe to unlock the file without also untying
|
|
it, because if you do, changes may remain unwritten inside the object.
|
|
That is why there is no shortcut for unlocking. If you really want to
|
|
unlock the file prematurely, you know what to do; if you don't know
|
|
what to do, then don't do it.
|
|
|
|
All the usual warnings about file locking apply here. In particular,
|
|
note that file locking in Perl is B<advisory>, which means that
|
|
holding a lock will not prevent anyone else from reading, writing, or
|
|
erasing the file; it only prevents them from getting another lock at
|
|
the same time. Locks are analogous to green traffic lights: If you
|
|
have a green light, that does not prevent the idiot coming the other
|
|
way from plowing into you sideways; it merely guarantees to you that
|
|
the idiot does not also have a green light at the same time.
|
|
|
|
=head2 C<autochomp>
|
|
|
|
my $old_value = $o->autochomp(0); # disable autochomp option
|
|
my $old_value = $o->autochomp(1); # enable autochomp option
|
|
|
|
my $ac = $o->autochomp(); # recover current value
|
|
|
|
See L<"autochomp">, above.
|
|
|
|
=head2 C<defer>, C<flush>, C<discard>, and C<autodefer>
|
|
|
|
See L<"Deferred Writing">, below.
|
|
|
|
=head2 C<offset>
|
|
|
|
$off = $o->offset($n);
|
|
|
|
This method returns the byte offset of the start of the C<$n>th record
|
|
in the file. If there is no such record, it returns an undefined
|
|
value.
|
|
|
|
=head1 Tying to an already-opened filehandle
|
|
|
|
If C<$fh> is a filehandle, such as is returned by C<IO::File> or one
|
|
of the other C<IO> modules, you may use:
|
|
|
|
tie @array, 'Tie::File', $fh, ...;
|
|
|
|
Similarly if you opened that handle C<FH> with regular C<open> or
|
|
C<sysopen>, you may use:
|
|
|
|
tie @array, 'Tie::File', \*FH, ...;
|
|
|
|
Handles that were opened write-only won't work. Handles that were
|
|
opened read-only will work as long as you don't try to modify the
|
|
array. Handles must be attached to seekable sources of data---that
|
|
means no pipes or sockets. If C<Tie::File> can detect that you
|
|
supplied a non-seekable handle, the C<tie> call will throw an
|
|
exception. (On Unix systems, it can detect this.)
|
|
|
|
Note that Tie::File will only close any filehandles that it opened
|
|
internally. If you passed it a filehandle as above, you "own" the
|
|
filehandle, and are responsible for closing it after you have untied
|
|
the @array.
|
|
|
|
Tie::File calls C<binmode> on filehandles that it opens internally,
|
|
but not on filehandles passed in by the user. For consistency,
|
|
especially if using the tied files cross-platform, you may wish to
|
|
call C<binmode> on the filehandle prior to tying the file.
|
|
|
|
=head1 Deferred Writing
|
|
|
|
(This is an advanced feature. Skip this section on first reading.)
|
|
|
|
Normally, modifying a C<Tie::File> array writes to the underlying file
|
|
immediately. Every assignment like C<$a[3] = ...> rewrites as much of
|
|
the file as is necessary; typically, everything from line 3 through
|
|
the end will need to be rewritten. This is the simplest and most
|
|
transparent behavior. Performance even for large files is reasonably
|
|
good.
|
|
|
|
However, under some circumstances, this behavior may be excessively
|
|
slow. For example, suppose you have a million-record file, and you
|
|
want to do:
|
|
|
|
for (@FILE) {
|
|
$_ = "> $_";
|
|
}
|
|
|
|
The first time through the loop, you will rewrite the entire file,
|
|
from line 0 through the end. The second time through the loop, you
|
|
will rewrite the entire file from line 1 through the end. The third
|
|
time through the loop, you will rewrite the entire file from line 2 to
|
|
the end. And so on.
|
|
|
|
If the performance in such cases is unacceptable, you may defer the
|
|
actual writing, and then have it done all at once. The following loop
|
|
will perform much better for large files:
|
|
|
|
(tied @a)->defer;
|
|
for (@a) {
|
|
$_ = "> $_";
|
|
}
|
|
(tied @a)->flush;
|
|
|
|
If C<Tie::File>'s memory limit is large enough, all the writing will
|
|
done in memory. Then, when you call C<-E<gt>flush>, the entire file
|
|
will be rewritten in a single pass.
|
|
|
|
(Actually, the preceding discussion is something of a fib. You don't
|
|
need to enable deferred writing to get good performance for this
|
|
common case, because C<Tie::File> will do it for you automatically
|
|
unless you specifically tell it not to. See L</Autodeferring>,
|
|
below.)
|
|
|
|
Calling C<-E<gt>flush> returns the array to immediate-write mode. If
|
|
you wish to discard the deferred writes, you may call C<-E<gt>discard>
|
|
instead of C<-E<gt>flush>. Note that in some cases, some of the data
|
|
will have been written already, and it will be too late for
|
|
C<-E<gt>discard> to discard all the changes. Support for
|
|
C<-E<gt>discard> may be withdrawn in a future version of C<Tie::File>.
|
|
|
|
Deferred writes are cached in memory up to the limit specified by the
|
|
C<dw_size> option (see above). If the deferred-write buffer is full
|
|
and you try to write still more deferred data, the buffer will be
|
|
flushed. All buffered data will be written immediately, the buffer
|
|
will be emptied, and the now-empty space will be used for future
|
|
deferred writes.
|
|
|
|
If the deferred-write buffer isn't yet full, but the total size of the
|
|
buffer and the read cache would exceed the C<memory> limit, the oldest
|
|
records will be expired from the read cache until the total size is
|
|
under the limit.
|
|
|
|
C<push>, C<pop>, C<shift>, C<unshift>, and C<splice> cannot be
|
|
deferred. When you perform one of these operations, any deferred data
|
|
is written to the file and the operation is performed immediately.
|
|
This may change in a future version.
|
|
|
|
If you resize the array with deferred writing enabled, the file will
|
|
be resized immediately, but deferred records will not be written.
|
|
This has a surprising consequence: C<@a = (...)> erases the file
|
|
immediately, but the writing of the actual data is deferred. This
|
|
might be a bug. If it is a bug, it will be fixed in a future version.
|
|
|
|
=head2 Autodeferring
|
|
|
|
C<Tie::File> tries to guess when deferred writing might be helpful,
|
|
and to turn it on and off automatically.
|
|
|
|
for (@a) {
|
|
$_ = "> $_";
|
|
}
|
|
|
|
In this example, only the first two assignments will be done
|
|
immediately; after this, all the changes to the file will be deferred
|
|
up to the user-specified memory limit.
|
|
|
|
You should usually be able to ignore this and just use the module
|
|
without thinking about deferring. However, special applications may
|
|
require fine control over which writes are deferred, or may require
|
|
that all writes be immediate. To disable the autodeferment feature,
|
|
use
|
|
|
|
(tied @o)->autodefer(0);
|
|
|
|
or
|
|
|
|
tie @array, 'Tie::File', $file, autodefer => 0;
|
|
|
|
|
|
Similarly, C<-E<gt>autodefer(1)> re-enables autodeferment, and
|
|
C<-E<gt>autodefer()> recovers the current value of the autodefer setting.
|
|
|
|
|
|
=head1 CONCURRENT ACCESS TO FILES
|
|
|
|
Caching and deferred writing are inappropriate if you want the same
|
|
file to be accessed simultaneously from more than one process. Other
|
|
optimizations performed internally by this module are also
|
|
incompatible with concurrent access. A future version of this module will
|
|
support a C<concurrent =E<gt> 1> option that enables safe concurrent access.
|
|
|
|
Previous versions of this documentation suggested using C<memory
|
|
=E<gt> 0> for safe concurrent access. This was mistaken. Tie::File
|
|
will not support safe concurrent access before version 0.96.
|
|
|
|
=head1 CAVEATS
|
|
|
|
(That's Latin for 'warnings'.)
|
|
|
|
=over 4
|
|
|
|
=item *
|
|
|
|
Reasonable effort was made to make this module efficient. Nevertheless,
|
|
changing the size of a record in the middle of a large file will
|
|
always be fairly slow, because everything after the new record must be
|
|
moved.
|
|
|
|
=item *
|
|
|
|
The behavior of tied arrays is not precisely the same as for regular
|
|
arrays. For example:
|
|
|
|
# This DOES print "How unusual!"
|
|
undef $a[10]; print "How unusual!\n" if defined $a[10];
|
|
|
|
C<undef>-ing a C<Tie::File> array element just blanks out the
|
|
corresponding record in the file. When you read it back again, you'll
|
|
get the empty string, so the supposedly-C<undef>'ed value will be
|
|
defined. Similarly, if you have C<autochomp> disabled, then
|
|
|
|
# This DOES print "How unusual!" if 'autochomp' is disabled
|
|
undef $a[10];
|
|
print "How unusual!\n" if $a[10];
|
|
|
|
Because when C<autochomp> is disabled, C<$a[10]> will read back as
|
|
C<"\n"> (or whatever the record separator string is.)
|
|
|
|
There are other minor differences, particularly regarding C<exists>
|
|
and C<delete>, but in general, the correspondence is extremely close.
|
|
|
|
=item *
|
|
|
|
I have supposed that since this module is concerned with file I/O,
|
|
almost all normal use of it will be heavily I/O bound. This means
|
|
that the time to maintain complicated data structures inside the
|
|
module will be dominated by the time to actually perform the I/O.
|
|
When there was an opportunity to spend CPU time to avoid doing I/O, I
|
|
usually tried to take it.
|
|
|
|
=item *
|
|
|
|
You might be tempted to think that deferred writing is like
|
|
transactions, with C<flush> as C<commit> and C<discard> as
|
|
C<rollback>, but it isn't, so don't.
|
|
|
|
=item *
|
|
|
|
There is a large memory overhead for each record offset and for each
|
|
cache entry: about 310 bytes per cached data record, and about 21 bytes
|
|
per offset table entry.
|
|
|
|
The per-record overhead will limit the maximum number of records you
|
|
can access per file. Note that I<accessing> the length of the array
|
|
via C<$x = scalar @tied_file> accesses B<all> records and stores their
|
|
offsets. The same for C<foreach (@tied_file)>, even if you exit the
|
|
loop early.
|
|
|
|
=back
|
|
|
|
=head1 SUBCLASSING
|
|
|
|
This version promises absolutely nothing about the internals, which
|
|
may change without notice. A future version of the module will have a
|
|
well-defined and stable subclassing API.
|
|
|
|
=head1 WHAT ABOUT C<DB_File>?
|
|
|
|
People sometimes point out that L<DB_File> will do something similar,
|
|
and ask why C<Tie::File> module is necessary.
|
|
|
|
There are a number of reasons that you might prefer C<Tie::File>.
|
|
A list is available at C<L<http://perl.plover.com/TieFile/why-not-DB_File>>.
|
|
|
|
=head1 AUTHOR
|
|
|
|
Mark Jason Dominus
|
|
|
|
To contact the author, send email to: C<mjd-perl-tiefile+@plover.com>
|
|
|
|
To receive an announcement whenever a new version of this module is
|
|
released, send a blank email message to
|
|
C<mjd-perl-tiefile-subscribe@plover.com>.
|
|
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The most recent version of this module, including documentation and
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any news of importance, will be available at
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http://perl.plover.com/TieFile/
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=head1 LICENSE
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C<Tie::File> version 0.96 is copyright (C) 2003 Mark Jason Dominus.
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This library is free software; you may redistribute it and/or modify
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it under the same terms as Perl itself.
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These terms are your choice of any of (1) the Perl Artistic Licence,
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or (2) version 2 of the GNU General Public License as published by the
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Free Software Foundation, or (3) any later version of the GNU General
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Public License.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this library program; it should be in the file C<COPYING>.
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If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
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Fifth Floor, Boston, MA 02110-1301, USA
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For licensing inquiries, contact the author at:
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Mark Jason Dominus
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255 S. Warnock St.
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Philadelphia, PA 19107
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=head1 WARRANTY
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C<Tie::File> version 0.98 comes with ABSOLUTELY NO WARRANTY.
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For details, see the license.
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=head1 THANKS
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Gigantic thanks to Jarkko Hietaniemi, for agreeing to put this in the
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core when I hadn't written it yet, and for generally being helpful,
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supportive, and competent. (Usually the rule is "choose any one.")
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Also big thanks to Abhijit Menon-Sen for all of the same things.
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Special thanks to Craig Berry and Peter Prymmer (for VMS portability
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help), Randy Kobes (for Win32 portability help), Clinton Pierce and
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Autrijus Tang (for heroic eleventh-hour Win32 testing above and beyond
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the call of duty), Michael G Schwern (for testing advice), and the
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rest of the CPAN testers (for testing generally).
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Special thanks to Tels for suggesting several speed and memory
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optimizations.
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Additional thanks to:
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Edward Avis /
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Mattia Barbon /
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Tom Christiansen /
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Gerrit Haase /
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Gurusamy Sarathy /
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Jarkko Hietaniemi (again) /
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Nikola Knezevic /
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John Kominetz /
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Nick Ing-Simmons /
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Tassilo von Parseval /
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H. Dieter Pearcey /
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Slaven Rezic /
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Eric Roode /
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Peter Scott /
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Peter Somu /
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Autrijus Tang (again) /
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Tels (again) /
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Juerd Waalboer /
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Todd Rinaldo
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=head1 TODO
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More tests. (Stuff I didn't think of yet.)
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Paragraph mode?
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Fixed-length mode. Leave-blanks mode.
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Maybe an autolocking mode?
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For many common uses of the module, the read cache is a liability.
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For example, a program that inserts a single record, or that scans the
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file once, will have a cache hit rate of zero. This suggests a major
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optimization: The cache should be initially disabled. Here's a hybrid
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approach: Initially, the cache is disabled, but the cache code
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maintains statistics about how high the hit rate would be *if* it were
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enabled. When it sees the hit rate get high enough, it enables
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itself. The STAT comments in this code are the beginning of an
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implementation of this.
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Record locking with fcntl()? Then the module might support an undo
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log and get real transactions. What a tour de force that would be.
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Keeping track of the highest cached record. This would allow reads-in-a-row
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to skip the cache lookup faster (if reading from 1..N with empty cache at
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start, the last cached value will be always N-1).
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More tests.
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=cut
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