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-rw-r--r--Master/tlpkg/tlperl/lib/Tie/File.pm2632
1 files changed, 0 insertions, 2632 deletions
diff --git a/Master/tlpkg/tlperl/lib/Tie/File.pm b/Master/tlpkg/tlperl/lib/Tie/File.pm
deleted file mode 100644
index a1f40afe199..00000000000
--- a/Master/tlpkg/tlperl/lib/Tie/File.pm
+++ /dev/null
@@ -1,2632 +0,0 @@
-
-package Tie::File;
-require 5.005;
-use Carp ':DEFAULT', 'confess';
-use POSIX 'SEEK_SET';
-use Fcntl 'O_CREAT', 'O_RDWR', 'LOCK_EX', 'LOCK_SH', 'O_WRONLY', 'O_RDONLY';
-sub O_ACCMODE () { O_RDONLY | O_RDWR | O_WRONLY }
-
-
-$VERSION = "0.97";
-my $DEFAULT_MEMORY_SIZE = 1<<21; # 2 megabytes
-my $DEFAULT_AUTODEFER_THRESHHOLD = 3; # 3 records
-my $DEFAULT_AUTODEFER_FILELEN_THRESHHOLD = 65536; # 16 disk blocksful
-
-my %good_opt = map {$_ => 1, "-$_" => 1}
- qw(memory dw_size mode recsep discipline
- autodefer autochomp autodefer_threshhold concurrent);
-
-sub TIEARRAY {
- if (@_ % 2 != 0) {
- croak "usage: tie \@array, $_[0], filename, [option => value]...";
- }
- my ($pack, $file, %opts) = @_;
-
- # transform '-foo' keys into 'foo' keys
- for my $key (keys %opts) {
- unless ($good_opt{$key}) {
- croak("$pack: Unrecognized option '$key'\n");
- }
- my $okey = $key;
- if ($key =~ s/^-+//) {
- $opts{$key} = delete $opts{$okey};
- }
- }
-
- if ($opts{concurrent}) {
- croak("$pack: concurrent access not supported yet\n");
- }
-
- unless (defined $opts{memory}) {
- # default is the larger of the default cache size and the
- # deferred-write buffer size (if specified)
- $opts{memory} = $DEFAULT_MEMORY_SIZE;
- $opts{memory} = $opts{dw_size}
- if defined $opts{dw_size} && $opts{dw_size} > $DEFAULT_MEMORY_SIZE;
- # Dora Winifred Read
- }
- $opts{dw_size} = $opts{memory} unless defined $opts{dw_size};
- if ($opts{dw_size} > $opts{memory}) {
- croak("$pack: dw_size may not be larger than total memory allocation\n");
- }
- # are we in deferred-write mode?
- $opts{defer} = 0 unless defined $opts{defer};
- $opts{deferred} = {}; # no records are presently deferred
- $opts{deferred_s} = 0; # count of total bytes in ->{deferred}
- $opts{deferred_max} = -1; # empty
-
- # What's a good way to arrange that this class can be overridden?
- $opts{cache} = Tie::File::Cache->new($opts{memory});
-
- # autodeferment is enabled by default
- $opts{autodefer} = 1 unless defined $opts{autodefer};
- $opts{autodeferring} = 0; # but is not initially active
- $opts{ad_history} = [];
- $opts{autodefer_threshhold} = $DEFAULT_AUTODEFER_THRESHHOLD
- unless defined $opts{autodefer_threshhold};
- $opts{autodefer_filelen_threshhold} = $DEFAULT_AUTODEFER_FILELEN_THRESHHOLD
- unless defined $opts{autodefer_filelen_threshhold};
-
- $opts{offsets} = [0];
- $opts{filename} = $file;
- unless (defined $opts{recsep}) {
- $opts{recsep} = _default_recsep();
- }
- $opts{recseplen} = length($opts{recsep});
- if ($opts{recseplen} == 0) {
- croak "Empty record separator not supported by $pack";
- }
-
- $opts{autochomp} = 1 unless defined $opts{autochomp};
-
- $opts{mode} = O_CREAT|O_RDWR unless defined $opts{mode};
- $opts{rdonly} = (($opts{mode} & O_ACCMODE) == O_RDONLY);
- $opts{sawlastrec} = undef;
-
- my $fh;
-
- if (UNIVERSAL::isa($file, 'GLOB')) {
- # We use 1 here on the theory that some systems
- # may not indicate failure if we use 0.
- # MSWin32 does not indicate failure with 0, but I don't know if
- # it will indicate failure with 1 or not.
- unless (seek $file, 1, SEEK_SET) {
- croak "$pack: your filehandle does not appear to be seekable";
- }
- seek $file, 0, SEEK_SET # put it back
- $fh = $file; # setting binmode is the user's problem
- } elsif (ref $file) {
- croak "usage: tie \@array, $pack, filename, [option => value]...";
- } else {
- # $fh = \do { local *FH }; # XXX this is buggy
- if ($] < 5.006) {
- # perl 5.005 and earlier don't autovivify filehandles
- require Symbol;
- $fh = Symbol::gensym();
- }
- sysopen $fh, $file, $opts{mode}, 0666 or return;
- binmode $fh;
- ++$opts{ourfh};
- }
- { my $ofh = select $fh; $| = 1; select $ofh } # autoflush on write
- if (defined $opts{discipline} && $] >= 5.006) {
- # This avoids a compile-time warning under 5.005
- eval 'binmode($fh, $opts{discipline})';
- croak $@ if $@ =~ /unknown discipline/i;
- die if $@;
- }
- $opts{fh} = $fh;
-
- bless \%opts => $pack;
-}
-
-sub FETCH {
- my ($self, $n) = @_;
- my $rec;
-
- # check the defer buffer
- $rec = $self->{deferred}{$n} if exists $self->{deferred}{$n};
- $rec = $self->_fetch($n) unless defined $rec;
-
- # inlined _chomp1
- substr($rec, - $self->{recseplen}) = ""
- if defined $rec && $self->{autochomp};
- $rec;
-}
-
-# Chomp many records in-place; return nothing useful
-sub _chomp {
- my $self = shift;
- return unless $self->{autochomp};
- if ($self->{autochomp}) {
- for (@_) {
- next unless defined;
- substr($_, - $self->{recseplen}) = "";
- }
- }
-}
-
-# Chomp one record in-place; return modified record
-sub _chomp1 {
- my ($self, $rec) = @_;
- return $rec unless $self->{autochomp};
- return unless defined $rec;
- substr($rec, - $self->{recseplen}) = "";
- $rec;
-}
-
-sub _fetch {
- my ($self, $n) = @_;
-
- # check the record cache
- { my $cached = $self->{cache}->lookup($n);
- return $cached if defined $cached;
- }
-
- if ($#{$self->{offsets}} < $n) {
- return if $self->{eof}; # request for record beyond 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;
- }
-
- my $fh = $self->{FH};
- $self->_seek($n); # we can do this now that offsets is populated
- my $rec = $self->_read_record;
-
-# If we happen to have just read the first record, check to see if
-# the length of the record matches what 'tell' says. If not, Tie::File
-# won't work, and should drop dead.
-#
-# if ($n == 0 && defined($rec) && tell($self->{fh}) != length($rec)) {
-# if (defined $self->{discipline}) {
-# croak "I/O discipline $self->{discipline} not supported";
-# } else {
-# croak "File encoding not supported";
-# }
-# }
-
- $self->{cache}->insert($n, $rec) if defined $rec && not $self->{flushing};
- $rec;
-}
-
-sub STORE {
- my ($self, $n, $rec) = @_;
- die "STORE called from _check_integrity!" if $DIAGNOSTIC;
-
- $self->_fixrecs($rec);
-
- if ($self->{autodefer}) {
- $self->_annotate_ad_history($n);
- }
-
- return $self->_store_deferred($n, $rec) if $self->_is_deferring;
-
-
- # We need this to decide whether the new record will fit
- # It incidentally populates the offsets table
- # Note we have to do this before we alter the cache
- # 20020324 Wait, but this DOES alter the cache. TODO BUG?
- my $oldrec = $self->_fetch($n);
-
- if (not defined $oldrec) {
- # We're storing a record beyond the end of the file
- $self->_extend_file_to($n+1);
- $oldrec = $self->{recsep};
- }
-# return if $oldrec eq $rec; # don't bother
- my $len_diff = length($rec) - length($oldrec);
-
- # length($oldrec) here is not consistent with text mode TODO XXX BUG
- $self->_mtwrite($rec, $self->{offsets}[$n], length($oldrec));
- $self->_oadjust([$n, 1, $rec]);
- $self->{cache}->update($n, $rec);
-}
-
-sub _store_deferred {
- my ($self, $n, $rec) = @_;
- $self->{cache}->remove($n);
- my $old_deferred = $self->{deferred}{$n};
-
- if (defined $self->{deferred_max} && $n > $self->{deferred_max}) {
- $self->{deferred_max} = $n;
- }
- $self->{deferred}{$n} = $rec;
-
- my $len_diff = length($rec);
- $len_diff -= length($old_deferred) if defined $old_deferred;
- $self->{deferred_s} += $len_diff;
- $self->{cache}->adj_limit(-$len_diff);
- if ($self->{deferred_s} > $self->{dw_size}) {
- $self->_flush;
- } elsif ($self->_cache_too_full) {
- $self->_cache_flush;
- }
-}
-
-# Remove a single record from the deferred-write buffer without writing it
-# The record need not be present
-sub _delete_deferred {
- my ($self, $n) = @_;
- my $rec = delete $self->{deferred}{$n};
- return unless defined $rec;
-
- if (defined $self->{deferred_max}
- && $n == $self->{deferred_max}) {
- undef $self->{deferred_max};
- }
-
- $self->{deferred_s} -= length $rec;
- $self->{cache}->adj_limit(length $rec);
-}
-
-sub FETCHSIZE {
- my $self = shift;
- my $n = $self->{eof} ? $#{$self->{offsets}} : $self->_fill_offsets;
-
- my $top_deferred = $self->_defer_max;
- $n = $top_deferred+1 if defined $top_deferred && $n < $top_deferred+1;
- $n;
-}
-
-sub STORESIZE {
- my ($self, $len) = @_;
-
- if ($self->{autodefer}) {
- $self->_annotate_ad_history('STORESIZE');
- }
-
- my $olen = $self->FETCHSIZE;
- return if $len == $olen; # Woo-hoo!
-
- # file gets longer
- if ($len > $olen) {
- if ($self->_is_deferring) {
- for ($olen .. $len-1) {
- $self->_store_deferred($_, $self->{recsep});
- }
- } else {
- $self->_extend_file_to($len);
- }
- return;
- }
-
- # file gets shorter
- if ($self->_is_deferring) {
- # TODO maybe replace this with map-plus-assignment?
- for (grep $_ >= $len, keys %{$self->{deferred}}) {
- $self->_delete_deferred($_);
- }
- $self->{deferred_max} = $len-1;
- }
-
- $self->_seek($len);
- $self->_chop_file;
- $#{$self->{offsets}} = $len;
-# $self->{offsets}[0] = 0; # in case we just chopped this
-
- $self->{cache}->remove(grep $_ >= $len, $self->{cache}->ckeys);
-}
-
-### OPTIMIZE ME
-### It should not be necessary to do FETCHSIZE
-### Just seek to the end of the file.
-sub PUSH {
- my $self = shift;
- $self->SPLICE($self->FETCHSIZE, scalar(@_), @_);
-
- # No need to return:
- # $self->FETCHSIZE; # because av.c takes care of this for me
-}
-
-sub POP {
- my $self = shift;
- my $size = $self->FETCHSIZE;
- return if $size == 0;
-# print STDERR "# POPPITY POP POP POP\n";
- scalar $self->SPLICE($size-1, 1);
-}
-
-sub SHIFT {
- my $self = shift;
- scalar $self->SPLICE(0, 1);
-}
-
-sub UNSHIFT {
- my $self = shift;
- $self->SPLICE(0, 0, @_);
- # $self->FETCHSIZE; # av.c takes care of this for me
-}
-
-sub CLEAR {
- my $self = shift;
-
- if ($self->{autodefer}) {
- $self->_annotate_ad_history('CLEAR');
- }
-
- $self->_seekb(0);
- $self->_chop_file;
- $self->{cache}->set_limit($self->{memory});
- $self->{cache}->empty;
- @{$self->{offsets}} = (0);
- %{$self->{deferred}}= ();
- $self->{deferred_s} = 0;
- $self->{deferred_max} = -1;
-}
-
-sub EXTEND {
- my ($self, $n) = @_;
-
- # No need to pre-extend anything in this case
- return if $self->_is_deferring;
-
- $self->_fill_offsets_to($n);
- $self->_extend_file_to($n);
-}
-
-sub DELETE {
- my ($self, $n) = @_;
-
- if ($self->{autodefer}) {
- $self->_annotate_ad_history('DELETE');
- }
-
- my $lastrec = $self->FETCHSIZE-1;
- my $rec = $self->FETCH($n);
- $self->_delete_deferred($n) if $self->_is_deferring;
- if ($n == $lastrec) {
- $self->_seek($n);
- $self->_chop_file;
- $#{$self->{offsets}}--;
- $self->{cache}->remove($n);
- # perhaps in this case I should also remove trailing null records?
- # 20020316
- # Note that delete @a[-3..-1] deletes the records in the wrong order,
- # so we only chop the very last one out of the file. We could repair this
- # by tracking deleted records inside the object.
- } elsif ($n < $lastrec) {
- $self->STORE($n, "");
- }
- $rec;
-}
-
-sub EXISTS {
- my ($self, $n) = @_;
- return 1 if exists $self->{deferred}{$n};
- $n < $self->FETCHSIZE;
-}
-
-sub SPLICE {
- my $self = shift;
-
- if ($self->{autodefer}) {
- $self->_annotate_ad_history('SPLICE');
- }
-
- $self->_flush if $self->_is_deferring; # move this up?
- if (wantarray) {
- $self->_chomp(my @a = $self->_splice(@_));
- @a;
- } else {
- $self->_chomp1(scalar $self->_splice(@_));
- }
-}
-
-sub DESTROY {
- my $self = shift;
- $self->flush if $self->_is_deferring;
- $self->{cache}->delink if defined $self->{cache}; # break circular link
- if ($self->{fh} and $self->{ourfh}) {
- delete $self->{ourfh};
- close delete $self->{fh};
- }
-}
-
-sub _splice {
- my ($self, $pos, $nrecs, @data) = @_;
- my @result;
-
- $pos = 0 unless defined $pos;
-
- # Deal with negative and other out-of-range positions
- # Also set default for $nrecs
- {
- my $oldsize = $self->FETCHSIZE;
- $nrecs = $oldsize unless defined $nrecs;
- my $oldpos = $pos;
-
- if ($pos < 0) {
- $pos += $oldsize;
- if ($pos < 0) {
- croak "Modification of non-creatable array value attempted, subscript $oldpos";
- }
- }
-
- if ($pos > $oldsize) {
- return unless @data;
- $pos = $oldsize; # This is what perl does for normal arrays
- }
-
- # The manual is very unclear here
- if ($nrecs < 0) {
- $nrecs = $oldsize - $pos + $nrecs;
- $nrecs = 0 if $nrecs < 0;
- }
-
- # nrecs is too big---it really means "until the end"
- # 20030507
- if ($nrecs + $pos > $oldsize) {
- $nrecs = $oldsize - $pos;
- }
- }
-
- $self->_fixrecs(@data);
- my $data = join '', @data;
- my $datalen = length $data;
- my $oldlen = 0;
-
- # compute length of data being removed
- for ($pos .. $pos+$nrecs-1) {
- last unless defined $self->_fill_offsets_to($_);
- my $rec = $self->_fetch($_);
- last unless defined $rec;
- push @result, $rec;
-
- # Why don't we just use length($rec) here?
- # Because that record might have come from the cache. _splice
- # might have been called to flush out the deferred-write records,
- # and in this case length($rec) is the length of the record to be
- # *written*, not the length of the actual record in the file. But
- # the offsets are still true. 20020322
- $oldlen += $self->{offsets}[$_+1] - $self->{offsets}[$_]
- if defined $self->{offsets}[$_+1];
- }
- $self->_fill_offsets_to($pos+$nrecs);
-
- # Modify the file
- $self->_mtwrite($data, $self->{offsets}[$pos], $oldlen);
- # Adjust the offsets table
- $self->_oadjust([$pos, $nrecs, @data]);
-
- { # Take this read cache stuff out into a separate function
- # You made a half-attempt to put it into _oadjust.
- # Finish something like that up eventually.
- # STORE also needs to do something similarish
-
- # update the read cache, part 1
- # modified records
- for ($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 accomodate the last segment that doesn'
- $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 $prev_end = -1;
- my %newkeys;
-
- for (@_) {
- my ($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;
- $newkey{$i} = $i + $delta_recs;
- }
-
- $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;
- }
-
-# # also this data has changed, so update it in the cache
-# for (0 .. $#data) {
-# $self->{cache}->update($pos + $_, $data[$_]);
-# }
-# if ($delta_recs) {
-# my @oldkeys = grep $_ >= $pos + @data, $self->{cache}->ckeys;
-# my @newkeys = map $_ + $delta_recs, @oldkeys;
-# $self->{cache}->rekey(\@oldkeys, \@newkeys);
-# }
-
- # replace old offsets with new
- splice @{$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 $oval;
-}
-
-# The hask key has changed for an item;
-# alter the heap's record of the hash key
-sub rekey {
- my ($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));
-}
-
-"Cogito, ergo sum."; # don't forget to return a true value from the file
-
-__END__
-
-=head1 NAME
-
-Tie::File - Access the lines of a disk file via a Perl array
-
-=head1 SYNOPSIS
-
- # This file documents Tie::File version 0.97
- use Tie::File;
-
- tie @array, 'Tie::File', filename or die ...;
-
- $array[13] = 'blah'; # line 13 of the file is now 'blah'
- print $array[42]; # display line 42 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', $fh, ...;
-
-Similarly if you opened that handle C<FH> with regular C<open> or
-C<sysopen>, you may use:
-
- tie @array, 'Tie::File', \*FH, ...;
-
-Handles that were opened write-only won't work. Handles that were
-opened read-only will work as long as you don't try to modify the
-array. Handles must be attached to seekable sources of data---that
-means no pipes or sockets. If C<Tie::File> can detect that you
-supplied a non-seekable handle, the C<tie> call will throw an
-exception. (On Unix systems, it can detect this.)
-
-Note that Tie::File will only close any filehandles that it opened
-internally. If you passed it a filehandle as above, you "own" the
-filehandle, and are responsible for closing it after you have untied
-the @array.
-
-=head1 Deferred Writing
-
-(This is an advanced feature. Skip this section on first reading.)
-
-Normally, modifying a C<Tie::File> array writes to the underlying file
-immediately. Every assignment like C<$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 0.98.
-
-=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<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>.
-
-The most recent version of this module, including documentation and
-any news of importance, will be available at
-
- http://perl.plover.com/TieFile/
-
-
-=head1 LICENSE
-
-C<Tie::File> version 0.97 is copyright (C) 2003 Mark Jason Dominus.
-
-This library is free software; you may redistribute it and/or modify
-it under the same terms as Perl itself.
-
-These terms are your choice of any of (1) the Perl Artistic Licence,
-or (2) version 2 of the GNU General Public License as published by the
-Free Software Foundation, or (3) any later version of the GNU General
-Public License.
-
-This library is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this library program; it should be in the file C<COPYING>.
-If not, write to the Free Software Foundation, Inc., 59 Temple Place,
-Suite 330, Boston, MA 02111 USA
-
-For licensing inquiries, contact the author at:
-
- Mark Jason Dominus
- 255 S. Warnock St.
- Philadelphia, PA 19107
-
-=head1 WARRANTY
-
-C<Tie::File> version 0.97 comes with ABSOLUTELY NO WARRANTY.
-For details, see the license.
-
-=head1 THANKS
-
-Gigantic thanks to Jarkko Hietaniemi, for agreeing to put this in the
-core when I hadn't written it yet, and for generally being helpful,
-supportive, and competent. (Usually the rule is "choose any one.")
-Also big thanks to Abhijit Menon-Sen for all of the same things.
-
-Special thanks to Craig Berry and Peter Prymmer (for VMS portability
-help), Randy Kobes (for Win32 portability help), Clinton Pierce and
-Autrijus Tang (for heroic eleventh-hour Win32 testing above and beyond
-the call of duty), Michael G Schwern (for testing advice), and the
-rest of the CPAN testers (for testing generally).
-
-Special thanks to Tels for suggesting several speed and memory
-optimizations.
-
-Additional thanks to:
-Edward Avis /
-Mattia Barbon /
-Tom Christiansen /
-Gerrit Haase /
-Gurusamy Sarathy /
-Jarkko Hietaniemi (again) /
-Nikola Knezevic /
-John Kominetz /
-Nick Ing-Simmons /
-Tassilo von Parseval /
-H. Dieter Pearcey /
-Slaven Rezic /
-Eric Roode /
-Peter Scott /
-Peter Somu /
-Autrijus Tang (again) /
-Tels (again) /
-Juerd Waalboer
-
-=head1 TODO
-
-More tests. (Stuff I didn't think of yet.)
-
-Paragraph mode?
-
-Fixed-length mode. Leave-blanks mode.
-
-Maybe an autolocking mode?
-
-For many common uses of the module, the read cache is a liability.
-For example, a program that inserts a single record, or that scans the
-file once, will have a cache hit rate of zero. This suggests a major
-optimization: The cache should be initially disabled. Here's a hybrid
-approach: Initially, the cache is disabled, but the cache code
-maintains statistics about how high the hit rate would be *if* it were
-enabled. When it sees the hit rate get high enough, it enables
-itself. The STAT comments in this code are the beginning of an
-implementation of this.
-
-Record locking with fcntl()? Then the module might support an undo
-log and get real transactions. What a tour de force that would be.
-
-Keeping track of the highest cached record. This would allow reads-in-a-row
-to skip the cache lookup faster (if reading from 1..N with empty cache at
-start, the last cached value will be always N-1).
-
-More tests.
-
-=cut
-
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