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| | # Copyright (C) 2020 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
# temporary stack for public-inbox-index
package PublicInbox::IdxStack;
use v5.10.1;
use strict;
use Fcntl qw(:seek);
use constant FMT => eval { pack('Q', 1) } ? 'A1QQH*' : 'A1IIH*';
# start off in write-only mode
sub new {
open(my $io, '+>', undef) or die "open: $!";
bless { wr => $io, latest_cmt => $_[1] }, __PACKAGE__
}
# file_char = [d|m]
sub push_rec {
my ($self, $file_char, $at, $ct, $blob_oid) = @_;
my $rec = pack(FMT, $file_char, $at, $ct, $blob_oid);
$self->{rec_size} //= length($rec);
print { $self->{wr} } $rec or die "print: $!";
$self->{tot_size} += length($rec);
}
sub num_records {
my ($self) = @_;
$self->{rec_size} ? $self->{tot_size} / $self->{rec_size} : 0;
}
# switch into read-only mode and returns self
sub read_prepare {
my ($self) = @_;
my $io = $self->{rd} = delete($self->{wr});
$io->flush or die "flush: $!";
$self;
}
sub pop_rec {
my ($self) = @_;
my $sz = $self->{rec_size} or return;
my $rec_pos = $self->{tot_size} -= $sz;
return if $rec_pos < 0;
my $io = $self->{rd};
seek($io, $rec_pos, SEEK_SET) or die "seek: $!";
my $r = read($io, my $buf, $sz);
defined($r) or die "read: $!";
$r == $sz or die "read($r != $sz)";
unpack(FMT, $buf);
}
1;
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