# Copyright (C) 2015-2020 all contributors
# License: AGPL-3.0+
# bidirectional Message-ID <-> Article Number mapping for the NNTP
# and web interfaces. This is required for implementing stable article
# numbers for NNTP and allows prefix lookups for partial Message-IDs
# in case URLs get truncated from copy-n-paste errors by users.
#
# This is maintained by ::SearchIdx
package PublicInbox::Msgmap;
use strict;
use warnings;
use DBI;
use DBD::SQLite;
use File::Temp qw(tempfile);
sub new {
my ($class, $git_dir, $writable) = @_;
my $d = "$git_dir/public-inbox";
if ($writable && !-d $d && !mkdir $d) {
my $err = $!;
-d $d or die "$d not created: $err";
}
new_file($class, "$d/msgmap.sqlite3", $writable);
}
sub dbh_new {
my ($f, $writable) = @_;
if ($writable && !-f $f) { # SQLite defaults mode to 0644, we want 0666
open my $fh, '+>>', $f or die "failed to open $f: $!";
}
my $dbh = DBI->connect("dbi:SQLite:dbname=$f",'','', {
AutoCommit => 1,
RaiseError => 1,
PrintError => 0,
ReadOnly => !$writable,
sqlite_use_immediate_transaction => 1,
});
$dbh;
}
sub new_file {
my ($class, $f, $writable) = @_;
return if !$writable && !-r $f;
my $dbh = dbh_new($f, $writable);
my $self = bless { dbh => $dbh }, $class;
if ($writable) {
create_tables($dbh);
# TRUNCATE reduces I/O compared to the default (DELETE)
$dbh->do('PRAGMA journal_mode = TRUNCATE');
$dbh->begin_work;
$self->created_at(time) unless $self->created_at;
my $max = $self->max // 0;
$self->num_highwater($max);
$dbh->commit;
}
$self;
}
# used to keep track of used numeric mappings for v2 reindex
sub tmp_clone {
my ($self) = @_;
my ($fh, $fn) = tempfile('msgmap-XXXXXXXX', EXLOCK => 0, TMPDIR => 1);
$self->{dbh}->sqlite_backup_to_file($fn);
my $tmp = ref($self)->new_file($fn, 1);
$tmp->{dbh}->do('PRAGMA synchronous = OFF');
$tmp->{dbh}->do('PRAGMA journal_mode = MEMORY');
$tmp->{tmp_name} = $fn; # SQLite won't work if unlinked, apparently
$tmp->{pid} = $$;
close $fh or die "failed to close $fn: $!";
$tmp;
}
# n.b. invoked directly by scripts/xhdr-num2mid
sub meta_accessor {
my ($self, $key, $value) = @_;
my $sql = 'SELECT val FROM meta WHERE key = ? LIMIT 1';
my $dbh = $self->{dbh};
my $prev;
defined $value or return $dbh->selectrow_array($sql, undef, $key);
$prev = $dbh->selectrow_array($sql, undef, $key);
if (defined $prev) {
$sql = 'UPDATE meta SET val = ? WHERE key = ?';
$dbh->do($sql, undef, $value, $key);
} else {
$sql = 'INSERT INTO meta (key,val) VALUES (?,?)';
$dbh->do($sql, undef, $key, $value);
}
$prev;
}
sub last_commit {
my ($self, $commit) = @_;
$self->meta_accessor('last_commit', $commit);
}
# v2 uses this to keep track of how up-to-date Xapian is
# old versions may be automatically GC'ed away in the future,
# but it's a trivial amount of storage.
sub last_commit_xap {
my ($self, $version, $i, $commit) = @_;
$self->meta_accessor("last_xap$version-$i", $commit);
}
sub created_at {
my ($self, $second) = @_;
$self->meta_accessor('created_at', $second);
}
sub num_highwater {
my ($self, $num) = @_;
my $high = $self->{num_highwater} ||=
$self->meta_accessor('num_highwater');
if (defined($num) && (!defined($high) || ($num > $high))) {
$self->{num_highwater} = $num;
$self->meta_accessor('num_highwater', $num);
}
$self->{num_highwater};
}
sub mid_insert {
my ($self, $mid) = @_;
my $dbh = $self->{dbh};
my $sth = $dbh->prepare_cached(<<'');
INSERT INTO msgmap (mid) VALUES (?)
return unless eval { $sth->execute($mid) };
my $num = $dbh->last_insert_id(undef, undef, 'msgmap', 'num');
$self->num_highwater($num) if defined($num);
$num;
}
sub mid_for {
my ($self, $num) = @_;
my $dbh = $self->{dbh};
my $sth = $self->{mid_for} ||=
$dbh->prepare('SELECT mid FROM msgmap WHERE num = ? LIMIT 1');
$sth->bind_param(1, $num);
$sth->execute;
$sth->fetchrow_array;
}
sub num_for {
my ($self, $mid) = @_;
my $dbh = $self->{dbh};
my $sth = $self->{num_for} ||=
$dbh->prepare('SELECT num FROM msgmap WHERE mid = ? LIMIT 1');
$sth->bind_param(1, $mid);
$sth->execute;
$sth->fetchrow_array;
}
sub max {
my $sth = $_[0]->{dbh}->prepare_cached('SELECT MAX(num) FROM msgmap',
undef, 1);
$sth->execute;
$sth->fetchrow_array;
}
sub minmax {
# breaking MIN and MAX into separate queries speeds up from 250ms
# to around 700us with 2.7million messages.
my $sth = $_[0]->{dbh}->prepare_cached('SELECT MIN(num) FROM msgmap',
undef, 1);
$sth->execute;
($sth->fetchrow_array, max($_[0]));
}
sub mid_delete {
my ($self, $mid) = @_;
my $dbh = $self->{dbh};
my $sth = $dbh->prepare('DELETE FROM msgmap WHERE mid = ?');
$sth->bind_param(1, $mid);
$sth->execute;
}
sub num_delete {
my ($self, $num) = @_;
my $dbh = $self->{dbh};
my $sth = $dbh->prepare('DELETE FROM msgmap WHERE num = ?');
$sth->bind_param(1, $num);
$sth->execute;
}
sub create_tables {
my ($dbh) = @_;
my $e;
$e = eval { $dbh->selectrow_array('EXPLAIN SELECT * FROM msgmap;') };
defined $e or $dbh->do('CREATE TABLE msgmap (' .
'num INTEGER PRIMARY KEY AUTOINCREMENT, '.
'mid VARCHAR(1000) NOT NULL, ' .
'UNIQUE (mid) )');
$e = eval { $dbh->selectrow_array('EXPLAIN SELECT * FROM meta') };
defined $e or $dbh->do('CREATE TABLE meta (' .
'key VARCHAR(32) PRIMARY KEY, '.
'val VARCHAR(255) NOT NULL)');
}
# used by NNTP.pm
sub ids_after {
my ($self, $num) = @_;
my $ids = $self->{dbh}->selectcol_arrayref(<<'', undef, $$num);
SELECT num FROM msgmap WHERE num > ?
ORDER BY num ASC LIMIT 1000
$$num = $ids->[-1] if @$ids;
$ids;
}
sub msg_range {
my ($self, $beg, $end, $cols) = @_;
$cols //= 'num,mid';
my $dbh = $self->{dbh};
my $attr = { Columns => [] };
my $mids = $dbh->selectall_arrayref(<<"", $attr, $$beg, $end);
SELECT $cols FROM msgmap WHERE num >= ? AND num <= ?
ORDER BY num ASC LIMIT 1000
$$beg = $mids->[-1]->[0] + 1 if @$mids;
$mids
}
# only used for mapping external serial numbers (e.g. articles from gmane)
# see scripts/xhdr-num2mid or PublicInbox::Filter::RubyLang for usage
sub mid_set {
my ($self, $num, $mid) = @_;
my $sth = $self->{mid_set} ||= do {
$self->{dbh}->prepare(
'INSERT OR IGNORE INTO msgmap (num,mid) VALUES (?,?)');
};
my $result = $sth->execute($num, $mid);
$self->num_highwater($num) if (defined($result) && $result == 1);
$result;
}
sub DESTROY {
my ($self) = @_;
delete $self->{dbh};
my $f = delete $self->{tmp_name};
if (defined $f && $self->{pid} == $$) {
unlink $f or warn "failed to unlink $f: $!\n";
}
}
sub atfork_parent {
my ($self) = @_;
my $f = $self->{tmp_name} or die "not a temporary clone\n";
delete $self->{dbh} and die "tmp_clone dbh not prepared for parent";
my $dbh = $self->{dbh} = dbh_new($f, 1);
$dbh->do('PRAGMA synchronous = OFF');
}
sub atfork_prepare {
my ($self) = @_;
my $f = $self->{tmp_name} or die "not a temporary clone\n";
$self->{pid} == $$ or
die "BUG: atfork_prepare not called from $self->{pid}\n";
$self->{dbh} or die "temporary clone not open\n";
# must clobber prepared statements
%$self = (tmp_name => $f, pid => $$);
}
sub skip_artnum {
my ($self, $skip_artnum) = @_;
return meta_accessor($self, 'skip_artnum') if !defined($skip_artnum);
my $cur = num_highwater($self) // 0;
if ($skip_artnum < $cur) {
die "E: current article number $cur ",
"exceeds --skip-artnum=$skip_artnum\n";
} else {
my $ok;
for (1..10) {
my $mid = 'skip'.rand.'@'.rand.'.example.com';
$ok = mid_set($self, $skip_artnum, $mid);
if ($ok) {
mid_delete($self, $mid);
last;
}
}
$ok or die '--skip-artnum failed';
# in the future, the indexer may use this value for
# new messages in old epochs
meta_accessor($self, 'skip_artnum', $skip_artnum);
}
}
1;