[PATCH 1/5] msgmap: add message mapping via SQLite

[Eric Wong <e@80x24.org>]

This will allow us to maintain stable article numbers for an
NNTP server independently of Xapian.
---
 lib/PublicInbox/Msgmap.pm | 137 ++++++++++++++++++++++++++++++++++++++++++++++
 t/msgmap.t                |  53 ++++++++++++++++++
 2 files changed, 190 insertions(+)
 create mode 100644 lib/PublicInbox/Msgmap.pm
 create mode 100644 t/msgmap.t

diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
new file mode 100644
index 0000000..a1748af
--- /dev/null
+++ b/lib/PublicInbox/Msgmap.pm
@@ -0,0 +1,137 @@
+# Copyright (C) 2015 all contributors <meta@public-inbox.org>
+# License: AGPLv3 or later (https://www.gnu.org/licenses/agpl-3.0.txt)
+# bidirectional Message-ID <-> Article Number mapping
+package PublicInbox::Msgmap;
+use strict;
+use warnings;
+use fields qw(dbh mid_insert mid_for num_for);
+use DBI;
+use DBD::SQLite;
+
+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";
+	}
+	my $f = "$d/msgmap.sqlite3";
+	my $dbh = DBI->connect("dbi:SQLite:dbname=$f",'','', {
+		AutoCommit => 1,
+		RaiseError => 1,
+		PrintError => 0,
+		sqlite_use_immediate_transaction => 1,
+	});
+	$dbh->do('PRAGMA case_sensitive_like = ON');
+
+	$writable and create_tables($dbh);
+	my $self = fields::new($class);
+	$self->{dbh} = $dbh;
+	$self;
+}
+
+# accessor
+sub last_commit {
+	my ($self, $commit) = @_;
+	my $dbh = $self->{dbh};
+	my $prev;
+	use constant {
+		key => 'last_commit',
+		meta_select => 'SELECT val FROM meta WHERE key = ? LIMIT 1',
+		meta_update => 'UPDATE meta SET val = ? WHERE key = ? LIMIT 1',
+		meta_insert => 'INSERT INTO meta (key,val) VALUES (?,?)',
+	};
+
+	defined $commit or
+		return $dbh->selectrow_array(meta_select, undef, key);
+
+	$dbh->begin_work;
+	eval {
+		$prev = $dbh->selectrow_array(meta_select, undef, key);
+
+		if (defined $prev) {
+			$dbh->do(meta_update, undef, $commit, key);
+		} else {
+			$dbh->do(meta_insert, undef, key, $commit);
+		}
+		$dbh->commit;
+	};
+	return $prev unless $@;
+
+	$dbh->rollback;
+	die $@;
+}
+
+sub mid_insert {
+	my ($self, $mid) = @_;
+	my $dbh = $self->{dbh};
+	use constant MID_INSERT => 'INSERT INTO msgmap (mid) VALUES (?)';
+	my $sth = $self->{mid_insert} ||= $dbh->prepare(MID_INSERT);
+	$sth->bind_param(1, $mid);
+	$sth->execute;
+	$dbh->last_insert_id(undef, undef, 'msgmap', 'num');
+}
+
+use constant MID_FOR => 'SELECT mid FROM msgmap WHERE num = ? LIMIT 1';
+sub mid_for {
+	my ($self, $num) = @_;
+	my $dbh = $self->{dbh};
+	my $sth = $self->{mid_for} ||= $dbh->prepare(MID_FOR);
+	$sth->bind_param(1, $num);
+	$sth->execute;
+	$sth->fetchrow_array;
+}
+
+sub num_for {
+	my ($self, $mid) = @_;
+	my $dbh = $self->{dbh};
+	use constant NUM_FOR => 'SELECT num FROM msgmap WHERE mid = ? LIMIT 1';
+	my $sth = $self->{num_for} ||= $dbh->prepare(NUM_FOR);
+	$sth->bind_param(1, $mid);
+	$sth->execute;
+	$sth->fetchrow_array;
+}
+
+sub mid_prefixes {
+	my ($self, $pfx, $limit) = @_;
+
+	die "No prefix given" unless (defined $pfx && $pfx ne '');
+	$pfx =~ s/([%_])/\\$1/g;
+	$pfx .= '%';
+
+	$limit ||= 100;
+	$limit += 0; # force to integer
+	$limit ||= 100;
+
+	$self->{dbh}->selectcol_arrayref('SELECT mid FROM msgmap ' .
+					 'WHERE mid LIKE ? ESCAPE ? ' .
+					 "ORDER BY num DESC LIMIT $limit",
+					 undef, $pfx, '\\');
+}
+
+sub mid_delete {
+	my ($self, $mid) = @_;
+	my $dbh = $self->{dbh};
+	use constant MID_DELETE => 'DELETE FROM msgmap WHERE mid = ?';
+	my $sth = $dbh->prepare(MID_DELETE);
+	$sth->bind_param(1, $mid);
+	$sth->execute;
+}
+
+sub create_tables {
+	my ($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)');
+}
+
+1;
diff --git a/t/msgmap.t b/t/msgmap.t
new file mode 100644
index 0000000..a34fd71
--- /dev/null
+++ b/t/msgmap.t
@@ -0,0 +1,53 @@
+# Copyright (C) 2015 all contributors <meta@public-inbox.org>
+# License: AGPLv3 or later (https://www.gnu.org/licenses/agpl-3.0.txt)
+use strict;
+use warnings;
+use Test::More;
+use File::Temp qw/tempdir/;
+
+use_ok 'PublicInbox::Msgmap';
+my $tmpdir = tempdir(CLEANUP => 1);
+my $d = PublicInbox::Msgmap->new($tmpdir, 1);
+
+my %mid2num;
+my %num2mid;
+my @mids = qw(a@b c@d e@f g@h aa@bb aa@cc);
+foreach my $mid (@mids) {
+	my $n = $d->mid_insert($mid);
+	ok($n, "mid $mid inserted");
+	$mid2num{$mid} = $n;
+	$num2mid{$n} = $mid;
+}
+
+$@ = undef;
+eval { $d->mid_insert('a@b') };
+ok($@, 'error raised when attempting duplicate message ID');
+
+foreach my $n (keys %num2mid) {
+	is($d->mid_for($n), $num2mid{$n}, "num:$n maps correctly");
+}
+foreach my $mid (@mids) {
+	is($d->num_for($mid), $mid2num{$mid}, "mid:$mid maps correctly");
+}
+
+is_deeply($d->mid_prefixes('a'), [qw(aa@cc aa@bb a@b)], "mid_prefixes match");
+is_deeply($d->mid_prefixes('A'), [], "mid_prefixes is case sensitive");
+
+is(undef, $d->last_commit, "last commit not set");
+my $lc = 'deadbeef' x 5;
+is(undef, $d->last_commit($lc), 'previous last commit (undef) returned');
+is($lc, $d->last_commit, 'last commit was set correctly');
+
+my $nc = 'deaddead' x 5;
+is($lc, $d->last_commit($nc), 'returned previously set commit');
+is($nc, $d->last_commit, 'new commit was set correctly');
+
+is($d->mid_delete('a@b'), 1, 'deleted a@b');
+is($d->mid_delete('a@b') + 0, 0, 'delete again returns zero');
+is(undef, $d->num_for('a@b'), 'num_for fails on deleted msg');
+$d = undef;
+
+# idempotent
+ok(PublicInbox::Msgmap->new($tmpdir, 1), 'idempotent DB creation');
+
+done_testing();
-- 
EW