msgmap: add message mapping via SQLite

This will allow us to maintain stable article numbers for an
NNTP server independently of Xapian.

2 files changed, 190 insertions, 0 deletions

diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
new file mode 100644
index 00000000..a1748af9
--- /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 00000000..a34fd712
--- /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();