[PATCH 1/2] IMAPTracker: Add a helper to track our place in reading imap mailboxes

[ebiederm@xmission.com (Eric W. Biederman)]

By tracking which messages in an imap mailbox have been already downloaded
they imap messages do not need to be deleted immediately.

It is recommended to implement one connection per IMAP mailbox,
so this tracker caches the entire url for a mailbox at creation time.

If you need to process multiple IMAP mailboxes you will need multiple trackers.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 lib/PublicInbox/IMAPTracker.pm | 73 ++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 lib/PublicInbox/IMAPTracker.pm

diff --git a/lib/PublicInbox/IMAPTracker.pm b/lib/PublicInbox/IMAPTracker.pm
new file mode 100644
index 000000000000..d445555c0fd9
--- /dev/null
+++ b/lib/PublicInbox/IMAPTracker.pm
@@ -0,0 +1,73 @@
+# Copyright (C) 2018 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+package PublicInbox::IMAPTracker;
+use strict;
+use warnings;
+use DBI;
+use DBD::SQLite;
+use PublicInbox::Config;
+
+sub create_tables ($)
+{
+	my ($dbh) = @_;
+
+	$dbh->do(<<'');
+CREATE TABLE IF NOT EXISTS imap_last (
+	url VARCHAR PRIMARY KEY NOT NULL,
+	uid_validity INTEGER NOT NULL,
+	uid INTEGER NOT NULL,
+	UNIQUE (url)
+)
+
+}
+
+
+sub dbh_new ($)
+{
+	my ($dbname) = @_;
+	my $dbh = DBI->connect("dbi:SQLite:dbname=$dbname", '', '', {
+		AutoCommit => 1,
+		RaiseError => 1,
+		PrintError => 0,
+		ReadOnly => 0,
+		sqlite_use_immediate_transaction => 1,
+	});
+	$dbh->{sqlite_unicode} = 1;
+	$dbh->do('PRAGMA journal_mode = TRUNCATE');
+	$dbh->do('PRAGMA cache_size = 80000');
+	create_tables($dbh);
+	$dbh;
+}
+
+sub get_last($)
+{
+	my ($self) = @_;
+	my $dbh = $self->{dbh};
+
+	my $sth = $dbh->prepare_cached(<<'', undef, 1);
+SELECT uid_validity, uid FROM imap_last WHERE url = ?
+
+	$sth->execute($self->{url});
+	$sth->fetchrow_array;
+}
+
+sub update_last($$$)
+{
+	my ($self, $validity, $last) = @_;
+	my $dbh = $self->{dbh};
+	my $sth = $dbh->prepare_cached(<<'');
+INSERT OR REPLACE INTO imap_last (url, uid_validity, uid)
+VALUES (?, ?, ?)
+
+	$sth->execute($self->{url}, $validity, $last);
+}
+
+sub new ($) {
+	my ($class, $url) = @_;
+	my $dbname = PublicInbox::Config->config_dir() . "/imap.sqlite3";
+	my $dbh = dbh_new($dbname);
+	bless { dbname => $dbname, dbh => $dbh, url => $url }, $class;
+}
+
+1;
-- 
2.20.1