nntpd+imapd: detect unlinked msgmap

While it's even less common to experience a replaced
msgmap.sqlite3 file, BOFHs may do the darndest things.  This is
another step towards reducing the number of needless wakeups
we need to do in long-lived read-only daemons.

1 files changed, 31 insertions, 28 deletions

diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index aa07e344..e86fb854 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -13,6 +13,7 @@ use warnings;
 use DBI;
 use DBD::SQLite;
 use File::Temp qw(tempfile);
+use PublicInbox::Over;
 
 sub new {
         my ($class, $git_dir, $writable) = @_;
@@ -24,29 +25,13 @@ sub new {
         new_file($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 $f;
+        my ($class, $f, $rw) = @_;
+        return if !$rw && !-r $f;
 
-        my $dbh = dbh_new($f, $writable);
-        my $self = bless { dbh => $dbh }, $class;
-
-        if ($writable) {
+        my $self = bless { filename => $f }, $class;
+        my $dbh = $self->{dbh} = PublicInbox::Over::dbh_new($self, $rw);
+        if ($rw) {
                 create_tables($dbh);
 
                 # TRUNCATE reduces I/O compared to the default (DELETE)
@@ -70,7 +55,6 @@ sub tmp_clone {
         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} = $$;
         close $fh or die "failed to close $fn: $!";
         $tmp;
@@ -246,28 +230,28 @@ sub mid_set {
 sub DESTROY {
         my ($self) = @_;
         delete $self->{dbh};
-        my $f = delete $self->{tmp_name};
-        if (defined $f && $self->{pid} == $$) {
+        my $f = $self->{filename};
+        if (($self->{pid} // 0) == $$) {
                 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";
+        $self->{pid} 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);
+        my $dbh = $self->{dbh} = PublicInbox::Over::dbh_new($self, 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 "not a temporary clone\n";
         $self->{pid} == $$ or
                 die "BUG: atfork_prepare not called from $self->{pid}\n";
         $self->{dbh} or die "temporary clone not open\n";
         # must clobber prepared statements
-        %$self = (tmp_name => $f, pid => $$);
+        %$self = (filename => $self->{filename}, pid => $$);
 }
 
 sub skip_artnum {
@@ -296,4 +280,23 @@ sub skip_artnum {
         }
 }
 
+sub check_inodes {
+        my ($self) = @_;
+        # no filename if in-:memory:
+        my $f = $self->{dbh}->sqlite_db_filename // return;
+        if (my @st = stat($f)) { # did st_dev, st_ino change?
+                my $st = pack('dd', $st[0], $st[1]);
+                if ($st ne ($self->{st} // $st)) {
+                        my $tmp = eval { ref($self)->new_file($f) };
+                        if ($@) {
+                                warn "E: DBI->connect($f): $@\n";
+                        } else {
+                                %$self = %$tmp;
+                        }
+                }
+        } else {
+                warn "W: stat $f: $!\n";
+        }
+}
+
 1;