sharedkv: use lock_for_scope_fast

This allows us to avoid repeated open() and close() syscalls
and speeds up the new xt/stress-sharedkv.t maintainer test
by roughly 7%.

2 files changed, 24 insertions, 7 deletions

diff --git a/lib/PublicInbox/Lock.pm b/lib/PublicInbox/Lock.pm
index bb213de4..c0c4c15c 100644
--- a/lib/PublicInbox/Lock.pm
+++ b/lib/PublicInbox/Lock.pm
@@ -41,6 +41,23 @@ sub lock_for_scope {
         PublicInbox::OnDestroy->new(@single_pid, \&lock_release, $self);
 }
 
+sub lock_acquire_fast {
+        $_[0]->{lockfh} or return lock_acquire($_[0]);
+        flock($_[0]->{lockfh}, LOCK_EX) or croak "lock (fast) failed: $!";
+}
+
+sub lock_release_fast {
+        flock($_[0]->{lockfh} // return, LOCK_UN) or
+                        croak "unlock (fast) $_[0]->{lock_path}: $!";
+}
+
+# caller must use return value
+sub lock_for_scope_fast {
+        my ($self, @single_pid) = @_;
+        lock_acquire_fast($self) or return; # lock_path not set
+        PublicInbox::OnDestroy->new(@single_pid, \&lock_release_fast, $self);
+}
+
 sub new_tmp {
         my ($cls, $ident) = @_;
         my $tmp = File::Temp->new("$ident.lock-XXXXXX", TMPDIR => 1);
diff --git a/lib/PublicInbox/SharedKV.pm b/lib/PublicInbox/SharedKV.pm
index 77df0fb4..b0588060 100644
--- a/lib/PublicInbox/SharedKV.pm
+++ b/lib/PublicInbox/SharedKV.pm
@@ -17,7 +17,7 @@ sub dbh {
         my ($self, $lock) = @_;
         $self->{dbh} //= do {
                 my $f = $self->{filename};
-                $lock //= $self->lock_for_scope;
+                $lock //= $self->lock_for_scope_fast;
                 my $dbh = DBI->connect("dbi:SQLite:dbname=$f", '', '', {
                         AutoCommit => 1,
                         RaiseError => 1,
@@ -58,13 +58,13 @@ sub new {
 
 sub index_values {
         my ($self) = @_;
-        my $lock = $self->lock_for_scope;
+        my $lock = $self->lock_for_scope_fast;
         $self->dbh($lock)->do('CREATE INDEX IF NOT EXISTS idx_v ON kv (v)');
 }
 
 sub set_maybe {
         my ($self, $key, $val, $lock) = @_;
-        $lock //= $self->lock_for_scope;
+        $lock //= $self->lock_for_scope_fast;
         my $e = $self->{dbh}->prepare_cached(<<'')->execute($key, $val);
 INSERT OR IGNORE INTO kv (k,v) VALUES (?, ?)
 
@@ -83,7 +83,7 @@ SELECT k,v FROM kv
 
 sub delete_by_val {
         my ($self, $val, $lock) = @_;
-        $lock //= $self->lock_for_scope;
+        $lock //= $self->lock_for_scope_fast;
         $self->{dbh}->prepare_cached(<<'')->execute($val) + 0;
 DELETE FROM kv WHERE v = ?
 
@@ -91,7 +91,7 @@ DELETE FROM kv WHERE v = ?
 
 sub replace_values {
         my ($self, $oldval, $newval, $lock) = @_;
-        $lock //= $self->lock_for_scope;
+        $lock //= $self->lock_for_scope_fast;
         $self->{dbh}->prepare_cached(<<'')->execute($newval, $oldval) + 0;
 UPDATE kv SET v = ? WHERE v = ?
 
@@ -122,7 +122,7 @@ SELECT v FROM kv WHERE k = ?
 
 sub xchg {
         my ($self, $key, $newval, $lock) = @_;
-        $lock //= $self->lock_for_scope;
+        $lock //= $self->lock_for_scope_fast;
         my $oldval = get($self, $key);
         if (defined $newval) {
                 set($self, $key, $newval);
@@ -146,7 +146,7 @@ SELECT COUNT(k) FROM kv
 sub dbh_release {
         my ($self, $lock) = @_;
         my $dbh = delete $self->{dbh} or return;
-        $lock //= $self->lock_for_scope; # may be needed for WAL
+        $lock //= $self->lock_for_scope_fast; # may be needed for WAL
         %{$dbh->{CachedKids}} = (); # cleanup prepare_cached
         $dbh->disconnect;
 }