From 0382a677df24a9d8b9178ca08e0e7ba10b94c3ce Mon Sep 17 00:00:00 2001
From: Isaac Connor <isaac@zoneminder.com>
Date: Mon, 13 Dec 2021 14:58:32 -0500
Subject: [PATCH] Add ExecuteInterval to Filter Object. Allow empty sort_field
 to have the effort of not sorting. Always add FOR SHARE which adds a
 read-only lock the returned records.  Add SKIP LOCKED functionality so that
 filters can simply skip locked records. This should reduce contention. Also
 specify FOR UPDATE of the events table, otherwise we also lock Monitors and
 Storage.

---
 scripts/ZoneMinder/lib/ZoneMinder/Filter.pm | 26 +++++++++++++--------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/scripts/ZoneMinder/lib/ZoneMinder/Filter.pm b/scripts/ZoneMinder/lib/ZoneMinder/Filter.pm
index 0db46ff0d..7b3efad46 100644
--- a/scripts/ZoneMinder/lib/ZoneMinder/Filter.pm
+++ b/scripts/ZoneMinder/lib/ZoneMinder/Filter.pm
@@ -56,6 +56,7 @@ $primary_key = 'Id';
 %fields = map { $_ => $_ } qw(
 Id
 Name
+ExecuteInterval
 Query_json
 AutoArchive
 AutoUnarchive
@@ -106,7 +107,6 @@ sub Execute {
     $sql =~ s/zmSystemLoad/$load/g;
   }
 
-  $sql .= ' FOR UPDATE' if $$self{LockRows};
 
   Debug("Filter::Execute SQL ($sql)");
   my $sth = $ZoneMinder::Database::dbh->prepare_cached($sql)
@@ -371,10 +371,7 @@ sub Sql {
     if ( @auto_terms ) {
       $sql .= ' AND ( '.join(' or ', @auto_terms).' )';
     }
-    if ( !$filter_expr->{sort_field} ) {
-      $filter_expr->{sort_field} = 'StartDateTime';
-      $filter_expr->{sort_asc} = 0;
-    }
+
     my $sort_column = '';
     if ( $filter_expr->{sort_field} eq 'Id' ) {
       $sort_column = 'E.Id';
@@ -406,14 +403,23 @@ sub Sql {
       $sort_column = 'E.MaxScore';
     } elsif ( $filter_expr->{sort_field} eq 'DiskSpace' ) {
       $sort_column = 'E.DiskSpace';
-    } else {
-      $sort_column = 'E.StartDateTime';
+    } elsif ( $filter_expr->{sort_field} ne '' ) {
+      $sort_column = 'E.'.$filter_expr->{sort_field};
     }
-    my $sort_order = $filter_expr->{sort_asc} ? 'ASC' : 'DESC';
-    $sql .= ' ORDER BY '.$sort_column.' '.$sort_order;
-    if ( $filter_expr->{limit} ) {
+    if ( $sort_column ne '' ) {
+      $sql .= ' ORDER BY '.$sort_column.' '.($filter_expr->{sort_asc} ? 'ASC' : 'DESC');
+    }
+    if ($filter_expr->{limit}) {
       $sql .= ' LIMIT 0,'.$filter_expr->{limit};
     }
+    if ($$self{LockRows}) {
+      $sql .= ' FOR UPDATE OF E'
+    } else {
+      $sql .= ' FOR SHARE OF E'
+    }
+    if ($filter_expr->{skip_locked}) {
+      $sql .= ' SKIP LOCKED';
+    }
     $self->{Sql} = $sql;
   } # end if has Sql
   return $self->{Sql};