Bug 39164: Add max_statement_time to SQL report queries

Reports may consume too much resources of the db. To avoid that a new config param
'report_sql_max_statement_time_seconds' was created, which sets the maximum time a report statement may
take to execute in seconds. If it takes longer it will be aborted.

reflowed the code, so that is is executed after is_sql_valid, and put
the code in a subroutine

Test plan:
0. if you run this test in ktd you should check if you are running
   mysql or mariadb, and then be able to switch database
1. create a new report by going to
More > Reports > New SQL Report
(/cgi-bin/koha/reports/guided_reports.pl?op=add_form_sql)

enter the following SQL (which only purpose is to run long)

select ExtractValue(bm1.metadata,'//controlfield[@tag="001"]')
  from biblio_metadata bm1
  join biblio_metadata bm2 on
    ExtractValue(bm1.metadata,'//controlfield[@tag="001"]') =
    ExtractValue(bm2.metadata,'//datafield[@tag="773"]/subfield[@code="w"]')

give the Report a name eg "extract_long"
2. run the report
3. report should be executed and return several 1000 lines on ktd
4. apply patch
5. add a the parameter to koha-conf.xml to the <config> </config> part
<report_sql_max_statement_time_seconds>0.001</report_sql_max_statement_time_seconds>

OR use the following statemtn
sed -i '/<biblioserver>/a <report_sql_max_statement_time_seconds>0.001<\/report_sql_max_statement_time_seconds>' /etc/koha/sites/kohadev/koha-conf.xml
6. restart koha
    koha-plack --restart kohadev
7. go back to the report page and rerun report which now should lead to an error
The following error was encountered:
The database returned the following error:
Query execution was interrupted, maximum statement execution time exceeded
Please check the log for further details.
8. in koha-conf.xml set
<report_sql_max_statement_time_seconds>20</report_sql_max_statement_time_seconds>
9. restart koha
10. rerun query, which now should execute as before
11. stop ktd, and restart with the "other" database

DB_IMAGE=mysql:8.0 ktd up
DB_IMAGE=mariadb:10.5 ktd up

12. repeat from step 1 (omit applying the patch)
13. Sign off
14. Thx

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 07ee120d50)
Signed-off-by: Jacob O'Mara <Jacob.omara@openfifth.co.uk>

C4/Reports/Guided.pm

@@ -54,6 +54,7 @@ use Koha::Logger;
 use Koha::Notice::Templates;
 use Koha::Patron::Categories;
 use Koha::Patrons;
+use Koha::Report;
 use Koha::Reports;
 use Koha::SharedContent;
 use Koha::TemplateUtils qw( process_tt );
@@ -604,6 +605,7 @@ sub execute_query {
 
     my ( $is_sql_valid, $errors ) = Koha::Report->new( { savedsql => $sql } )->is_sql_valid;
     return ( undef, @{$errors}[0] ) unless $is_sql_valid;
+    $sql = Koha::Report->apply_execution_time_limit($sql);
 
     foreach my $sql_param (@$sql_params) {
         if ( $sql_param =~ m/\n/ ) {

Koha/Report.pm

@@ -258,6 +258,38 @@ sub _might_add_limit {
     return $sql;
 }
 
+=head3 apply_execution_time_limit
+
+    $sql = Koha::Report->apply_execution_time_limit($sql);
+
+Apply SQL execution time limits based on report_sql_max_statement_time_seconds.
+
+=cut
+
+sub apply_execution_time_limit {
+    my ( $class, $sql ) = @_;
+
+    # https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=39164
+    my $report_sql_max_statement_time_seconds = C4::Context->config('report_sql_max_statement_time_seconds') // 0;
+    if ($report_sql_max_statement_time_seconds) {
+        my %versions = C4::Context::get_versions();
+        if ( $versions{'mysqlVersion'} =~ /MariaDB/i ) {
+            $sql = sprintf(
+                'SET STATEMENT max_statement_time=%f FOR %s',
+                $report_sql_max_statement_time_seconds,
+                $sql
+            );
+        } else {
+
+            # mysql timing is in milliseconds
+            $report_sql_max_statement_time_seconds *= 1000;
+            $sql =~ s#select#select /*+ MAX_EXECUTION_TIME($report_sql_max_statement_time_seconds) */#i;
+        }
+    }
+
+    return $sql;
+}
+
 =head3 _type
 
 Returns name of corresponding DBIC resultset

t/db_dependent/Koha/Reports.t

@@ -18,7 +18,7 @@
 use Modern::Perl;
 
 use Test::NoWarnings;
-use Test::More tests => 9;
+use Test::More tests => 10;
 
 use Koha::Report;
 use Koha::Reports;
@@ -185,4 +185,29 @@ subtest '_might_add_limit' => sub {
     );
 };
 
+subtest 'apply_execution_time_limit' => sub {
+    plan tests => 3;
+
+    my $sql = "SELECT * FROM biblio";
+
+    t::lib::Mocks::mock_config( 'report_sql_max_statement_time_seconds', 0 );
+    is( Koha::Report->apply_execution_time_limit($sql), $sql, 'No execution time limit configured' );
+
+    t::lib::Mocks::mock_config( 'report_sql_max_statement_time_seconds', 1.5 );
+    my $context = Test::MockModule->new('C4::Context');
+    $context->mock( 'get_versions', sub { return ( mysqlVersion => '10.6.0-MariaDB' ); } );
+    is(
+        Koha::Report->apply_execution_time_limit($sql),
+        'SET STATEMENT max_statement_time=1.500000 FOR SELECT * FROM biblio',
+        'MariaDB max statement time applied'
+    );
+
+    $context->mock( 'get_versions', sub { return ( mysqlVersion => '8.0.36' ); } );
+    like(
+        Koha::Report->apply_execution_time_limit($sql),
+        qr!^(?i:select) /\*\+ MAX_EXECUTION_TIME\(1500\) \*/ \* FROM biblio$!,
+        'MySQL max execution time hint applied'
+    );
+};
+
 $schema->storage->txn_rollback;