Changeset 32581

Timestamp:

2018-11-07T19:04:30+13:00 (5 years ago)

Author:

ak19

Message:

Adding sigint, sigterm and sigkill handlers to gssql, which all call finish_signal_handler which does a die(). When perl executes a die statement, it always calls the object destructor. Added an destructor sub DESTRUCT to gssql to close the connection to the db, on GLOBAL DESTRUCT PHASE, if singleton db_handle is not undef. I'm thinking that this is where autocommit rollbacks will need to be added as well.

File:

• main/trunk/greenstone2/perllib/gssql.pm (modified) (2 diffs)

main/trunk/greenstone2/perllib/gssql.pm

@@ -33 +33 @@
 use DBI; # the central package for this module used by GreenstoneSQL Plugout and Plugin
 
+#$SIG{INT}  = sub { die "Caught a sigint $!" };
+#$SIG{TERM}  = sub { die "Caught a sigterm $!" };
+#$SIG{KILL}  = sub { die "Caught a sigkill $!" };
+
+
+$SIG{INT}  = \&finish_signal_handler;
+$SIG{TERM}  = \&finish_signal_handler;
+$SIG{KILL}  = \&finish_signal_handler;
+
+sub finish_signal_handler {
+    my ($sig) = @_; # one of INT|KILL|TERM
+    die "Caught a $sig signal $!"; # will call destructor
+}
 ##############################
 
@@ -94 +107 @@
 }
 
-
+# On die(), an object's destructor is called. 
+# See https://www.perl.com/article/37/2013/8/18/Catch-and-Handle-Signals-in-Perl/
+# We want to ensure we've closed the db connection in such cases.
+# "It’s common to call die when handling SIGINT and SIGTERM. die is useful because it will ensure that Perl stops correctly: for example Perl will execute a destructor method if present when die is called, but the destructor method will not be called if a SIGINT or SIGTERM is received and no signal handler calls die."
+# https://perldoc.perl.org/perlobj.html#Destructors
+sub DESTROY {
+    my $self = shift;
+
+    if (${^GLOBAL_PHASE} eq 'DESTRUCT') {
+    if ($_dbh_instance) {
+        print STDERR "XXXXXXXX Global Destruct: Disconnecting from database\n";
+        $_dbh_instance->disconnect or warn $_dbh_instance->errstr;
+        $_dbh_instance = undef;
+        $ref_count = 0;
+    }
+    return;
+    }
+}
 
 #################################