From ecd77dffba30aa3a7f38b217772de52c5a76e9b6 Mon Sep 17 00:00:00 2001
From: Ramon Novoa <ramonnovoa@gmail.com>
Date: Mon, 28 Mar 2022 20:56:05 +0200
Subject: [PATCH] Fix locking issues in pandora_db.

Implement a persistent lock using Pandora FMS's database. Ref.
pandora_enterprise#8565.
---
 pandora_server/lib/PandoraFMS/DB.pm | 48 +++++++++++++++++++++++++++++
 pandora_server/util/pandora_db.pl   | 21 +++++++++----
 2 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/pandora_server/lib/PandoraFMS/DB.pm b/pandora_server/lib/PandoraFMS/DB.pm
index f7cd712293..ea29918e34 100644
--- a/pandora_server/lib/PandoraFMS/DB.pm
+++ b/pandora_server/lib/PandoraFMS/DB.pm
@@ -42,6 +42,7 @@ our @EXPORT = qw(
 		db_disconnect
 		db_do
 		db_get_lock
+		db_get_pandora_lock
 		db_insert
 		db_insert_get_values
 		db_insert_from_array_hash
@@ -49,6 +50,7 @@ our @EXPORT = qw(
 		db_process_insert
 		db_process_update
 		db_release_lock
+		db_release_pandora_lock
 		db_string
 		db_text
 		db_update
@@ -1575,6 +1577,52 @@ sub db_release_lock($$) {
 	my ($lock) = $sth->fetchrow;
 }
 
+########################################################################
+## Try to obtain a persistent lock using Pandora FMS's database.
+########################################################################
+sub db_get_pandora_lock($$;$) {
+	my ($dbh, $lock_name, $lock_timeout) = @_;
+	my $rv;
+
+	# Lock.
+	my $lock = db_get_lock($dbh, $lock_name, $lock_timeout);
+	if ($lock != 0) {
+		my $lock_value = get_db_value($dbh, "SELECT `value` FROM tconfig WHERE token = 'pandora_lock_$lock_name'");
+		if (!defined($lock_value)) {
+			my $sth = $dbh->prepare('INSERT INTO tconfig (`token`, `value`) VALUES (?, ?)');
+			$rv = $sth->execute('pandora_lock_' . $lock_name, '1');
+		} elsif ($lock_value == 0) {
+			my $sth = $dbh->prepare('UPDATE tconfig SET `value`=? WHERE `token`=?');
+			$rv = $sth->execute('1', 'pandora_lock_' . $lock_name);
+		}
+		db_release_lock($dbh, $lock_name);
+	}
+
+	# Lock acquired.
+	if ($rv) {
+		return 1;
+	}
+
+	# Something went wrong.
+	return 0;
+}
+
+########################################################################
+## Release a persistent lock.
+########################################################################
+sub db_release_pandora_lock($$;$) {
+	my ($dbh, $lock_name, $lock_timeout) = @_;
+	my $rv;
+
+	# Lock.
+	my $lock = db_get_lock($dbh, $lock_name, $lock_timeout);
+	if ($lock != 0) {
+		my $sth = $dbh->prepare('UPDATE tconfig SET `value`=? WHERE `token`=?');
+		$rv = $sth->execute('0', 'pandora_lock_' . $lock_name);
+		db_release_lock($dbh, $lock_name);
+	}
+}
+
 ########################################################################
 ## Set SSL options globally for the module.
 ########################################################################
diff --git a/pandora_server/util/pandora_db.pl b/pandora_server/util/pandora_db.pl
index f4fe7f88d7..6216f669ba 100755
--- a/pandora_server/util/pandora_db.pl
+++ b/pandora_server/util/pandora_db.pl
@@ -47,6 +47,9 @@ my $BIG_OPERATION_STEP = 100;	# 100 is default
 #Increate to 3000~5000 in fast systems decrease to 500 or 250 on systems with locks
 my $SMALL_OPERATION_STEP = 1000;	# 1000 is default
 
+# Timeout for lock acquisition.
+my $LOCK_TIMEOUT = 60;
+
 # FLUSH in each IO 
 $| = 1;
 
@@ -1211,10 +1214,18 @@ if ($conf{'_force'} == 0 && pandora_is_master(\%conf) == 0) {
 	exit 1;
 }
 
-# Get a lock on dbname.
+# Set the lock name for pandora_db.
 my $lock_name = $conf{'dbname'};
-my $lock = db_get_lock ($dbh, $lock_name);
-if ($lock == 0 && $conf{'_force'} == 0) { 
+
+# Release the database lock in forced mode.
+if ($conf{'_force'} == 1) {
+	log_message ('', " [*] Releasing database lock.\n\n");
+	db_release_pandora_lock($dbh, $lock_name, $LOCK_TIMEOUT);
+}
+
+# Get a lock on dbname.
+my $lock = db_get_pandora_lock ($dbh, $lock_name, $LOCK_TIMEOUT);
+if ($lock == 0) { 
 	log_message ('', " [*] Another instance of DB Tool seems to be running.\n\n");
 	exit 1;
 }
@@ -1257,9 +1268,7 @@ if (scalar(@types) != 0) {
 }
 
 # Release the lock
-if ($lock == 1) {
-	db_release_lock ($dbh, $lock_name);
-}
+db_release_pandora_lock ($dbh, $lock_name);
 
 # Cleanup and exit
 db_disconnect ($history_dbh) if defined ($history_dbh);