In long-running processes, allows checking the database connection by…

… pinging it, thus avoiding exceptions. Additionally, it provides the flexibility to configure the frequency of the check to be performed in the case of long-running processes.

src/Connection.php

@@ -17,6 +17,7 @@
 use Doctrine\DBAL\Exception\ConnectionLost;
 use Doctrine\DBAL\Exception\DriverException;
 use Doctrine\DBAL\Exception\InvalidArgumentException;
+use Doctrine\DBAL\Exception as DBALException;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Query\Expression\ExpressionBuilder;
 use Doctrine\DBAL\Query\QueryBuilder;
@@ -29,6 +30,7 @@
 use Doctrine\Deprecations\Deprecation;
 use LogicException;
 use SensitiveParameter;
+use Symfony\Bridge\Doctrine\ConnectionLossAwareHandler;
 use Throwable;
 use Traversable;
 
@@ -166,6 +168,12 @@ class Connection
 
     private SchemaManagerFactory $schemaManagerFactory;
 
+    private static bool $isChecking = false;
+
+    private static ?int $lastCheckedAt = null;
+
+    private ?int $checkFrequency;
+
     /**
      * Initializes a new instance of the Connection class.
      *
@@ -186,6 +194,7 @@ public function __construct(
         ?Configuration $config = null,
         ?EventManager $eventManager = null
     ) {
+        $this->checkFrequency = $params['check_connection_frequency'] ?? null;
         $this->_driver = $driver;
         $this->params  = $params;
 
@@ -371,6 +380,21 @@ public function connect()
         );
 
         if ($this->_conn !== null) {
+            if (null === $this->checkFrequency) {
+                return false;
+            }
+
+            if (! self::$isChecking) {
+                if (null === self::$lastCheckedAt || time() - self::$lastCheckedAt >= $this->checkFrequency) {
+                    self::$isChecking = true;
+
+                    $this->reconnectOnFailure($this);
+
+                    self::$lastCheckedAt = time();
+                    self::$isChecking = false;
+                }
+            }
+
             return false;
         }
 
@@ -2002,4 +2026,15 @@ public function exec(string $sql): int
 
         return $this->executeStatement($sql);
     }
+
+    private function reconnectOnFailure(Connection $connection)
+    {
+        try {
+            $connection->executeQuery($connection->getDatabasePlatform($connection)->getDummySelectSQL());
+        } catch (DBALException) {
+            $connection->close();
+            // Attempt to reestablish the lazy connection by sending another query.
+            $connection->executeQuery($connection->getDatabasePlatform($connection)->getDummySelectSQL());
+        }
+    }
 }