Add retry mechanism when connecting to Oracle

src/Field/EmailField.php

@@ -71,7 +71,9 @@ private function hasAnyDnsRecord(string $domain, array $types = ['MX', 'A', 'AAA
 
             $records = @dns_get_record($domain . '.', $dnsConsts[$t]);
             if ($records === false) { // retry once on failure
+                // @codeCoverageIgnoreStart
                 $records = dns_get_record($domain . '.', $dnsConsts[$t]);
+                // @codeCoverageIgnoreEnd
             }
             if ($records !== false && count($records) > 0) {
                 return true;

src/Persistence/Sql/Oracle/Connection.php

@@ -19,6 +19,7 @@ protected static function createDbalConfiguration(): Configuration
 
         $configuration->setMiddlewares([
             ...$configuration->getMiddlewares(),
+            new RetryListenerConnectionMiddleware(),
             new InitializeSessionMiddleware(),
         ]);
 

src/Persistence/Sql/Oracle/RetryListenerConnectionMiddleware.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Atk4\Data\Persistence\Sql\Oracle;
+
+use Doctrine\DBAL\Driver;
+use Doctrine\DBAL\Driver\Connection;
+use Doctrine\DBAL\Driver\Exception as DbalDriverException;
+use Doctrine\DBAL\Driver\Middleware;
+use Doctrine\DBAL\Driver\Middleware\AbstractDriverMiddleware;
+
+/**
+ * Oracle listener may temporarily return ORA-12516 when connecting and when the listener has not yet
+ * fully released previous connections.
+ *
+ * Needed for reliable connecting for Oracle v23.4 or higher (at least v23.26.3).
+ */
+class RetryListenerConnectionMiddleware implements Middleware
+{
+    #[\Override]
+    public function wrap(Driver $driver): Driver
+    {
+        return new class($driver) extends AbstractDriverMiddleware {
+            private const RETRY_MAX_SECONDS = 10.0;
+            private const RETRY_INTERVAL_SECONDS = 0.02;
+
+            #[\Override]
+            public function connect(
+                #[\SensitiveParameter]
+                array $params
+            ): Connection {
+                $sleepSecondsSum = 0;
+                while (true) {
+                    try {
+                        return parent::connect($params);
+                        // @codeCoverageIgnoreStart
+                    } catch (DbalDriverException $e) {
+                        $sleepSeconds = self::RETRY_INTERVAL_SECONDS;
+                        $sleepSecondsSum += $sleepSeconds;
+
+                        if ($e->getCode() !== 12516 || $sleepSecondsSum > self::RETRY_MAX_SECONDS) {
+                            throw $e;
+                        }
+
+                        usleep((int) round($sleepSeconds * 1_000_000));
+                        // @codeCoverageIgnoreEnd
+                    }
+                }
+            }
+        };
+    }
+}