Issue #3494951: Delayed logging feature

solrlog.services.yml

 services:
   logger.solr:
     class: Drupal\solrlog\Logger\SolrLogger
-    arguments: ['@entity_type.manager', '@logger.log_message_parser']
+    arguments:
+      - '@config.factory'
+      - '@entity_type.manager'
+      - '@logger.log_message_parser'
     tags:
       - { name: logger }
       - { name: backend_overridable }
+  terminate_subscriber:
+    class: Drupal\solrlog\EventSubscriber\TerminateSubscriber
+    arguments: ['@logger.solr']
+    tags:
+      - { name: event_subscriber }

src/DelayedLoggerInterface.php

+<?php
+
+namespace Drupal\solrlog;
+
+use Psr\Log\LoggerInterface;
+
+/**
+ * Logger that processes log messages in a bulk.
+ *
+ * Normally, messages are dumped in the end of the request (react on
+ * Symfony\Component\HttpKernel\KernelEvents::TERMINATE).
+ */
+interface DelayedLoggerInterface extends LoggerInterface {
+
+  /**
+   * Dump the log que.
+   */
+  public function dump() : void;
+}

src/EventSubscriber/TerminateSubscriber.php

+<?php
+
+namespace Drupal\solrlog\EventSubscriber;
+
+use Drupal\solrlog\DelayedLoggerInterface;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\HttpKernel\Event\TerminateEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+
+/**
+ * Dump log messages to solr in the end of request.
+ *
+ * @package Drupal\solrlog\EventSubscriber
+ */
+class TerminateSubscriber implements EventSubscriberInterface {
+
+  /**
+   * TerminateSubscriber constructor.
+   *
+   * @param \Drupal\solrlog\DelayedLoggerInterface $delayedLogger
+   *   The logger.
+   */
+  public function __construct(
+    protected DelayedLoggerInterface $delayedLogger) {
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    return [
+      KernelEvents::TERMINATE => [
+        ['onTerminate', 100],
+      ],
+    ];
+  }
+
+  /**
+   * Dump delayed log messages.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\TerminateEvent $event
+   *   The terminate request event.
+   */
+  public function onTerminate(TerminateEvent $event) : void {
+    $this->delayedLogger->dump();
+  }
+
+}

src/Form/SolrSettingsForm.php

@@ -69,6 +69,12 @@ class SolrSettingsForm extends ConfigFormBase {
         '#markup' => '<p class="messages--error">' . $this->t('No solr servers found.') . '</p>',
       ];
     }
+    $form['delayed_log'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Delayed log'),
+      '#description' => $this->t('Log messages in a bulk in the end of the request.'),
+      '#default_value' => $config->get('delayed_log'),
+    ];
     return $form;
   }
 
@@ -77,7 +83,9 @@ class SolrSettingsForm extends ConfigFormBase {
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $config = $this->config('solrlog.settings');
-    $config->set('server', $form_state->getValue('server'))->save();
+    $config->set('server', $form_state->getValue('server'))
+      ->set('delayed_log', $form_state->getValue('delayed_log'))
+      ->save();
     parent::submitForm($form, $form_state);
   }
 

src/Logger/SolrLogger.php

@@ -2,22 +2,24 @@
 
 namespace Drupal\solrlog\Logger;
 
+use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\DependencyInjection\DependencySerializationTrait;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Logger\LogMessageParserInterface;
 use Drupal\Core\Logger\RfcLoggerTrait;
+use Drupal\solrlog\DelayedLoggerInterface;
 use Drupal\solrlog\SolariumTrait;
-use Psr\Log\LoggerInterface;
 
 /**
  * Logs events in Search API.
  */
-class SolrLogger implements LoggerInterface {
+class SolrLogger implements DelayedLoggerInterface {
   use RfcLoggerTrait;
   use DependencySerializationTrait;
-
   use SolariumTrait;
 
+  protected array $delayedMessages = [];
+
   protected bool $serviceFunctional = TRUE;
 
   /**
@@ -29,18 +31,26 @@ class SolrLogger implements LoggerInterface {
    */
   protected static int $runCount = 0;
 
+  protected bool $delayedLogging = FALSE;
+
   /**
    * SolrLogger constructor.
    *
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $configFactory
+   *   Configuration factory.
    * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
    *   The entity type manager.
    * @param \Drupal\Core\Logger\LogMessageParserInterface $parser
    *   The parser to use when extracting message variables.
    */
   public function __construct(
+    ConfigFactoryInterface $configFactory,
     protected EntityTypeManagerInterface $entityTypeManager,
     protected LogMessageParserInterface $parser,
-  ) {}
+  ) {
+    $this->delayedLogging = (bool) $configFactory->get('solrlog.settings')
+      ->get('delayed_log');
+  }
 
   /**
    * {@inheritdoc}
@@ -52,14 +62,10 @@ class SolrLogger implements LoggerInterface {
     // Remove backtrace and exception since they may contain
     // an unserializable variable.
     unset($context['exception']);
-    $connector = $this->getConnector();
-    if (!$connector) {
-      return;
-    }
     // Convert PSR3-style messages to \Drupal\Component\Render\FormattableMarkup
     // style, so they can be translated too in runtime.
     $message_placeholders = $this->parser->parseMessagePlaceholders($message, $context);
-    $values = [
+    $log = [
       'id' => \time() . (++self::$runCount),
       // This helps to clear/filter the documents.
       'ss_module_id' => 'solrlog',
@@ -74,8 +80,34 @@ class SolrLogger implements LoggerInterface {
       'ss_hostname' => mb_substr($context['ip'], 0, 128),
       'dt_timestamp' => $context['timestamp'],
     ];
+    if ($this->delayedLogging) {
+      $this->delayedMessages[] = $log;
+      return;
+    }
+    $this->logMultiple([$log]);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  public function dump(): void {
+    $this->logMultiple($this->delayedMessages);
+    $this->delayedMessages = [];
+  }
+
+  protected function logMultiple(array $values) {
+    if (empty($values)) {
+      return;
+    }
+    $connector = $this->getConnector();
+    if (!$connector) {
+      return;
+    }
     $query = $connector->getUpdateQuery();
-    $query->addDocument($query->createDocument($values))->addCommit();
+    foreach ($values as $value) {
+      $query->addDocument($query->createDocument($value));
+    }
+    $query->addCommit();
     try {
       $connector->update($query);
     }

src/SolariumTrait.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\solrlog;
 
+use Drupal\search_api\SearchApiException;
 use Drupal\search_api_solr\SolrBackendInterface;
 use Drupal\search_api_solr\SolrConnectorInterface;
 
@@ -10,6 +11,11 @@ use Drupal\search_api_solr\SolrConnectorInterface;
  */
 trait SolariumTrait {
 
+  /**
+   * @var \Drupal\search_api_solr\SolrConnectorInterface
+   */
+  protected SolrConnectorInterface $solrConnector;
+
   /**
    * Array of Solr field names, keyed by Drupal field names.
    *
@@ -35,6 +41,9 @@ trait SolariumTrait {
    *   Solr connector.
    */
   protected function getConnector() : ?SolrConnectorInterface {
+    if (!empty($this->solrConnector)) {
+      return $this->solrConnector;
+    }
     $server = \Drupal::config('solrlog.settings')
       ->get('server');
     if (!$server) {
@@ -52,7 +61,13 @@ trait SolariumTrait {
     catch (\Throwable) {
       return NULL;
     }
-    return $backend->getSolrConnector();
+    try {
+      return $backend->getSolrConnector();
+    }
+    catch (SearchApiException) {
+      $this->serviceFunctional = FALSE;
+      return NULL;
+    }
   }
 
   /**