Issue #1784548 by btopro, Fabianx, Berdir, rbayliss, xaa: DB Log is missing watchdog table after enabling - Need to catch and ignore exceptions thrown in dblog_watchdog()

CHANGELOG.txt

@@ -1,6 +1,7 @@
 
 Drupal 7.51, xxxx-xx-xx (development version)
 -----------------------
+- Exceptions thrown in dblog_watchdog() are now caught and ignored.
 - Numerous API documentation improvements.
 
 Drupal 7.50, 2016-07-07 

modules/dblog/dblog.install

@@ -154,6 +154,15 @@ function dblog_update_7002() {
   db_add_index('watchdog', 'severity', array('severity'));
 }
 
+/**
+ * Account for possible legacy systems where dblog was not installed.
+ */
+function dblog_update_7003() {
+  if (!db_table_exists('watchdog')) {
+    db_create_table('watchdog', drupal_get_schema_unprocessed('dblog', 'watchdog'));
+  }
+}
+
 /**
  * @} End of "addtogroup updates-7.x-extra".
  */

modules/dblog/dblog.module

@@ -147,20 +147,27 @@ function dblog_watchdog(array $log_entry) {
   if (!function_exists('drupal_substr')) {
     require_once DRUPAL_ROOT . '/includes/unicode.inc';
   }
-  Database::getConnection('default', 'default')->insert('watchdog')
-    ->fields(array(
-      'uid' => $log_entry['uid'],
-      'type' => drupal_substr($log_entry['type'], 0, 64),
-      'message' => $log_entry['message'],
-      'variables' => serialize($log_entry['variables']),
-      'severity' => $log_entry['severity'],
-      'link' => drupal_substr($log_entry['link'], 0, 255),
-      'location' => $log_entry['request_uri'],
-      'referer' => $log_entry['referer'],
-      'hostname' => drupal_substr($log_entry['ip'], 0, 128),
-      'timestamp' => $log_entry['timestamp'],
-    ))
-    ->execute();
+  try {
+    Database::getConnection('default', 'default')->insert('watchdog')
+      ->fields(array(
+        'uid' => $log_entry['uid'],
+        'type' => drupal_substr($log_entry['type'], 0, 64),
+        'message' => $log_entry['message'],
+        'variables' => serialize($log_entry['variables']),
+        'severity' => $log_entry['severity'],
+        'link' => drupal_substr($log_entry['link'], 0, 255),
+        'location' => $log_entry['request_uri'],
+        'referer' => $log_entry['referer'],
+        'hostname' => drupal_substr($log_entry['ip'], 0, 128),
+        'timestamp' => $log_entry['timestamp'],
+      ))
+      ->execute();
+  }
+  catch (Exception $e) {
+    // Exception is ignored so that watchdog does not break pages during the
+    // installation process or is not able to create the watchdog table during
+    // installation.
+  }
 }
 
 /**

modules/dblog/dblog.test

@@ -520,6 +520,33 @@ class DBLogTestCase extends DrupalWebTestCase {
     $this->assertText(t('Database log cleared.'), 'Confirmation message found');
   }
 
+  /**
+   * Verifies that exceptions are caught in dblog_watchdog().
+   */
+  protected function testDBLogException() {
+    $log = array(
+      'type'        => 'custom',
+      'message'     => 'Log entry added to test watchdog handling of Exceptions.',
+      'variables'   => array(),
+      'severity'    => WATCHDOG_NOTICE,
+      'link'        => NULL,
+      'user'        => $this->big_user,
+      'uid'         => isset($this->big_user->uid) ? $this->big_user->uid : 0,
+      'request_uri' => request_uri(),
+      'referer'     => $_SERVER['HTTP_REFERER'],
+      'ip'          => ip_address(),
+      'timestamp'   => REQUEST_TIME,
+    );
+
+    // Remove watchdog table temporarily to simulate it missing during
+    // installation.
+    db_query("DROP TABLE {watchdog}");
+
+    // Add a watchdog entry.
+    // This should not throw an Exception, but fail silently.
+    dblog_watchdog($log);
+  }
+
   /**
    * Gets the database log event information from the browser page.
    *