Fixes #7017 (Infinite loop when logging to database at debug level) + tests

The query log is momentarily disabled when the database log handler inserts in database

core/Db.php

@@ -35,6 +35,8 @@ class Db
 {
     private static $connection = null;
 
+    private static $logQueries = true;
+
     /**
      * Returns the database connection and creates it if it hasn't been already.
      *
@@ -710,7 +712,27 @@ class Db
 
     private static function logSql($functionName, $sql, $parameters = array())
     {
+        if (self::$logQueries === false) {
+            return;
+        }
+
         // NOTE: at the moment we don't log parameters in order to avoid sensitive information leaks
         Log::debug("Db::%s() executing SQL: %s", $functionName, $sql);
     }
+
+    /**
+     * @param bool $enable
+     */
+    public static function enableQueryLog($enable)
+    {
+        self::$logQueries = $enable;
+    }
+
+    /**
+     * @return boolean
+     */
+    public static function isQueryLogEnabled()
+    {
+        return self::$logQueries;
+    }
 }

core/Log/Handler/DatabaseHandler.php

@@ -19,12 +19,21 @@ class DatabaseHandler extends AbstractProcessingHandler
 {
     protected function write(array $record)
     {
-        $sql = "INSERT INTO " . Common::prefixTable('logger_message')
-            . " (tag, timestamp, level, message)"
-            . " VALUES (?, ?, ?, ?)";
+        $sql = sprintf(
+            'INSERT INTO %s (tag, timestamp, level, message) VALUES (?, ?, ?, ?)',
+            Common::prefixTable('logger_message')
+        );
 
-        $message = trim($record['formatted']);
+        $queryLog = Db::isQueryLogEnabled();
+        Db::enableQueryLog(false);
 
-        Db::query($sql, array($record['extra']['class'], $record['datetime']->format('Y-m-d H:i:s'), $record['level_name'], $message));
+        Db::query($sql, array(
+            $record['extra']['class'],
+            $record['datetime']->format('Y-m-d H:i:s'),
+            $record['level_name'],
+            trim($record['formatted'])
+        ));
+
+        Db::enableQueryLog($queryLog);
     }
 }

tests/PHPUnit/Integration/Log/LogTest.php

@@ -164,6 +164,21 @@ class LogTest extends IntegrationTestCase
         $this->checkBackend($backend, self::TESTMESSAGE, $formatMessage = true, $tag);
     }
 
+    /**
+     * The database logs requests at DEBUG level, so we check that there is no recursive
+     * loop (logger insert in databases, which logs the query, ...)
+     * @link https://github.com/piwik/piwik/issues/7017
+     */
+    public function testNoInfiniteLoopWhenLoggingToDatabase()
+    {
+        Config::getInstance()->log['log_writers'] = array('database');
+        Config::getInstance()->log['log_level'] = 'DEBUG';
+
+        Log::info(self::TESTMESSAGE);
+
+        $this->checkBackend('database', self::TESTMESSAGE, $formatMessage = true, $tag = __CLASS__);
+    }
+
     private function checkBackend($backend, $expectedMessage, $formatMessage = false, $tag = false)
     {
         if ($formatMessage) {
@@ -178,6 +193,9 @@ class LogTest extends IntegrationTestCase
 
             $this->assertEquals($expectedMessage . "\n", $fileContents);
         } else if ($backend == 'database') {
+            $queryLog = Db::isQueryLogEnabled();
+            Db::enableQueryLog(false);
+
             $count = Db::fetchOne("SELECT COUNT(*) FROM " . Common::prefixTable('logger_message'));
             $this->assertEquals(1, $count);
 
@@ -191,6 +209,8 @@ class LogTest extends IntegrationTestCase
             } else {
                 $this->assertEquals($tag, $tagInDb);
             }
+
+            Db::enableQueryLog($queryLog);
         }
     }