Minz allow parallel sessions (#3096)

* Minz allow parallel sessions

#fix https://github.com/FreshRSS/FreshRSS/issues/3093

* Array optimisation

* Array optimisation missing

* Reduce direct access to $_SESSION except in install process

* Fix session start headers warning

* Use cookie only the first time the session is started:
`PHP Warning:  session_start(): Cannot start session when headers
already sent in /var/www/FreshRSS/lib/Minz/Session.php on line 39`

* New concept of volatile session for API calls

Optimisation: do not use cookies or local storage at all for API calls
without a Web session
Fix warning:

```
PHP Warning:  session_destroy(): Trying to destroy uninitialized session
in Unknown on line 0
```

* Only call Minz_Session::init once in our index

It was called twice (once indirectly via FreshRSS->init())

* Whitespace

* Mutex for notifications

Implement mutex for notifications
https://github.com/FreshRSS/FreshRSS/pull/3208#discussion_r499509809

* Typo

* Install script is not ready for using Minz_Session

1 files changed, 5 insertions, 7 deletions

diff --git a/app/Models/DatabaseDAO.php b/app/Models/DatabaseDAO.php
index 2e0ee25a0..9d762a615 100644
--- a/app/Models/DatabaseDAO.php
+++ b/app/Models/DatabaseDAO.php
@@ -20,11 +20,10 @@ class FreshRSS_DatabaseDAO extends Minz_ModelPdo {
 
 		try {
 			$sql = sprintf($SQL_CREATE_DB, empty($db['base']) ? '' : $db['base']);
-			return $this->pdo->exec($sql) !== false;
+			return $this->pdo->exec($sql) === false ? 'Error during CREATE DATABASE' : '';
 		} catch (Exception $e) {
-			$_SESSION['bd_error'] = $e->getMessage();
-			syslog(LOG_DEBUG, __method__ . ' warning: ' . $e->getMessage());
-			return false;
+			syslog(LOG_DEBUG, __method__ . ' notice: ' . $e->getMessage());
+			return $e->getMessage();
 		}
 	}
 
@@ -33,11 +32,10 @@ class FreshRSS_DatabaseDAO extends Minz_ModelPdo {
 			$sql = 'SELECT 1';
 			$stm = $this->pdo->query($sql);
 			$res = $stm->fetchAll(PDO::FETCH_COLUMN, 0);
-			return $res != false;
+			return $res == false ? 'Error during SQL connection test!' : '';
 		} catch (Exception $e) {
-			$_SESSION['bd_error'] = $e->getMessage();
 			syslog(LOG_DEBUG, __method__ . ' warning: ' . $e->getMessage());
-			return false;
+			return $e->getMessage();
 		}
 	}