dbLayer : don't connect multiple times to the same database/username

git-svn-id: https://svn.fournier38.fr/svn/ProgSVN/trunk@1949 bf3deb0d-5f1a-0410-827f-c0cc1f45334c

dblayer.php

@@ -85,6 +85,9 @@ class dblayer extends PDO
       Attention : SQLite don't supports adding Foreign keys without deleting all
       the table, and re-import the datas (http://www.sqlite.org/omitted.html) */
 
+  /** Limit to one instance of the connection to the same database */
+  private static $instance = null;
+
   /** Connection to the database engine
       See http://fr2.php.net/manual/en/pdo.construct.php for the $dsn format
       @param string $dsn PDO Data Source Name
@@ -98,6 +101,16 @@ class dblayer extends PDO
     if (! isset ($driver[0]))
       throw new Exception (_("No valid DSN provided"), 500);
     // Force specifics initialisations
+    $oldInst = self::getInstance($dsn, $username);
+
+    if ($oldInst !== null)
+    {
+      $this->db = $oldInst["db"];
+      $this->sep = $oldInst["sep"];
+      $this->dsn = $oldInst["dsn"];
+      return;
+    }
+
     switch ($driver[0])
     {
     case "sqlite":
@@ -161,6 +174,20 @@ class dblayer extends PDO
       break;
     }
     $this->dsn = $dsn;
+    self::$instance["$dsn-$username"]["db"] = $this->db;
+    self::$instance["$dsn-$username"]["dsn"] = $this->dsn;
+    self::$instance["$dsn-$username"]["sep"] = $this->sep;
+  }
+
+  /** Singleton function to open one connection to each database/user wanted */
+  private function getInstance ($dsn, $username)
+  {
+    if (self::$instance === null ||
+        array_key_exists ("$dsn-$username", self::$instance) === false)
+    {
+      return null;
+    }
+    return self::$instance["$dsn-$username"];
   }
 
   /** Return the connected database name from DSN used to connect */