Merge pull request #719 from fhjbalfoort/develop

DB_driver failover if a connection cannot be established to the main connection

4 files changed, 77 insertions, 6 deletions

diff --git a/application/config/database.php b/application/config/database.php
index 28b792f75..58eec4b30 100644
--- a/application/config/database.php
+++ b/application/config/database.php
@@ -62,6 +62,7 @@
 |	['autoinit'] Whether or not to automatically initialize the database.
 |	['stricton'] TRUE/FALSE - forces 'Strict Mode' connections
 |							- good for ensuring strict SQL while developing
+|	['failover'] array - A array with 0 or more data for connections if the main should fail.
 |
 | The $active_group variable lets you choose which connection group to
 | make active.  By default there is only one group (the 'default' group).
@@ -88,7 +89,7 @@ $db['default']['dbcollat'] = 'utf8_general_ci';
 $db['default']['swap_pre'] = '';
 $db['default']['autoinit'] = TRUE;
 $db['default']['stricton'] = FALSE;
-
+$db['default']['failover'] = array();
 
 /* End of file database.php */
 /* Location: ./application/config/database.php */
\ No newline at end of file
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index cc40ba48a..c2d57a833 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -126,16 +126,43 @@ class CI_DB_driver {
 		// Connect to the database and set the connection ID
 		$this->conn_id = ($this->pconnect == FALSE) ? $this->db_connect() : $this->db_pconnect();
 
-		// No connection resource?  Throw an error
+		// No connection resource?  Check if there is a failover else throw an error
 		if ( ! $this->conn_id)
 		{
-			log_message('error', 'Unable to connect to the database');
+			// Check if there is a failover set
+			if ( ! empty($this->failover) && is_array($this->failover))
+			{
+				// Go over all the failovers
+				foreach ($this->failover as $failover)
+				{
+					// Replace the current settings with those of the failover
+					foreach ($failover as $key => $val)
+					{
+						$this->$key = $val;
+					}
 
-			if ($this->db_debug)
+					// Try to connect
+					$this->conn_id = ($this->pconnect == FALSE) ? $this->db_connect() : $this->db_pconnect();
+
+					// If a connection is made break the foreach loop
+					if ($this->conn_id)
+					{
+						break;
+					}
+				}
+			}
+
+			// We still don't have a connection?
+			if ( ! $this->conn_id)
 			{
-				$this->display_error('db_unable_to_connect');
+				log_message('error', 'Unable to connect to the database');
+
+				if ($this->db_debug)
+				{
+					$this->display_error('db_unable_to_connect');
+				}
+				return FALSE;
 			}
-			return FALSE;
 		}
 
 		// ----------------------------------------------------------------
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 979755c06..5c7fd8d59 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -97,6 +97,7 @@ Release Date: Not Released
       $this->db->like() in the :doc:`Database
       Driver <database/active_record>`.
    -  Added $this->db->insert_batch() support to the OCI8 (Oracle) driver.
+   -  Added failover if the main connections in the config should fail
 
 -  Libraries
 
diff --git a/user_guide_src/source/database/configuration.rst b/user_guide_src/source/database/configuration.rst
index 687f0d920..433c67152 100644
--- a/user_guide_src/source/database/configuration.rst
+++ b/user_guide_src/source/database/configuration.rst
@@ -28,6 +28,48 @@ prototype::
 	$db['default']['autoinit'] = TRUE;
 	$db['default']['stricton'] = FALSE;
 
+You can also specify failovers for the situation when the main connection cannot connect for some reason.
+These failovers can be specified by setting the failover for a connection like this::
+
+	$db['default']['failover'] = array(
+			array(
+				'hostname' => 'localhost1',
+				'username' => '',
+				'password' => '',
+				'database' => '',
+				'dbdriver' => 'mysql',
+				'dbprefix' => '',
+				'pconnect' => TRUE,
+				'db_debug' => TRUE,
+				'cache_on' => FALSE,
+				'cachedir' => '',
+				'char_set' => 'utf8',
+				'dbcollat' => 'utf8_general_ci',
+				'swap_pre' => '',
+				'autoinit' => TRUE,
+				'stricton' => FALSE
+			),
+			array(
+				'hostname' => 'localhost2',
+				'username' => '',
+				'password' => '',
+				'database' => '',
+				'dbdriver' => 'mysql',
+				'dbprefix' => '',
+				'pconnect' => TRUE,
+				'db_debug' => TRUE,
+				'cache_on' => FALSE,
+				'cachedir' => '',
+				'char_set' => 'utf8',
+				'dbcollat' => 'utf8_general_ci',
+				'swap_pre' => '',
+				'autoinit' => TRUE,
+				'stricton' => FALSE
+			)
+		);
+
+You can specify as many failovers as you like.
+
 The reason we use a multi-dimensional array rather than a more simple
 one is to permit you to optionally store multiple sets of connection
 values. If, for example, you run multiple environments (development,