Check for gone-away database server and reconnect

Should stop the worker process crashing if mysql closes the connection
due to timeout.

source/lib/SihnonFramework/Database.class.php

@@ -2,6 +2,8 @@
 
 class SihnonFramework_Database {
     
+    const SQLSTATE_SERVER_GONE = 'HY000';
+
     private $config;
     private $dbh;
 
@@ -31,7 +33,7 @@ class SihnonFramework_Database {
         $this->dbname   = $this->getDatabaseConfig('dbname');
 
         try {
-            $this->dbh  = new PDO("mysql:host={$this->hostname};dbname={$this->dbname}", $this->username, $this->password);
+            $this->dbh  = new PDO("mysql:host={$this->hostname};dbname={$this->dbname}", $this->username, $this->password, array(PDO::ATTR_PERSISTENT => true));
         } catch (PDOException $e) {
             throw new Sihnon_Exception_DatabaseConnectFailed($e->getMessage());
         }
@@ -42,6 +44,16 @@ class SihnonFramework_Database {
         $this->dbh = null;
     }
     
+    protected function reconnect() {
+        $this->dbh = null;
+        
+        try {
+            $this->dbh  = new PDO("mysql:host={$this->hostname};dbname={$this->dbname}", $this->username, $this->password, array(PDO::ATTR_PERSISTENT => true));
+        } catch (PDOException $e) {
+            throw new Sihnon_Exception_DatabaseConnectFailed($e->getMessage());
+        }
+    }
+    
     /**
      * Returns the value of the named item from the database configuration file
      *
@@ -55,10 +67,27 @@ class SihnonFramework_Database {
         return $this->database_config[$key];
     }
     
+    private function query($sql, $count = 0) {
+        $results = $this->dbh->query($sql);
+        if (! $results) {
+            list($std_code, $driver_code, $message) = $this->dbh->errorInfo();
+            
+            if ($count == 0 && $std_code == static::SQLSTATE_SERVER_GONE) {
+                // Retry the query before failing
+                return $this->query($sql, ++$count);
+            } else {
+                throw new Sihnon_Exception_DatabaseQueryFailed($message, $driver_code);
+            }
+        }
+        
+        return $results;
+    }
+
+    
     public function selectAssoc($sql, $key_col, $value_cols) {
         $results = array();
 
-        foreach ($this->dbh->query($sql) as $row) {
+        foreach ($this->query($sql) as $row) {
             if (is_array($value_cols)) {
                 $values = array();
                 foreach ($value_cols as $value_col) {
@@ -74,7 +103,7 @@ class SihnonFramework_Database {
         return $results;
     }
 
-	public function selectList($sql, $bind_params = null) {
+	public function selectList($sql, $bind_params = null, $count = 0) {
 		if ($bind_params) {
 	        $stmt = $this->dbh->prepare($sql);
 	        
@@ -84,8 +113,14 @@ class SihnonFramework_Database {
 
             $result = $stmt->execute();
             if (! $result) {
-                list($dummy, $code, $message) = $stmt->errorInfo();
+                list($std_code, $driver_code, $message) = $stmt->errorInfo();
-                throw new Sihnon_Exception_DatabaseQueryFailed($message, $code);
+                
+                if ($count == 0 && $std_code == static::SQLSTATE_SERVER_GONE) {
+                    $this->reconnect();
+                    return $this->insert($sql, $bind_params, ++$count);
+                } else {
+                    throw new Sihnon_Exception_DatabaseQueryFailed($message, $driver_code);
+                }
             }
             
 			return $stmt->fetchAll();
@@ -93,7 +128,7 @@ class SihnonFramework_Database {
 		} else {
 			$results = array();
 
-			$result = $this->dbh->query($sql);
+			$result = $this->query($sql);
 	        foreach ($result as $row) {
 				$results[] = $row;
 			}
@@ -111,7 +146,7 @@ class SihnonFramework_Database {
 		return $rows[0];
 	}
 
-    public function insert($sql, $bind_params = null) {
+    public function insert($sql, $bind_params = null, $count = 0) {
         $stmt = $this->dbh->prepare($sql);
 
         if ($bind_params) {
@@ -126,12 +161,19 @@ class SihnonFramework_Database {
 
         $result = $stmt->execute();
         if (! $result) {
-            list($code, $dummy, $message) = $stmt->errorInfo();
+            list($std_code, $driver_code, $message) = $stmt->errorInfo();
-            throw new Sihnon_Exception_DatabaseQueryFailed($message, $code);
+            
+            if ($count == 0 && $std_code == static::SQLSTATE_SERVER_GONE) {
+                $this->reconnect();
+                return $this->insert($sql, $bind_params, ++$count);
+            } else {
+                var_dump($std_code, $driver_code, $message);
+                throw new Sihnon_Exception_DatabaseQueryFailed($message, $driver_code);
+            }
         }
     }
     
-    public function update($sql, $bind_params = null) {
+    public function update($sql, $bind_params = null, $count = 0) {
         $stmt = $this->dbh->prepare($sql);
 
         if ($bind_params) {
@@ -146,8 +188,14 @@ class SihnonFramework_Database {
 
         $result = $stmt->execute();
         if (! $result) {
-            list($code, $dummy, $message) = $stmt->errorInfo();
+            list($std_code, $driver_code, $message) = $stmt->errorInfo();
-            throw new Sihnon_Exception_DatabaseQueryFailed($message, $code);
+            
+            if ($count == 0 && $std_code == static::SQLSTATE_SERVER_GONE) {
+                $this->reconnect();
+                return $this->update($sql, $bind_params, ++$count);
+            } else {
+                throw new Sihnon_Exception_DatabaseQueryFailed($message, $driver_code);
+            }
         }
     }