Implement cache for prepared statements.

MyDBD.php

@@ -47,6 +47,7 @@ class MyDBD
         $link                   = null,
         $connected              = false,
         $connectionInfo         = null,
+        $statementCache         = array(),
         $lastQueryHandle        = null,
         $extendedConnectionInfo = array(),
         $extendedQueryInfo      = array(),
@@ -83,6 +84,8 @@ class MyDBD
      * - query_log:           If query_log is on, all queries will be logged using MyDBD_Logger. (bool)
      * - pear_compat:         Activate the PEAR Db compatibility layer. (bool)
      * - pear_compat_class:   Change the default PEAR Db compatibility class. (string)
+     * - query_prepare_cache: Make the query() method to use prepareCached() instead of prepare()
+     *                        when needed.
      * - client_interactive:  Allow interactive_timeout seconds (instead of wait_timeout seconds)
      *                        of inactivity before closing the connection. (bool)
      * - connect_timeout:     Connection timeout in seconds (int)
@@ -130,6 +133,7 @@ public function __construct(array $connectionInfo = array(), array $options = ar
                 'query_log'             => false,
                 'pear_compat'           => false,
                 'pear_compat_class'     => 'MyDBD_PearCompat',
+                'query_prepare_cache'   => false,
                 'connect_timeout'       => 0,
                 'wait_timeout'          => 0,
                 'client_interactive'    => false,
@@ -268,14 +272,14 @@ public function query()
 
         if (count($params) > 0)
         {
-            $sth = $this->prepare($query);
+            $sth = $this->options['query_prepare_cache'] ? $this->prepareCached($query) : $this->prepare($query);
             $result = call_user_func_array(array($sth, 'execute'), $params);
         }
         else
         {
             $result = new MyDBD_ResultSet($this->link()->query($query), $this->options);
             $this->handleErrors();
-            $this->lastQueryHandle = $this->link(); // used by affectedRows()
+            $this->lastQueryHandle = $this->link(); // used by getAffectedRows()
 
             if ($this->options['query_log']) MyDBD_Logger::log('query', $query, null, microtime(true) - $start);
         }
@@ -290,7 +294,7 @@ public function query()
      * @see MyDBD_PreparedStatement::prepare()
      * @see MyDBD_PreparedStatement::execute()
      *
-     * @param string $query The SQL query to prepare
+     * @param string $query   The SQL query to prepare
      * @param string $type... List of query parameters types. If provided, the number of items MUST
      *                        match the number of markers in the prepared query. If omited, types will
      *                        be automatically guessed from the first execute() parameters PHP ctypes.
@@ -325,6 +329,32 @@ public function prepare()
         return $sth;
     }
 
+    /**
+     * Same as prepare() with statement cache management.
+     *
+     * @see prepare()
+     *
+     * @param string $query   The SQL query to prepare
+     * @param string $type... List of query parameters types. If provided, the number of items MUST
+     *                        match the number of markers in the prepared query. If omited, types will
+     *                        be automatically guessed from the first execute() parameters PHP ctypes.
+     *                        Items of the string can by one of the following: 'double', 'integer', 'string'.
+     *
+     * @return MyDBD_PreparedStatement
+     */
+    public function prepareCached()
+    {
+        $args = func_get_args();
+        $cacheKey = md5($args[0]);
+
+        if (!isset($this->statementCache[$cacheKey]))
+        {
+            $this->statementCache[$cacheKey] = call_user_func_array(array($this, 'prepare'), $args);
+        }
+
+        return $this->statementCache[$cacheKey];
+    }
+
     /**
      * Start a new transaction.
      *

MyDBD/PreparedStatement.php

@@ -13,7 +13,9 @@ class MyDBD_PreparedStatement
     private
         $stmt           = null,
         $options        = null,
+        $frozen         = false,
         $preparedQuery  = null,
+        $resultSet      = null,
         $boundParams    = null;
 
     /**
@@ -27,6 +29,18 @@ public function __construct(mysqli_stmt $preparedStatement, array $options)
         $this->options = $options;
     }
 
+    /**
+     * Freeze the statement so it's not possible to prepare another query with it. This permits to
+     * store this statement in a cache safely.
+     *
+     * @return $this
+     */
+    public function freeze()
+    {
+        $this->frozen = true;
+        return $this;
+    }
+
     /**
      * Prepare a SQL statement for execution. Once prepared, a statement can be executed one or several
      * time with different parameters if placeholder where used.
@@ -57,6 +71,7 @@ public function __construct(mysqli_stmt $preparedStatement, array $options)
      * with NULL by ? IS NULL too. In general, parameters are legal only in Data Manipulation
      * Languange (DML) statements, and not in Data Defination Language (DDL) statements.
      *
+     * @throws RuntimeException         If calling this method on a frozen statement (stored in cache).
      * @throws InvalidArgumentException If a given type doesn't match autorized list.
      * @throws SQLMismatchException     If number of types given doesn't match the number of markers
      *                                  in the query.
@@ -65,6 +80,11 @@ public function __construct(mysqli_stmt $preparedStatement, array $options)
      */
     public function prepare()
     {
+        if ($this->frozen)
+        {
+            throw new RuntimeException('Cannot call prepare() on a frozen statement.');
+        }
+
         $args = func_get_args();
         $query = array_shift($args);
 
@@ -151,7 +171,12 @@ public function execute()
             // integrity problem due to mysqli design limitation
             // you can't store several result set on several executed query
             // from the same prepared statment
-            return new MyDBD_StatementResultSet($this->stmt, $metadata, $this->options);
+            if (!isset($this->resultSet))
+            {
+                $this->resultSet = new MyDBD_StatementResultSet($this->stmt, $metadata, $this->options);
+            }
+
+            return $this->resultSet->reset();
         }
         else
         {
@@ -171,7 +196,7 @@ public function execute()
      *                 matched the WHERE clause in the query or that no query has yet been executed.
      *                 -1 indicates that the query returned an error.
      */
-    public function affectedRows()
+    public function getAffectedRows()
     {
         return $this->stmt->affected_rows;
     }

MyDBD/StatementResultSet.php

@@ -48,6 +48,25 @@ public function __construct(mysqli_stmt $result, mysqli_result $metadata, array
         call_user_func_array(array($this->result, 'bind_result'), $args);
     }
 
+    /**
+     * Reset the object so it can be reused for anoter row.
+     *
+     * @return $this
+     */
+    public function reset()
+    {
+        if ($this->cursor !== 0)
+        {
+            $this->seek(0);
+        }
+
+        $this->fetchMode  = self::FETCH_ORDERED;
+        $this->fetchClass = 'stdClass';
+        $this->fetchCol   = 0;
+
+        return $this;
+    }
+
     /**
      * @see ResultSet::fetchArray()
      */