From: Cameron Ball <c.ball1729@gmail.com>
Date: Mon, 15 Dec 2014 11:24:19 +0000 (+0800)
Subject: Tricks to reduce memory usage.
X-Git-Url: http://git.cameron1729.xyz/?p=rock.divinelegy.git;a=commitdiff_plain;h=293e002cbca1aa39361c5050a1af4b0f7298c4aa

Tricks to reduce memory usage.
---

diff --git a/DataAccess/DataMapper/DataMapper.php b/DataAccess/DataMapper/DataMapper.php
index 384627d..4936aaf 100644
--- a/DataAccess/DataMapper/DataMapper.php
+++ b/DataAccess/DataMapper/DataMapper.php
@@ -7,6 +7,7 @@ use DataAccess\IDatabaseFactory;
 use DataAccess\DataMapper\IDataMapper;
 use DataAccess\Queries\IQueryBuilder;
 use DataAccess\DataMapper\Helpers\AbstractPopulationHelper;
+use DataAccess\DataMapper\LazyLoadedEntities;
 use ReflectionClass;
 
 class DataMapper implements IDataMapper
@@ -31,6 +32,12 @@ class DataMapper implements IDataMapper
         $rows = $statement->fetchAll();
         
         $entities = array();
+
+        if(count($rows) > 2)
+        {
+            //TODO: Factory?
+            return new LazyLoadedEntities($rows, $entityName, $this->_maps, $this->_db);
+        }
         
         foreach($rows as $row)
         {
@@ -48,7 +55,7 @@ class DataMapper implements IDataMapper
             $class->setId($row['id']);
             $entities[$row['id']] = $class;
         }
-        
+                
         return $entities;
     }
         
diff --git a/DataAccess/DataMapper/LazyLoadedEntities.php b/DataAccess/DataMapper/LazyLoadedEntities.php
new file mode 100644
index 0000000..724e635
--- /dev/null
+++ b/DataAccess/DataMapper/LazyLoadedEntities.php
@@ -0,0 +1,103 @@
+<?php
+
+namespace DataAccess\DataMapper;
+
+use DataAccess\DataMapper\Helpers\AbstractPopulationHelper;
+use ReflectionClass;
+use Iterator;
+
+class LazyLoadedEntities implements Iterator
+{
+    private $_maps;
+    private $_entityName;
+    private $_rows;
+    private $_rowIndex = 0;
+    private $_loadedEntitiesIndex = 0;
+    private $_loadedEntities = array();
+    private $_db;
+    
+    public function __construct(array $rows, $entityName, $maps, $db)
+    {
+        $this->_rows = $rows;
+        $this->_entityName = $entityName;
+        $this->_maps = $maps;
+        $this->_db = $db;
+    }
+    
+    public function current()
+    {
+        return $this->_loadedEntities[$this->_loadedEntitiesIndex];
+    }
+    
+    public function key()
+    {
+        return $this->_loadedEntitiesIndex;
+    }
+    
+    public function next()
+    {
+        $keys = array_keys($this->_loadedEntities);
+        $pos = array_search($this->_loadedEntitiesIndex, $keys);
+        if(isset($keys[$pos + 1]))
+        {
+            $this->_loadedEntitiesIndex = $keys[$pos+1];
+        } else {
+            $this->mapEntities(); //sets the loaded entites index
+        }
+    }
+    
+    public function rewind()
+    {
+        $this->_rowIndex = 0;
+        $this->mapEntities();
+    }
+    
+    public function valid()
+    {
+        //next will always load more entities when it runs out, therefore if
+        //we have an empty loadEntities array, it means there were no more and we are done.
+        if($this->_loadedEntities)
+        {
+            return true;
+        }
+        
+        return false;
+    }
+
+    //unsets the current entities array, and maps in the next 10
+    private function mapEntities()
+    {
+        $numToMap = 50;
+        $tick = 0;
+        
+        unset($this->_loadedEentities);
+        $this->_loadedEntities = array();
+        
+        $entityName = $this->_entityName;
+        for($i = $this->_rowIndex; $i<$this->_rowIndex+$numToMap; $i++)
+        {
+            if(isset($this->_rows[$i]))
+            {
+                $row = $this->_rows[$i];
+                $className = $this->_maps[$entityName]['class']; //the entity to instantiate and return
+                $constructors = AbstractPopulationHelper::getConstrutorArray($this->_maps, $entityName, $row, $this->_db);
+
+                if(count($constructors) == 0)
+                {
+                    $class = new $className;            
+                } else {
+                    $r = new ReflectionClass($className);
+                    $class = $r->newInstanceArgs($constructors);
+                }
+
+                $class->setId($row['id']);
+                $this->_loadedEntities[$row['id']] = $class;
+                
+                if($tick == 0) $this->_loadedEntitiesIndex = $row['id'];
+                $tick++;
+            }
+        }
+        
+        $this->_rowIndex += $numToMap;
+    }
+}
\ No newline at end of file