cache model lookups

3 files changed, 54 insertions, 6 deletions

diff --git a/Digitigrade/Db.php b/Digitigrade/Db.php
index c9f9df9..8ee23b9 100644
--- a/Digitigrade/Db.php
+++ b/Digitigrade/Db.php
@@ -1,8 +1,6 @@
 <?php
 namespace Digitigrade;
 
-use Digitigrade\Model\Actor;
-
 class Db extends Singleton {
     private const INIT_SCHEMA_PATH = __DIR__ . '/../schema.sql';
 
diff --git a/Digitigrade/Model.php b/Digitigrade/Model.php
index 71cfa5c..6a4fe27 100644
--- a/Digitigrade/Model.php
+++ b/Digitigrade/Model.php
@@ -6,6 +6,9 @@ use Digitigrade\Model\FetchableModel;
 abstract class Model {
     private bool $saved = false;
 
+    protected static array $cachedLookups = [];
+    private static bool $memoEnabled = false;
+
     protected function setOwnerId(int $id) {
     }
 
@@ -148,9 +151,22 @@ abstract class Model {
         $className = $classNameParts[count($classNameParts) - 1];
         $tableName = self::mangleName($className);
 
-        $stmt = Db::getInstance()->getPdo()->prepare("SELECT * FROM $tableName WHERE $whereClause LIMIT 1");
+        $query = "SELECT * FROM $tableName WHERE $whereClause LIMIT 1";
+
+        if (self::$memoEnabled) {
+            $memoKey = $query . implode('~~~', $parameters);
+            if (isset(self::$cachedLookups[$memoKey]))
+                return self::$cachedLookups[$memoKey];
+        }
+
+        $stmt = Db::getInstance()->getPdo()->prepare($query);
         $stmt->execute($parameters);
-        return static::fromDbRow($stmt->fetch(\PDO::FETCH_ASSOC));
+
+        $result = static::fromDbRow($stmt->fetch(\PDO::FETCH_ASSOC));
+        if (self::$memoEnabled) {
+            self::$cachedLookups[$memoKey] = $result;
+        }
+        return $result;
     }
 
     public static function findAllWhere(
@@ -171,11 +187,23 @@ abstract class Model {
         if ($limit != null) {
             $query .= " LIMIT $limit OFFSET $offset";
         }
+
+        if (self::$memoEnabled) {
+            $memoKey = $query . implode('~~~', $parameters);
+            if (isset(self::$cachedLookups[$memoKey]))
+                return self::$cachedLookups[$memoKey];
+        }
+
         $stmt = Db::getInstance()->getPdo()->prepare($query);
         $stmt->execute($parameters);
-        return array_map(function ($row) {
+
+        $result = array_map(function ($row) {
             return static::fromDbRow($row);
         }, $stmt->fetchAll(\PDO::FETCH_ASSOC));
+        if (self::$memoEnabled) {
+            self::$cachedLookups[$memoKey] = $result;
+        }
+        return $result;
     }
 
     public static function findAll(): array {
@@ -189,9 +217,21 @@ abstract class Model {
         $tableName = self::mangleName($className);
 
         $query = "SELECT count(*) FROM $tableName WHERE $whereClause";
+
+        if (self::$memoEnabled) {
+            $memoKey = $query . implode('~~~', $parameters);
+            if (isset(self::$cachedLookups[$memoKey]))
+                return self::$cachedLookups[$memoKey];
+        }
+
         $stmt = Db::getInstance()->getPdo()->prepare($query);
         $stmt->execute($parameters);
-        return $stmt->fetchColumn(0);
+
+        $result = $stmt->fetchColumn(0);
+        if (self::$memoEnabled) {
+            self::$cachedLookups[$memoKey] = $result;
+        }
+        return $result;
     }
 
     public static function count(): int {
@@ -289,6 +329,14 @@ abstract class Model {
     }
 
     /**
+     * Enables caching of lookups for all Models.
+     * @return void
+     */
+    public static function enableMemoisation() {
+        self::$memoEnabled = true;
+    }
+
+    /**
      * Converts the model to an opaque string, to be used for equality checking or debugging purposes only.
      * @return string
      */
diff --git a/index.php b/index.php
index fe0357d..4a2c2be 100644
--- a/index.php
+++ b/index.php
@@ -15,4 +15,6 @@ $lang = get_ui_language();
 header('Content-Language: ' . str_replace('_', '-', $lang));
 Digitigrade\Text::setDefaultLanguage($lang);
 
+Digitigrade\Model::enableMemoisation();
+
 Digitigrade\Router::getInstance()->processRequest();