# DB Memory Cache for PrestaShop

A high-performance caching module for PrestaShop 8 and 9 that utilizes the MySQL/MariaDB `MEMORY` (HEAP) engine. This module provides a fast, ephemeral key-value store directly in RAM without requiring external services like Redis or Memcached.

## Features

*   **Speed:** Uses the `MEMORY` database engine to store data in RAM, avoiding disk I/O.
*   **TTL Support:** Simulates Time-To-Live expiration for cached items.
*   **Unicode Optimized:** Uses `JSON_UNESCAPED_UNICODE` to save space and support multi-byte characters efficiently.
*   **Safety:** Automatically rejects data larger than the defined limit (~16KB) to prevent SQL errors or JSON truncation.
*   **Strict Logic:** Ensures clean writes by deleting existing keys before insertion.

## Requirements

*   PrestaShop 8.0.0 or higher (Compatible with PS 9).
*   MySQL or MariaDB.
*   The database user must have `CREATE` and `DROP` privileges (standard for PS).

## Installation

1.  Create a folder named `dbmemorycache` in your PrestaShop `modules/` directory.
2.  Upload `dbmemorycache.php` and `logo.png` (optional) to that folder.
3.  Go to **Back Office > Modules > Module Manager**.
4.  Search for "MySQL Memory Cache Optimized".
5.  Click **Install**.

## Technical Limitations

*   **Volatility:** Data stored in `MEMORY` tables is lost if the MySQL server restarts. Do not use this for persistent data.
*   **Size Limit:** The maximum value size is approximately **16,000 characters** (due to `VARCHAR` limits in MEMORY tables and `utf8mb4` encoding). If you attempt to cache data larger than this, the `set()` method will return `false` and the data will not be cached.

## Usage Examples

You can call this module from any other module, controller, or hook in PrestaShop.

### 1. Basic Usage (Get & Set)

```php
// 1. Get the module instance
$cache = Module::getInstanceByName('dbmemorycache');

// Ensure module is installed and active
if ($cache && Module::isInstalled('dbmemorycache')) {
    $key = 'my_custom_api_data_v1';

    // 2. Check if data exists and is valid (not expired)
    if ($cache->existsValue($key)) {
        $data = $cache->getValue($key);
        // $data is now your array/object
    } else {
        // 3. Fetch your expensive data
        $data = [
            'id' => 123,
            'name' => 'Product Name',
            'features' => ['A', 'B', 'C']
        ];

        // 4. Store in cache for 1 hour (3600 seconds)
        // Returns true on success, false if data is too big
        $cache->setValue($key, $data, 3600);
    }
}