PHP Cache Class Documentation

Table of Contents

• Overview
• Features
• Requirements
• Installation
• Basic Usage
• Advanced Usage
• API Reference
• Security Considerations
• Examples

Overview

The Cache class provides a simple yet robust file-based caching system for PHP applications. It supports subfolder organization, cache expiration, and automatic compression of cached content.

Features

• File-based caching with SHA1 hashing
• Support for subfolder organization
• Automatic content compression using gzip
• Cache expiration management
• Maximum cache file limit with automatic cleanup
• Security features (.htaccess protection)
• Directory structure auto-creation

Requirements

• PHP 7.4 or higher
• Write permissions on the cache directory
• zlib extension (for compression)

Installation

1. Copy the Cache.php file to your project
2. Include the class in your PHP script:

require_once 'path/to/Cache.php';

Basic Usage

Initialize the Cache

// Create a cache instance with default settings
$cache = new Cache('/path/to/cache/directory');

// Or with custom max files limit
$cache = new Cache('/path/to/cache/directory', 5000);

Write to Cache

// Store data in cache
$cache->write('unique-key', 'Data to be cached');

Read from Cache

// Basic read
$data = $cache->read('unique-key');

// Read with expiration (86400 seconds = 1 day)
$data = $cache->read('unique-key', 86400);

Delete Cache

// Delete specific cache entry
$cache->delete('unique-key');

// Clear all cache
$cache->clearAll();

Advanced Usage

Using Subfolders

// Set a subfolder for organizing cache files
$cache->setSubFolder('api-responses');
$cache->write('api-key', $apiResponse);

Cache with Expiration

// Write cache
$cache->write('temp-data', $data);

// Read with 1-hour expiration
$data = $cache->read('temp-data', 3600);

// Check if cache exists and is valid
if ($cache->checkCache('temp-data', 3600)) {
    // Cache is valid
}

Cleanup Old Cache Files

// Clear cache files older than 1 day
$cache->clear(86400);

// Clear all cache files
$cache->clear(0);

API Reference

Constructor

public function __construct(string $cacheDirectory, int $maxCacheFiles = 10000)

Main Methods

write()

public function write(string $cacheName, string $content): void

read()

public function read(string $cacheName, int $maxAge = 0, bool $deleteExpired = TRUE): ?string

delete()

public function delete(string $cacheName): void

clear()

public function clear(int $maxAge = 0): void

clearAll()

public function clearAll(): bool

setSubFolder()

public function setSubFolder(string $subFolder): void

checkCache()

public function checkCache(string $cacheName, int $maxAge = 0, bool $deleteExpired = TRUE): bool

Security Considerations

1. The class automatically creates a .htaccess file to prevent direct access to cache files
2. Cache directory should be outside the web root
3. Proper permissions should be set on the cache directory
4. Cache keys should be validated before use

Examples

Caching API Responses

$cache = new Cache('/path/to/cache');
$cache->setSubFolder('api');

$apiUrl = 'https://api.example.com/data';
$cacheKey = 'api-' . md5($apiUrl);

// Try to get from cache first
if ($data = $cache->read($cacheKey, 3600)) {
    return json_decode($data);
}

// If not in cache, fetch and store
$response = file_get_contents($apiUrl);
$cache->write($cacheKey, $response);

return json_decode($response);

Caching Database Results

$cache = new Cache('/path/to/cache');
$cache->setSubFolder('db-queries');

$queryKey = 'user-list-' . md5($sql);

// Try cache first
if ($data = $cache->read($queryKey, 1800)) {
    return unserialize($data);
}

// If not in cache, query and store
$result = $db->query($sql)->fetchAll();
$cache->write($queryKey, serialize($result));

return $result;

Managing Multiple Cache Types

$cache = new Cache('/path/to/cache');

// API responses - 1 hour cache
$cache->setSubFolder('api');
$apiData = $cache->read('api-key', 3600);

// User sessions - 24 hour cache
$cache->setSubFolder('sessions');
$sessionData = $cache->read('session-key', 86400);

// Template fragments - 1 week cache
$cache->setSubFolder('templates');
$templateData = $cache->read('template-key', 604800);