Cache Manager

Introduction

The CacheManager class in JiFramework provides a flexible and unified interface for caching mechanisms within your application. It supports two types of cache drivers:

  • File Cache: Stores cached data as files on the filesystem.
  • SQLite Database Cache: Stores cached data in an SQLite database file.

By default, the framework uses the file cache driver, but you can switch to the SQLite database cache by updating the configuration. Both cache drivers implement the CacheInterface, ensuring consistent method availability and behavior across different caching mechanisms.

Configuration

By default, the framework uses the file cache driver, but you can configure the cache driver in your Config class.

Setting the Cache Driver

In your Config class, set the CACHE_DRIVER constant to specify which cache driver to use.

namespace JIFramework\Config;

class Config {
    // Available options: 'file', 'sqlite'
    const CACHE_DRIVER = 'file'; // Default is 'file' if not set
}

 

Configuring File Cache (Default)

The file cache stores cached data in files within a specified directory. You can configure the cache directory:

class Config {
    const CACHE_DRIVER = 'file';
    const CACHE_PATH = self::STORAGE_PATH . 'Cache/FileCache/'; // Ensure this directory exists and is writable
}
  • CACHE_PATH: Defines the directory where cache files are stored.

Note: Ensure that the cache directory exists and has appropriate read/write permissions.

 

Configuring SQLite Database Cache

If you choose to use the SQLite database cache, specify the path to the SQLite database file:

class Config {
    const CACHE_DRIVER = 'sqlite';
    const CACHE_DATABASE_PATH = self::STORAGE_PATH . 'Cache/DatabaseCache/ji_sqlite_cache.db';
}
  • CACHE_DATABASE_PATH: Defines the path to the SQLite database file used for caching.

Note: Ensure that the directory for the database file exists and is writable.

getInstance()

Method: getInstance(string $cacheDriver = null): CacheInterface

Description: Retrieves the cache instance based on the configured cache driver. This method ensures that only one instance of the cache driver is used throughout your application (Singleton pattern).

Parameters:

  • $cacheDriver (string, optional): The cache driver to use ('file' or 'sqlite'). If not provided, it uses the value from Config::CACHE_DRIVER.

Returns: An instance of CacheInterface (either FileCache or DatabaseCache).

Usage:

use JIFramework\Core\App\App;

$app = new App();

// Get the cache instance based on configuration
$cache = $app->cache;

OR

use JIFramework\Core\Cache\CacheManager;

// Get the cache instance based on configuration
$cache = CacheManager::getInstance();

// Or specify the cache driver explicitly
$cache = CacheManager::getInstance('sqlite');

 

Explanation:

  • The getInstance method checks the configured cache driver and initializes the appropriate cache instance.
  • If an unsupported cache driver is specified, it throws an exception.

get()

Method: get(string $key)

Description: Retrieves an item from the cache by key.

Parameters:

  • $key (string): The cache key.

Returns: The cached value, or null if the item does not exist or is expired.

Usage:

// Get the cache instance based on configuration
$cache = CacheManager::getInstance();

// Retrieve a cached value
$value = $cache->get('user_123');

if ($value !== null) {
    // Cache hit
    echo 'Cached value: ' . $value;
} else {
    // Cache miss
    echo 'Cache miss. Fetching data...';
}

Explanation:

  • The method generates the cache file path based on the key.
  • It reads the cache file, unserializes the data, and checks for expiration.
  • If the item is expired or does not exist, it returns null.

set()

Method: set(string $key, $value, int $ttl = null): bool

Description: Stores an item in the cache.

Parameters:

  • $key (string): The cache key.
  • $value (mixed): The data to cache.
  • $ttl (int, optional): Time-to-live in seconds. If not provided, the item does not expire.

Returns: bool indicating success.

Usage:

// Cache data without expiration
$cache->set('user_123', $userData);

// Cache data with a TTL of 3600 seconds (1 hour)
$cache->set('user_123', $userData, 3600);

Explanation:

  • The method generates the cache file path and calculates the expiration time.
  • It serializes the value along with the expiration time and writes it to the cache file.

delete()

Method: delete(string $key): bool

Description: Deletes an item from the cache.

Parameters:

  • $key (string): The cache key.

Returns: bool indicating success.

Usage:

// Delete a cache item
$success = $cache->delete('user_123');

if ($success) {
    echo 'Cache item deleted.';
} else {
    echo 'Cache item not found.';
}

Explanation:

  • The method checks if the cache file exists and attempts to delete it.
  • Returns true if the file was deleted, false otherwise.

has()

Method: has(string $key): bool

Description: Checks if a cache item exists and is still valid.

Parameters:

  • $key (string): The cache key.

Returns: bool

Usage:

// Check if a cache item exists
if ($cache->has('user_123')) {
    echo 'Cache item exists.';
} else {
    echo 'Cache item does not exist or is expired.';
}

Explanation:

  • Similar to get, but returns a boolean instead of the value.
  • Useful for checking the existence of a cache item without retrieving it.

increment()

Method: increment(string $key, int $value = 1): int|bool

Description: Increments the value of a numeric cache item.

Parameters:

  • $key (string): The cache key.
  • $value (int, optional): The value to increment by. Defaults to 1.

Returns: The new value after incrementing, or false on failure.

Usage:

// Increment a counter
$newValue = $fileCache->increment('page_views');

if ($newValue !== false) {
    echo 'New page views count: ' . $newValue;
} else {
    echo 'Failed to increment.';
}

Explanation:

  • Retrieves the current value, ensures it's numeric, increments it, and saves it back.
  • Returns the new value or false if the operation fails.

decrement()

Method: decrement(string $key, int $value = 1): int|bool

Description: 

Decrements the value of a numeric cache item.

Parameters:

  • $key (string): The cache key.
  • $value (int, optional): The value to decrement by. Defaults to 1.

Returns: The new value after decrementing, or false on failure.

Usage:

// Decrement a counter
$newValue = $cache->decrement('available_slots', 2);

if ($newValue !== false) {
    echo 'Available slots: ' . $newValue;
} else {
    echo 'Failed to decrement.';
}

Explanation:

  • Similar to increment, but decreases the value.
  • Useful for tracking counts that decrease over time.

clear()

Method: clear(): void

Description: Clears all cache items.

Parameters: None

Returns: void

Usage:

// Clear all cache items
$cache->clear();

echo 'All cache items cleared.';
Explanation:
  • Deletes all cache files within the cache directory.
  • Use with caution as it removes all cached data.

gc()

Method: gc(): void

Description: Performs garbage collection to remove expired cache items.

Parameters: None

Returns: void

Usage:

// Perform garbage collection
$cache->gc();

echo 'Expired cache items removed.';

Explanation:

  • Iterates over cache files and deletes those that have expired.
  • Helps prevent accumulation of outdated cache files.

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