samuelantonioli/cache.php

## cache.php
<?php

/***
 *
 * CACHE
 *
 * create the cache_directory BEFORE you use this cache.
 * it doesn't generate it automatically to avoid possible bugs.
 *
 ***/

class CACHE {
    protected static $_instance = null;
    protected static $_config = null;

    public static function getInstance() {
        if (null === self::$_instance) {
            self::$_instance = new self;
            self::$_config = array(
                'hash_key' => true,
                'cache_directory' => './cache',
                'expires' => 86400, // seconds; 1 day
            );
        }
        return self::$_instance;
    }

    protected static function to_key($key) {
        if (null != self::$_instance) {
            if (
                true === @array_key_exists('hash_key', self::$_config) &&
                // truthy value
                true == self::$_config['hash_key']
            ) {
                // md5 could cause collisions, but it is pretty unlikely
                // we substr the $key to prevent DoS attacks
                return md5(substr($key, 0, 1024));
            }
        }
        return $key;
    }

    protected function to_path($key) {
        $key = self::to_key($key);
        $cache_dir = self::$_config['cache_directory'];
        // DIRECTORY_SEPARATOR
        $path = join('/', array(rtrim($cache_dir, '/'), $key));
        return $path;
    }

    public function config($data = null) {
        if (true === @is_array($data)) {
            self::$_config = array_merge(self::$_config, $data);
        }
        return self::$_config;
    }

    public function is_valid($key) {
        $path = $this->to_path($key);
        if (true === @is_file($path)) {
            $timestamp = @filemtime($path);
            if ($timestamp === false) {
                return false;
            }
            $current = (new DateTime('now'))->getTimestamp();
            $diff = $current - $timestamp;
            if (
                $diff <= self::$_config['expires'] ||
                $diff < 0
            ) {
                return true;
            } else {
                return false;
            }
        } else {
            return false;
        }
    }

    public function get($key) {
        $path = $this->to_path($key);
        return @file_get_contents($path);
    }

    public function get_filename($key) {
        return $this->to_path($key);
    }

    public function set($key, $value) {
        $path = $this->to_path($key);
        return @file_put_contents($path, $value, LOCK_EX);
    }

    public function invalidate($key) {
        $path = $this->to_path($key);
        if (true === @is_file($path)) {
            return @unlink($path);
        }
        return true;
    }

    // prevent creation and cloning
    protected function __clone() {
    }
    protected function __construct() {
    }
}

## usage.php
<?php
/**
 * simple singleton cache
 *
 * - uses filesystem
 * - implements lifetime strategy
 *
 **/
require_once('cache.php');

function normalized_request_uri($uri = null) {
    if (null == $uri) {
        $uri = $_SERVER['REQUEST_URI'];
    }
    $val = explode('?', $uri, 2);
    return rtrim($val[0], '/');
}

$key = normalized_request_uri();

$cache = CACHE::getInstance();

// (optional) configurate
$config = array(
    'hash_key' => true,
    'cache_directory' => './cache',
    'expires' => 3600, // 1 hour
);
$cache->config($config);


// show usage
if ($cache->is_valid($key)) {
    // get cache file content
    echo $cache->get($key) . "\n";
    // get cache filename
    echo $cache->get_filename($key) . "\n";
} else {
    // e.g. render template
    $value = '<html>...</html>';
    echo $cache->set($key, $value) . "\n";
}

// if you want to invalidate a cache entry
$cache->invalidate($key);
	<?php

	/***
	*
	* CACHE
	*
	* create the cache_directory BEFORE you use this cache.
	* it doesn't generate it automatically to avoid possible bugs.
	*
	***/

	class CACHE {
	protected static $_instance = null;
	protected static $_config = null;

	public static function getInstance() {
	if (null === self::$_instance) {
	self::$_instance = new self;
	self::$_config = array(
	'hash_key' => true,
	'cache_directory' => './cache',
	'expires' => 86400, // seconds; 1 day
	);
	}
	return self::$_instance;
	}

	protected static function to_key($key) {
	if (null != self::$_instance) {
	if (
	true === @array_key_exists('hash_key', self::$_config) &&
	// truthy value
	true == self::$_config['hash_key']
	) {
	// md5 could cause collisions, but it is pretty unlikely
	// we substr the $key to prevent DoS attacks
	return md5(substr($key, 0, 1024));
	}
	}
	return $key;
	}

	protected function to_path($key) {
	$key = self::to_key($key);
	$cache_dir = self::$_config['cache_directory'];
	// DIRECTORY_SEPARATOR
	$path = join('/', array(rtrim($cache_dir, '/'), $key));
	return $path;
	}

	public function config($data = null) {
	if (true === @is_array($data)) {
	self::$_config = array_merge(self::$_config, $data);
	}
	return self::$_config;
	}

	public function is_valid($key) {
	$path = $this->to_path($key);
	if (true === @is_file($path)) {
	$timestamp = @filemtime($path);
	if ($timestamp === false) {
	return false;
	}
	$current = (new DateTime('now'))->getTimestamp();
	$diff = $current - $timestamp;
	if (
	$diff <= self::$_config['expires'] \|\|
	$diff < 0
	) {
	return true;
	} else {
	return false;
	}
	} else {
	return false;
	}
	}

	public function get($key) {
	$path = $this->to_path($key);
	return @file_get_contents($path);
	}

	public function get_filename($key) {
	return $this->to_path($key);
	}

	public function set($key, $value) {
	$path = $this->to_path($key);
	return @file_put_contents($path, $value, LOCK_EX);
	}

	public function invalidate($key) {
	$path = $this->to_path($key);
	if (true === @is_file($path)) {
	return @unlink($path);
	}
	return true;
	}

	// prevent creation and cloning
	protected function __clone() {
	}
	protected function __construct() {
	}
	}
	<?php
	/**
	* simple singleton cache
	*
	* - uses filesystem
	* - implements lifetime strategy
	*
	**/
	require_once('cache.php');

	function normalized_request_uri($uri = null) {
	if (null == $uri) {
	$uri = $_SERVER['REQUEST_URI'];
	}
	$val = explode('?', $uri, 2);
	return rtrim($val[0], '/');
	}

	$key = normalized_request_uri();

	$cache = CACHE::getInstance();

	// (optional) configurate
	$config = array(
	'hash_key' => true,
	'cache_directory' => './cache',
	'expires' => 3600, // 1 hour
	);
	$cache->config($config);


	// show usage
	if ($cache->is_valid($key)) {
	// get cache file content
	echo $cache->get($key) . "\n";
	// get cache filename
	echo $cache->get_filename($key) . "\n";
	} else {
	// e.g. render template
	$value = '<html>...</html>';
	echo $cache->set($key, $value) . "\n";
	}

	// if you want to invalidate a cache entry
	$cache->invalidate($key);