core/source/helpers/cache.php

<?php
/*
davina — Calendar data CalDAV conditioner
Copyright (C) 2025 Fenris <fenris@folksprak.org>

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public 
License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later 
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied 
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see 
<https://www.gnu.org/licenses/>. 
 */

namespace davina\helpers\cache;


/**
 */
interface interface_cache/*<type_value>*/
{
	
	/**
	 */
	public function has(
		string $key
	) : bool
	;
	
	
	/**
	 */
	public function get(
		string $key
	)/* : type_value*/
	;
	
	
	/**
	 */
	public function set(
		string $key,
		/*type_value */$value
	) : void
	;
	
}


/**
 */
class class_cache_encoded
	implements interface_cache/*<type_value_inner, type_value_outer>*/
{
	
	/**
	 */
	private interface_cache $core;
	
	
	/**
	 */
	private \Closure $encode;
	
	
	/**
	 */
	private \Closure $decode;
	
	
	/**
	 */
	public function __construct(
		interface_cache $core,
		\Closure $encode,
		\Closure $decode
	)
	{
		$this->core = $core;
		$this->encode = $encode;
		$this->decode = $decode;
	}
	
	
	/**
	 * [implementation]
	 */
	public function has(
		string $key
	) : bool
	{
		return $this->core->has($key);
	}
	
	
	/**
	 * [implementation]
	 */
	public function get(
		string $key
	)/* : type_value*/
	{
		return ($this->decode)($this->core->get($key));
	}
	
	
	/**
	 * [implementation]
	 */
	public function set(
		string $key,
		/*type_value */$value
	) : void
	{
		$this->core->set($key, ($this->encode)($value));
	}
	
}


/**
 */
class class_cache_memory
	implements interface_cache/*<any>*/
{
	
	/**
	 * @property array $data {map<string,any>}
	 */
	private array $data;
	
	
	/**
	 */
	public function __construct(
	)
	{
		$this->data = [];
	}
	
	
	/**
	 * [implementation]
	 */
	public function has(
		string $key
	) : bool
	{
		return \array_key_exists($key, $this->data);
	}
	
	
	/**
	 * [implementation]
	 */
	public function get(
		string $key
	)/* : any*/
	{
		if (! \array_key_exists($key, $this->data))
		{
			throw (new \Exception('missing'));
		}
		else
		{
			return $this->data[$key];
		}
	}
	
	
	/**
	 * [implementation]
	 */
	public function set(
		string $key,
		/*any */$value
	) : void
	{
		$this->data[$key] = $value;
	}
	
}


/**
 */
class class_cache_file
	implements interface_cache/*<string>*/
{
	
	/**
	 */
	private $directory;
	
	
	/**
	 */
	public function __construct(
		string $directory
	)
	{
		$this->directory = $directory;
	}
	
	
	public function compose_path(
		string $key
	) : string
	{
		return \sprintf(
			'%s/%s', $this->directory,
			\hash('sha256', $key)
		);
	}
	
	
	/**
	 * [implementation]
	 */
	public function has(
		string $key
	) : bool
	{
		$path = $this->compose_path($key);
		return \file_exists($path);
	}
	
	
	/**
	 * [implementation]
	 */
	public function get(
		string $key
	)/* : string*/
	{
		$path = $this->compose_path($key);
		if (! \file_exists($path))
		{
			throw (new \Exception('missing'));
		}
		else
		{
			return \file_get_contents($path);
		}
	}
	
	
	/**
	 * [implementation]
	 */
	public function set(
		string $key,
		/*string */$value
	) : void
	{
		$path = $this->compose_path($key);
		\file_put_contents($path, $value);
	}
	
}


/**
 */
class class_cache_apcu
	implements interface_cache/*<any>*/
{
	
	/**
	 */
	private string $prefix;
	
	
	/**
	 */
	public function __construct(
		?array $options = null
	)
	{
		$options = \array_merge(
			[
				'prefix' => 'davina_',
			],
			($options ?? [])
		);
		$this->prefix = $options['prefix'];
	}
	
	
	/**
	 */
	private function compose_id(
		string $key
	) : string
	{
		return \sprintf('%s%s', $this->prefix, $key);
	}
	
	
	/**
	 * [implementation]
	 */
	public function has(
		string $key
	) : bool
	{
		$id = $this->compose_id($key);
		return \apcu_exists($id);
	}
	
	
	/**
	 * [implementation]
	 */
	public function get(
		string $key
	)/* : any*/
	{
		$id = $this->compose_id($key);
		return \apcu_fetch($id);
	}
	
	
	/**
	 * [implementation]
	 */
	public function set(
		string $key,
		/*any */$value
	) : void
	{
		$id = $this->compose_id($key);
		\apcu_store($id, $value);
	}
	
}


/**
 */
function get/*<type_value>*/(
	interface_cache $cache/*<type_value>*/,
	string $key,
	\Closure $retrieve,
	?array $options = null
)/* : type_value*/
{
	$options = \array_merge(
		[
			'ttl' => null,
			'now' => \time(),
		],
		($options ?? [])
	);
	if (! $cache->has($key))
	{
		$entry = null;
		$shall_retrieve = true;
	}
	else
	{
		$entry = $cache->get($key);
		$shall_retrieve = (($entry['expiry'] !== null) && ($options['now'] >= $entry['expiry']));
	}
	if ($shall_retrieve)
	{
		$value = ($retrieve)();
		$entry = [
			'expiry' => (($options['ttl'] === null) ? null : ($options['now'] + $options['ttl'])),
			'value' => $value,
		];
		$cache->set($key, $entry);
	}
	else
	{
		$value = $entry['value'];
	}
	return $value;
}

 ?>