MemoizedCallable.php

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<?php
namespace Wikimedia\ObjectCache;
 
use Closure;
use InvalidArgumentException;
 
class MemoizedCallable {
 
    private $callable;
 
    private $callableName;
 
    private $ttl;
 
    public function __construct( $callable, $ttl = 3600 ) {
        if ( !is_callable( $callable, false, $this->callableName ) ) {
            throw new InvalidArgumentException(
                'Argument 1 passed to MemoizedCallable::__construct() must ' .
                'be a callable; ' . get_debug_type( $callable ) . ' given'
            );
        }
 
        if ( $callable instanceof Closure ) {
            throw new InvalidArgumentException( 'Cannot memoize unnamed closure' );
        }
 
        if ( is_object( $callable ) || is_object( $callable[ 0 ] ) ) {
            throw new InvalidArgumentException( 'Cannot memoize object-bound callable' );
        }
 
        $this->callable = $callable;
        $this->ttl = min( max( $ttl, 1 ), 86400 );
    }
 
    protected function fetchResult( $key, &$success ) {
        $success = false;
        if ( function_exists( 'apcu_fetch' ) ) {
            return apcu_fetch( $key, $success );
        }
        return false;
    }
 
    protected function storeResult( $key, $result ) {
        if ( function_exists( 'apcu_store' ) ) {
            apcu_store( $key, $result, $this->ttl );
        }
    }
 
    public function invokeArgs( array $args = [] ) {
        foreach ( $args as $arg ) {
            if ( $arg !== null && !is_scalar( $arg ) ) {
                throw new InvalidArgumentException(
                    'MemoizedCallable::invoke() called with non-scalar ' .
                    'argument'
                );
            }
        }
 
        $hash = md5( serialize( $args ) );
        $key = __CLASS__ . ':' . $this->callableName . ':' . $hash;
        $success = false;
        $result = $this->fetchResult( $key, $success );
        if ( !$success ) {
            $result = ( $this->callable )( ...$args );
            $this->storeResult( $key, $result );
        }
 
        return $result;
    }
 
    public function invoke( ...$params ) {
        return $this->invokeArgs( $params );
    }
 
    public static function call( $callable, array $args = [], $ttl = 3600 ) {
        $instance = new self( $callable, $ttl );
        return $instance->invokeArgs( $args );
    }
}
 
class_alias( MemoizedCallable::class, 'MemoizedCallable' );