includes/libs/MemoizedCallable.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  * @author Ori Livneh
  20  */
  21
  22 /**
  23  * APCu-backed function memoization
  24  *
  25  * This class provides memoization for pure functions. A function is pure
  26  * if its result value depends on nothing other than its input parameters
  27  * and if invoking it does not cause any side-effects.
  28  *
  29  * The first invocation of the memoized callable with a particular set of
  30  * arguments will be delegated to the underlying callable. Repeat invocations
  31  * with the same input parameters will be served from APCu.
  32  *
  33  * @par Example:
  34  * @code
  35  * $memoizedStrrev = new MemoizedCallable( 'range' );
  36  * $memoizedStrrev->invoke( 5, 8 );  // result: array( 5, 6, 7, 8 )
  37  * $memoizedStrrev->invokeArgs( array( 5, 8 ) );  // same
  38  * MemoizedCallable::call( 'range', array( 5, 8 ) );  // same
  39  * @endcode
  40  *
  41  * @since 1.27
  42  */
  43 class MemoizedCallable {
  44
  45         /** @var callable */
  46         private $callable;
  47
  48         /** @var string Unique name of callable; used for cache keys. */
  49         private $callableName;
  50
  51         /** @var int */
  52         private $ttl;
  53
  54         /**
  55          * @param callable $callable Function or method to memoize.
  56          * @param int $ttl TTL in seconds. Defaults to 3600 (1hr). Capped at 86400 (24h).
  57          */
  58         public function __construct( $callable, $ttl = 3600 ) {
  59                 if ( !is_callable( $callable, false, $this->callableName ) ) {
  60                         throw new InvalidArgumentException(
  61                                 'Argument 1 passed to MemoizedCallable::__construct() must ' .
  62                                 'be an instance of callable; ' . get_debug_type( $callable ) . ' given'
  63                         );
  64                 }
  65
  66                 if ( $this->callableName === 'Closure::__invoke' ) {
  67                         throw new InvalidArgumentException( 'Cannot memoize unnamed closure' );
  68                 }
  69
  70                 $this->callable = $callable;
  71                 $this->ttl = min( max( $ttl, 1 ), 86400 );
  72         }
  73
  74         /**
  75          * Fetch the result of a previous invocation.
  76          *
  77          * @param string $key
  78          * @param bool &$success
  79          * @return bool
  80          */
  81         protected function fetchResult( $key, &$success ) {
  82                 $success = false;
  83                 if ( function_exists( 'apcu_fetch' ) ) {
  84                         return apcu_fetch( $key, $success );
  85                 }
  86                 return false;
  87         }
  88
  89         /**
  90          * Store the result of an invocation.
  91          *
  92          * @param string $key
  93          * @param mixed $result
  94          */
  95         protected function storeResult( $key, $result ) {
  96                 if ( function_exists( 'apcu_store' ) ) {
  97                         apcu_store( $key, $result, $this->ttl );
  98                 }
  99         }
 100
 101         /**
 102          * Invoke the memoized function or method.
 103          *
 104          * @throws InvalidArgumentException If parameters list contains non-scalar items.
 105          * @param array $args Parameters for memoized function or method.
 106          * @return mixed The memoized callable's return value.
 107          */
 108         public function invokeArgs( array $args = [] ) {
 109                 foreach ( $args as $arg ) {
 110                         if ( $arg !== null && !is_scalar( $arg ) ) {
 111                                 throw new InvalidArgumentException(
 112                                         'MemoizedCallable::invoke() called with non-scalar ' .
 113                                         'argument'
 114                                 );
 115                         }
 116                 }
 117
 118                 $hash = md5( serialize( $args ) );
 119                 $key = __CLASS__ . ':' . $this->callableName . ':' . $hash;
 120                 $success = false;
 121                 $result = $this->fetchResult( $key, $success );
 122                 if ( !$success ) {
 123                         $result = ( $this->callable )( ...$args );
 124                         $this->storeResult( $key, $result );
 125                 }
 126
 127                 return $result;
 128         }
 129
 130         /**
 131          * Invoke the memoized function or method.
 132          *
 133          * Like MemoizedCallable::invokeArgs(), but variadic.
 134          *
 135          * @param mixed ...$params Parameters for memoized function or method.
 136          * @return mixed The memoized callable's return value.
 137          */
 138         public function invoke( ...$params ) {
 139                 return $this->invokeArgs( $params );
 140         }
 141
 142         /**
 143          * Shortcut method for creating a MemoizedCallable and invoking it
 144          * with the specified arguments.
 145          *
 146          * @param callable $callable
 147          * @param array $args
 148          * @param int $ttl
 149          * @return mixed
 150          */
 151         public static function call( $callable, array $args = [], $ttl = 3600 ) {
 152                 $instance = new self( $callable, $ttl );
 153                 return $instance->invokeArgs( $args );
 154         }
 155 }