includes/libs/MemoizedCallable.php

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