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1 | <?php |
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2 | /** |
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3 | * APC-backed and APCu-backed function memoization |
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4 | * |
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5 | * This class provides memoization for pure functions. A function is pure |
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6 | * if its result value depends on nothing other than its input parameters |
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7 | * and if invoking it does not cause any side-effects. |
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8 | * |
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9 | * The first invocation of the memoized callable with a particular set of |
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10 | * arguments will be delegated to the underlying callable. Repeat invocations |
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11 | * with the same input parameters will be served from APC or APCu. |
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12 | * |
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13 | * @par Example: |
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14 | * @code |
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15 | * $memoizedStrrev = new MemoizedCallable( 'range' ); |
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16 | * $memoizedStrrev->invoke( 5, 8 ); // result: array( 5, 6, 7, 8 ) |
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17 | * $memoizedStrrev->invokeArgs( array( 5, 8 ) ); // same |
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18 | * MemoizedCallable::call( 'range', array( 5, 8 ) ); // same |
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19 | * @endcode |
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20 | * |
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21 | * This program is free software; you can redistribute it and/or modify |
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22 | * it under the terms of the GNU General Public License as published by |
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23 | * the Free Software Foundation; either version 2 of the License, or |
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24 | * (at your option) any later version. |
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25 | * |
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26 | * This program is distributed in the hope that it will be useful, |
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27 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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28 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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29 | * GNU General Public License for more details. |
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30 | * |
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31 | * You should have received a copy of the GNU General Public License along |
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32 | * with this program; if not, write to the Free Software Foundation, Inc., |
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33 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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34 | * http://www.gnu.org/copyleft/gpl.html |
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35 | * |
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36 | * @file |
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37 | * @author Ori Livneh |
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38 | * @since 1.27 |
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39 | */ |
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40 | class MemoizedCallable { |
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41 | |||
42 | /** @var callable */ |
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43 | private $callable; |
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44 | |||
45 | /** @var string Unique name of callable; used for cache keys. */ |
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46 | private $callableName; |
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47 | |||
48 | /** |
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49 | * Constructor. |
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50 | * |
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51 | * @throws InvalidArgumentException if $callable is not a callable. |
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52 | * @param callable $callable Function or method to memoize. |
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53 | * @param int $ttl TTL in seconds. Defaults to 3600 (1hr). Capped at 86400 (24h). |
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54 | */ |
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55 | public function __construct( $callable, $ttl = 3600 ) { |
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56 | if ( !is_callable( $callable, false, $this->callableName ) ) { |
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57 | throw new InvalidArgumentException( |
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58 | 'Argument 1 passed to MemoizedCallable::__construct() must ' . |
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59 | 'be an instance of callable; ' . gettype( $callable ) . ' given' |
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60 | ); |
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61 | } |
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62 | |||
63 | if ( $this->callableName === 'Closure::__invoke' ) { |
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64 | // Differentiate anonymous functions from one another |
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65 | $this->callableName .= uniqid(); |
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66 | } |
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67 | |||
68 | $this->callable = $callable; |
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69 | $this->ttl = min( max( $ttl, 1 ), 86400 ); |
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70 | } |
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71 | |||
72 | /** |
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73 | * Fetch the result of a previous invocation from APC or APCu. |
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74 | * |
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75 | * @param string $key |
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76 | * @param bool &$success |
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77 | */ |
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78 | protected function fetchResult( $key, &$success ) { |
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79 | $success = false; |
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80 | if ( function_exists( 'apc_fetch' ) ) { |
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81 | return apc_fetch( $key, $success ); |
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82 | } elseif ( function_exists( 'apcu_fetch' ) ) { |
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83 | return apcu_fetch( $key, $success ); |
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84 | } |
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85 | return false; |
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86 | } |
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87 | |||
88 | /** |
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89 | * Store the result of an invocation in APC or APCu. |
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90 | * |
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91 | * @param string $key |
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92 | * @param mixed $result |
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93 | */ |
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94 | protected function storeResult( $key, $result ) { |
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95 | if ( function_exists( 'apc_store' ) ) { |
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96 | apc_store( $key, $result, $this->ttl ); |
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97 | } elseif ( function_exists( 'apcu_store' ) ) { |
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98 | apcu_store( $key, $result, $this->ttl ); |
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99 | } |
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100 | } |
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101 | |||
102 | /** |
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103 | * Invoke the memoized function or method. |
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104 | * |
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105 | * @throws InvalidArgumentException If parameters list contains non-scalar items. |
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106 | * @param array $args Parameters for memoized function or method. |
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107 | * @return mixed The memoized callable's return value. |
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108 | */ |
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109 | public function invokeArgs( array $args = [] ) { |
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110 | foreach ( $args as $arg ) { |
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111 | if ( $arg !== null && !is_scalar( $arg ) ) { |
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112 | throw new InvalidArgumentException( |
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113 | 'MemoizedCallable::invoke() called with non-scalar ' . |
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114 | 'argument' |
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115 | ); |
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116 | } |
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117 | } |
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118 | |||
119 | $hash = md5( serialize( $args ) ); |
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120 | $key = __CLASS__ . ':' . $this->callableName . ':' . $hash; |
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121 | $success = false; |
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122 | $result = $this->fetchResult( $key, $success ); |
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123 | if ( !$success ) { |
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124 | $result = call_user_func_array( $this->callable, $args ); |
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125 | $this->storeResult( $key, $result ); |
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126 | } |
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127 | |||
128 | return $result; |
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129 | } |
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130 | |||
131 | /** |
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132 | * Invoke the memoized function or method. |
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133 | * |
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134 | * Like MemoizedCallable::invokeArgs(), but variadic. |
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135 | * |
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136 | * @param mixed ...$params Parameters for memoized function or method. |
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137 | * @return mixed The memoized callable's return value. |
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138 | */ |
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139 | public function invoke() { |
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140 | return $this->invokeArgs( func_get_args() ); |
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141 | } |
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142 | |||
143 | /** |
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144 | * Shortcut method for creating a MemoizedCallable and invoking it |
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145 | * with the specified arguments. |
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146 | * |
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147 | * @param callable $callable |
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148 | * @param array $args |
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149 | * @param int $ttl |
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150 | */ |
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151 | public static function call( $callable, array $args = [], $ttl = 3600 ) { |
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152 | $instance = new self( $callable, $ttl ); |
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153 | return $instance->invokeArgs( $args ); |
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154 | } |
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155 | } |
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156 |
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: