includes/parser/CacheTime.php

   1 <?php
   2 /**
   3  * Parser cache specific expiry check.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Parser
  22  */
  23
  24 /**
  25  * Parser cache specific expiry check.
  26  *
  27  * @ingroup Parser
  28  */
  29 class CacheTime {
  30         /**
  31          * @var string[] ParserOptions which have been taken into account to produce output.
  32          */
  33         public $mUsedOptions;
  34
  35         /**
  36          * @var string|null Compatibility check
  37          */
  38         public $mVersion = Parser::VERSION;
  39
  40         /**
  41          * @var string|int TS_MW timestamp when this object was generated, or -1 for not cacheable. Used
  42          * in ParserCache.
  43          */
  44         public $mCacheTime = '';
  45
  46         /**
  47          * @var int|null Seconds after which the object should expire, use 0 for not cacheable. Used in
  48          * ParserCache.
  49          */
  50         public $mCacheExpiry = null;
  51
  52         /**
  53          * @var int|null Revision ID that was parsed
  54          */
  55         public $mCacheRevisionId = null;
  56
  57         /**
  58          * @return string TS_MW timestamp
  59          */
  60         public function getCacheTime() {
  61                 // NOTE: keep support for undocumented used of -1 to mean "not cacheable".
  62                 if ( $this->mCacheTime === '' ) {
  63                         $this->mCacheTime = MWTimestamp::now();
  64                 }
  65                 return $this->mCacheTime;
  66         }
  67
  68         /**
  69          * setCacheTime() sets the timestamp expressing when the page has been rendered.
  70          * This does not control expiry, see updateCacheExpiry() for that!
  71          * @param string $t TS_MW timestamp
  72          * @return string
  73          */
  74         public function setCacheTime( $t ) {
  75                 // NOTE: keep support for undocumented used of -1 to mean "not cacheable".
  76                 if ( is_string( $t ) && $t !== '-1' ) {
  77                         $t = MWTimestamp::convert( TS_MW, $t );
  78                 }
  79
  80                 return wfSetVar( $this->mCacheTime, $t );
  81         }
  82
  83         /**
  84          * @since 1.23
  85          * @return int|null Revision id, if any was set
  86          */
  87         public function getCacheRevisionId() {
  88                 return $this->mCacheRevisionId;
  89         }
  90
  91         /**
  92          * @since 1.23
  93          * @param int|null $id Revision ID
  94          */
  95         public function setCacheRevisionId( $id ) {
  96                 $this->mCacheRevisionId = $id;
  97         }
  98
  99         /**
 100          * Sets the number of seconds after which this object should expire.
 101          *
 102          * This value is used with the ParserCache.
 103          * If called with a value greater than the value provided at any previous call,
 104          * the new call has no effect. The value returned by getCacheExpiry is smaller
 105          * or equal to the smallest number that was provided as an argument to
 106          * updateCacheExpiry().
 107          *
 108          * Avoid using 0 if at all possible. Consider JavaScript for highly dynamic content.
 109          *
 110          * @param int $seconds
 111          */
 112         public function updateCacheExpiry( $seconds ) {
 113                 $seconds = (int)$seconds;
 114
 115                 if ( $this->mCacheExpiry === null || $this->mCacheExpiry > $seconds ) {
 116                         $this->mCacheExpiry = $seconds;
 117                 }
 118         }
 119
 120         /**
 121          * Returns the number of seconds after which this object should expire.
 122          * This method is used by ParserCache to determine how long the ParserOutput can be cached.
 123          * The timestamp of expiry can be calculated by adding getCacheExpiry() to getCacheTime().
 124          * The value returned by getCacheExpiry is smaller or equal to the smallest number
 125          * that was provided to a call of updateCacheExpiry(), and smaller or equal to the
 126          * value of $wgParserCacheExpireTime.
 127          * @return int
 128          */
 129         public function getCacheExpiry() {
 130                 global $wgParserCacheExpireTime;
 131
 132                 // NOTE: keep support for undocumented used of -1 to mean "not cacheable".
 133                 if ( $this->mCacheTime < 0 ) {
 134                         return 0;
 135                 }
 136
 137                 $expire = $this->mCacheExpiry;
 138
 139                 if ( $expire === null ) {
 140                         $expire = $wgParserCacheExpireTime;
 141                 } else {
 142                         $expire = min( $expire, $wgParserCacheExpireTime );
 143                 }
 144
 145                 if ( $expire <= 0 ) {
 146                         return 0; // not cacheable
 147                 } else {
 148                         return $expire;
 149                 }
 150         }
 151
 152         /**
 153          * @return bool
 154          */
 155         public function isCacheable() {
 156                 return $this->getCacheExpiry() > 0;
 157         }
 158
 159         /**
 160          * Return true if this cached output object predates the global or
 161          * per-article cache invalidation timestamps, or if it comes from
 162          * an incompatible older version.
 163          *
 164          * @param string $touched The affected article's last touched timestamp
 165          * @return bool
 166          */
 167         public function expired( $touched ) {
 168                 global $wgCacheEpoch;
 169
 170                 $expiry = MWTimestamp::convert( TS_MW, MWTimestamp::time() - $this->getCacheExpiry() );
 171
 172                 return !$this->isCacheable() // parser says it's not cacheable
 173                         || $this->getCacheTime() < $touched
 174                         || $this->getCacheTime() <= $wgCacheEpoch
 175                         || $this->getCacheTime() < $expiry // expiry period has passed
 176                         || !isset( $this->mVersion )
 177                         || version_compare( $this->mVersion, Parser::VERSION, "lt" );
 178         }
 179
 180         /**
 181          * Return true if this cached output object is for a different revision of
 182          * the page.
 183          *
 184          * @todo We always return false if $this->getCacheRevisionId() is null;
 185          * this prevents invalidating the whole parser cache when this change is
 186          * deployed. Someday that should probably be changed.
 187          *
 188          * @since 1.23
 189          * @param int $id The affected article's current revision id
 190          * @return bool
 191          */
 192         public function isDifferentRevision( $id ) {
 193                 $cached = $this->getCacheRevisionId();
 194                 return $cached !== null && $id !== $cached;
 195         }
 196 }