includes/Cdb.php

   1 <?php
   2 /**
   3  * Native CDB file reader and writer
   4  *
   5  * @file
   6  */
   7
   8 /**
   9  * Read from a CDB file.
  10  * Native and pure PHP implementations are provided.
  11  * http://cr.yp.to/cdb.html
  12  */
  13 abstract class CdbReader {
  14         /**
  15          * Open a file and return a subclass instance
  16          *
  17          * @param $fileName string
  18          *
  19          * @return CdbReader
  20          */
  21         public static function open( $fileName ) {
  22                 if ( self::haveExtension() ) {
  23                         return new CdbReader_DBA( $fileName );
  24                 } else {
  25                         wfDebug( "Warning: no dba extension found, using emulation.\n" );
  26                         return new CdbReader_PHP( $fileName );
  27                 }
  28         }
  29
  30         /**
  31          * Returns true if the native extension is available
  32          *
  33          * @return bool
  34          */
  35         public static function haveExtension() {
  36                 if ( !function_exists( 'dba_handlers' ) ) {
  37                         return false;
  38                 }
  39                 $handlers = dba_handlers();
  40                 if ( !in_array( 'cdb', $handlers ) || !in_array( 'cdb_make', $handlers ) ) {
  41                         return false;
  42                 }
  43                 return true;
  44         }
  45
  46         /**
  47          * Construct the object and open the file
  48          */
  49         abstract function __construct( $fileName );
  50
  51         /**
  52          * Close the file. Optional, you can just let the variable go out of scope.
  53          */
  54         abstract function close();
  55
  56         /**
  57          * Get a value with a given key. Only string values are supported.
  58          */
  59         abstract public function get( $key );
  60 }
  61
  62 /**
  63  * Write to a CDB file.
  64  * Native and pure PHP implementations are provided.
  65  */
  66 abstract class CdbWriter {
  67         /**
  68          * Open a writer and return a subclass instance.
  69          * The user must have write access to the directory, for temporary file creation.
  70          *
  71          * @param $fileName string
  72          *
  73          * @return bool
  74          */
  75         public static function open( $fileName ) {
  76                 if ( CdbReader::haveExtension() ) {
  77                         return new CdbWriter_DBA( $fileName );
  78                 } else {
  79                         wfDebug( "Warning: no dba extension found, using emulation.\n" );
  80                         return new CdbWriter_PHP( $fileName );
  81                 }
  82         }
  83
  84         /**
  85          * Create the object and open the file
  86          */
  87         abstract function __construct( $fileName );
  88
  89         /**
  90          * Set a key to a given value. The value will be converted to string.
  91          */
  92         abstract public function set( $key, $value );
  93
  94         /**
  95          * Close the writer object. You should call this function before the object
  96          * goes out of scope, to write out the final hashtables.
  97          */
  98         abstract public function close();
  99 }
 100
 101
 102 /**
 103  * Reader class which uses the DBA extension
 104  */
 105 class CdbReader_DBA {
 106         var $handle;
 107
 108         function __construct( $fileName ) {
 109                 $this->handle = dba_open( $fileName, 'r-', 'cdb' );
 110                 if ( !$this->handle ) {
 111                         throw new MWException( 'Unable to open CDB file "' . $fileName . '"' );
 112                 }
 113         }
 114
 115         function close() {
 116                 if( isset($this->handle) )
 117                         dba_close( $this->handle );
 118                 unset( $this->handle );
 119         }
 120
 121         function get( $key ) {
 122                 return dba_fetch( $key, $this->handle );
 123         }
 124 }
 125
 126
 127 /**
 128  * Writer class which uses the DBA extension
 129  */
 130 class CdbWriter_DBA {
 131         var $handle, $realFileName, $tmpFileName;
 132
 133         function __construct( $fileName ) {
 134                 $this->realFileName = $fileName;
 135                 $this->tmpFileName = $fileName . '.tmp.' . mt_rand( 0, 0x7fffffff );
 136                 $this->handle = dba_open( $this->tmpFileName, 'n', 'cdb_make' );
 137                 if ( !$this->handle ) {
 138                         throw new MWException( 'Unable to open CDB file for write "' . $fileName . '"' );
 139                 }
 140         }
 141
 142         function set( $key, $value ) {
 143                 return dba_insert( $key, $value, $this->handle );
 144         }
 145
 146         function close() {
 147                 if( isset($this->handle) )
 148                         dba_close( $this->handle );
 149                 if ( wfIsWindows() ) {
 150                         unlink( $this->realFileName );
 151                 }
 152                 if ( !rename( $this->tmpFileName, $this->realFileName ) ) {
 153                         throw new MWException( 'Unable to move the new CDB file into place.' );
 154                 }
 155                 unset( $this->handle );
 156         }
 157
 158         function __destruct() {
 159                 if ( isset( $this->handle ) ) {
 160                         $this->close();
 161                 }
 162         }
 163 }
 164