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          * @param $key string
  60          */
  61         abstract public function get( $key );
  62 }
  63
  64 /**
  65  * Write to a CDB file.
  66  * Native and pure PHP implementations are provided.
  67  */
  68 abstract class CdbWriter {
  69         /**
  70          * Open a writer and return a subclass instance.
  71          * The user must have write access to the directory, for temporary file creation.
  72          *
  73          * @param $fileName string
  74          *
  75          * @return CdbWriter_DBA|CdbWriter_PHP
  76          */
  77         public static function open( $fileName ) {
  78                 if ( CdbReader::haveExtension() ) {
  79                         return new CdbWriter_DBA( $fileName );
  80                 } else {
  81                         wfDebug( "Warning: no dba extension found, using emulation.\n" );
  82                         return new CdbWriter_PHP( $fileName );
  83                 }
  84         }
  85
  86         /**
  87          * Create the object and open the file
  88          *
  89          * @param $fileName string
  90          */
  91         abstract function __construct( $fileName );
  92
  93         /**
  94          * Set a key to a given value. The value will be converted to string.
  95          * @param $key string
  96          * @param $value string
  97          */
  98         abstract public function set( $key, $value );
  99
 100         /**
 101          * Close the writer object. You should call this function before the object
 102          * goes out of scope, to write out the final hashtables.
 103          */
 104         abstract public function close();
 105 }
 106
 107 /**
 108  * Reader class which uses the DBA extension
 109  */
 110 class CdbReader_DBA {
 111         var $handle;
 112
 113         function __construct( $fileName ) {
 114                 $this->handle = dba_open( $fileName, 'r-', 'cdb' );
 115                 if ( !$this->handle ) {
 116                         throw new MWException( 'Unable to open CDB file "' . $fileName . '"' );
 117                 }
 118         }
 119
 120         function close() {
 121                 if( isset($this->handle) )
 122                         dba_close( $this->handle );
 123                 unset( $this->handle );
 124         }
 125
 126         function get( $key ) {
 127                 return dba_fetch( $key, $this->handle );
 128         }
 129 }
 130
 131
 132 /**
 133  * Writer class which uses the DBA extension
 134  */
 135 class CdbWriter_DBA {
 136         var $handle, $realFileName, $tmpFileName;
 137
 138         function __construct( $fileName ) {
 139                 $this->realFileName = $fileName;
 140                 $this->tmpFileName = $fileName . '.tmp.' . mt_rand( 0, 0x7fffffff );
 141                 $this->handle = dba_open( $this->tmpFileName, 'n', 'cdb_make' );
 142                 if ( !$this->handle ) {
 143                         throw new MWException( 'Unable to open CDB file for write "' . $fileName . '"' );
 144                 }
 145         }
 146
 147         function set( $key, $value ) {
 148                 return dba_insert( $key, $value, $this->handle );
 149         }
 150
 151         function close() {
 152                 if( isset($this->handle) )
 153                         dba_close( $this->handle );
 154                 if ( wfIsWindows() ) {
 155                         unlink( $this->realFileName );
 156                 }
 157                 if ( !rename( $this->tmpFileName, $this->realFileName ) ) {
 158                         throw new MWException( 'Unable to move the new CDB file into place.' );
 159                 }
 160                 unset( $this->handle );
 161         }
 162
 163         function __destruct() {
 164                 if ( isset( $this->handle ) ) {
 165                         $this->close();
 166                 }
 167         }
 168 }
 169