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