includes/Cdb.php

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