includes/objectcache/MemcachedClient.php

   1 <?php
   2 /**
   3  * Memcached client for PHP.
   4  *
   5  * +---------------------------------------------------------------------------+
   6  * | memcached client, PHP                                                     |
   7  * +---------------------------------------------------------------------------+
   8  * | Copyright (c) 2003 Ryan T. Dean <rtdean@cytherianage.net>                 |
   9  * | All rights reserved.                                                      |
  10  * |                                                                           |
  11  * | Redistribution and use in source and binary forms, with or without        |
  12  * | modification, are permitted provided that the following conditions        |
  13  * | are met:                                                                  |
  14  * |                                                                           |
  15  * | 1. Redistributions of source code must retain the above copyright         |
  16  * |    notice, this list of conditions and the following disclaimer.          |
  17  * | 2. Redistributions in binary form must reproduce the above copyright      |
  18  * |    notice, this list of conditions and the following disclaimer in the    |
  19  * |    documentation and/or other materials provided with the distribution.   |
  20  * |                                                                           |
  21  * | THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR      |
  22  * | IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
  23  * | OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.   |
  24  * | IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,          |
  25  * | INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT  |
  26  * | NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
  27  * | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY     |
  28  * | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT       |
  29  * | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF  |
  30  * | THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.         |
  31  * +---------------------------------------------------------------------------+
  32  * | Author: Ryan T. Dean <rtdean@cytherianage.net>                            |
  33  * | Heavily influenced by the Perl memcached client by Brad Fitzpatrick.      |
  34  * |   Permission granted by Brad Fitzpatrick for relicense of ported Perl     |
  35  * |   client logic under 2-clause BSD license.                                |
  36  * +---------------------------------------------------------------------------+
  37  *
  38  * @file
  39  * $TCAnet$
  40  */
  41
  42 /**
  43  * This is the PHP client for memcached - a distributed memory cache daemon.
  44  * More information is available at http://www.danga.com/memcached/
  45  *
  46  * Usage example:
  47  *
  48  * require_once 'memcached.php';
  49  *
  50  * $mc = new MWMemcached(array(
  51  *              'servers' => array('127.0.0.1:10000',
  52  *                                 array('192.0.0.1:10010', 2),
  53  *                                 '127.0.0.1:10020'),
  54  *              'debug'   => false,
  55  *              'compress_threshold' => 10240,
  56  *              'persistent' => true));
  57  *
  58  * $mc->add('key', array('some', 'array'));
  59  * $mc->replace('key', 'some random string');
  60  * $val = $mc->get('key');
  61  *
  62  * @author  Ryan T. Dean <rtdean@cytherianage.net>
  63  * @version 0.1.2
  64  */
  65
  66 // {{{ requirements
  67 // }}}
  68
  69 // {{{ class MWMemcached
  70 /**
  71  * memcached client class implemented using (p)fsockopen()
  72  *
  73  * @author  Ryan T. Dean <rtdean@cytherianage.net>
  74  * @ingroup Cache
  75  */
  76 class MWMemcached {
  77         // {{{ properties
  78         // {{{ public
  79
  80         // {{{ constants
  81         // {{{ flags
  82
  83         /**
  84          * Flag: indicates data is serialized
  85          */
  86         const SERIALIZED = 1;
  87
  88         /**
  89          * Flag: indicates data is compressed
  90          */
  91         const COMPRESSED = 2;
  92
  93         // }}}
  94
  95         /**
  96          * Minimum savings to store data compressed
  97          */
  98         const COMPRESSION_SAVINGS = 0.20;
  99
 100         // }}}
 101
 102
 103         /**
 104          * Command statistics
 105          *
 106          * @var     array
 107          * @access  public
 108          */
 109         var $stats;
 110
 111         // }}}
 112         // {{{ private
 113
 114         /**
 115          * Cached Sockets that are connected
 116          *
 117          * @var     array
 118          * @access  private
 119          */
 120         var $_cache_sock;
 121
 122         /**
 123          * Current debug status; 0 - none to 9 - profiling
 124          *
 125          * @var     boolean
 126          * @access  private
 127          */
 128         var $_debug;
 129
 130         /**
 131          * Dead hosts, assoc array, 'host'=>'unixtime when ok to check again'
 132          *
 133          * @var     array
 134          * @access  private
 135          */
 136         var $_host_dead;
 137
 138         /**
 139          * Is compression available?
 140          *
 141          * @var     boolean
 142          * @access  private
 143          */
 144         var $_have_zlib;
 145
 146         /**
 147          * Do we want to use compression?
 148          *
 149          * @var     boolean
 150          * @access  private
 151          */
 152         var $_compress_enable;
 153
 154         /**
 155          * At how many bytes should we compress?
 156          *
 157          * @var     integer
 158          * @access  private
 159          */
 160         var $_compress_threshold;
 161
 162         /**
 163          * Are we using persistent links?
 164          *
 165          * @var     boolean
 166          * @access  private
 167          */
 168         var $_persistent;
 169
 170         /**
 171          * If only using one server; contains ip:port to connect to
 172          *
 173          * @var     string
 174          * @access  private
 175          */
 176         var $_single_sock;
 177
 178         /**
 179          * Array containing ip:port or array(ip:port, weight)
 180          *
 181          * @var     array
 182          * @access  private
 183          */
 184         var $_servers;
 185
 186         /**
 187          * Our bit buckets
 188          *
 189          * @var     array
 190          * @access  private
 191          */
 192         var $_buckets;
 193
 194         /**
 195          * Total # of bit buckets we have
 196          *
 197          * @var     integer
 198          * @access  private
 199          */
 200         var $_bucketcount;
 201
 202         /**
 203          * # of total servers we have
 204          *
 205          * @var     integer
 206          * @access  private
 207          */
 208         var $_active;
 209
 210         /**
 211          * Stream timeout in seconds. Applies for example to fread()
 212          *
 213          * @var     integer
 214          * @access  private
 215          */
 216         var $_timeout_seconds;
 217
 218         /**
 219          * Stream timeout in microseconds
 220          *
 221          * @var     integer
 222          * @access  private
 223          */
 224         var $_timeout_microseconds;
 225
 226         /**
 227          * Connect timeout in seconds
 228          */
 229         var $_connect_timeout;
 230
 231         /**
 232          * Number of connection attempts for each server
 233          */
 234         var $_connect_attempts;
 235
 236         // }}}
 237         // }}}
 238         // {{{ methods
 239         // {{{ public functions
 240         // {{{ memcached()
 241
 242         /**
 243          * Memcache initializer
 244          *
 245          * @param $args Array Associative array of settings
 246          *
 247          * @return  mixed
 248          */
 249         public function __construct( $args ) {
 250                 $this->set_servers( isset( $args['servers'] ) ? $args['servers'] : array() );
 251                 $this->_debug = isset( $args['debug'] ) ? $args['debug'] : false;
 252                 $this->stats = array();
 253                 $this->_compress_threshold = isset( $args['compress_threshold'] ) ? $args['compress_threshold'] : 0;
 254                 $this->_persistent = isset( $args['persistent'] ) ? $args['persistent'] : false;
 255                 $this->_compress_enable = true;
 256                 $this->_have_zlib = function_exists( 'gzcompress' );
 257
 258                 $this->_cache_sock = array();
 259                 $this->_host_dead = array();
 260
 261                 $this->_timeout_seconds = 0;
 262                 $this->_timeout_microseconds = isset( $args['timeout'] ) ? $args['timeout'] : 100000;
 263
 264                 $this->_connect_timeout = isset( $args['connect_timeout'] ) ? $args['connect_timeout'] : 0.1;
 265                 $this->_connect_attempts = 2;
 266         }
 267
 268         // }}}
 269         // {{{ add()
 270
 271         /**
 272          * Adds a key/value to the memcache server if one isn't already set with
 273          * that key
 274          *
 275          * @param $key String: key to set with data
 276          * @param $val Mixed: value to store
 277          * @param $exp Integer: (optional) Expiration time. This can be a number of seconds
 278          * to cache for (up to 30 days inclusive).  Any timespans of 30 days + 1 second or
 279          * longer must be the timestamp of the time at which the mapping should expire. It
 280          * is safe to use timestamps in all cases, regardless of exipration
 281          * eg: strtotime("+3 hour")
 282          *
 283          * @return Boolean
 284          */
 285         public function add( $key, $val, $exp = 0 ) {
 286                 return $this->_set( 'add', $key, $val, $exp );
 287         }
 288
 289         // }}}
 290         // {{{ decr()
 291
 292         /**
 293          * Decrease a value stored on the memcache server
 294          *
 295          * @param $key String: key to decrease
 296          * @param $amt Integer: (optional) amount to decrease
 297          *
 298          * @return Mixed: FALSE on failure, value on success
 299          */
 300         public function decr( $key, $amt = 1 ) {
 301                 return $this->_incrdecr( 'decr', $key, $amt );
 302         }
 303
 304         // }}}
 305         // {{{ delete()
 306
 307         /**
 308          * Deletes a key from the server, optionally after $time
 309          *
 310          * @param $key String: key to delete
 311          * @param $time Integer: (optional) how long to wait before deleting
 312          *
 313          * @return Boolean: TRUE on success, FALSE on failure
 314          */
 315         public function delete( $key, $time = 0 ) {
 316                 if ( !$this->_active ) {
 317                         return false;
 318                 }
 319
 320                 $sock = $this->get_sock( $key );
 321                 if ( !is_resource( $sock ) ) {
 322                         return false;
 323                 }
 324
 325                 $key = is_array( $key ) ? $key[1] : $key;
 326
 327                 if ( isset( $this->stats['delete'] ) ) {
 328                         $this->stats['delete']++;
 329                 } else {
 330                         $this->stats['delete'] = 1;
 331                 }
 332                 $cmd = "delete $key $time\r\n";
 333                 if( !$this->_safe_fwrite( $sock, $cmd, strlen( $cmd ) ) ) {
 334                         $this->_dead_sock( $sock );
 335                         return false;
 336                 }
 337                 $res = trim( fgets( $sock ) );
 338
 339                 if ( $this->_debug ) {
 340                         $this->_debugprint( sprintf( "MemCache: delete %s (%s)\n", $key, $res ) );
 341                 }
 342
 343                 if ( $res == "DELETED" || $res == "NOT_FOUND" ) {
 344                         return true;
 345                 }
 346
 347                 return false;
 348         }
 349
 350         /**
 351          * @param $key
 352          * @param $timeout int
 353          * @return bool
 354          */
 355         public function lock( $key, $timeout = 0 ) {
 356                 /* stub */
 357                 return true;
 358         }
 359
 360         /**
 361          * @param $key
 362          * @return bool
 363          */
 364         public function unlock( $key ) {
 365                 /* stub */
 366                 return true;
 367         }
 368
 369         // }}}
 370         // {{{ disconnect_all()
 371
 372         /**
 373          * Disconnects all connected sockets
 374          */
 375         public function disconnect_all() {
 376                 foreach ( $this->_cache_sock as $sock ) {
 377                         fclose( $sock );
 378                 }
 379
 380                 $this->_cache_sock = array();
 381         }
 382
 383         // }}}
 384         // {{{ enable_compress()
 385
 386         /**
 387          * Enable / Disable compression
 388          *
 389          * @param $enable Boolean: TRUE to enable, FALSE to disable
 390          */
 391         public function enable_compress( $enable ) {
 392                 $this->_compress_enable = $enable;
 393         }
 394
 395         // }}}
 396         // {{{ forget_dead_hosts()
 397
 398         /**
 399          * Forget about all of the dead hosts
 400          */
 401         public function forget_dead_hosts() {
 402                 $this->_host_dead = array();
 403         }
 404
 405         // }}}
 406         // {{{ get()
 407
 408         /**
 409          * Retrieves the value associated with the key from the memcache server
 410          *
 411          * @param $key array|string key to retrieve
 412          *
 413          * @return Mixed
 414          */
 415         public function get( $key ) {
 416                 wfProfileIn( __METHOD__ );
 417
 418                 if ( $this->_debug ) {
 419                         $this->_debugprint( "get($key)\n" );
 420                 }
 421
 422                 if ( !$this->_active ) {
 423                         wfProfileOut( __METHOD__ );
 424                         return false;
 425                 }
 426
 427                 $sock = $this->get_sock( $key );
 428
 429                 if ( !is_resource( $sock ) ) {
 430                         wfProfileOut( __METHOD__ );
 431                         return false;
 432                 }
 433
 434                 $key = is_array( $key ) ? $key[1] : $key;
 435                 if ( isset( $this->stats['get'] ) ) {
 436                         $this->stats['get']++;
 437                 } else {
 438                         $this->stats['get'] = 1;
 439                 }
 440
 441                 $cmd = "get $key\r\n";
 442                 if ( !$this->_safe_fwrite( $sock, $cmd, strlen( $cmd ) ) ) {
 443                         $this->_dead_sock( $sock );
 444                         wfProfileOut( __METHOD__ );
 445                         return false;
 446                 }
 447
 448                 $val = array();
 449                 $this->_load_items( $sock, $val );
 450
 451                 if ( $this->_debug ) {
 452                         foreach ( $val as $k => $v ) {
 453                                 $this->_debugprint( sprintf( "MemCache: sock %s got %s\n", serialize( $sock ), $k ) );
 454                         }
 455                 }
 456
 457                 $value = false;
 458                 if ( isset( $val[$key] ) ) {
 459                         $value = $val[$key];
 460                 }
 461                 wfProfileOut( __METHOD__ );
 462                 return $value;
 463         }
 464
 465         // }}}
 466         // {{{ get_multi()
 467
 468         /**
 469          * Get multiple keys from the server(s)
 470          *
 471          * @param $keys Array: keys to retrieve
 472          *
 473          * @return Array
 474          */
 475         public function get_multi( $keys ) {
 476                 if ( !$this->_active ) {
 477                         return false;
 478                 }
 479
 480                 if ( isset( $this->stats['get_multi'] ) ) {
 481                         $this->stats['get_multi']++;
 482                 } else {
 483                         $this->stats['get_multi'] = 1;
 484                 }
 485                 $sock_keys = array();
 486                 $socks = array();
 487                 foreach ( $keys as $key ) {
 488                         $sock = $this->get_sock( $key );
 489                         if ( !is_resource( $sock ) ) {
 490                                 continue;
 491                         }
 492                         $key = is_array( $key ) ? $key[1] : $key;
 493                         if ( !isset( $sock_keys[$sock] ) ) {
 494                                 $sock_keys[$sock] = array();
 495                                 $socks[] = $sock;
 496                         }
 497                         $sock_keys[$sock][] = $key;
 498                 }
 499
 500                 $gather = array();
 501                 // Send out the requests
 502                 foreach ( $socks as $sock ) {
 503                         $cmd = 'get';
 504                         foreach ( $sock_keys[$sock] as $key ) {
 505                                 $cmd .= ' ' . $key;
 506                         }
 507                         $cmd .= "\r\n";
 508
 509                         if ( $this->_safe_fwrite( $sock, $cmd, strlen( $cmd ) ) ) {
 510                                 $gather[] = $sock;
 511                         } else {
 512                                 $this->_dead_sock( $sock );
 513                         }
 514                 }
 515
 516                 // Parse responses
 517                 $val = array();
 518                 foreach ( $gather as $sock ) {
 519                         $this->_load_items( $sock, $val );
 520                 }
 521
 522                 if ( $this->_debug ) {
 523                         foreach ( $val as $k => $v ) {
 524                                 $this->_debugprint( sprintf( "MemCache: got %s\n", $k ) );
 525                         }
 526                 }
 527
 528                 return $val;
 529         }
 530
 531         // }}}
 532         // {{{ incr()
 533
 534         /**
 535          * Increments $key (optionally) by $amt
 536          *
 537          * @param $key String: key to increment
 538          * @param $amt Integer: (optional) amount to increment
 539          *
 540          * @return Integer: null if the key does not exist yet (this does NOT
 541          * create new mappings if the key does not exist). If the key does
 542          * exist, this returns the new value for that key.
 543          */
 544         public function incr( $key, $amt = 1 ) {
 545                 return $this->_incrdecr( 'incr', $key, $amt );
 546         }
 547
 548         // }}}
 549         // {{{ replace()
 550
 551         /**
 552          * Overwrites an existing value for key; only works if key is already set
 553          *
 554          * @param $key String: key to set value as
 555          * @param $value Mixed: value to store
 556          * @param $exp Integer: (optional) Expiration time. This can be a number of seconds
 557          * to cache for (up to 30 days inclusive).  Any timespans of 30 days + 1 second or
 558          * longer must be the timestamp of the time at which the mapping should expire. It
 559          * is safe to use timestamps in all cases, regardless of exipration
 560          * eg: strtotime("+3 hour")
 561          *
 562          * @return Boolean
 563          */
 564         public function replace( $key, $value, $exp = 0 ) {
 565                 return $this->_set( 'replace', $key, $value, $exp );
 566         }
 567
 568         // }}}
 569         // {{{ run_command()
 570
 571         /**
 572          * Passes through $cmd to the memcache server connected by $sock; returns
 573          * output as an array (null array if no output)
 574          *
 575          * NOTE: due to a possible bug in how PHP reads while using fgets(), each
 576          *       line may not be terminated by a "\r\n".  More specifically, my testing
 577          *       has shown that, on FreeBSD at least, each line is terminated only
 578          *       with a "\n".  This is with the PHP flag auto_detect_line_endings set
 579          *       to false (the default).
 580          *
 581          * @param $sock Resource: socket to send command on
 582          * @param $cmd String: command to run
 583          *
 584          * @return Array: output array
 585          */
 586         public function run_command( $sock, $cmd ) {
 587                 if ( !is_resource( $sock ) ) {
 588                         return array();
 589                 }
 590
 591                 if ( !$this->_safe_fwrite( $sock, $cmd, strlen( $cmd ) ) ) {
 592                         return array();
 593                 }
 594
 595                 $ret = array();
 596                 while ( true ) {
 597                         $res = fgets( $sock );
 598                         $ret[] = $res;
 599                         if ( preg_match( '/^END/', $res ) ) {
 600                                 break;
 601                         }
 602                         if ( strlen( $res ) == 0 ) {
 603                                 break;
 604                         }
 605                 }
 606                 return $ret;
 607         }
 608
 609         // }}}
 610         // {{{ set()
 611
 612         /**
 613          * Unconditionally sets a key to a given value in the memcache.  Returns true
 614          * if set successfully.
 615          *
 616          * @param $key String: key to set value as
 617          * @param $value Mixed: value to set
 618          * @param $exp Integer: (optional) Expiration time. This can be a number of seconds
 619          * to cache for (up to 30 days inclusive).  Any timespans of 30 days + 1 second or
 620          * longer must be the timestamp of the time at which the mapping should expire. It
 621          * is safe to use timestamps in all cases, regardless of exipration
 622          * eg: strtotime("+3 hour")
 623          *
 624          * @return Boolean: TRUE on success
 625          */
 626         public function set( $key, $value, $exp = 0 ) {
 627                 return $this->_set( 'set', $key, $value, $exp );
 628         }
 629
 630         // }}}
 631         // {{{ set_compress_threshold()
 632
 633         /**
 634          * Sets the compression threshold
 635          *
 636          * @param $thresh Integer: threshold to compress if larger than
 637          */
 638         public function set_compress_threshold( $thresh ) {
 639                 $this->_compress_threshold = $thresh;
 640         }
 641
 642         // }}}
 643         // {{{ set_debug()
 644
 645         /**
 646          * Sets the debug flag
 647          *
 648          * @param $dbg Boolean: TRUE for debugging, FALSE otherwise
 649          *
 650          * @see     MWMemcached::__construct
 651          */
 652         public function set_debug( $dbg ) {
 653                 $this->_debug = $dbg;
 654         }
 655
 656         // }}}
 657         // {{{ set_servers()
 658
 659         /**
 660          * Sets the server list to distribute key gets and puts between
 661          *
 662          * @param $list Array of servers to connect to
 663          *
 664          * @see     MWMemcached::__construct()
 665          */
 666         public function set_servers( $list ) {
 667                 $this->_servers = $list;
 668                 $this->_active = count( $list );
 669                 $this->_buckets = null;
 670                 $this->_bucketcount = 0;
 671
 672                 $this->_single_sock = null;
 673                 if ( $this->_active == 1 ) {
 674                         $this->_single_sock = $this->_servers[0];
 675                 }
 676         }
 677
 678         /**
 679          * Sets the timeout for new connections
 680          *
 681          * @param $seconds Integer: number of seconds
 682          * @param $microseconds Integer: number of microseconds
 683          */
 684         public function set_timeout( $seconds, $microseconds ) {
 685                 $this->_timeout_seconds = $seconds;
 686                 $this->_timeout_microseconds = $microseconds;
 687         }
 688
 689         // }}}
 690         // }}}
 691         // {{{ private methods
 692         // {{{ _close_sock()
 693
 694         /**
 695          * Close the specified socket
 696          *
 697          * @param $sock String: socket to close
 698          *
 699          * @access  private
 700          */
 701         function _close_sock( $sock ) {
 702                 $host = array_search( $sock, $this->_cache_sock );
 703                 fclose( $this->_cache_sock[$host] );
 704                 unset( $this->_cache_sock[$host] );
 705         }
 706
 707         // }}}
 708         // {{{ _connect_sock()
 709
 710         /**
 711          * Connects $sock to $host, timing out after $timeout
 712          *
 713          * @param $sock Integer: socket to connect
 714          * @param $host String: Host:IP to connect to
 715          *
 716          * @return  boolean
 717          * @access  private
 718          */
 719         function _connect_sock( &$sock, $host ) {
 720                 list( $ip, $port ) = explode( ':', $host );
 721                 $sock = false;
 722                 $timeout = $this->_connect_timeout;
 723                 $errno = $errstr = null;
 724                 for( $i = 0; !$sock && $i < $this->_connect_attempts; $i++ ) {
 725                         wfSuppressWarnings();
 726                         if ( $this->_persistent == 1 ) {
 727                                 $sock = pfsockopen( $ip, $port, $errno, $errstr, $timeout );
 728                         } else {
 729                                 $sock = fsockopen( $ip, $port, $errno, $errstr, $timeout );
 730                         }
 731                         wfRestoreWarnings();
 732                 }
 733                 if ( !$sock ) {
 734                         if ( $this->_debug ) {
 735                                 $this->_debugprint( "Error connecting to $host: $errstr\n" );
 736                         }
 737                         return false;
 738                 }
 739
 740                 // Initialise timeout
 741                 stream_set_timeout( $sock, $this->_timeout_seconds, $this->_timeout_microseconds );
 742
 743                 return true;
 744         }
 745
 746         // }}}
 747         // {{{ _dead_sock()
 748
 749         /**
 750          * Marks a host as dead until 30-40 seconds in the future
 751          *
 752          * @param $sock String: socket to mark as dead
 753          *
 754          * @access  private
 755          */
 756         function _dead_sock( $sock ) {
 757                 $host = array_search( $sock, $this->_cache_sock );
 758                 $this->_dead_host( $host );
 759         }
 760
 761         /**
 762          * @param $host
 763          */
 764         function _dead_host( $host ) {
 765                 $parts = explode( ':', $host );
 766                 $ip = $parts[0];
 767                 $this->_host_dead[$ip] = time() + 30 + intval( rand( 0, 10 ) );
 768                 $this->_host_dead[$host] = $this->_host_dead[$ip];
 769                 unset( $this->_cache_sock[$host] );
 770         }
 771
 772         // }}}
 773         // {{{ get_sock()
 774
 775         /**
 776          * get_sock
 777          *
 778          * @param $key String: key to retrieve value for;
 779          *
 780          * @return Mixed: resource on success, false on failure
 781          * @access private
 782          */
 783         function get_sock( $key ) {
 784                 if ( !$this->_active ) {
 785                         return false;
 786                 }
 787
 788                 if ( $this->_single_sock !== null ) {
 789                         $this->_flush_read_buffer( $this->_single_sock );
 790                         return $this->sock_to_host( $this->_single_sock );
 791                 }
 792
 793                 $hv = is_array( $key ) ? intval( $key[0] ) : $this->_hashfunc( $key );
 794                 if ( $this->_buckets === null ) {
 795                         $bu = array();
 796                         foreach ( $this->_servers as $v ) {
 797                                 if ( is_array( $v ) ) {
 798                                         for( $i = 0; $i < $v[1]; $i++ ) {
 799                                                 $bu[] = $v[0];
 800                                         }
 801                                 } else {
 802                                         $bu[] = $v;
 803                                 }
 804                         }
 805                         $this->_buckets = $bu;
 806                         $this->_bucketcount = count( $bu );
 807                 }
 808
 809                 $realkey = is_array( $key ) ? $key[1] : $key;
 810                 for( $tries = 0; $tries < 20; $tries++ ) {
 811                         $host = $this->_buckets[$hv % $this->_bucketcount];
 812                         $sock = $this->sock_to_host( $host );
 813                         if ( is_resource( $sock ) ) {
 814                                 $this->_flush_read_buffer( $sock );
 815                                 return $sock;
 816                         }
 817                         $hv = $this->_hashfunc( $hv . $realkey );
 818                 }
 819
 820                 return false;
 821         }
 822
 823         // }}}
 824         // {{{ _hashfunc()
 825
 826         /**
 827          * Creates a hash integer based on the $key
 828          *
 829          * @param $key String: key to hash
 830          *
 831          * @return Integer: hash value
 832          * @access private
 833          */
 834         function _hashfunc( $key ) {
 835                 # Hash function must be in [0,0x7ffffff]
 836                 # We take the first 31 bits of the MD5 hash, which unlike the hash
 837                 # function used in a previous version of this client, works
 838                 return hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
 839         }
 840
 841         // }}}
 842         // {{{ _incrdecr()
 843
 844         /**
 845          * Perform increment/decriment on $key
 846          *
 847          * @param $cmd String command to perform
 848          * @param $key String|array key to perform it on
 849          * @param $amt Integer amount to adjust
 850          *
 851          * @return Integer: new value of $key
 852          * @access private
 853          */
 854         function _incrdecr( $cmd, $key, $amt = 1 ) {
 855                 if ( !$this->_active ) {
 856                         return null;
 857                 }
 858
 859                 $sock = $this->get_sock( $key );
 860                 if ( !is_resource( $sock ) ) {
 861                         return null;
 862                 }
 863
 864                 $key = is_array( $key ) ? $key[1] : $key;
 865                 if ( isset( $this->stats[$cmd] ) ) {
 866                         $this->stats[$cmd]++;
 867                 } else {
 868                         $this->stats[$cmd] = 1;
 869                 }
 870                 if ( !$this->_safe_fwrite( $sock, "$cmd $key $amt\r\n" ) ) {
 871                         $this->_dead_sock( $sock );
 872                         return null;
 873                 }
 874
 875                 $line = fgets( $sock );
 876                 $match = array();
 877                 if ( !preg_match( '/^(\d+)/', $line, $match ) ) {
 878                         return null;
 879                 }
 880                 return $match[1];
 881         }
 882
 883         // }}}
 884         // {{{ _load_items()
 885
 886         /**
 887          * Load items into $ret from $sock
 888          *
 889          * @param $sock Resource: socket to read from
 890          * @param $ret Array: returned values
 891          *
 892          * @return bool|int
 893          * @access private
 894          */
 895         function _load_items( $sock, &$ret ) {
 896                 while ( 1 ) {
 897                         $decl = fgets( $sock );
 898                         if ( $decl == "END\r\n" ) {
 899                                 return true;
 900                         } elseif ( preg_match( '/^VALUE (\S+) (\d+) (\d+)\r\n$/', $decl, $match ) ) {
 901                                 list( $rkey, $flags, $len ) = array( $match[1], $match[2], $match[3] );
 902                                 $bneed = $len + 2;
 903                                 $offset = 0;
 904
 905                                 while ( $bneed > 0 ) {
 906                                         $data = fread( $sock, $bneed );
 907                                         $n = strlen( $data );
 908                                         if ( $n == 0 ) {
 909                                                 break;
 910                                         }
 911                                         $offset += $n;
 912                                         $bneed -= $n;
 913                                         if ( isset( $ret[$rkey] ) ) {
 914                                                 $ret[$rkey] .= $data;
 915                                         } else {
 916                                                 $ret[$rkey] = $data;
 917                                         }
 918                                 }
 919
 920                                 if ( $offset != $len + 2 ) {
 921                                         // Something is borked!
 922                                         if ( $this->_debug ) {
 923                                                 $this->_debugprint( sprintf( "Something is borked!  key %s expecting %d got %d length\n", $rkey, $len + 2, $offset ) );
 924                                         }
 925
 926                                         unset( $ret[$rkey] );
 927                                         $this->_close_sock( $sock );
 928                                         return false;
 929                                 }
 930
 931                                 if ( $this->_have_zlib && $flags & self::COMPRESSED ) {
 932                                         $ret[$rkey] = gzuncompress( $ret[$rkey] );
 933                                 }
 934
 935                                 $ret[$rkey] = rtrim( $ret[$rkey] );
 936
 937                                 if ( $flags & self::SERIALIZED ) {
 938                                         $ret[$rkey] = unserialize( $ret[$rkey] );
 939                                 }
 940
 941                         } else {
 942                                 $this->_debugprint( "Error parsing memcached response\n" );
 943                                 return 0;
 944                         }
 945                 }
 946         }
 947
 948         // }}}
 949         // {{{ _set()
 950
 951         /**
 952          * Performs the requested storage operation to the memcache server
 953          *
 954          * @param $cmd String: command to perform
 955          * @param $key String: key to act on
 956          * @param $val Mixed: what we need to store
 957          * @param $exp Integer: (optional) Expiration time. This can be a number of seconds
 958          * to cache for (up to 30 days inclusive).  Any timespans of 30 days + 1 second or
 959          * longer must be the timestamp of the time at which the mapping should expire. It
 960          * is safe to use timestamps in all cases, regardless of exipration
 961          * eg: strtotime("+3 hour")
 962          *
 963          * @return Boolean
 964          * @access private
 965          */
 966         function _set( $cmd, $key, $val, $exp ) {
 967                 if ( !$this->_active ) {
 968                         return false;
 969                 }
 970
 971                 $sock = $this->get_sock( $key );
 972                 if ( !is_resource( $sock ) ) {
 973                         return false;
 974                 }
 975
 976                 if ( isset( $this->stats[$cmd] ) ) {
 977                         $this->stats[$cmd]++;
 978                 } else {
 979                         $this->stats[$cmd] = 1;
 980                 }
 981
 982                 $flags = 0;
 983
 984                 if ( !is_scalar( $val ) ) {
 985                         $val = serialize( $val );
 986                         $flags |= self::SERIALIZED;
 987                         if ( $this->_debug ) {
 988                                 $this->_debugprint( sprintf( "client: serializing data as it is not scalar\n" ) );
 989                         }
 990                 }
 991
 992                 $len = strlen( $val );
 993
 994                 if ( $this->_have_zlib && $this->_compress_enable &&
 995                          $this->_compress_threshold && $len >= $this->_compress_threshold )
 996                 {
 997                         $c_val = gzcompress( $val, 9 );
 998                         $c_len = strlen( $c_val );
 999
1000                         if ( $c_len < $len * ( 1 - self::COMPRESSION_SAVINGS ) ) {
1001                                 if ( $this->_debug ) {
1002                                         $this->_debugprint( sprintf( "client: compressing data; was %d bytes is now %d bytes\n", $len, $c_len ) );
1003                                 }
1004                                 $val = $c_val;
1005                                 $len = $c_len;
1006                                 $flags |= self::COMPRESSED;
1007                         }
1008                 }
1009                 if ( !$this->_safe_fwrite( $sock, "$cmd $key $flags $exp $len\r\n$val\r\n" ) ) {
1010                         $this->_dead_sock( $sock );
1011                         return false;
1012                 }
1013
1014                 $line = trim( fgets( $sock ) );
1015
1016                 if ( $this->_debug ) {
1017                         $this->_debugprint( sprintf( "%s %s (%s)\n", $cmd, $key, $line ) );
1018                 }
1019                 if ( $line == "STORED" ) {
1020                         return true;
1021                 }
1022                 return false;
1023         }
1024
1025         // }}}
1026         // {{{ sock_to_host()
1027
1028         /**
1029          * Returns the socket for the host
1030          *
1031          * @param $host String: Host:IP to get socket for
1032          *
1033          * @return Mixed: IO Stream or false
1034          * @access private
1035          */
1036         function sock_to_host( $host ) {
1037                 if ( isset( $this->_cache_sock[$host] ) ) {
1038                         return $this->_cache_sock[$host];
1039                 }
1040
1041                 $sock = null;
1042                 $now = time();
1043                 list( $ip, /* $port */) = explode( ':', $host );
1044                 if ( isset( $this->_host_dead[$host] ) && $this->_host_dead[$host] > $now ||
1045                         isset( $this->_host_dead[$ip] ) && $this->_host_dead[$ip] > $now
1046                 ) {
1047                         return null;
1048                 }
1049
1050                 if ( !$this->_connect_sock( $sock, $host ) ) {
1051                         $this->_dead_host( $host );
1052                         return null;
1053                 }
1054
1055                 // Do not buffer writes
1056                 stream_set_write_buffer( $sock, 0 );
1057
1058                 $this->_cache_sock[$host] = $sock;
1059
1060                 return $this->_cache_sock[$host];
1061         }
1062
1063         /**
1064          * @param $str string
1065          */
1066         function _debugprint( $str ) {
1067                 print( $str );
1068         }
1069
1070         /**
1071          * Write to a stream, timing out after the correct amount of time
1072          *
1073          * @return Boolean: false on failure, true on success
1074          */
1075         /*
1076         function _safe_fwrite( $f, $buf, $len = false ) {
1077                 stream_set_blocking( $f, 0 );
1078
1079                 if ( $len === false ) {
1080                         wfDebug( "Writing " . strlen( $buf ) . " bytes\n" );
1081                         $bytesWritten = fwrite( $f, $buf );
1082                 } else {
1083                         wfDebug( "Writing $len bytes\n" );
1084                         $bytesWritten = fwrite( $f, $buf, $len );
1085                 }
1086                 $n = stream_select( $r = null, $w = array( $f ), $e = null, 10, 0 );
1087                 #   $this->_timeout_seconds, $this->_timeout_microseconds );
1088
1089                 wfDebug( "stream_select returned $n\n" );
1090                 stream_set_blocking( $f, 1 );
1091                 return $n == 1;
1092                 return $bytesWritten;
1093         }*/
1094
1095         /**
1096          * Original behaviour
1097          * @param $f
1098          * @param $buf
1099          * @param $len bool
1100          * @return int
1101          */
1102         function _safe_fwrite( $f, $buf, $len = false ) {
1103                 if ( $len === false ) {
1104                         $bytesWritten = fwrite( $f, $buf );
1105                 } else {
1106                         $bytesWritten = fwrite( $f, $buf, $len );
1107                 }
1108                 return $bytesWritten;
1109         }
1110
1111         /**
1112          * Flush the read buffer of a stream
1113          * @param $f Resource
1114          */
1115         function _flush_read_buffer( $f ) {
1116                 if ( !is_resource( $f ) ) {
1117                         return;
1118                 }
1119                 $n = stream_select( $r = array( $f ), $w = null, $e = null, 0, 0 );
1120                 while ( $n == 1 && !feof( $f ) ) {
1121                         fread( $f, 1024 );
1122                         $n = stream_select( $r = array( $f ), $w = null, $e = null, 0, 0 );
1123                 }
1124         }
1125
1126         // }}}
1127         // }}}
1128         // }}}
1129 }
1130
1131 // vim: sts=3 sw=3 et
1132
1133 // }}}
1134
1135 class MemCachedClientforWiki extends MWMemcached {
1136
1137         function _debugprint( $text ) {
1138                 global $wgDebugLogGroups;
1139                 if( !isset( $wgDebugLogGroups['memcached'] ) ) {
1140                         # Prefix message since it will end up in main debug log file
1141                         $text = "memcached: $text";
1142                 }
1143                 wfDebugLog( 'memcached', $text );
1144         }
1145 }