git.m6w6.name Git - m6w6/libmemcached/blob - libmemcached/memcached.hpp

   1 /*
   2  * Summary: C++ interface for memcached server
   3  *
   4  * Copy: See Copyright for the status of this software.
   5  *
   6  * Authors: Padraig O'Sullivan <osullivan.padraig@gmail.com>
   7  *          Patrick Galbraith <patg@patg.net>
   8  */
   9
  10 /**
  11  * @file memcached.hpp
  12  * @brief Libmemcached C++ interface
  13  */
  14
  15 #ifndef LIBMEMCACHEDPP_H
  16 #define LIBMEMCACHEDPP_H
  17
  18 #include <libmemcached/memcached.h>
  19 #include <libmemcached/exception.hpp>
  20
  21 #include <string.h>
  22
  23 #include <sstream>
  24 #include <string>
  25 #include <vector>
  26 #include <map>
  27
  28 namespace memcache
  29 {
  30
  31 /**
  32  * This is the core memcached library (if later, other objects
  33  * are needed, they will be created from this class).
  34  */
  35 class Memcache
  36 {
  37 public:
  38
  39   Memcache()
  40     :
  41       servers_list(),
  42       memc(),
  43       servers(NULL),
  44       result()
  45   {
  46     memcached_create(&memc);
  47   }
  48
  49   Memcache(const std::string &in_servers_list)
  50     :
  51       servers_list(in_servers_list),
  52       memc(),
  53       servers(NULL),
  54       result()
  55   {
  56     memcached_create(&memc);
  57     servers= memcached_servers_parse(servers_list.c_str());
  58     memcached_server_push(&memc, servers);
  59   }
  60
  61   Memcache(const std::string &hostname,
  62            unsigned int port)
  63     :
  64       servers_list(),
  65       memc(),
  66       servers(NULL),
  67       result()
  68   {
  69     memcached_create(&memc);
  70     servers_list.append(hostname);
  71     servers_list.append(":");
  72     std::ostringstream strsmt;
  73     strsmt << port;
  74     servers_list.append(strsmt.str());
  75     servers= memcached_servers_parse(servers_list.c_str());
  76     memcached_server_push(&memc, servers);
  77   }
  78
  79   Memcache(memcached_st *clone)
  80     :
  81       servers_list(),
  82       memc(),
  83       servers(NULL),
  84       result()
  85   {
  86     memcached_clone(&memc, clone);
  87   }
  88
  89   Memcache(const Memcache &rhs)
  90     :
  91       servers_list(rhs.servers_list),
  92       memc(),
  93       servers(NULL),
  94       result()
  95   {
  96     memcached_clone(&memc, const_cast<memcached_st *>(&rhs.getImpl()));
  97     servers= memcached_servers_parse(servers_list.c_str());
  98     memcached_server_push(&memc, servers);
  99   }
 100
 101   Memcache &operator=(const Memcache &rhs)
 102   {
 103     if (this != &rhs)
 104     {
 105       memcached_clone(&memc, const_cast<memcached_st *>(&rhs.getImpl()));
 106       servers= memcached_servers_parse(servers_list.c_str());
 107       memcached_server_push(&memc, servers);
 108     }
 109     return *this;
 110   }
 111
 112   ~Memcache()
 113   {
 114     memcached_free(&memc);
 115     memcached_server_list_free(servers);
 116   }
 117
 118   /**
 119    * Get the internal memcached_st *
 120    */
 121   memcached_st &getImpl()
 122   {
 123     return memc;
 124   }
 125
 126   /**
 127    * Get the internal memcached_st *
 128    */
 129   const memcached_st &getImpl() const
 130   {
 131     return memc;
 132   }
 133
 134   /**
 135    * Return an error string for the given return structure.
 136    *
 137    * @param[in] rc a memcached_return structure
 138    * @return error string corresponding to given return code in the library.
 139    */
 140   const std::string getError(memcached_return rc) const
 141   {
 142     /* first parameter to strerror is unused */
 143     return memcached_strerror(NULL, rc);
 144   }
 145
 146   /**
 147    * Return the string which contains the list of memcached servers being
 148    * used.
 149    *
 150    * @return a std::string containing the list of memcached servers
 151    */
 152   const std::string getServersList() const
 153   {
 154     return servers_list;
 155   }
 156
 157   /**
 158    * Set the list of memcached servers to use.
 159    *
 160    * @param[in] in_servers_list list of servers
 161    * @return true on success; false otherwise
 162    */
 163   bool setServers(const std::string &in_servers_list)
 164   {
 165     servers_list.assign(in_servers_list);
 166     servers= memcached_servers_parse(in_servers_list.c_str());
 167     return (servers == NULL);
 168   }
 169
 170   /**
 171    * Add a server to the list of memcached servers to use.
 172    *
 173    * @param[in] server_name name of the server to add
 174    * @param[in[ port port number of server to add
 175    * @return true on success; false otherwise
 176    */
 177   bool addServer(const std::string &server_name, unsigned int port)
 178   {
 179     memcached_return rc;
 180     std::ostringstream strstm;
 181     servers_list.append(",");
 182     servers_list.append(server_name);
 183     servers_list.append(":");
 184     strstm << port;
 185     servers_list.append(strstm.str());
 186     servers= memcached_server_list_append(servers,
 187                                           server_name.c_str(),
 188                                           port,
 189                                           &rc);
 190     return (rc == MEMCACHED_SUCCESS);
 191   }
 192
 193   /**
 194    * Fetches an individual value from the server. mget() must always
 195    * be called before using this method.
 196    *
 197    * @param[in] key key of object to fetch
 198    * @param[out] ret_val store returned object in this vector
 199    * @return a memcached return structure
 200    */
 201   memcached_return fetch(std::string &key,
 202                          std::vector<char> &ret_val)
 203   {
 204     char ret_key[MEMCACHED_MAX_KEY];
 205     size_t value_length= 0;
 206     size_t key_length= 0;
 207     memcached_return rc;
 208     uint32_t flags= 0;
 209     char *value= memcached_fetch(&memc, ret_key, &key_length,
 210                                  &value_length, &flags, &rc);
 211     if (value && ret_val.empty())
 212     {
 213       ret_val.reserve(value_length);
 214       ret_val.assign(value, value + value_length);
 215       key.assign(ret_key);
 216     }
 217     return rc;
 218   }
 219
 220   /**
 221    * Fetches an individual value from the server.
 222    *
 223    * @param[in] key key of object whose value to get
 224    * @param[out] ret_val object that is retrieved is stored in
 225    *                     this vector
 226    * @return true on success; false otherwise
 227    */
 228   bool get(const std::string &key,
 229            std::vector<char> &ret_val) throw (Error)
 230   {
 231     uint32_t flags= 0;
 232     memcached_return rc;
 233     size_t value_length= 0;
 234
 235     if (key.empty())
 236     {
 237       throw(Error("the key supplied is empty!", false));
 238     }
 239     char *value= memcached_get(&memc, key.c_str(), key.length(),
 240                                &value_length, &flags, &rc);
 241     if (value != NULL && ret_val.empty())
 242     {
 243       ret_val.reserve(value_length);
 244       ret_val.assign(value, value + value_length);
 245       return true;
 246     }
 247     return false;
 248   }
 249
 250   /**
 251    * Fetches an individual from a server which is specified by
 252    * the master_key parameter that is used for determining which
 253    * server an object was stored in if key partitioning was
 254    * used for storage.
 255    *
 256    * @param[in] master_key key that specifies server object is stored on
 257    * @param[in] key key of object whose value to get
 258    * @param[out] ret_val object that is retrieved is stored in
 259    *                     this vector
 260    * @return true on success; false otherwise
 261    */
 262   bool getByKey(const std::string &master_key,
 263                 const std::string &key,
 264                 std::vector<char> &ret_val) throw(Error)
 265   {
 266     uint32_t flags= 0;
 267     memcached_return rc;
 268     size_t value_length= 0;
 269
 270     if (master_key.empty() || key.empty())
 271     {
 272       throw(Error("the master key or key supplied is empty!", false));
 273     }
 274     char *value= memcached_get_by_key(&memc,
 275                                       master_key.c_str(), master_key.length(),
 276                                       key.c_str(), key.length(),
 277                                       &value_length, &flags, &rc);
 278     if (value)
 279     {
 280       ret_val.reserve(value_length);
 281       ret_val.assign(value, value + value_length);
 282       return true;
 283     }
 284     return false;
 285   }
 286
 287   /**
 288    * Selects multiple keys at once. This method always
 289    * works asynchronously.
 290    *
 291    * @param[in] keys vector of keys to select
 292    * @return true if all keys are found
 293    */
 294   bool mget(std::vector<std::string> &keys)
 295   {
 296     std::vector<const char *> real_keys;
 297     std::vector<size_t> key_len;
 298     /*
 299      * Construct an array which will contain the length
 300      * of each of the strings in the input vector. Also, to
 301      * interface with the memcached C API, we need to convert
 302      * the vector of std::string's to a vector of char *.
 303      */
 304     real_keys.reserve(keys.size());
 305     key_len.reserve(keys.size());
 306
 307     std::vector<std::string>::iterator it= keys.begin();
 308
 309     while (it != keys.end())
 310     {
 311       real_keys.push_back(const_cast<char *>((*it).c_str()));
 312       key_len.push_back((*it).length());
 313       ++it;
 314     }
 315
 316     /*
 317      * If the std::vector of keys is empty then we cannot
 318      * call memcached_mget as we will get undefined behavior.
 319      */
 320     if (! real_keys.empty())
 321     {
 322       memcached_return rc= memcached_mget(&memc, &real_keys[0], &key_len[0],
 323                                           real_keys.size());
 324       return (rc == MEMCACHED_SUCCESS);
 325     }
 326
 327     return false;
 328   }
 329
 330   /**
 331    * Writes an object to the server. If the object already exists, it will
 332    * overwrite the existing object. This method always returns true
 333    * when using non-blocking mode unless a network error occurs.
 334    *
 335    * @param[in] key key of object to write to server
 336    * @param[in] value value of object to write to server
 337    * @param[in] expiration time to keep the object stored in the server for
 338    * @param[in] flags flags to store with the object
 339    * @return true on succcess; false otherwise
 340    */
 341   bool set(const std::string &key,
 342            const std::vector<char> &value,
 343            time_t expiration,
 344            uint32_t flags) throw(Error)
 345   {
 346     if (key.empty() || value.empty())
 347     {
 348       throw(Error("the key or value supplied is empty!", false));
 349     }
 350     memcached_return rc= memcached_set(&memc,
 351                                        key.c_str(), key.length(),
 352                                        &value[0], value.size(),
 353                                        expiration, flags);
 354     return (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_BUFFERED);
 355   }
 356
 357   /**
 358    * Writes an object to a server specified by the master_key parameter.
 359    * If the object already exists, it will overwrite the existing object.
 360    *
 361    * @param[in] master_key key that specifies server to write to
 362    * @param[in] key key of object to write to server
 363    * @param[in] value value of object to write to server
 364    * @param[in] expiration time to keep the object stored in the server for
 365    * @param[in] flags flags to store with the object
 366    * @return true on succcess; false otherwise
 367    */
 368   bool setByKey(const std::string &master_key,
 369                 const std::string &key,
 370                 const std::vector<char> &value,
 371                 time_t expiration,
 372                 uint32_t flags) throw(Error)
 373   {
 374     if (master_key.empty() ||
 375         key.empty() ||
 376         value.empty())
 377     {
 378       throw(Error("the key or value supplied is empty!", false));
 379     }
 380     memcached_return rc= memcached_set_by_key(&memc, master_key.c_str(),
 381                                               master_key.length(),
 382                                               key.c_str(), key.length(),
 383                                               &value[0], value.size(),
 384                                               expiration,
 385                                               flags);
 386     return (rc == MEMCACHED_SUCCESS);
 387   }
 388
 389   /**
 390    * Writes a list of objects to the server. Objects are specified by
 391    * 2 vectors - 1 vector of keys and 1 vector of values.
 392    *
 393    * @param[in] keys vector of keys of objects to write to server
 394    * @param[in] values vector of values of objects to write to server
 395    * @param[in] expiration time to keep the objects stored in server for
 396    * @param[in] flags flags to store with the objects
 397    * @return true on success; false otherwise
 398    */
 399   bool setAll(std::vector<std::string> &keys,
 400               std::vector< std::vector<char> *> &values,
 401               time_t expiration,
 402               uint32_t flags) throw(Error)
 403   {
 404     if (keys.size() != values.size())
 405     {
 406       throw(Error("The number of keys and values do not match!", false));
 407     }
 408     bool retval= true;
 409     std::vector<std::string>::iterator key_it= keys.begin();
 410     std::vector< std::vector<char> *>::iterator val_it= values.begin();
 411     while (key_it != keys.end())
 412     {
 413       retval= set((*key_it), *(*val_it), expiration, flags);
 414       if (retval == false)
 415       {
 416         return retval;
 417       }
 418       ++key_it;
 419       ++val_it;
 420     }
 421     return retval;
 422   }
 423
 424   /**
 425    * Writes a list of objects to the server. Objects are specified by
 426    * a map of keys to values.
 427    *
 428    * @param[in] key_value_map map of keys and values to store in server
 429    * @param[in] expiration time to keep the objects stored in server for
 430    * @param[in] flags flags to store with the objects
 431    * @return true on success; false otherwise
 432    */
 433   bool setAll(std::map<const std::string, std::vector<char> > &key_value_map,
 434               time_t expiration,
 435               uint32_t flags) throw(Error)
 436   {
 437     if (key_value_map.empty())
 438     {
 439       throw(Error("The key/values are not properly set!", false));
 440     }
 441     bool retval= true;
 442     std::map<const std::string, std::vector<char> >::iterator it=
 443       key_value_map.begin();
 444     while (it != key_value_map.end())
 445     {
 446       retval= set(it->first, it->second, expiration, flags);
 447       if (retval == false)
 448       {
 449         std::string err_buff("There was an error setting the key ");
 450         err_buff.append(it->first);
 451         throw(Error(err_buff, false));
 452       }
 453       ++it;
 454     }
 455     return true;
 456   }
 457
 458   /**
 459    * Increment the value of the object associated with the specified
 460    * key by the offset given. The resulting value is saved in the value
 461    * parameter.
 462    *
 463    * @param[in] key key of object in server whose value to increment
 464    * @param[in] offset amount to increment object's value by
 465    * @param[out] value store the result of the increment here
 466    * @return true on success; false otherwise
 467    */
 468   bool increment(const std::string &key, uint32_t offset, uint64_t *value) throw(Error)
 469   {
 470     if (key.empty())
 471     {
 472       throw(Error("the key supplied is empty!", false));
 473     }
 474     memcached_return rc= memcached_increment(&memc, key.c_str(), key.length(),
 475                                              offset, value);
 476     return (rc == MEMCACHED_SUCCESS);
 477   }
 478
 479   /**
 480    * Decrement the value of the object associated with the specified
 481    * key by the offset given. The resulting value is saved in the value
 482    * parameter.
 483    *
 484    * @param[in] key key of object in server whose value to decrement
 485    * @param[in] offset amount to increment object's value by
 486    * @param[out] value store the result of the decrement here
 487    * @return true on success; false otherwise
 488    */
 489   bool decrement(const std::string &key, uint32_t offset, uint64_t *value)
 490     throw(Error)
 491   {
 492     if (key.empty())
 493     {
 494       throw(Error("the key supplied is empty!", false));
 495     }
 496     memcached_return rc= memcached_decrement(&memc, key.c_str(),
 497                                              key.length(),
 498                                              offset, value);
 499     return (rc == MEMCACHED_SUCCESS);
 500   }
 501
 502
 503   /**
 504    * Add an object with the specified key and value to the server. This
 505    * function returns false if the object already exists on the server.
 506    *
 507    * @param[in] key key of object to add
 508    * @param[in] value of object to add
 509    * @return true on success; false otherwise
 510    */
 511   bool add(const std::string &key, const std::vector<char> &value)
 512     throw(Error)
 513   {
 514     if (key.empty() || value.empty())
 515     {
 516       throw(Error("the key or value supplied is empty!", false));
 517     }
 518     memcached_return rc= memcached_add(&memc, key.c_str(), key.length(),
 519                                        &value[0], value.size(), 0, 0);
 520     return (rc == MEMCACHED_SUCCESS);
 521   }
 522
 523   /**
 524    * Add an object with the specified key and value to the server. This
 525    * function returns false if the object already exists on the server. The
 526    * server to add the object to is specified by the master_key parameter.
 527    *
 528    * @param[in[ master_key key of server to add object to
 529    * @param[in] key key of object to add
 530    * @param[in] value of object to add
 531    * @return true on success; false otherwise
 532    */
 533   bool addByKey(const std::string &master_key,
 534                 const std::string &key,
 535                 const std::vector<char> &value) throw(Error)
 536   {
 537     if (master_key.empty() ||
 538         key.empty() ||
 539         value.empty())
 540     {
 541       throw(Error("the master key or key supplied is empty!", false));
 542     }
 543     memcached_return rc= memcached_add_by_key(&memc,
 544                                               master_key.c_str(),
 545                                               master_key.length(),
 546                                               key.c_str(),
 547                                               key.length(),
 548                                               &value[0],
 549                                               value.size(),
 550                                               0, 0);
 551     return (rc == MEMCACHED_SUCCESS);
 552   }
 553
 554   /**
 555    * Replaces an object on the server. This method only succeeds
 556    * if the object is already present on the server.
 557    *
 558    * @param[in] key key of object to replace
 559    * @param[in[ value value to replace object with
 560    * @return true on success; false otherwise
 561    */
 562   bool replace(const std::string &key, const std::vector<char> &value) throw(Error)
 563   {
 564     if (key.empty() ||
 565         value.empty())
 566     {
 567       throw(Error("the key or value supplied is empty!", false));
 568     }
 569     memcached_return rc= memcached_replace(&memc, key.c_str(), key.length(),
 570                                            &value[0], value.size(),
 571                                            0, 0);
 572     return (rc == MEMCACHED_SUCCESS);
 573   }
 574
 575   /**
 576    * Replaces an object on the server. This method only succeeds
 577    * if the object is already present on the server. The server
 578    * to replace the object on is specified by the master_key param.
 579    *
 580    * @param[in] master_key key of server to replace object on
 581    * @param[in] key key of object to replace
 582    * @param[in[ value value to replace object with
 583    * @return true on success; false otherwise
 584    */
 585   bool replaceByKey(const std::string &master_key,
 586                     const std::string &key,
 587                     const std::vector<char> &value)
 588   {
 589     if (master_key.empty() ||
 590         key.empty() ||
 591         value.empty())
 592     {
 593       throw(Error("the master key or key supplied is empty!", false));
 594     }
 595     memcached_return rc= memcached_replace_by_key(&memc,
 596                                                   master_key.c_str(),
 597                                                   master_key.length(),
 598                                                   key.c_str(),
 599                                                   key.length(),
 600                                                   &value[0],
 601                                                   value.size(),
 602                                                   0, 0);
 603     return (rc == MEMCACHED_SUCCESS);
 604   }
 605
 606   /**
 607    * Places a segment of data before the last piece of data stored.
 608    *
 609    * @param[in] key key of object whose value we will prepend data to
 610    * @param[in] value data to prepend to object's value
 611    * @return true on success; false otherwise
 612    */
 613   bool prepend(const std::string &key, const std::vector<char> &value)
 614     throw(Error)
 615   {
 616     if (key.empty() || value.empty())
 617     {
 618       throw(Error("the key or value supplied is empty!", false));
 619     }
 620     memcached_return rc= memcached_prepend(&memc, key.c_str(), key.length(),
 621                                            &value[0], value.size(), 0, 0);
 622     return (rc == MEMCACHED_SUCCESS);
 623   }
 624
 625   /**
 626    * Places a segment of data before the last piece of data stored. The
 627    * server on which the object where we will be prepending data is stored
 628    * on is specified by the master_key parameter.
 629    *
 630    * @param[in] master_key key of server where object is stored
 631    * @param[in] key key of object whose value we will prepend data to
 632    * @param[in] value data to prepend to object's value
 633    * @return true on success; false otherwise
 634    */
 635   bool prependByKey(const std::string &master_key,
 636                     const std::string &key,
 637                     const std::vector<char> &value)
 638       throw(Error)
 639   {
 640     if (master_key.empty() ||
 641         key.empty() ||
 642         value.empty())
 643     {
 644       throw(Error("the master key or key supplied is empty!", false));
 645     }
 646     memcached_return rc= memcached_prepend_by_key(&memc,
 647                                                   master_key.c_str(),
 648                                                   master_key.length(),
 649                                                   key.c_str(),
 650                                                   key.length(),
 651                                                   &value[0],
 652                                                   value.size(),
 653                                                   0,
 654                                                   0);
 655     return (rc == MEMCACHED_SUCCESS);
 656   }
 657
 658   /**
 659    * Places a segment of data at the end of the last piece of data stored.
 660    *
 661    * @param[in] key key of object whose value we will append data to
 662    * @param[in] value data to append to object's value
 663    * @return true on success; false otherwise
 664    */
 665   bool append(const std::string &key, const std::vector<char> &value)
 666     throw(Error)
 667   {
 668     if (key.empty() || value.empty())
 669     {
 670       throw(Error("the key or value supplied is empty!", false));
 671     }
 672     memcached_return rc= memcached_append(&memc,
 673                                           key.c_str(),
 674                                           key.length(),
 675                                           &value[0],
 676                                           value.size(),
 677                                           0, 0);
 678     return (rc == MEMCACHED_SUCCESS);
 679   }
 680
 681   /**
 682    * Places a segment of data at the end of the last piece of data stored. The
 683    * server on which the object where we will be appending data is stored
 684    * on is specified by the master_key parameter.
 685    *
 686    * @param[in] master_key key of server where object is stored
 687    * @param[in] key key of object whose value we will append data to
 688    * @param[in] value data to append to object's value
 689    * @return true on success; false otherwise
 690    */
 691   bool appendByKey(const std::string &master_key,
 692                    const std::string &key,
 693                    const std::vector<char> &value)
 694     throw(Error)
 695   {
 696     if (master_key.empty() ||
 697         key.empty() ||
 698         value.empty())
 699     {
 700       throw(Error("the master key or key supplied is empty!", false));
 701     }
 702     memcached_return rc= memcached_append_by_key(&memc,
 703                                                  master_key.c_str(),
 704                                                  master_key.length(),
 705                                                  key.c_str(),
 706                                                  key.length(),
 707                                                  &value[0],
 708                                                  value.size(),
 709                                                  0, 0);
 710     return (rc == MEMCACHED_SUCCESS);
 711   }
 712
 713   /**
 714    * Overwrite data in the server as long as the cas_arg value
 715    * is still the same in the server.
 716    *
 717    * @param[in] key key of object in server
 718    * @param[in] value value to store for object in server
 719    * @param[in] cas_arg "cas" value
 720    */
 721   bool cas(const std::string &key,
 722            const std::vector<char> &value,
 723            uint64_t cas_arg) throw(Error)
 724   {
 725     if (key.empty() || value.empty())
 726     {
 727       throw(Error("the key or value supplied is empty!", false));
 728     }
 729     memcached_return rc= memcached_cas(&memc, key.c_str(), key.length(),
 730                                        &value[0], value.size(),
 731                                        0, 0, cas_arg);
 732     return (rc == MEMCACHED_SUCCESS);
 733   }
 734
 735   /**
 736    * Overwrite data in the server as long as the cas_arg value
 737    * is still the same in the server. The server to use is
 738    * specified by the master_key parameter.
 739    *
 740    * @param[in] master_key specifies server to operate on
 741    * @param[in] key key of object in server
 742    * @param[in] value value to store for object in server
 743    * @param[in] cas_arg "cas" value
 744    */
 745   bool casByKey(const std::string &master_key,
 746                 const std::string &key,
 747                 const std::vector<char> &value,
 748                 uint64_t cas_arg) throw(Error)
 749   {
 750     if (master_key.empty() ||
 751         key.empty() ||
 752         value.empty())
 753     {
 754       throw(Error("the master key, key or value supplied is empty!", false));
 755     }
 756     memcached_return rc= memcached_cas_by_key(&memc,
 757                                               master_key.c_str(),
 758                                               master_key.length(),
 759                                               key.c_str(),
 760                                               key.length(),
 761                                               &value[0],
 762                                               value.size(),
 763                                               0, 0, cas_arg);
 764     return (rc == MEMCACHED_SUCCESS);
 765   }
 766
 767   /**
 768    * Delete an object from the server specified by the key given.
 769    *
 770    * @param[in] key key of object to delete
 771    * @return true on success; false otherwise
 772    */
 773   bool remove(const std::string &key) throw(Error)
 774   {
 775     if (key.empty())
 776     {
 777       throw(Error("the key supplied is empty!", false));
 778     }
 779     memcached_return rc= memcached_delete(&memc, key.c_str(), key.length(), 0);
 780     return (rc == MEMCACHED_SUCCESS);
 781   }
 782
 783   /**
 784    * Delete an object from the server specified by the key given.
 785    *
 786    * @param[in] key key of object to delete
 787    * @param[in] expiration time to delete the object after
 788    * @return true on success; false otherwise
 789    */
 790   bool remove(const std::string &key,
 791               time_t expiration) throw(Error)
 792   {
 793     if (key.empty())
 794     {
 795       throw(Error("the key supplied is empty!", false));
 796     }
 797     memcached_return rc= memcached_delete(&memc,
 798                                           key.c_str(),
 799                                           key.length(),
 800                                           expiration);
 801     return (rc == MEMCACHED_SUCCESS);
 802   }
 803
 804   /**
 805    * Delete an object from the server specified by the key given.
 806    *
 807    * @param[in] master_key specifies server to remove object from
 808    * @param[in] key key of object to delete
 809    * @return true on success; false otherwise
 810    */
 811   bool removeByKey(const std::string &master_key,
 812                    const std::string &key) throw(Error)
 813   {
 814     if (master_key.empty() || key.empty())
 815     {
 816       throw(Error("the master key or key supplied is empty!", false));
 817     }
 818     memcached_return rc= memcached_delete_by_key(&memc,
 819                                                  master_key.c_str(),
 820                                                  master_key.length(),
 821                                                  key.c_str(),
 822                                                  key.length(),
 823                                                  0);
 824     return (rc == MEMCACHED_SUCCESS);
 825   }
 826
 827   /**
 828    * Delete an object from the server specified by the key given.
 829    *
 830    * @param[in] master_key specifies server to remove object from
 831    * @param[in] key key of object to delete
 832    * @param[in] expiration time to delete the object after
 833    * @return true on success; false otherwise
 834    */
 835   bool removeByKey(const std::string &master_key,
 836                    const std::string &key,
 837                    time_t expiration) throw(Error)
 838   {
 839     if (master_key.empty() || key.empty())
 840     {
 841       throw(Error("the master key or key supplied is empty!", false));
 842     }
 843     memcached_return rc= memcached_delete_by_key(&memc,
 844                                                  master_key.c_str(),
 845                                                  master_key.length(),
 846                                                  key.c_str(),
 847                                                  key.length(),
 848                                                  expiration);
 849     return (rc == MEMCACHED_SUCCESS);
 850   }
 851
 852   /**
 853    * Wipe the contents of memcached servers.
 854    *
 855    * @param[in] expiration time to wait until wiping contents of
 856    *                       memcached servers
 857    * @return true on success; false otherwise
 858    */
 859   bool flush(time_t expiration)
 860   {
 861     memcached_return rc= memcached_flush(&memc, expiration);
 862     return (rc == MEMCACHED_SUCCESS);
 863   }
 864
 865   /**
 866    * Callback function for result sets. It passes the result
 867    * sets to the list of functions provided.
 868    *
 869    * @param[in] callback list of callback functions
 870    * @param[in] context pointer to memory reference that is
 871    *                    supplied to the calling function
 872    * @param[in] num_of_callbacks number of callback functions
 873    * @return true on success; false otherwise
 874    */
 875   bool fetchExecute(memcached_execute_function *callback,
 876                     void *context,
 877                     unsigned int num_of_callbacks)
 878   {
 879     memcached_return rc= memcached_fetch_execute(&memc,
 880                                                  callback,
 881                                                  context,
 882                                                  num_of_callbacks);
 883     return (rc == MEMCACHED_SUCCESS);
 884   }
 885
 886   /**
 887    * Get the library version string.
 888    * @return std::string containing a copy of the library version string.
 889    */
 890   const std::string libVersion() const
 891   {
 892     const char *ver= memcached_lib_version();
 893     const std::string version(ver);
 894     return version;
 895   }
 896
 897 private:
 898
 899   std::string servers_list;
 900   memcached_st memc;
 901   memcached_server_st *servers;
 902   memcached_result_st result;
 903 };
 904
 905 }
 906
 907 #endif /* LIBMEMCACHEDPP_H */