git.m6w6.name Git - awesomized/libmemcached/blob - libmemcached/get.cc

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  Libmemcached library
   4  *
   5  *  Copyright (C) 2011-2012 Data Differential, http://datadifferential.com/
   6  *  Copyright (C) 2006-2009 Brian Aker All rights reserved.
   7  *
   8  *  Redistribution and use in source and binary forms, with or without
   9  *  modification, are permitted provided that the following conditions are
  10  *  met:
  11  *
  12  *      * Redistributions of source code must retain the above copyright
  13  *  notice, this list of conditions and the following disclaimer.
  14  *
  15  *      * Redistributions in binary form must reproduce the above
  16  *  copyright notice, this list of conditions and the following disclaimer
  17  *  in the documentation and/or other materials provided with the
  18  *  distribution.
  19  *
  20  *      * The names of its contributors may not be used to endorse or
  21  *  promote products derived from this software without specific prior
  22  *  written permission.
  23  *
  24  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  25  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  26  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  27  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  28  *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  30  *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  34  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  *
  36  */
  37
  38 #include <libmemcached/common.h>
  39
  40 /*
  41   What happens if no servers exist?
  42 */
  43 char *memcached_get(memcached_st *ptr, const char *key,
  44                     size_t key_length,
  45                     size_t *value_length,
  46                     uint32_t *flags,
  47                     memcached_return_t *error)
  48 {
  49   return memcached_get_by_key(ptr, NULL, 0, key, key_length, value_length,
  50                               flags, error);
  51 }
  52
  53 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
  54                                                      const char *group_key,
  55                                                      size_t group_key_length,
  56                                                      const char * const *keys,
  57                                                      const size_t *key_length,
  58                                                      size_t number_of_keys,
  59                                                      bool mget_mode);
  60
  61 char *memcached_get_by_key(memcached_st *shell,
  62                            const char *group_key,
  63                            size_t group_key_length,
  64                            const char *key, size_t key_length,
  65                            size_t *value_length,
  66                            uint32_t *flags,
  67                            memcached_return_t *error)
  68 {
  69   Memcached* ptr= memcached2Memcached(shell);
  70   memcached_return_t unused;
  71   if (error == NULL)
  72   {
  73     error= &unused;
  74   }
  75
  76   uint64_t query_id= 0;
  77   if (ptr)
  78   {
  79     query_id= ptr->query_id;
  80   }
  81
  82   /* Request the key */
  83   *error= memcached_mget_by_key_real(ptr, group_key, group_key_length,
  84                                      (const char * const *)&key, &key_length,
  85                                      1, false);
  86   if (ptr)
  87   {
  88     assert_msg(ptr->query_id == query_id +1, "Programmer error, the query_id was not incremented.");
  89   }
  90
  91   if (memcached_failed(*error))
  92   {
  93     if (ptr)
  94     {
  95       if (memcached_has_current_error(*ptr)) // Find the most accurate error
  96       {
  97         *error= memcached_last_error(ptr);
  98       }
  99     }
 100
 101     if (value_length)
 102     {
 103       *value_length= 0;
 104     }
 105
 106     return NULL;
 107   }
 108
 109   char *value= memcached_fetch(ptr, NULL, NULL,
 110                                value_length, flags, error);
 111   assert_msg(ptr->query_id == query_id +1, "Programmer error, the query_id was not incremented.");
 112
 113   /* This is for historical reasons */
 114   if (*error == MEMCACHED_END)
 115   {
 116     *error= MEMCACHED_NOTFOUND;
 117   }
 118
 119   if (value == NULL)
 120   {
 121     if (ptr->get_key_failure and *error == MEMCACHED_NOTFOUND)
 122     {
 123       memcached_result_st key_failure_result;
 124       memcached_result_st* result_ptr= memcached_result_create(ptr, &key_failure_result);
 125       memcached_return_t rc= ptr->get_key_failure(ptr, key, key_length, result_ptr);
 126
 127       /* On all failure drop to returning NULL */
 128       if (rc == MEMCACHED_SUCCESS or rc == MEMCACHED_BUFFERED)
 129       {
 130         if (rc == MEMCACHED_BUFFERED)
 131         {
 132           uint64_t latch; /* We use latch to track the state of the original socket */
 133           latch= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS);
 134           if (latch == 0)
 135           {
 136             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 1);
 137           }
 138
 139           rc= memcached_set(ptr, key, key_length,
 140                             (memcached_result_value(result_ptr)),
 141                             (memcached_result_length(result_ptr)),
 142                             0,
 143                             (memcached_result_flags(result_ptr)));
 144
 145           if (rc == MEMCACHED_BUFFERED and latch == 0)
 146           {
 147             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 0);
 148           }
 149         }
 150         else
 151         {
 152           rc= memcached_set(ptr, key, key_length,
 153                             (memcached_result_value(result_ptr)),
 154                             (memcached_result_length(result_ptr)),
 155                             0,
 156                             (memcached_result_flags(result_ptr)));
 157         }
 158
 159         if (rc == MEMCACHED_SUCCESS or rc == MEMCACHED_BUFFERED)
 160         {
 161           *error= rc;
 162           *value_length= memcached_result_length(result_ptr);
 163           *flags= memcached_result_flags(result_ptr);
 164           char *result_value=  memcached_string_take_value(&result_ptr->value);
 165           memcached_result_free(result_ptr);
 166
 167           return result_value;
 168         }
 169       }
 170
 171       memcached_result_free(result_ptr);
 172     }
 173     assert_msg(ptr->query_id == query_id +1, "Programmer error, the query_id was not incremented.");
 174
 175     return NULL;
 176   }
 177
 178   return value;
 179 }
 180
 181 memcached_return_t memcached_mget(memcached_st *ptr,
 182                                   const char * const *keys,
 183                                   const size_t *key_length,
 184                                   size_t number_of_keys)
 185 {
 186   return memcached_mget_by_key(ptr, NULL, 0, keys, key_length, number_of_keys);
 187 }
 188
 189 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 190                                              uint32_t master_server_key,
 191                                              bool is_group_key_set,
 192                                              const char * const *keys,
 193                                              const size_t *key_length,
 194                                              size_t number_of_keys,
 195                                              bool mget_mode);
 196
 197 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
 198                                                      const char *group_key,
 199                                                      size_t group_key_length,
 200                                                      const char * const *keys,
 201                                                      const size_t *key_length,
 202                                                      size_t number_of_keys,
 203                                                      bool mget_mode)
 204 {
 205   bool failures_occured_in_sending= false;
 206   const char *get_command= "get";
 207   uint8_t get_command_length= 3;
 208   unsigned int master_server_key= (unsigned int)-1; /* 0 is a valid server id! */
 209
 210   memcached_return_t rc;
 211   if (memcached_failed(rc= initialize_query(ptr, true)))
 212   {
 213     return rc;
 214   }
 215
 216   if (memcached_is_udp(ptr))
 217   {
 218     return memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT);
 219   }
 220
 221   LIBMEMCACHED_MEMCACHED_MGET_START();
 222
 223   if (number_of_keys == 0)
 224   {
 225     return memcached_set_error(*ptr, MEMCACHED_NOTFOUND, MEMCACHED_AT, memcached_literal_param("number_of_keys was zero"));
 226   }
 227
 228   if (memcached_failed(memcached_key_test(*ptr, keys, key_length, number_of_keys)))
 229   {
 230     return memcached_last_error(ptr);
 231   }
 232
 233   bool is_group_key_set= false;
 234   if (group_key and group_key_length)
 235   {
 236     master_server_key= memcached_generate_hash_with_redistribution(ptr, group_key, group_key_length);
 237     is_group_key_set= true;
 238   }
 239
 240   /*
 241     Here is where we pay for the non-block API. We need to remove any data sitting
 242     in the queue before we start our get.
 243
 244     It might be optimum to bounce the connection if count > some number.
 245   */
 246   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 247   {
 248     org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, x);
 249
 250     if (instance->response_count())
 251     {
 252       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 253
 254       if (ptr->flags.no_block)
 255       {
 256         memcached_io_write(instance);
 257       }
 258
 259       while(instance->response_count())
 260       {
 261         (void)memcached_response(instance, buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 262       }
 263     }
 264   }
 265
 266   if (memcached_is_binary(ptr))
 267   {
 268     return binary_mget_by_key(ptr, master_server_key, is_group_key_set, keys,
 269                               key_length, number_of_keys, mget_mode);
 270   }
 271
 272   if (ptr->flags.support_cas)
 273   {
 274     get_command= "gets";
 275     get_command_length= 4;
 276   }
 277
 278   /*
 279     If a server fails we warn about errors and start all over with sending keys
 280     to the server.
 281   */
 282   WATCHPOINT_ASSERT(rc == MEMCACHED_SUCCESS);
 283   size_t hosts_connected= 0;
 284   for (uint32_t x= 0; x < number_of_keys; x++)
 285   {
 286     uint32_t server_key;
 287
 288     if (is_group_key_set)
 289     {
 290       server_key= master_server_key;
 291     }
 292     else
 293     {
 294       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 295     }
 296
 297     org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, server_key);
 298
 299     libmemcached_io_vector_st vector[]=
 300     {
 301       { get_command, get_command_length },
 302       { memcached_literal_param(" ") },
 303       { memcached_array_string(ptr->_namespace), memcached_array_size(ptr->_namespace) },
 304       { keys[x], key_length[x] }
 305     };
 306
 307
 308     if (instance->response_count() == 0)
 309     {
 310       rc= memcached_connect(instance);
 311
 312       if (memcached_failed(rc))
 313       {
 314         memcached_set_error(*instance, rc, MEMCACHED_AT);
 315         continue;
 316       }
 317       hosts_connected++;
 318
 319       if ((memcached_io_writev(instance, vector, 1, false)) == false)
 320       {
 321         failures_occured_in_sending= true;
 322         continue;
 323       }
 324       WATCHPOINT_ASSERT(instance->cursor_active_ == 0);
 325       memcached_instance_response_increment(instance);
 326       WATCHPOINT_ASSERT(instance->cursor_active_ == 1);
 327     }
 328
 329     {
 330       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == false)
 331       {
 332         memcached_instance_response_reset(instance);
 333         failures_occured_in_sending= true;
 334         continue;
 335       }
 336     }
 337   }
 338
 339   if (hosts_connected == 0)
 340   {
 341     LIBMEMCACHED_MEMCACHED_MGET_END();
 342
 343     if (memcached_failed(rc))
 344     {
 345       return rc;
 346     }
 347
 348     return memcached_set_error(*ptr, MEMCACHED_NO_SERVERS, MEMCACHED_AT);
 349   }
 350
 351
 352   /*
 353     Should we muddle on if some servers are dead?
 354   */
 355   bool success_happened= false;
 356   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 357   {
 358     org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, x);
 359
 360     if (instance->response_count())
 361     {
 362       /* We need to do something about non-connnected hosts in the future */
 363       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 364       {
 365         failures_occured_in_sending= true;
 366       }
 367       else
 368       {
 369         success_happened= true;
 370       }
 371     }
 372   }
 373
 374   LIBMEMCACHED_MEMCACHED_MGET_END();
 375
 376   if (failures_occured_in_sending and success_happened)
 377   {
 378     return MEMCACHED_SOME_ERRORS;
 379   }
 380
 381   if (success_happened)
 382   {
 383     return MEMCACHED_SUCCESS;
 384   }
 385
 386   return MEMCACHED_FAILURE; // Complete failure occurred
 387 }
 388
 389 memcached_return_t memcached_mget_by_key(memcached_st *shell,
 390                                          const char *group_key,
 391                                          size_t group_key_length,
 392                                          const char * const *keys,
 393                                          const size_t *key_length,
 394                                          size_t number_of_keys)
 395 {
 396   Memcached* ptr= memcached2Memcached(shell);
 397   return memcached_mget_by_key_real(ptr, group_key, group_key_length, keys,
 398                                     key_length, number_of_keys, true);
 399 }
 400
 401 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 402                                           const char * const *keys,
 403                                           const size_t *key_length,
 404                                           size_t number_of_keys,
 405                                           memcached_execute_fn *callback,
 406                                           void *context,
 407                                           unsigned int number_of_callbacks)
 408 {
 409   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 410                                        number_of_keys, callback,
 411                                        context, number_of_callbacks);
 412 }
 413
 414 memcached_return_t memcached_mget_execute_by_key(memcached_st *shell,
 415                                                  const char *group_key,
 416                                                  size_t group_key_length,
 417                                                  const char * const *keys,
 418                                                  const size_t *key_length,
 419                                                  size_t number_of_keys,
 420                                                  memcached_execute_fn *callback,
 421                                                  void *context,
 422                                                  unsigned int number_of_callbacks)
 423 {
 424   Memcached* ptr= memcached2Memcached(shell);
 425   memcached_return_t rc;
 426   if (memcached_failed(rc= initialize_query(ptr, false)))
 427   {
 428     return rc;
 429   }
 430
 431   if (memcached_is_udp(ptr))
 432   {
 433     return memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT);
 434   }
 435
 436   if (memcached_is_binary(ptr) == false)
 437   {
 438     return memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT,
 439                                memcached_literal_param("ASCII protocol is not supported for memcached_mget_execute_by_key()"));
 440   }
 441
 442   memcached_callback_st *original_callbacks= ptr->callbacks;
 443   memcached_callback_st cb= {
 444     callback,
 445     context,
 446     number_of_callbacks
 447   };
 448
 449   ptr->callbacks= &cb;
 450   rc= memcached_mget_by_key(ptr, group_key, group_key_length, keys,
 451                             key_length, number_of_keys);
 452   ptr->callbacks= original_callbacks;
 453   return rc;
 454 }
 455
 456 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 457                                              uint32_t master_server_key,
 458                                              bool is_group_key_set,
 459                                              const char * const *keys,
 460                                              const size_t *key_length,
 461                                              size_t number_of_keys, bool mget_mode)
 462 {
 463   memcached_return_t rc= MEMCACHED_NOTFOUND;
 464
 465   bool flush= (number_of_keys == 1);
 466
 467   /*
 468     If a server fails we warn about errors and start all over with sending keys
 469     to the server.
 470   */
 471   for (uint32_t x= 0; x < number_of_keys; ++x)
 472   {
 473     uint32_t server_key;
 474
 475     if (is_group_key_set)
 476     {
 477       server_key= master_server_key;
 478     }
 479     else
 480     {
 481       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 482     }
 483
 484     org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, server_key);
 485
 486     if (instance->response_count() == 0)
 487     {
 488       rc= memcached_connect(instance);
 489       if (memcached_failed(rc))
 490       {
 491         continue;
 492       }
 493     }
 494
 495     protocol_binary_request_getk request= { }; //= {.bytes= {0}};
 496     initialize_binary_request(instance, request.message.header);
 497     if (mget_mode)
 498     {
 499       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 500     }
 501     else
 502     {
 503       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 504     }
 505
 506     memcached_return_t vk;
 507     vk= memcached_validate_key_length(key_length[x],
 508                                       ptr->flags.binary_protocol);
 509     if (vk != MEMCACHED_SUCCESS)
 510     {
 511       if (x > 0)
 512       {
 513         memcached_io_reset(instance);
 514       }
 515
 516       return vk;
 517     }
 518
 519     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->_namespace)));
 520     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 521     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + memcached_array_size(ptr->_namespace)));
 522
 523     libmemcached_io_vector_st vector[]=
 524     {
 525       { request.bytes, sizeof(request.bytes) },
 526       { memcached_array_string(ptr->_namespace), memcached_array_size(ptr->_namespace) },
 527       { keys[x], key_length[x] }
 528     };
 529
 530     if (memcached_io_writev(instance, vector, 3, flush) == false)
 531     {
 532       memcached_server_response_reset(instance);
 533       rc= MEMCACHED_SOME_ERRORS;
 534       continue;
 535     }
 536
 537     /* We just want one pending response per server */
 538     memcached_server_response_reset(instance);
 539     memcached_server_response_increment(instance);
 540     if ((x > 0 and x == ptr->io_key_prefetch) and memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 541     {
 542       rc= MEMCACHED_SOME_ERRORS;
 543     }
 544   }
 545
 546   if (mget_mode)
 547   {
 548     /*
 549       Send a noop command to flush the buffers
 550     */
 551     protocol_binary_request_noop request= {}; //= {.bytes= {0}};
 552     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 553     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 554
 555     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 556     {
 557       org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, x);
 558       initialize_binary_request(instance, request.message.header);
 559
 560       if (instance->response_count())
 561       {
 562         if (memcached_io_write(instance) == false)
 563         {
 564           memcached_instance_response_reset(instance);
 565           memcached_io_reset(instance);
 566           rc= MEMCACHED_SOME_ERRORS;
 567         }
 568
 569         if (memcached_io_write(instance, request.bytes,
 570                                sizeof(request.bytes), true) == -1)
 571         {
 572           memcached_instance_response_reset(instance);
 573           memcached_io_reset(instance);
 574           rc= MEMCACHED_SOME_ERRORS;
 575         }
 576       }
 577     }
 578   }
 579
 580
 581   return rc;
 582 }
 583
 584 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 585                                                   uint32_t* hash,
 586                                                   bool* dead_servers,
 587                                                   const char *const *keys,
 588                                                   const size_t *key_length,
 589                                                   size_t number_of_keys)
 590 {
 591   memcached_return_t rc= MEMCACHED_NOTFOUND;
 592   uint32_t start= 0;
 593   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 594
 595   if (randomize_read)
 596   {
 597     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 598   }
 599
 600   /* Loop for each replica */
 601   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 602   {
 603     bool success= true;
 604
 605     for (uint32_t x= 0; x < number_of_keys; ++x)
 606     {
 607       if (hash[x] == memcached_server_count(ptr))
 608         continue; /* Already successfully sent */
 609
 610       uint32_t server= hash[x] + replica;
 611
 612       /* In case of randomized reads */
 613       if (randomize_read and ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 614       {
 615         server+= start;
 616       }
 617
 618       while (server >= memcached_server_count(ptr))
 619       {
 620         server -= memcached_server_count(ptr);
 621       }
 622
 623       if (dead_servers[server])
 624       {
 625         continue;
 626       }
 627
 628       org::libmemcached::Instance* instance= memcached_instance_fetch(ptr, server);
 629
 630       if (instance->response_count() == 0)
 631       {
 632         rc= memcached_connect(instance);
 633
 634         if (memcached_failed(rc))
 635         {
 636           memcached_io_reset(instance);
 637           dead_servers[server]= true;
 638           success= false;
 639           continue;
 640         }
 641       }
 642
 643       protocol_binary_request_getk request= {};
 644       initialize_binary_request(instance, request.message.header);
 645       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 646       request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->_namespace)));
 647       request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 648       request.message.header.request.bodylen= htonl((uint32_t)(key_length[x] + memcached_array_size(ptr->_namespace)));
 649
 650       /*
 651        * We need to disable buffering to actually know that the request was
 652        * successfully sent to the server (so that we should expect a result
 653        * back). It would be nice to do this in buffered mode, but then it
 654        * would be complex to handle all error situations if we got to send
 655        * some of the messages, and then we failed on writing out some others
 656        * and we used the callback interface from memcached_mget_execute so
 657        * that we might have processed some of the responses etc. For now,
 658        * just make sure we work _correctly_
 659      */
 660       libmemcached_io_vector_st vector[]=
 661       {
 662         { request.bytes, sizeof(request.bytes) },
 663         { memcached_array_string(ptr->_namespace), memcached_array_size(ptr->_namespace) },
 664         { keys[x], key_length[x] }
 665       };
 666
 667       if (memcached_io_writev(instance, vector, 3, true) == false)
 668       {
 669         memcached_io_reset(instance);
 670         dead_servers[server]= true;
 671         success= false;
 672         continue;
 673       }
 674
 675       memcached_server_response_increment(instance);
 676       hash[x]= memcached_server_count(ptr);
 677     }
 678
 679     if (success)
 680     {
 681       break;
 682     }
 683   }
 684
 685   return rc;
 686 }
 687
 688 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 689                                              uint32_t master_server_key,
 690                                              bool is_group_key_set,
 691                                              const char * const *keys,
 692                                              const size_t *key_length,
 693                                              size_t number_of_keys,
 694                                              bool mget_mode)
 695 {
 696   if (ptr->number_of_replicas == 0)
 697   {
 698     return simple_binary_mget(ptr, master_server_key, is_group_key_set,
 699                               keys, key_length, number_of_keys, mget_mode);
 700   }
 701
 702   uint32_t* hash= libmemcached_xvalloc(ptr, number_of_keys, uint32_t);
 703   bool* dead_servers= libmemcached_xcalloc(ptr, memcached_server_count(ptr), bool);
 704
 705   if (hash == NULL or dead_servers == NULL)
 706   {
 707     libmemcached_free(ptr, hash);
 708     libmemcached_free(ptr, dead_servers);
 709     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 710   }
 711
 712   if (is_group_key_set)
 713   {
 714     for (size_t x= 0; x < number_of_keys; x++)
 715     {
 716       hash[x]= master_server_key;
 717     }
 718   }
 719   else
 720   {
 721     for (size_t x= 0; x < number_of_keys; x++)
 722     {
 723       hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 724     }
 725   }
 726
 727   memcached_return_t rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 728                                                  key_length, number_of_keys);
 729
 730   WATCHPOINT_IFERROR(rc);
 731   libmemcached_free(ptr, hash);
 732   libmemcached_free(ptr, dead_servers);
 733
 734   return MEMCACHED_SUCCESS;
 735 }