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 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 #include <cassert>
  40
  41 /*
  42   What happens if no servers exist?
  43 */
  44 char *memcached_get(memcached_st *ptr, const char *key,
  45                     size_t key_length,
  46                     size_t *value_length,
  47                     uint32_t *flags,
  48                     memcached_return_t *error)
  49 {
  50   return memcached_get_by_key(ptr, NULL, 0, key, key_length, value_length,
  51                               flags, error);
  52 }
  53
  54 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
  55                                                      const char *group_key,
  56                                                      size_t group_key_length,
  57                                                      const char * const *keys,
  58                                                      const size_t *key_length,
  59                                                      size_t number_of_keys,
  60                                                      bool mget_mode);
  61
  62 char *memcached_get_by_key(memcached_st *ptr,
  63                            const char *group_key,
  64                            size_t group_key_length,
  65                            const char *key, size_t key_length,
  66                            size_t *value_length,
  67                            uint32_t *flags,
  68                            memcached_return_t *error)
  69 {
  70   unlikely (ptr->flags.use_udp)
  71   {
  72     if (value_length)
  73       *value_length= 0;
  74
  75     *error= memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT);
  76     return NULL;
  77   }
  78
  79   uint64_t query_id= ptr->query_id;
  80   (void)query_id;
  81
  82   /* Request the key */
  83   *error= memcached_mget_by_key_real(ptr, group_key, group_key_length,
  84                                      (const char * const *)&key,
  85                                      &key_length, 1, false);
  86   assert(ptr->query_id == query_id +1);
  87
  88
  89   if (memcached_failed(*error))
  90   {
  91     if (memcached_has_current_error(*ptr)) // Find the most accurate error
  92     {
  93       *error= memcached_last_error(ptr);
  94     }
  95
  96     if (value_length)
  97       *value_length= 0;
  98
  99     return NULL;
 100   }
 101
 102   char *value= memcached_fetch(ptr, NULL, NULL,
 103                                value_length, flags, error);
 104   assert(ptr->query_id == query_id +1);
 105
 106   /* This is for historical reasons */
 107   if (*error == MEMCACHED_END)
 108     *error= MEMCACHED_NOTFOUND;
 109
 110   if (value == NULL)
 111   {
 112     if (ptr->get_key_failure && *error == MEMCACHED_NOTFOUND)
 113     {
 114
 115       memcached_result_reset(&ptr->result);
 116       memcached_return_t rc= ptr->get_key_failure(ptr, key, key_length, &ptr->result);
 117
 118       /* On all failure drop to returning NULL */
 119       if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_BUFFERED)
 120       {
 121         if (rc == MEMCACHED_BUFFERED)
 122         {
 123           uint64_t latch; /* We use latch to track the state of the original socket */
 124           latch= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS);
 125           if (latch == 0)
 126             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 1);
 127
 128           rc= memcached_set(ptr, key, key_length,
 129                             (memcached_result_value(&ptr->result)),
 130                             (memcached_result_length(&ptr->result)),
 131                             0,
 132                             (memcached_result_flags(&ptr->result)));
 133
 134           if (rc == MEMCACHED_BUFFERED && latch == 0)
 135             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 0);
 136         }
 137         else
 138         {
 139           rc= memcached_set(ptr, key, key_length,
 140                             (memcached_result_value(&ptr->result)),
 141                             (memcached_result_length(&ptr->result)),
 142                             0,
 143                             (memcached_result_flags(&ptr->result)));
 144         }
 145
 146         if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_BUFFERED)
 147         {
 148           *error= rc;
 149           *value_length= memcached_result_length(&ptr->result);
 150           *flags= memcached_result_flags(&ptr->result);
 151           return memcached_string_c_copy(&ptr->result.value);
 152         }
 153       }
 154     }
 155     assert(ptr->query_id == query_id +1);
 156
 157     return NULL;
 158   }
 159
 160   size_t dummy_length;
 161   uint32_t dummy_flags;
 162   memcached_return_t dummy_error;
 163
 164   char *dummy_value= memcached_fetch(ptr, NULL, NULL,
 165                                      &dummy_length, &dummy_flags,
 166                                      &dummy_error);
 167   WATCHPOINT_ASSERT(dummy_length == 0);
 168   WATCHPOINT_ASSERT(dummy_value == 0);
 169   assert(ptr->query_id == query_id +1);
 170
 171   return value;
 172 }
 173
 174 memcached_return_t memcached_mget(memcached_st *ptr,
 175                                   const char * const *keys,
 176                                   const size_t *key_length,
 177                                   size_t number_of_keys)
 178 {
 179   return memcached_mget_by_key(ptr, NULL, 0, keys, key_length, number_of_keys);
 180 }
 181
 182 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 183                                              uint32_t master_server_key,
 184                                              bool is_group_key_set,
 185                                              const char * const *keys,
 186                                              const size_t *key_length,
 187                                              size_t number_of_keys,
 188                                              bool mget_mode);
 189
 190 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
 191                                                      const char *group_key,
 192                                                      size_t group_key_length,
 193                                                      const char * const *keys,
 194                                                      const size_t *key_length,
 195                                                      size_t number_of_keys,
 196                                                      bool mget_mode)
 197 {
 198   bool failures_occured_in_sending= false;
 199   const char *get_command= "get ";
 200   uint8_t get_command_length= 4;
 201   unsigned int master_server_key= (unsigned int)-1; /* 0 is a valid server id! */
 202
 203   memcached_return_t rc;
 204   if (memcached_failed(rc= initialize_query(ptr)))
 205   {
 206     return rc;
 207   }
 208
 209   unlikely (ptr->flags.use_udp)
 210   {
 211     return memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT);
 212   }
 213
 214   LIBMEMCACHED_MEMCACHED_MGET_START();
 215
 216   if (number_of_keys == 0)
 217   {
 218     return memcached_set_error(*ptr, MEMCACHED_NOTFOUND, MEMCACHED_AT, memcached_literal_param("number_of_keys was zero"));
 219   }
 220
 221   if (ptr->flags.verify_key && (memcached_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
 222   {
 223     return memcached_set_error(*ptr, MEMCACHED_BAD_KEY_PROVIDED, MEMCACHED_AT, memcached_literal_param("A bad key value was provided"));
 224   }
 225
 226   bool is_group_key_set= false;
 227   if (group_key && group_key_length)
 228   {
 229     if (ptr->flags.verify_key and (memcached_key_test((const char * const *)&group_key, &group_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
 230     {
 231       return memcached_set_error(*ptr, MEMCACHED_BAD_KEY_PROVIDED, MEMCACHED_AT, memcached_literal_param("A bad group key was provided."));
 232     }
 233
 234     master_server_key= memcached_generate_hash_with_redistribution(ptr, group_key, group_key_length);
 235     is_group_key_set= true;
 236   }
 237
 238   /*
 239     Here is where we pay for the non-block API. We need to remove any data sitting
 240     in the queue before we start our get.
 241
 242     It might be optimum to bounce the connection if count > some number.
 243   */
 244   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 245   {
 246     memcached_server_write_instance_st instance=
 247       memcached_server_instance_fetch(ptr, x);
 248
 249     if (memcached_server_response_count(instance))
 250     {
 251       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 252
 253       if (ptr->flags.no_block)
 254         (void)memcached_io_write(instance, NULL, 0, true);
 255
 256       while(memcached_server_response_count(instance))
 257         (void)memcached_response(instance, buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 258     }
 259   }
 260
 261   if (ptr->flags.binary_protocol)
 262   {
 263     return binary_mget_by_key(ptr, master_server_key, is_group_key_set, keys,
 264                               key_length, number_of_keys, mget_mode);
 265   }
 266
 267   if (ptr->flags.support_cas)
 268   {
 269     get_command= "gets ";
 270     get_command_length= 5;
 271   }
 272
 273   /*
 274     If a server fails we warn about errors and start all over with sending keys
 275     to the server.
 276   */
 277   WATCHPOINT_ASSERT(rc == MEMCACHED_SUCCESS);
 278   size_t hosts_connected= 0;
 279   for (uint32_t x= 0; x < number_of_keys; x++)
 280   {
 281     memcached_server_write_instance_st instance;
 282     uint32_t server_key;
 283
 284     if (is_group_key_set)
 285     {
 286       server_key= master_server_key;
 287     }
 288     else
 289     {
 290       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 291     }
 292
 293     instance= memcached_server_instance_fetch(ptr, server_key);
 294
 295     struct libmemcached_io_vector_st vector[]=
 296     {
 297       { get_command_length, get_command },
 298       { memcached_array_size(ptr->prefix_key), memcached_array_string(ptr->prefix_key) },
 299       { key_length[x], keys[x] },
 300       { 1, " " }
 301     };
 302
 303
 304     if (memcached_server_response_count(instance) == 0)
 305     {
 306       rc= memcached_connect(instance);
 307
 308       if (memcached_failed(rc))
 309       {
 310         memcached_set_error(*instance, rc, MEMCACHED_AT);
 311         continue;
 312       }
 313       hosts_connected++;
 314
 315       if ((memcached_io_writev(instance, vector, 4, false)) == -1)
 316       {
 317         failures_occured_in_sending= true;
 318         continue;
 319       }
 320       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 321       memcached_server_response_increment(instance);
 322       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 323     }
 324     else
 325     {
 326       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == -1)
 327       {
 328         memcached_server_response_reset(instance);
 329         failures_occured_in_sending= true;
 330         continue;
 331       }
 332     }
 333   }
 334
 335   if (hosts_connected == 0)
 336   {
 337     LIBMEMCACHED_MEMCACHED_MGET_END();
 338
 339     if (memcached_failed(rc))
 340       return rc;
 341
 342     return memcached_set_error(*ptr, MEMCACHED_NO_SERVERS, MEMCACHED_AT);
 343   }
 344
 345
 346   /*
 347     Should we muddle on if some servers are dead?
 348   */
 349   bool success_happened= false;
 350   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 351   {
 352     memcached_server_write_instance_st instance=
 353       memcached_server_instance_fetch(ptr, x);
 354
 355     if (memcached_server_response_count(instance))
 356     {
 357       /* We need to do something about non-connnected hosts in the future */
 358       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 359       {
 360         failures_occured_in_sending= true;
 361       }
 362       else
 363       {
 364         success_happened= true;
 365       }
 366     }
 367   }
 368
 369   LIBMEMCACHED_MEMCACHED_MGET_END();
 370
 371   if (failures_occured_in_sending && success_happened)
 372   {
 373     return MEMCACHED_SOME_ERRORS;
 374   }
 375
 376   if (success_happened)
 377     return MEMCACHED_SUCCESS;
 378
 379   return MEMCACHED_FAILURE; // Complete failure occurred
 380 }
 381
 382 memcached_return_t memcached_mget_by_key(memcached_st *ptr,
 383                                          const char *group_key,
 384                                          size_t group_key_length,
 385                                          const char * const *keys,
 386                                          const size_t *key_length,
 387                                          size_t number_of_keys)
 388 {
 389   return memcached_mget_by_key_real(ptr, group_key, group_key_length, keys,
 390                                     key_length, number_of_keys, true);
 391 }
 392
 393 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 394                                           const char * const *keys,
 395                                           const size_t *key_length,
 396                                           size_t number_of_keys,
 397                                           memcached_execute_fn *callback,
 398                                           void *context,
 399                                           unsigned int number_of_callbacks)
 400 {
 401   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 402                                        number_of_keys, callback,
 403                                        context, number_of_callbacks);
 404 }
 405
 406 memcached_return_t memcached_mget_execute_by_key(memcached_st *ptr,
 407                                                  const char *group_key,
 408                                                  size_t group_key_length,
 409                                                  const char * const *keys,
 410                                                  const size_t *key_length,
 411                                                  size_t number_of_keys,
 412                                                  memcached_execute_fn *callback,
 413                                                  void *context,
 414                                                  unsigned int number_of_callbacks)
 415 {
 416   if ((ptr->flags.binary_protocol) == 0)
 417     return MEMCACHED_NOT_SUPPORTED;
 418
 419   memcached_return_t rc;
 420   memcached_callback_st *original_callbacks= ptr->callbacks;
 421   memcached_callback_st cb= {
 422     callback,
 423     context,
 424     number_of_callbacks
 425   };
 426
 427   ptr->callbacks= &cb;
 428   rc= memcached_mget_by_key(ptr, group_key, group_key_length, keys,
 429                             key_length, number_of_keys);
 430   ptr->callbacks= original_callbacks;
 431   return rc;
 432 }
 433
 434 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 435                                              uint32_t master_server_key,
 436                                              bool is_group_key_set,
 437                                              const char * const *keys,
 438                                              const size_t *key_length,
 439                                              size_t number_of_keys, bool mget_mode)
 440 {
 441   memcached_return_t rc= MEMCACHED_NOTFOUND;
 442
 443   bool flush= (number_of_keys == 1);
 444
 445   /*
 446     If a server fails we warn about errors and start all over with sending keys
 447     to the server.
 448   */
 449   for (uint32_t x= 0; x < number_of_keys; ++x)
 450   {
 451     uint32_t server_key;
 452
 453     if (is_group_key_set)
 454     {
 455       server_key= master_server_key;
 456     }
 457     else
 458     {
 459       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 460     }
 461
 462     memcached_server_write_instance_st instance= memcached_server_instance_fetch(ptr, server_key);
 463
 464     if (memcached_server_response_count(instance) == 0)
 465     {
 466       rc= memcached_connect(instance);
 467       if (memcached_failed(rc))
 468         continue;
 469     }
 470
 471     protocol_binary_request_getk request= { }; //= {.bytes= {0}};
 472     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 473     if (mget_mode)
 474       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 475     else
 476       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 477
 478     memcached_return_t vk;
 479     vk= memcached_validate_key_length(key_length[x],
 480                                       ptr->flags.binary_protocol);
 481     unlikely (vk != MEMCACHED_SUCCESS)
 482     {
 483       if (x > 0)
 484       {
 485         memcached_io_reset(instance);
 486       }
 487
 488       return vk;
 489     }
 490
 491     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key)));
 492     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 493     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + memcached_array_size(ptr->prefix_key)));
 494
 495     struct libmemcached_io_vector_st vector[]=
 496     {
 497       { sizeof(request.bytes), request.bytes },
 498       { memcached_array_size(ptr->prefix_key), memcached_array_string(ptr->prefix_key) },
 499       { key_length[x], keys[x] }
 500     };
 501
 502     if (memcached_io_writev(instance, vector, 3, flush) == -1)
 503     {
 504       memcached_server_response_reset(instance);
 505       rc= MEMCACHED_SOME_ERRORS;
 506       continue;
 507     }
 508
 509     /* We just want one pending response per server */
 510     memcached_server_response_reset(instance);
 511     memcached_server_response_increment(instance);
 512     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 513     {
 514       rc= MEMCACHED_SOME_ERRORS;
 515     }
 516   }
 517
 518   if (mget_mode)
 519   {
 520     /*
 521       Send a noop command to flush the buffers
 522     */
 523     protocol_binary_request_noop request= {}; //= {.bytes= {0}};
 524     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 525     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 526     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 527
 528     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 529     {
 530       memcached_server_write_instance_st instance=
 531         memcached_server_instance_fetch(ptr, x);
 532
 533       if (memcached_server_response_count(instance))
 534       {
 535         if (memcached_io_write(instance, NULL, 0, true) == -1)
 536         {
 537           memcached_server_response_reset(instance);
 538           memcached_io_reset(instance);
 539           rc= MEMCACHED_SOME_ERRORS;
 540         }
 541
 542         if (memcached_io_write(instance, request.bytes,
 543                                sizeof(request.bytes), true) == -1)
 544         {
 545           memcached_server_response_reset(instance);
 546           memcached_io_reset(instance);
 547           rc= MEMCACHED_SOME_ERRORS;
 548         }
 549       }
 550     }
 551   }
 552
 553
 554   return rc;
 555 }
 556
 557 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 558                                                   uint32_t* hash,
 559                                                   bool* dead_servers,
 560                                                   const char *const *keys,
 561                                                   const size_t *key_length,
 562                                                   size_t number_of_keys)
 563 {
 564   memcached_return_t rc= MEMCACHED_NOTFOUND;
 565   uint32_t start= 0;
 566   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 567
 568   if (randomize_read)
 569     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 570
 571   /* Loop for each replica */
 572   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 573   {
 574     bool success= true;
 575
 576     for (uint32_t x= 0; x < number_of_keys; ++x)
 577     {
 578       if (hash[x] == memcached_server_count(ptr))
 579         continue; /* Already successfully sent */
 580
 581       uint32_t server= hash[x] + replica;
 582
 583       /* In case of randomized reads */
 584       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 585         server += start;
 586
 587       while (server >= memcached_server_count(ptr))
 588         server -= memcached_server_count(ptr);
 589
 590       if (dead_servers[server])
 591         continue;
 592
 593       memcached_server_write_instance_st instance= memcached_server_instance_fetch(ptr, server);
 594
 595       if (memcached_server_response_count(instance) == 0)
 596       {
 597         rc= memcached_connect(instance);
 598         if (memcached_failed(rc))
 599         {
 600           memcached_io_reset(instance);
 601           dead_servers[server]= true;
 602           success= false;
 603           continue;
 604         }
 605       }
 606
 607       protocol_binary_request_getk request= {};
 608       request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 609       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 610       request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key)));
 611       request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 612       request.message.header.request.bodylen= htonl((uint32_t)(key_length[x] + memcached_array_size(ptr->prefix_key)));
 613
 614       /*
 615        * We need to disable buffering to actually know that the request was
 616        * successfully sent to the server (so that we should expect a result
 617        * back). It would be nice to do this in buffered mode, but then it
 618        * would be complex to handle all error situations if we got to send
 619        * some of the messages, and then we failed on writing out some others
 620        * and we used the callback interface from memcached_mget_execute so
 621        * that we might have processed some of the responses etc. For now,
 622        * just make sure we work _correctly_
 623      */
 624       struct libmemcached_io_vector_st vector[]=
 625       {
 626         { sizeof(request.bytes), request.bytes },
 627         { memcached_array_size(ptr->prefix_key), memcached_array_string(ptr->prefix_key) },
 628         { key_length[x], keys[x] }
 629       };
 630
 631       if (memcached_io_writev(instance, vector, 3, true) == -1)
 632       {
 633         memcached_io_reset(instance);
 634         dead_servers[server]= true;
 635         success= false;
 636         continue;
 637       }
 638
 639       memcached_server_response_increment(instance);
 640       hash[x]= memcached_server_count(ptr);
 641     }
 642
 643     if (success)
 644       break;
 645   }
 646
 647   return rc;
 648 }
 649
 650 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 651                                              uint32_t master_server_key,
 652                                              bool is_group_key_set,
 653                                              const char * const *keys,
 654                                              const size_t *key_length,
 655                                              size_t number_of_keys,
 656                                              bool mget_mode)
 657 {
 658   if (ptr->number_of_replicas == 0)
 659   {
 660     return simple_binary_mget(ptr, master_server_key, is_group_key_set,
 661                               keys, key_length, number_of_keys, mget_mode);
 662   }
 663
 664   uint32_t* hash= static_cast<uint32_t*>(libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys));
 665   bool* dead_servers= static_cast<bool*>(libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool)));
 666
 667   if (hash == NULL || dead_servers == NULL)
 668   {
 669     libmemcached_free(ptr, hash);
 670     libmemcached_free(ptr, dead_servers);
 671     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 672   }
 673
 674   if (is_group_key_set)
 675   {
 676     for (size_t x= 0; x < number_of_keys; x++)
 677     {
 678       hash[x]= master_server_key;
 679     }
 680   }
 681   else
 682   {
 683     for (size_t x= 0; x < number_of_keys; x++)
 684     {
 685       hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 686     }
 687   }
 688
 689   memcached_return_t rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 690                                                  key_length, number_of_keys);
 691
 692   WATCHPOINT_IFERROR(rc);
 693   libmemcached_free(ptr, hash);
 694   libmemcached_free(ptr, dead_servers);
 695
 696   return MEMCACHED_SUCCESS;
 697 }