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

   1 /* LibMemcached
   2  * Copyright (C) 2006-2009 Brian Aker
   3  * All rights reserved.
   4  *
   5  * Use and distribution licensed under the BSD license.  See
   6  * the COPYING file in the parent directory for full text.
   7  *
   8  * Summary: Get functions for libmemcached
   9  *
  10  */
  11
  12 #include "common.h"
  13
  14 /*
  15   What happens if no servers exist?
  16 */
  17 char *memcached_get(memcached_st *ptr, const char *key,
  18                     size_t key_length,
  19                     size_t *value_length,
  20                     uint32_t *flags,
  21                     memcached_return_t *error)
  22 {
  23   return memcached_get_by_key(ptr, NULL, 0, key, key_length, value_length,
  24                               flags, error);
  25 }
  26
  27 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
  28                                                      const char *master_key,
  29                                                      size_t master_key_length,
  30                                                      const char * const *keys,
  31                                                      const size_t *key_length,
  32                                                      size_t number_of_keys,
  33                                                      bool mget_mode);
  34
  35 char *memcached_get_by_key(memcached_st *ptr,
  36                            const char *master_key,
  37                            size_t master_key_length,
  38                            const char *key, size_t key_length,
  39                            size_t *value_length,
  40                            uint32_t *flags,
  41                            memcached_return_t *error)
  42 {
  43   char *value;
  44   size_t dummy_length;
  45   uint32_t dummy_flags;
  46   memcached_return_t dummy_error;
  47
  48   unlikely (ptr->flags.use_udp)
  49   {
  50     *error= MEMCACHED_NOT_SUPPORTED;
  51     return NULL;
  52   }
  53
  54   /* Request the key */
  55   *error= memcached_mget_by_key_real(ptr, master_key, master_key_length,
  56                                      (const char * const *)&key,
  57                                      &key_length, 1, false);
  58
  59   value= memcached_fetch(ptr, NULL, NULL,
  60                          value_length, flags, error);
  61   /* This is for historical reasons */
  62   if (*error == MEMCACHED_END)
  63     *error= MEMCACHED_NOTFOUND;
  64
  65   if (value == NULL)
  66   {
  67     if (ptr->get_key_failure && *error == MEMCACHED_NOTFOUND)
  68     {
  69       memcached_return_t rc;
  70
  71       memcached_result_reset(&ptr->result);
  72       rc= ptr->get_key_failure(ptr, key, key_length, &ptr->result);
  73
  74       /* On all failure drop to returning NULL */
  75       if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_BUFFERED)
  76       {
  77         if (rc == MEMCACHED_BUFFERED)
  78         {
  79           uint64_t latch; /* We use latch to track the state of the original socket */
  80           latch= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS);
  81           if (latch == 0)
  82             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 1);
  83
  84           rc= memcached_set(ptr, key, key_length,
  85                             (memcached_result_value(&ptr->result)),
  86                             (memcached_result_length(&ptr->result)),
  87                             0,
  88                             (memcached_result_flags(&ptr->result)));
  89
  90           if (rc == MEMCACHED_BUFFERED && latch == 0)
  91             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 0);
  92         }
  93         else
  94         {
  95           rc= memcached_set(ptr, key, key_length,
  96                             (memcached_result_value(&ptr->result)),
  97                             (memcached_result_length(&ptr->result)),
  98                             0,
  99                             (memcached_result_flags(&ptr->result)));
 100         }
 101
 102         if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_BUFFERED)
 103         {
 104           *error= rc;
 105           *value_length= memcached_result_length(&ptr->result);
 106           *flags= memcached_result_flags(&ptr->result);
 107           return memcached_string_c_copy(&ptr->result.value);
 108         }
 109       }
 110     }
 111
 112     return NULL;
 113   }
 114
 115   (void)memcached_fetch(ptr, NULL, NULL,
 116                         &dummy_length, &dummy_flags,
 117                         &dummy_error);
 118   WATCHPOINT_ASSERT(dummy_length == 0);
 119
 120   return value;
 121 }
 122
 123 memcached_return_t memcached_mget(memcached_st *ptr,
 124                                   const char * const *keys,
 125                                   const size_t *key_length,
 126                                   size_t number_of_keys)
 127 {
 128   return memcached_mget_by_key(ptr, NULL, 0, keys, key_length, number_of_keys);
 129 }
 130
 131 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 132                                              uint32_t master_server_key,
 133                                              bool is_master_key_set,
 134                                              const char * const *keys,
 135                                              const size_t *key_length,
 136                                              size_t number_of_keys,
 137                                              bool mget_mode);
 138
 139 static memcached_return_t memcached_mget_by_key_real(memcached_st *ptr,
 140                                                      const char *master_key,
 141                                                      size_t master_key_length,
 142                                                      const char * const *keys,
 143                                                      const size_t *key_length,
 144                                                      size_t number_of_keys,
 145                                                      bool mget_mode)
 146 {
 147   bool failures_occured_in_sending= false;
 148   const char *get_command= "get ";
 149   uint8_t get_command_length= 4;
 150   unsigned int master_server_key= (unsigned int)-1; /* 0 is a valid server id! */
 151   bool is_master_key_set= false;
 152
 153   unlikely (ptr->flags.use_udp)
 154     return MEMCACHED_NOT_SUPPORTED;
 155
 156   LIBMEMCACHED_MEMCACHED_MGET_START();
 157
 158   if (number_of_keys == 0)
 159     return MEMCACHED_NOTFOUND;
 160
 161   if (memcached_server_count(ptr) == 0)
 162     return MEMCACHED_NO_SERVERS;
 163
 164   if (ptr->flags.verify_key && (memcached_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
 165     return MEMCACHED_BAD_KEY_PROVIDED;
 166
 167   if (master_key && master_key_length)
 168   {
 169     if (ptr->flags.verify_key && (memcached_key_test((const char * const *)&master_key, &master_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
 170       return MEMCACHED_BAD_KEY_PROVIDED;
 171     master_server_key= memcached_generate_hash_with_redistribution(ptr, master_key, master_key_length);
 172     is_master_key_set= true;
 173   }
 174
 175   /*
 176     Here is where we pay for the non-block API. We need to remove any data sitting
 177     in the queue before we start our get.
 178
 179     It might be optimum to bounce the connection if count > some number.
 180   */
 181   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 182   {
 183     memcached_server_write_instance_st instance=
 184       memcached_server_instance_fetch(ptr, x);
 185
 186     if (memcached_server_response_count(instance))
 187     {
 188       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 189
 190       if (ptr->flags.no_block)
 191         (void)memcached_io_write(instance, NULL, 0, true);
 192
 193       while(memcached_server_response_count(instance))
 194         (void)memcached_response(instance, buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 195     }
 196   }
 197
 198   if (ptr->flags.binary_protocol)
 199   {
 200     return binary_mget_by_key(ptr, master_server_key, is_master_key_set, keys,
 201                               key_length, number_of_keys, mget_mode);
 202   }
 203
 204   if (ptr->flags.support_cas)
 205   {
 206     get_command= "gets ";
 207     get_command_length= 5;
 208   }
 209
 210   /*
 211     If a server fails we warn about errors and start all over with sending keys
 212     to the server.
 213   */
 214   memcached_return_t rc= MEMCACHED_SUCCESS;
 215   size_t hosts_connected= 0;
 216   for (uint32_t x= 0; x < number_of_keys; x++)
 217   {
 218     memcached_server_write_instance_st instance;
 219     uint32_t server_key;
 220
 221     if (is_master_key_set)
 222     {
 223       server_key= master_server_key;
 224     }
 225     else
 226     {
 227       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 228     }
 229
 230     instance= memcached_server_instance_fetch(ptr, server_key);
 231
 232     struct libmemcached_io_vector_st vector[]=
 233     {
 234       { .length= get_command_length, .buffer= get_command },
 235       { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 236       { .length= key_length[x], .buffer= keys[x] },
 237       { .length= 1, .buffer= " " }
 238     };
 239
 240
 241     if (memcached_server_response_count(instance) == 0)
 242     {
 243       rc= memcached_connect(instance);
 244
 245       if (rc != MEMCACHED_SUCCESS)
 246       {
 247         continue;
 248       }
 249       hosts_connected++;
 250
 251       if ((memcached_io_writev(instance, vector, 4, false)) == -1)
 252       {
 253         failures_occured_in_sending= true;
 254         continue;
 255       }
 256       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 257       memcached_server_response_increment(instance);
 258       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 259     }
 260     else
 261     {
 262       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == -1)
 263       {
 264         memcached_server_response_reset(instance);
 265         failures_occured_in_sending= true;
 266         continue;
 267       }
 268     }
 269   }
 270
 271   if (hosts_connected == 0)
 272   {
 273     LIBMEMCACHED_MEMCACHED_MGET_END();
 274
 275     if (rc != MEMCACHED_SUCCESS)
 276       return rc;
 277
 278     return MEMCACHED_NO_SERVERS;
 279   }
 280
 281
 282   /*
 283     Should we muddle on if some servers are dead?
 284   */
 285   bool success_happened= false;
 286   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 287   {
 288     memcached_server_write_instance_st instance=
 289       memcached_server_instance_fetch(ptr, x);
 290
 291     if (memcached_server_response_count(instance))
 292     {
 293       /* We need to do something about non-connnected hosts in the future */
 294       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 295       {
 296         failures_occured_in_sending= true;
 297       }
 298       else
 299       {
 300         success_happened= true;
 301       }
 302     }
 303   }
 304
 305   LIBMEMCACHED_MEMCACHED_MGET_END();
 306
 307   if (failures_occured_in_sending && success_happened)
 308     return MEMCACHED_SOME_ERRORS;
 309
 310   if (success_happened)
 311     return MEMCACHED_SUCCESS;
 312
 313   return MEMCACHED_FAILURE;
 314 }
 315
 316 memcached_return_t memcached_mget_by_key(memcached_st *ptr,
 317                                          const char *master_key,
 318                                          size_t master_key_length,
 319                                          const char * const *keys,
 320                                          const size_t *key_length,
 321                                          size_t number_of_keys)
 322 {
 323   return memcached_mget_by_key_real(ptr, master_key, master_key_length, keys,
 324                                     key_length, number_of_keys, true);
 325 }
 326
 327 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 328                                           const char * const *keys,
 329                                           const size_t *key_length,
 330                                           size_t number_of_keys,
 331                                           memcached_execute_fn *callback,
 332                                           void *context,
 333                                           unsigned int number_of_callbacks)
 334 {
 335   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 336                                        number_of_keys, callback,
 337                                        context, number_of_callbacks);
 338 }
 339
 340 memcached_return_t memcached_mget_execute_by_key(memcached_st *ptr,
 341                                                  const char *master_key,
 342                                                  size_t master_key_length,
 343                                                  const char * const *keys,
 344                                                  const size_t *key_length,
 345                                                  size_t number_of_keys,
 346                                                  memcached_execute_fn *callback,
 347                                                  void *context,
 348                                                  unsigned int number_of_callbacks)
 349 {
 350   if ((ptr->flags.binary_protocol) == 0)
 351     return MEMCACHED_NOT_SUPPORTED;
 352
 353   memcached_return_t rc;
 354   memcached_callback_st *original_callbacks= ptr->callbacks;
 355   memcached_callback_st cb= {
 356     .callback= callback,
 357     .context= context,
 358     .number_of_callback= number_of_callbacks
 359   };
 360
 361   ptr->callbacks= &cb;
 362   rc= memcached_mget_by_key(ptr, master_key, master_key_length, keys,
 363                             key_length, number_of_keys);
 364   ptr->callbacks= original_callbacks;
 365   return rc;
 366 }
 367
 368 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 369                                              uint32_t master_server_key,
 370                                              bool is_master_key_set,
 371                                              const char * const *keys,
 372                                              const size_t *key_length,
 373                                              size_t number_of_keys, bool mget_mode)
 374 {
 375   memcached_return_t rc= MEMCACHED_NOTFOUND;
 376
 377   bool flush= (number_of_keys == 1);
 378
 379   /*
 380     If a server fails we warn about errors and start all over with sending keys
 381     to the server.
 382   */
 383   for (uint32_t x= 0; x < number_of_keys; ++x)
 384   {
 385     uint32_t server_key;
 386     memcached_server_write_instance_st instance;
 387
 388     if (is_master_key_set)
 389     {
 390       server_key= master_server_key;
 391     }
 392     else
 393     {
 394       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 395     }
 396
 397     instance= memcached_server_instance_fetch(ptr, server_key);
 398
 399     if (memcached_server_response_count(instance) == 0)
 400     {
 401       rc= memcached_connect(instance);
 402       if (rc != MEMCACHED_SUCCESS)
 403         continue;
 404     }
 405
 406     protocol_binary_request_getk request= {.bytes= {0}};
 407     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 408     if (mget_mode)
 409       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 410     else
 411       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 412
 413     memcached_return_t vk;
 414     vk= memcached_validate_key_length(key_length[x],
 415                                       ptr->flags.binary_protocol);
 416     unlikely (vk != MEMCACHED_SUCCESS)
 417     {
 418       if (x > 0)
 419       {
 420         memcached_io_reset(instance);
 421       }
 422
 423       return vk;
 424     }
 425
 426     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key)));
 427     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 428     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + memcached_array_size(ptr->prefix_key)));
 429
 430     struct libmemcached_io_vector_st vector[]=
 431     {
 432       { .length= sizeof(request.bytes), .buffer= request.bytes },
 433       { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 434       { .length= key_length[x], .buffer= keys[x] }
 435     };
 436
 437     if (memcached_io_writev(instance, vector, 3, flush) == -1)
 438     {
 439       memcached_server_response_reset(instance);
 440       rc= MEMCACHED_SOME_ERRORS;
 441       continue;
 442     }
 443
 444     /* We just want one pending response per server */
 445     memcached_server_response_reset(instance);
 446     memcached_server_response_increment(instance);
 447     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 448     {
 449       rc= MEMCACHED_SOME_ERRORS;
 450     }
 451   }
 452
 453   if (mget_mode)
 454   {
 455     /*
 456      * Send a noop command to flush the buffers
 457    */
 458     protocol_binary_request_noop request= {.bytes= {0}};
 459     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 460     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 461     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 462
 463     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 464     {
 465       memcached_server_write_instance_st instance=
 466         memcached_server_instance_fetch(ptr, x);
 467
 468       if (memcached_server_response_count(instance))
 469       {
 470         if (memcached_io_write(instance, NULL, 0, true) == -1)
 471         {
 472           memcached_server_response_reset(instance);
 473           memcached_io_reset(instance);
 474           rc= MEMCACHED_SOME_ERRORS;
 475         }
 476
 477         if (memcached_io_write(instance, request.bytes,
 478                                sizeof(request.bytes), true) == -1)
 479         {
 480           memcached_server_response_reset(instance);
 481           memcached_io_reset(instance);
 482           rc= MEMCACHED_SOME_ERRORS;
 483         }
 484       }
 485     }
 486   }
 487
 488
 489   return rc;
 490 }
 491
 492 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 493                                                   uint32_t* hash,
 494                                                   bool* dead_servers,
 495                                                   const char *const *keys,
 496                                                   const size_t *key_length,
 497                                                   size_t number_of_keys)
 498 {
 499   memcached_return_t rc= MEMCACHED_NOTFOUND;
 500   uint32_t start= 0;
 501   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 502
 503   if (randomize_read)
 504     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 505
 506   /* Loop for each replica */
 507   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 508   {
 509     bool success= true;
 510
 511     for (uint32_t x= 0; x < number_of_keys; ++x)
 512     {
 513       memcached_server_write_instance_st instance;
 514
 515       if (hash[x] == memcached_server_count(ptr))
 516         continue; /* Already successfully sent */
 517
 518       uint32_t server= hash[x] + replica;
 519
 520       /* In case of randomized reads */
 521       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 522         server += start;
 523
 524       while (server >= memcached_server_count(ptr))
 525         server -= memcached_server_count(ptr);
 526
 527       if (dead_servers[server])
 528         continue;
 529
 530       instance= memcached_server_instance_fetch(ptr, server);
 531
 532       if (memcached_server_response_count(instance) == 0)
 533       {
 534         rc= memcached_connect(instance);
 535         if (rc != MEMCACHED_SUCCESS)
 536         {
 537           memcached_io_reset(instance);
 538           dead_servers[server]= true;
 539           success= false;
 540           continue;
 541         }
 542       }
 543
 544       protocol_binary_request_getk request= {
 545         .message.header.request= {
 546           .magic= PROTOCOL_BINARY_REQ,
 547           .opcode= PROTOCOL_BINARY_CMD_GETK,
 548           .keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key))),
 549           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 550           .bodylen= htonl((uint32_t)(key_length[x] + memcached_array_size(ptr->prefix_key)))
 551         }
 552       };
 553
 554       /*
 555        * We need to disable buffering to actually know that the request was
 556        * successfully sent to the server (so that we should expect a result
 557        * back). It would be nice to do this in buffered mode, but then it
 558        * would be complex to handle all error situations if we got to send
 559        * some of the messages, and then we failed on writing out some others
 560        * and we used the callback interface from memcached_mget_execute so
 561        * that we might have processed some of the responses etc. For now,
 562        * just make sure we work _correctly_
 563      */
 564       struct libmemcached_io_vector_st vector[]=
 565       {
 566         { .length= sizeof(request.bytes), .buffer= request.bytes },
 567         { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 568         { .length= key_length[x], .buffer= keys[x] }
 569       };
 570
 571       if (memcached_io_writev(instance, vector, 3, true) == -1)
 572       {
 573         memcached_io_reset(instance);
 574         dead_servers[server]= true;
 575         success= false;
 576         continue;
 577       }
 578
 579       memcached_server_response_increment(instance);
 580       hash[x]= memcached_server_count(ptr);
 581     }
 582
 583     if (success)
 584       break;
 585   }
 586
 587   return rc;
 588 }
 589
 590 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 591                                              uint32_t master_server_key,
 592                                              bool is_master_key_set,
 593                                              const char * const *keys,
 594                                              const size_t *key_length,
 595                                              size_t number_of_keys,
 596                                              bool mget_mode)
 597 {
 598   memcached_return_t rc;
 599
 600   if (ptr->number_of_replicas == 0)
 601   {
 602     rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
 603                            keys, key_length, number_of_keys, mget_mode);
 604   }
 605   else
 606   {
 607     uint32_t* hash;
 608     bool* dead_servers;
 609
 610     hash= libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 611     dead_servers= libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 612
 613     if (hash == NULL || dead_servers == NULL)
 614     {
 615       libmemcached_free(ptr, hash);
 616       libmemcached_free(ptr, dead_servers);
 617       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 618     }
 619
 620     if (is_master_key_set)
 621     {
 622       for (size_t x= 0; x < number_of_keys; x++)
 623       {
 624         hash[x]= master_server_key;
 625       }
 626     }
 627     else
 628     {
 629       for (size_t x= 0; x < number_of_keys; x++)
 630       {
 631         hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 632       }
 633     }
 634
 635     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 636                                 key_length, number_of_keys);
 637
 638     libmemcached_free(ptr, hash);
 639     libmemcached_free(ptr, dead_servers);
 640
 641     return MEMCACHED_SUCCESS;
 642   }
 643
 644   return rc;
 645 }