git.m6w6.name Git - m6w6/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   uint32_t x;
 148   memcached_return_t rc= MEMCACHED_NOTFOUND;
 149   const char *get_command= "get ";
 150   uint8_t get_command_length= 4;
 151   unsigned int master_server_key= (unsigned int)-1; /* 0 is a valid server id! */
 152   bool is_master_key_set= false;
 153
 154   unlikely (ptr->flags.use_udp)
 155     return MEMCACHED_NOT_SUPPORTED;
 156
 157   LIBMEMCACHED_MEMCACHED_MGET_START();
 158
 159   if (number_of_keys == 0)
 160     return MEMCACHED_NOTFOUND;
 161
 162   if (memcached_server_count(ptr) == 0)
 163     return MEMCACHED_NO_SERVERS;
 164
 165   if (ptr->flags.verify_key && (memcached_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
 166     return MEMCACHED_BAD_KEY_PROVIDED;
 167
 168   if (master_key && master_key_length)
 169   {
 170     if (ptr->flags.verify_key && (memcached_key_test((const char * const *)&master_key, &master_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
 171       return MEMCACHED_BAD_KEY_PROVIDED;
 172     master_server_key= memcached_generate_hash_with_redistribution(ptr, master_key, master_key_length);
 173     is_master_key_set= true;
 174   }
 175
 176   /*
 177     Here is where we pay for the non-block API. We need to remove any data sitting
 178     in the queue before we start our get.
 179
 180     It might be optimum to bounce the connection if count > some number.
 181   */
 182   for (x= 0; x < memcached_server_count(ptr); x++)
 183   {
 184     memcached_server_write_instance_st instance=
 185       memcached_server_instance_fetch(ptr, x);
 186
 187     if (memcached_server_response_count(instance))
 188     {
 189       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 190
 191       if (ptr->flags.no_block)
 192         (void)memcached_io_write(instance, NULL, 0, true);
 193
 194       while(memcached_server_response_count(instance))
 195         (void)memcached_response(instance, buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 196     }
 197   }
 198
 199   if (ptr->flags.binary_protocol)
 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   if (ptr->flags.support_cas)
 204   {
 205     get_command= "gets ";
 206     get_command_length= 5;
 207   }
 208
 209   /*
 210     If a server fails we warn about errors and start all over with sending keys
 211     to the server.
 212   */
 213   for (x= 0; x < number_of_keys; x++)
 214   {
 215     memcached_server_write_instance_st instance;
 216     uint32_t server_key;
 217
 218     if (is_master_key_set)
 219     {
 220       server_key= master_server_key;
 221     }
 222     else
 223     {
 224       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 225     }
 226
 227     instance= memcached_server_instance_fetch(ptr, server_key);
 228
 229     if (memcached_server_response_count(instance) == 0)
 230     {
 231       rc= memcached_connect(instance);
 232
 233       if (rc != MEMCACHED_SUCCESS)
 234         continue;
 235
 236       if ((memcached_io_write(instance, get_command, get_command_length, false)) == -1)
 237       {
 238         rc= MEMCACHED_SOME_ERRORS;
 239         continue;
 240       }
 241       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 242       memcached_server_response_increment(instance);
 243       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 244     }
 245
 246     struct __write_vector_st vector[]=
 247     {
 248       { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 249       { .length= key_length[x], .buffer= keys[x] },
 250       { .length= 1, .buffer= " " }
 251     };
 252
 253     if ((memcached_io_writev(instance, vector, 3, false)) == -1)
 254     {
 255       memcached_server_response_reset(instance);
 256       rc= MEMCACHED_SOME_ERRORS;
 257       continue;
 258     }
 259   }
 260
 261   /*
 262     Should we muddle on if some servers are dead?
 263   */
 264   for (x= 0; x < memcached_server_count(ptr); x++)
 265   {
 266     memcached_server_write_instance_st instance=
 267       memcached_server_instance_fetch(ptr, x);
 268
 269     if (memcached_server_response_count(instance))
 270     {
 271       /* We need to do something about non-connnected hosts in the future */
 272       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 273       {
 274         rc= MEMCACHED_SOME_ERRORS;
 275       }
 276     }
 277   }
 278
 279   LIBMEMCACHED_MEMCACHED_MGET_END();
 280   return rc;
 281 }
 282
 283 memcached_return_t memcached_mget_by_key(memcached_st *ptr,
 284                                          const char *master_key,
 285                                          size_t master_key_length,
 286                                          const char * const *keys,
 287                                          const size_t *key_length,
 288                                          size_t number_of_keys)
 289 {
 290   return memcached_mget_by_key_real(ptr, master_key, master_key_length, keys,
 291                                     key_length, number_of_keys, true);
 292 }
 293
 294 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 295                                           const char * const *keys,
 296                                           const size_t *key_length,
 297                                           size_t number_of_keys,
 298                                           memcached_execute_fn *callback,
 299                                           void *context,
 300                                           unsigned int number_of_callbacks)
 301 {
 302   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 303                                        number_of_keys, callback,
 304                                        context, number_of_callbacks);
 305 }
 306
 307 memcached_return_t memcached_mget_execute_by_key(memcached_st *ptr,
 308                                                  const char *master_key,
 309                                                  size_t master_key_length,
 310                                                  const char * const *keys,
 311                                                  const size_t *key_length,
 312                                                  size_t number_of_keys,
 313                                                  memcached_execute_fn *callback,
 314                                                  void *context,
 315                                                  unsigned int number_of_callbacks)
 316 {
 317   if ((ptr->flags.binary_protocol) == 0)
 318     return MEMCACHED_NOT_SUPPORTED;
 319
 320   memcached_return_t rc;
 321   memcached_callback_st *original_callbacks= ptr->callbacks;
 322   memcached_callback_st cb= {
 323     .callback= callback,
 324     .context= context,
 325     .number_of_callback= number_of_callbacks
 326   };
 327
 328   ptr->callbacks= &cb;
 329   rc= memcached_mget_by_key(ptr, master_key, master_key_length, keys,
 330                             key_length, number_of_keys);
 331   ptr->callbacks= original_callbacks;
 332   return rc;
 333 }
 334
 335 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 336                                              uint32_t master_server_key,
 337                                              bool is_master_key_set,
 338                                              const char * const *keys,
 339                                              const size_t *key_length,
 340                                              size_t number_of_keys, bool mget_mode)
 341 {
 342   memcached_return_t rc= MEMCACHED_NOTFOUND;
 343   uint32_t x;
 344
 345   int flush= number_of_keys == 1;
 346
 347   /*
 348     If a server fails we warn about errors and start all over with sending keys
 349     to the server.
 350   */
 351   for (x= 0; x < number_of_keys; x++)
 352   {
 353     uint32_t server_key;
 354     memcached_server_write_instance_st instance;
 355
 356     if (is_master_key_set)
 357     {
 358       server_key= master_server_key;
 359     }
 360     else
 361     {
 362       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 363     }
 364
 365     instance= memcached_server_instance_fetch(ptr, server_key);
 366
 367     if (memcached_server_response_count(instance) == 0)
 368     {
 369       rc= memcached_connect(instance);
 370       if (rc != MEMCACHED_SUCCESS)
 371         continue;
 372     }
 373
 374     protocol_binary_request_getk request= {.bytes= {0}};
 375     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 376     if (mget_mode)
 377       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 378     else
 379       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 380
 381     memcached_return_t vk;
 382     vk= memcached_validate_key_length(key_length[x],
 383                                       ptr->flags.binary_protocol);
 384     unlikely (vk != MEMCACHED_SUCCESS)
 385     {
 386       if (x > 0)
 387       {
 388         memcached_io_reset(instance);
 389       }
 390
 391       return vk;
 392     }
 393
 394     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + ptr->prefix_key_length));
 395     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 396     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + ptr->prefix_key_length));
 397
 398     if ((memcached_io_write(instance, request.bytes, sizeof(request.bytes), false) == -1) ||
 399         (memcached_io_write(instance, ptr->prefix_key, ptr->prefix_key_length, false) == -1) ||
 400         (memcached_io_write(instance, keys[x], key_length[x], flush) == -1))
 401     {
 402       memcached_server_response_reset(instance);
 403       rc= MEMCACHED_SOME_ERRORS;
 404       continue;
 405     }
 406
 407     /* We just want one pending response per server */
 408     memcached_server_response_reset(instance);
 409     memcached_server_response_increment(instance);
 410     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 411     {
 412       rc= MEMCACHED_SOME_ERRORS;
 413     }
 414   }
 415
 416   if (mget_mode)
 417   {
 418     /*
 419      * Send a noop command to flush the buffers
 420    */
 421     protocol_binary_request_noop request= {.bytes= {0}};
 422     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 423     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 424     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 425
 426     for (x= 0; x < memcached_server_count(ptr); x++)
 427     {
 428       memcached_server_write_instance_st instance=
 429         memcached_server_instance_fetch(ptr, x);
 430
 431       if (memcached_server_response_count(instance))
 432       {
 433         if (memcached_io_write(instance, NULL, 0, true) == -1)
 434         {
 435           memcached_server_response_reset(instance);
 436           memcached_io_reset(instance);
 437           rc= MEMCACHED_SOME_ERRORS;
 438         }
 439
 440         if (memcached_io_write(instance, request.bytes,
 441                                sizeof(request.bytes), true) == -1)
 442         {
 443           memcached_server_response_reset(instance);
 444           memcached_io_reset(instance);
 445           rc= MEMCACHED_SOME_ERRORS;
 446         }
 447       }
 448     }
 449   }
 450
 451
 452   return rc;
 453 }
 454
 455 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 456                                                   uint32_t* hash,
 457                                                   bool* dead_servers,
 458                                                   const char *const *keys,
 459                                                   const size_t *key_length,
 460                                                   size_t number_of_keys)
 461 {
 462   memcached_return_t rc= MEMCACHED_NOTFOUND;
 463   uint32_t x, start= 0;
 464   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 465
 466   if (randomize_read)
 467     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 468
 469   /* Loop for each replica */
 470   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 471   {
 472     bool success= true;
 473
 474     for (x= 0; x < number_of_keys; ++x)
 475     {
 476       memcached_server_write_instance_st instance;
 477
 478       if (hash[x] == memcached_server_count(ptr))
 479         continue; /* Already successfully sent */
 480
 481       uint32_t server= hash[x] + replica;
 482
 483       /* In case of randomized reads */
 484       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 485         server += start;
 486
 487       while (server >= memcached_server_count(ptr))
 488         server -= memcached_server_count(ptr);
 489
 490       if (dead_servers[server])
 491         continue;
 492
 493       instance= memcached_server_instance_fetch(ptr, server);
 494
 495       if (memcached_server_response_count(instance) == 0)
 496       {
 497         rc= memcached_connect(instance);
 498         if (rc != MEMCACHED_SUCCESS)
 499         {
 500           memcached_io_reset(instance);
 501           dead_servers[server]= true;
 502           success= false;
 503           continue;
 504         }
 505       }
 506
 507       protocol_binary_request_getk request= {
 508         .message.header.request= {
 509           .magic= PROTOCOL_BINARY_REQ,
 510           .opcode= PROTOCOL_BINARY_CMD_GETK,
 511           .keylen= htons((uint16_t)(key_length[x] + ptr->prefix_key_length)),
 512           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 513           .bodylen= htonl((uint32_t)(key_length[x] + ptr->prefix_key_length))
 514         }
 515       };
 516
 517       /*
 518        * We need to disable buffering to actually know that the request was
 519        * successfully sent to the server (so that we should expect a result
 520        * back). It would be nice to do this in buffered mode, but then it
 521        * would be complex to handle all error situations if we got to send
 522        * some of the messages, and then we failed on writing out some others
 523        * and we used the callback interface from memcached_mget_execute so
 524        * that we might have processed some of the responses etc. For now,
 525        * just make sure we work _correctly_
 526      */
 527       struct __write_vector_st vector[]=
 528       {
 529         { .length= sizeof(request.bytes), .buffer= request.bytes },
 530         { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 531         { .length= key_length[x], .buffer= keys[x] }
 532       };
 533
 534       if (memcached_io_writev(instance, vector, 3, true) == -1)
 535       {
 536         memcached_io_reset(instance);
 537         dead_servers[server]= true;
 538         success= false;
 539         continue;
 540       }
 541
 542       memcached_server_response_increment(instance);
 543       hash[x]= memcached_server_count(ptr);
 544     }
 545
 546     if (success)
 547       break;
 548   }
 549
 550   return rc;
 551 }
 552
 553 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 554                                              uint32_t master_server_key,
 555                                              bool is_master_key_set,
 556                                              const char * const *keys,
 557                                              const size_t *key_length,
 558                                              size_t number_of_keys,
 559                                              bool mget_mode)
 560 {
 561   memcached_return_t rc;
 562
 563   if (ptr->number_of_replicas == 0)
 564   {
 565     rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
 566                            keys, key_length, number_of_keys, mget_mode);
 567   }
 568   else
 569   {
 570     uint32_t* hash;
 571     bool* dead_servers;
 572
 573     hash= libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 574     dead_servers= libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 575
 576     if (hash == NULL || dead_servers == NULL)
 577     {
 578       libmemcached_free(ptr, hash);
 579       libmemcached_free(ptr, dead_servers);
 580       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 581     }
 582
 583     if (is_master_key_set)
 584     {
 585       for (size_t x= 0; x < number_of_keys; x++)
 586       {
 587         hash[x]= master_server_key;
 588       }
 589     }
 590     else
 591     {
 592       for (size_t x= 0; x < number_of_keys; x++)
 593       {
 594         hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 595       }
 596     }
 597
 598     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 599                                 key_length, number_of_keys);
 600
 601     libmemcached_free(ptr, hash);
 602     libmemcached_free(ptr, dead_servers);
 603
 604     return MEMCACHED_SUCCESS;
 605   }
 606
 607   return rc;
 608 }