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   unsigned int 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(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     if (memcached_server_response_count(&ptr->hosts[x]))
 185     {
 186       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 187
 188       if (ptr->flags.no_block)
 189         (void)memcached_io_write(&ptr->hosts[x], NULL, 0, 1);
 190
 191       while(memcached_server_response_count(&ptr->hosts[x]))
 192         (void)memcached_response(&ptr->hosts[x], buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 193     }
 194   }
 195
 196   if (ptr->flags.binary_protocol)
 197     return binary_mget_by_key(ptr, master_server_key, is_master_key_set, keys,
 198                               key_length, number_of_keys, mget_mode);
 199
 200   if (ptr->flags.support_cas)
 201   {
 202     get_command= "gets ";
 203     get_command_length= 5;
 204   }
 205
 206   /*
 207     If a server fails we warn about errors and start all over with sending keys
 208     to the server.
 209   */
 210   for (x= 0; x < number_of_keys; x++)
 211   {
 212     memcached_server_instance_st *instance;
 213     uint32_t server_key;
 214
 215     if (is_master_key_set)
 216     {
 217       server_key= master_server_key;
 218     }
 219     else
 220     {
 221       server_key= memcached_generate_hash(ptr, keys[x], key_length[x]);
 222     }
 223
 224     instance= memcached_server_instance_fetch(ptr, server_key);
 225
 226     if (memcached_server_response_count(instance) == 0)
 227     {
 228       rc= memcached_connect(instance);
 229
 230       if (rc != MEMCACHED_SUCCESS)
 231         continue;
 232
 233       if ((memcached_io_write(instance, get_command, get_command_length, 0)) == -1)
 234       {
 235         rc= MEMCACHED_SOME_ERRORS;
 236         continue;
 237       }
 238       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 239       memcached_server_response_increment(instance);
 240       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 241     }
 242
 243     /* Only called when we have a prefix key */
 244     if (ptr->prefix_key[0] != 0)
 245     {
 246       if ((memcached_io_write(instance, ptr->prefix_key, ptr->prefix_key_length, 0)) == -1)
 247       {
 248         memcached_server_response_reset(instance);
 249         rc= MEMCACHED_SOME_ERRORS;
 250         continue;
 251       }
 252     }
 253
 254     if ((memcached_io_write(instance, keys[x], key_length[x], 0)) == -1)
 255     {
 256       memcached_server_response_reset(instance);
 257       rc= MEMCACHED_SOME_ERRORS;
 258       continue;
 259     }
 260
 261     if ((memcached_io_write(instance, " ", 1, 0)) == -1)
 262     {
 263       memcached_server_response_reset(instance);
 264       rc= MEMCACHED_SOME_ERRORS;
 265       continue;
 266     }
 267   }
 268
 269   /*
 270     Should we muddle on if some servers are dead?
 271   */
 272   for (x= 0; x < memcached_server_count(ptr); x++)
 273   {
 274     if (memcached_server_response_count(&ptr->hosts[x]))
 275     {
 276       /* We need to do something about non-connnected hosts in the future */
 277       if ((memcached_io_write(&ptr->hosts[x], "\r\n", 2, 1)) == -1)
 278       {
 279         rc= MEMCACHED_SOME_ERRORS;
 280       }
 281     }
 282   }
 283
 284   LIBMEMCACHED_MEMCACHED_MGET_END();
 285   return rc;
 286 }
 287
 288 memcached_return_t memcached_mget_by_key(memcached_st *ptr,
 289                                          const char *master_key,
 290                                          size_t master_key_length,
 291                                          const char * const *keys,
 292                                          const size_t *key_length,
 293                                          size_t number_of_keys)
 294 {
 295   return memcached_mget_by_key_real(ptr, master_key, master_key_length, keys,
 296                                     key_length, number_of_keys, true);
 297 }
 298
 299 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 300                                           const char * const *keys,
 301                                           const size_t *key_length,
 302                                           size_t number_of_keys,
 303                                           memcached_execute_fn *callback,
 304                                           void *context,
 305                                           unsigned int number_of_callbacks)
 306 {
 307   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 308                                        number_of_keys, callback,
 309                                        context, number_of_callbacks);
 310 }
 311
 312 memcached_return_t memcached_mget_execute_by_key(memcached_st *ptr,
 313                                                  const char *master_key,
 314                                                  size_t master_key_length,
 315                                                  const char * const *keys,
 316                                                  const size_t *key_length,
 317                                                  size_t number_of_keys,
 318                                                  memcached_execute_fn *callback,
 319                                                  void *context,
 320                                                  unsigned int number_of_callbacks)
 321 {
 322   if ((ptr->flags.binary_protocol) == 0)
 323     return MEMCACHED_NOT_SUPPORTED;
 324
 325   memcached_return_t rc;
 326   memcached_callback_st *original_callbacks= ptr->callbacks;
 327   memcached_callback_st cb= {
 328     .callback= callback,
 329     .context= context,
 330     .number_of_callback= number_of_callbacks
 331   };
 332
 333   ptr->callbacks= &cb;
 334   rc= memcached_mget_by_key(ptr, master_key, master_key_length, keys,
 335                             key_length, number_of_keys);
 336   ptr->callbacks= original_callbacks;
 337   return rc;
 338 }
 339
 340 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 341                                              uint32_t master_server_key,
 342                                              bool is_master_key_set,
 343                                              const char * const *keys,
 344                                              const size_t *key_length,
 345                                              size_t number_of_keys, bool mget_mode)
 346 {
 347   memcached_return_t rc= MEMCACHED_NOTFOUND;
 348   uint32_t x;
 349
 350   int flush= number_of_keys == 1;
 351
 352   /*
 353     If a server fails we warn about errors and start all over with sending keys
 354     to the server.
 355   */
 356   for (x= 0; x < number_of_keys; x++)
 357   {
 358     uint32_t server_key;
 359     memcached_server_instance_st *instance;
 360
 361     if (is_master_key_set)
 362     {
 363       server_key= master_server_key;
 364     }
 365     else
 366     {
 367       server_key= memcached_generate_hash(ptr, keys[x], key_length[x]);
 368     }
 369
 370     instance= memcached_server_instance_fetch(ptr, server_key);
 371
 372     if (memcached_server_response_count(instance) == 0)
 373     {
 374       rc= memcached_connect(instance);
 375       if (rc != MEMCACHED_SUCCESS)
 376         continue;
 377     }
 378
 379     protocol_binary_request_getk request= {.bytes= {0}};
 380     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 381     if (mget_mode)
 382       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 383     else
 384       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 385
 386     memcached_return_t vk;
 387     vk= memcached_validate_key_length(key_length[x],
 388                                       ptr->flags.binary_protocol);
 389     unlikely (vk != MEMCACHED_SUCCESS)
 390     {
 391       if (x > 0)
 392       {
 393         memcached_io_reset(instance);
 394       }
 395
 396       return vk;
 397     }
 398
 399     request.message.header.request.keylen= htons((uint16_t)key_length[x]);
 400     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 401     request.message.header.request.bodylen= htonl((uint32_t) key_length[x]);
 402
 403     if ((memcached_io_write(instance, request.bytes,
 404                             sizeof(request.bytes), 0) == -1) ||
 405         (memcached_io_write(instance, keys[x],
 406                             key_length[x], (char) flush) == -1))
 407     {
 408       memcached_server_response_reset(instance);
 409       rc= MEMCACHED_SOME_ERRORS;
 410       continue;
 411     }
 412
 413     /* We just want one pending response per server */
 414     memcached_server_response_reset(instance);
 415     memcached_server_response_increment(instance);
 416     if ((x > 0 && x == ptr->io_key_prefetch) &&
 417         memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 418       rc= MEMCACHED_SOME_ERRORS;
 419   }
 420
 421   if (mget_mode)
 422   {
 423     /*
 424      * Send a noop command to flush the buffers
 425    */
 426     protocol_binary_request_noop request= {.bytes= {0}};
 427     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 428     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 429     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 430
 431     for (x= 0; x < memcached_server_count(ptr); x++)
 432       if (memcached_server_response_count(&ptr->hosts[x]))
 433       {
 434         if (memcached_io_write(&ptr->hosts[x], NULL, 0, 1) == -1)
 435         {
 436           memcached_server_response_reset(&ptr->hosts[x]);
 437           memcached_io_reset(&ptr->hosts[x]);
 438           rc= MEMCACHED_SOME_ERRORS;
 439         }
 440
 441         if (memcached_io_write(&ptr->hosts[x], request.bytes,
 442                                sizeof(request.bytes), 1) == -1)
 443         {
 444           memcached_server_response_reset(&ptr->hosts[x]);
 445           memcached_io_reset(&ptr->hosts[x]);
 446           rc= MEMCACHED_SOME_ERRORS;
 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       if (hash[x] == memcached_server_count(ptr))
 477         continue; /* Already successfully sent */
 478
 479       uint32_t server= hash[x] + replica;
 480
 481       /* In case of randomized reads */
 482       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 483         server += start;
 484
 485       while (server >= memcached_server_count(ptr))
 486         server -= memcached_server_count(ptr);
 487
 488       if (dead_servers[server])
 489         continue;
 490
 491       if (memcached_server_response_count(&ptr->hosts[server]) == 0)
 492       {
 493         rc= memcached_connect(&ptr->hosts[server]);
 494         if (rc != MEMCACHED_SUCCESS)
 495         {
 496           memcached_io_reset(&ptr->hosts[server]);
 497           dead_servers[server]= true;
 498           success= false;
 499           continue;
 500         }
 501       }
 502
 503       protocol_binary_request_getk request= {
 504         .message.header.request= {
 505           .magic= PROTOCOL_BINARY_REQ,
 506           .opcode= PROTOCOL_BINARY_CMD_GETK,
 507           .keylen= htons((uint16_t)key_length[x]),
 508           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 509           .bodylen= htonl((uint32_t)key_length[x])
 510         }
 511       };
 512
 513       /*
 514        * We need to disable buffering to actually know that the request was
 515        * successfully sent to the server (so that we should expect a result
 516        * back). It would be nice to do this in buffered mode, but then it
 517        * would be complex to handle all error situations if we got to send
 518        * some of the messages, and then we failed on writing out some others
 519        * and we used the callback interface from memcached_mget_execute so
 520        * that we might have processed some of the responses etc. For now,
 521        * just make sure we work _correctly_
 522      */
 523       if ((memcached_io_write(&ptr->hosts[server], request.bytes,
 524                               sizeof(request.bytes), 0) == -1) ||
 525           (memcached_io_write(&ptr->hosts[server], keys[x],
 526                               key_length[x], 1) == -1))
 527       {
 528         memcached_io_reset(&ptr->hosts[server]);
 529         dead_servers[server]= true;
 530         success= false;
 531         continue;
 532       }
 533
 534       memcached_server_response_increment(&ptr->hosts[server]);
 535       hash[x]= memcached_server_count(ptr);
 536     }
 537
 538     if (success)
 539       break;
 540   }
 541
 542   return rc;
 543 }
 544
 545 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 546                                              uint32_t master_server_key,
 547                                              bool is_master_key_set,
 548                                              const char * const *keys,
 549                                              const size_t *key_length,
 550                                              size_t number_of_keys,
 551                                              bool mget_mode)
 552 {
 553   memcached_return_t rc;
 554
 555   if (ptr->number_of_replicas == 0)
 556   {
 557     rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
 558                            keys, key_length, number_of_keys, mget_mode);
 559   }
 560   else
 561   {
 562     uint32_t* hash;
 563     bool* dead_servers;
 564
 565     hash= ptr->call_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 566     dead_servers= ptr->call_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 567
 568     if (hash == NULL || dead_servers == NULL)
 569     {
 570       ptr->call_free(ptr, hash);
 571       ptr->call_free(ptr, dead_servers);
 572       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 573     }
 574
 575     if (is_master_key_set)
 576       for (unsigned int x= 0; x < number_of_keys; x++)
 577         hash[x]= master_server_key;
 578     else
 579       for (unsigned int x= 0; x < number_of_keys; x++)
 580         hash[x]= memcached_generate_hash(ptr, keys[x], key_length[x]);
 581
 582     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 583                                 key_length, number_of_keys);
 584
 585     ptr->call_free(ptr, hash);
 586     ptr->call_free(ptr, dead_servers);
 587
 588     return MEMCACHED_SUCCESS;
 589   }
 590
 591   return rc;
 592 }