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 *group_key,
  29                                                      size_t group_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 *group_key,
  37                            size_t group_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, group_key, group_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_group_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 *group_key,
 141                                                      size_t group_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_group_key_set= false;
 152
 153   memcached_return_t rc;
 154   if ((rc= initialize_query(ptr)) != MEMCACHED_SUCCESS)
 155   {
 156     return rc;
 157   }
 158
 159   unlikely (ptr->flags.use_udp)
 160     return MEMCACHED_NOT_SUPPORTED;
 161
 162   LIBMEMCACHED_MEMCACHED_MGET_START();
 163
 164   if (number_of_keys == 0)
 165     return MEMCACHED_NOTFOUND;
 166
 167   if (ptr->flags.verify_key && (memcached_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
 168     return MEMCACHED_BAD_KEY_PROVIDED;
 169
 170   if (group_key && group_key_length)
 171   {
 172     if (ptr->flags.verify_key && (memcached_key_test((const char * const *)&group_key, &group_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
 173       return MEMCACHED_BAD_KEY_PROVIDED;
 174     master_server_key= memcached_generate_hash_with_redistribution(ptr, group_key, group_key_length);
 175     is_group_key_set= true;
 176   }
 177
 178   /*
 179     Here is where we pay for the non-block API. We need to remove any data sitting
 180     in the queue before we start our get.
 181
 182     It might be optimum to bounce the connection if count > some number.
 183   */
 184   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 185   {
 186     memcached_server_write_instance_st instance=
 187       memcached_server_instance_fetch(ptr, x);
 188
 189     if (memcached_server_response_count(instance))
 190     {
 191       char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
 192
 193       if (ptr->flags.no_block)
 194         (void)memcached_io_write(instance, NULL, 0, true);
 195
 196       while(memcached_server_response_count(instance))
 197         (void)memcached_response(instance, buffer, MEMCACHED_DEFAULT_COMMAND_SIZE, &ptr->result);
 198     }
 199   }
 200
 201   if (ptr->flags.binary_protocol)
 202   {
 203     return binary_mget_by_key(ptr, master_server_key, is_group_key_set, keys,
 204                               key_length, number_of_keys, mget_mode);
 205   }
 206
 207   if (ptr->flags.support_cas)
 208   {
 209     get_command= "gets ";
 210     get_command_length= 5;
 211   }
 212
 213   /*
 214     If a server fails we warn about errors and start all over with sending keys
 215     to the server.
 216   */
 217   WATCHPOINT_ASSERT(rc == MEMCACHED_SUCCESS);
 218   size_t hosts_connected= 0;
 219   for (uint32_t x= 0; x < number_of_keys; x++)
 220   {
 221     memcached_server_write_instance_st instance;
 222     uint32_t server_key;
 223
 224     if (is_group_key_set)
 225     {
 226       server_key= master_server_key;
 227     }
 228     else
 229     {
 230       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 231     }
 232
 233     instance= memcached_server_instance_fetch(ptr, server_key);
 234
 235     struct libmemcached_io_vector_st vector[]=
 236     {
 237       { .length= get_command_length, .buffer= get_command },
 238       { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 239       { .length= key_length[x], .buffer= keys[x] },
 240       { .length= 1, .buffer= " " }
 241     };
 242
 243
 244     if (memcached_server_response_count(instance) == 0)
 245     {
 246       rc= memcached_connect(instance);
 247
 248       if (rc != MEMCACHED_SUCCESS)
 249       {
 250         continue;
 251       }
 252       hosts_connected++;
 253
 254       if ((memcached_io_writev(instance, vector, 4, false)) == -1)
 255       {
 256         failures_occured_in_sending= true;
 257         continue;
 258       }
 259       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 260       memcached_server_response_increment(instance);
 261       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 262     }
 263     else
 264     {
 265       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == -1)
 266       {
 267         memcached_server_response_reset(instance);
 268         failures_occured_in_sending= true;
 269         continue;
 270       }
 271     }
 272   }
 273
 274   if (hosts_connected == 0)
 275   {
 276     LIBMEMCACHED_MEMCACHED_MGET_END();
 277
 278     if (rc != MEMCACHED_SUCCESS)
 279       return rc;
 280
 281     return MEMCACHED_NO_SERVERS;
 282   }
 283
 284
 285   /*
 286     Should we muddle on if some servers are dead?
 287   */
 288   bool success_happened= false;
 289   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 290   {
 291     memcached_server_write_instance_st instance=
 292       memcached_server_instance_fetch(ptr, x);
 293
 294     if (memcached_server_response_count(instance))
 295     {
 296       /* We need to do something about non-connnected hosts in the future */
 297       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 298       {
 299         failures_occured_in_sending= true;
 300       }
 301       else
 302       {
 303         success_happened= true;
 304       }
 305     }
 306   }
 307
 308   LIBMEMCACHED_MEMCACHED_MGET_END();
 309
 310   if (failures_occured_in_sending && success_happened)
 311     return MEMCACHED_SOME_ERRORS;
 312
 313   if (success_happened)
 314     return MEMCACHED_SUCCESS;
 315
 316   return MEMCACHED_FAILURE;
 317 }
 318
 319 memcached_return_t memcached_mget_by_key(memcached_st *ptr,
 320                                          const char *group_key,
 321                                          size_t group_key_length,
 322                                          const char * const *keys,
 323                                          const size_t *key_length,
 324                                          size_t number_of_keys)
 325 {
 326   return memcached_mget_by_key_real(ptr, group_key, group_key_length, keys,
 327                                     key_length, number_of_keys, true);
 328 }
 329
 330 memcached_return_t memcached_mget_execute(memcached_st *ptr,
 331                                           const char * const *keys,
 332                                           const size_t *key_length,
 333                                           size_t number_of_keys,
 334                                           memcached_execute_fn *callback,
 335                                           void *context,
 336                                           unsigned int number_of_callbacks)
 337 {
 338   return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
 339                                        number_of_keys, callback,
 340                                        context, number_of_callbacks);
 341 }
 342
 343 memcached_return_t memcached_mget_execute_by_key(memcached_st *ptr,
 344                                                  const char *group_key,
 345                                                  size_t group_key_length,
 346                                                  const char * const *keys,
 347                                                  const size_t *key_length,
 348                                                  size_t number_of_keys,
 349                                                  memcached_execute_fn *callback,
 350                                                  void *context,
 351                                                  unsigned int number_of_callbacks)
 352 {
 353   if ((ptr->flags.binary_protocol) == 0)
 354     return MEMCACHED_NOT_SUPPORTED;
 355
 356   memcached_return_t rc;
 357   memcached_callback_st *original_callbacks= ptr->callbacks;
 358   memcached_callback_st cb= {
 359     .callback= callback,
 360     .context= context,
 361     .number_of_callback= number_of_callbacks
 362   };
 363
 364   ptr->callbacks= &cb;
 365   rc= memcached_mget_by_key(ptr, group_key, group_key_length, keys,
 366                             key_length, number_of_keys);
 367   ptr->callbacks= original_callbacks;
 368   return rc;
 369 }
 370
 371 static memcached_return_t simple_binary_mget(memcached_st *ptr,
 372                                              uint32_t master_server_key,
 373                                              bool is_group_key_set,
 374                                              const char * const *keys,
 375                                              const size_t *key_length,
 376                                              size_t number_of_keys, bool mget_mode)
 377 {
 378   memcached_return_t rc= MEMCACHED_NOTFOUND;
 379
 380   bool flush= (number_of_keys == 1);
 381
 382   /*
 383     If a server fails we warn about errors and start all over with sending keys
 384     to the server.
 385   */
 386   for (uint32_t x= 0; x < number_of_keys; ++x)
 387   {
 388     uint32_t server_key;
 389     memcached_server_write_instance_st instance;
 390
 391     if (is_group_key_set)
 392     {
 393       server_key= master_server_key;
 394     }
 395     else
 396     {
 397       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 398     }
 399
 400     instance= memcached_server_instance_fetch(ptr, server_key);
 401
 402     if (memcached_server_response_count(instance) == 0)
 403     {
 404       rc= memcached_connect(instance);
 405       if (rc != MEMCACHED_SUCCESS)
 406         continue;
 407     }
 408
 409     protocol_binary_request_getk request= {.bytes= {0}};
 410     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 411     if (mget_mode)
 412       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 413     else
 414       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 415
 416     memcached_return_t vk;
 417     vk= memcached_validate_key_length(key_length[x],
 418                                       ptr->flags.binary_protocol);
 419     unlikely (vk != MEMCACHED_SUCCESS)
 420     {
 421       if (x > 0)
 422       {
 423         memcached_io_reset(instance);
 424       }
 425
 426       return vk;
 427     }
 428
 429     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key)));
 430     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 431     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + memcached_array_size(ptr->prefix_key)));
 432
 433     struct libmemcached_io_vector_st vector[]=
 434     {
 435       { .length= sizeof(request.bytes), .buffer= request.bytes },
 436       { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 437       { .length= key_length[x], .buffer= keys[x] }
 438     };
 439
 440     if (memcached_io_writev(instance, vector, 3, flush) == -1)
 441     {
 442       memcached_server_response_reset(instance);
 443       rc= MEMCACHED_SOME_ERRORS;
 444       continue;
 445     }
 446
 447     /* We just want one pending response per server */
 448     memcached_server_response_reset(instance);
 449     memcached_server_response_increment(instance);
 450     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 451     {
 452       rc= MEMCACHED_SOME_ERRORS;
 453     }
 454   }
 455
 456   if (mget_mode)
 457   {
 458     /*
 459      * Send a noop command to flush the buffers
 460    */
 461     protocol_binary_request_noop request= {.bytes= {0}};
 462     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 463     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 464     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 465
 466     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 467     {
 468       memcached_server_write_instance_st instance=
 469         memcached_server_instance_fetch(ptr, x);
 470
 471       if (memcached_server_response_count(instance))
 472       {
 473         if (memcached_io_write(instance, NULL, 0, true) == -1)
 474         {
 475           memcached_server_response_reset(instance);
 476           memcached_io_reset(instance);
 477           rc= MEMCACHED_SOME_ERRORS;
 478         }
 479
 480         if (memcached_io_write(instance, request.bytes,
 481                                sizeof(request.bytes), true) == -1)
 482         {
 483           memcached_server_response_reset(instance);
 484           memcached_io_reset(instance);
 485           rc= MEMCACHED_SOME_ERRORS;
 486         }
 487       }
 488     }
 489   }
 490
 491
 492   return rc;
 493 }
 494
 495 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 496                                                   uint32_t* hash,
 497                                                   bool* dead_servers,
 498                                                   const char *const *keys,
 499                                                   const size_t *key_length,
 500                                                   size_t number_of_keys)
 501 {
 502   memcached_return_t rc= MEMCACHED_NOTFOUND;
 503   uint32_t start= 0;
 504   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 505
 506   if (randomize_read)
 507     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 508
 509   /* Loop for each replica */
 510   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 511   {
 512     bool success= true;
 513
 514     for (uint32_t x= 0; x < number_of_keys; ++x)
 515     {
 516       memcached_server_write_instance_st instance;
 517
 518       if (hash[x] == memcached_server_count(ptr))
 519         continue; /* Already successfully sent */
 520
 521       uint32_t server= hash[x] + replica;
 522
 523       /* In case of randomized reads */
 524       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 525         server += start;
 526
 527       while (server >= memcached_server_count(ptr))
 528         server -= memcached_server_count(ptr);
 529
 530       if (dead_servers[server])
 531         continue;
 532
 533       instance= memcached_server_instance_fetch(ptr, server);
 534
 535       if (memcached_server_response_count(instance) == 0)
 536       {
 537         rc= memcached_connect(instance);
 538         if (rc != MEMCACHED_SUCCESS)
 539         {
 540           memcached_io_reset(instance);
 541           dead_servers[server]= true;
 542           success= false;
 543           continue;
 544         }
 545       }
 546
 547       protocol_binary_request_getk request= {
 548         .message.header.request= {
 549           .magic= PROTOCOL_BINARY_REQ,
 550           .opcode= PROTOCOL_BINARY_CMD_GETK,
 551           .keylen= htons((uint16_t)(key_length[x] + memcached_array_size(ptr->prefix_key))),
 552           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 553           .bodylen= htonl((uint32_t)(key_length[x] + memcached_array_size(ptr->prefix_key)))
 554         }
 555       };
 556
 557       /*
 558        * We need to disable buffering to actually know that the request was
 559        * successfully sent to the server (so that we should expect a result
 560        * back). It would be nice to do this in buffered mode, but then it
 561        * would be complex to handle all error situations if we got to send
 562        * some of the messages, and then we failed on writing out some others
 563        * and we used the callback interface from memcached_mget_execute so
 564        * that we might have processed some of the responses etc. For now,
 565        * just make sure we work _correctly_
 566      */
 567       struct libmemcached_io_vector_st vector[]=
 568       {
 569         { .length= sizeof(request.bytes), .buffer= request.bytes },
 570         { .length= memcached_array_size(ptr->prefix_key), .buffer= memcached_array_string(ptr->prefix_key) },
 571         { .length= key_length[x], .buffer= keys[x] }
 572       };
 573
 574       if (memcached_io_writev(instance, vector, 3, true) == -1)
 575       {
 576         memcached_io_reset(instance);
 577         dead_servers[server]= true;
 578         success= false;
 579         continue;
 580       }
 581
 582       memcached_server_response_increment(instance);
 583       hash[x]= memcached_server_count(ptr);
 584     }
 585
 586     if (success)
 587       break;
 588   }
 589
 590   return rc;
 591 }
 592
 593 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 594                                              uint32_t master_server_key,
 595                                              bool is_group_key_set,
 596                                              const char * const *keys,
 597                                              const size_t *key_length,
 598                                              size_t number_of_keys,
 599                                              bool mget_mode)
 600 {
 601   memcached_return_t rc;
 602
 603   if (ptr->number_of_replicas == 0)
 604   {
 605     rc= simple_binary_mget(ptr, master_server_key, is_group_key_set,
 606                            keys, key_length, number_of_keys, mget_mode);
 607   }
 608   else
 609   {
 610     uint32_t* hash;
 611     bool* dead_servers;
 612
 613     hash= libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 614     dead_servers= libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 615
 616     if (hash == NULL || dead_servers == NULL)
 617     {
 618       libmemcached_free(ptr, hash);
 619       libmemcached_free(ptr, dead_servers);
 620       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 621     }
 622
 623     if (is_group_key_set)
 624     {
 625       for (size_t x= 0; x < number_of_keys; x++)
 626       {
 627         hash[x]= master_server_key;
 628       }
 629     }
 630     else
 631     {
 632       for (size_t x= 0; x < number_of_keys; x++)
 633       {
 634         hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 635       }
 636     }
 637
 638     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 639                                 key_length, number_of_keys);
 640
 641     libmemcached_free(ptr, hash);
 642     libmemcached_free(ptr, dead_servers);
 643
 644     return MEMCACHED_SUCCESS;
 645   }
 646
 647   return rc;
 648 }