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= ptr->prefix_key_length, .buffer= 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         fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 254         failures_occured_in_sending= true;
 255         continue;
 256       }
 257       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 258       memcached_server_response_increment(instance);
 259       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 260     }
 261     else
 262     {
 263       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == -1)
 264       {
 265         memcached_server_response_reset(instance);
 266         fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 267         failures_occured_in_sending= true;
 268         continue;
 269       }
 270     }
 271   }
 272
 273   if (hosts_connected == 0)
 274   {
 275     LIBMEMCACHED_MEMCACHED_MGET_END();
 276
 277     if (rc != MEMCACHED_SUCCESS)
 278       return rc;
 279
 280     return MEMCACHED_NO_SERVERS;
 281   }
 282
 283
 284   /*
 285     Should we muddle on if some servers are dead?
 286   */
 287   bool success_happened= false;
 288   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 289   {
 290     memcached_server_write_instance_st instance=
 291       memcached_server_instance_fetch(ptr, x);
 292
 293     if (memcached_server_response_count(instance))
 294     {
 295       /* We need to do something about non-connnected hosts in the future */
 296       if ((memcached_io_write(instance, "\r\n", 2, true)) == -1)
 297       {
 298         fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 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 *master_key,
 321                                          size_t master_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, master_key, master_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 *master_key,
 345                                                  size_t master_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, master_key, master_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_master_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   int 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_master_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] + ptr->prefix_key_length));
 430     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 431     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + ptr->prefix_key_length));
 432
 433     struct libmemcached_io_vector_st vector[]=
 434     {
 435       { .length= sizeof(request.bytes), .buffer= request.bytes },
 436       { .length= ptr->prefix_key_length, .buffer= 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       fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 444       rc= MEMCACHED_SOME_ERRORS;
 445       continue;
 446     }
 447
 448     /* We just want one pending response per server */
 449     memcached_server_response_reset(instance);
 450     memcached_server_response_increment(instance);
 451     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 452     {
 453       fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 454       rc= MEMCACHED_SOME_ERRORS;
 455     }
 456   }
 457
 458   if (mget_mode)
 459   {
 460     /*
 461      * Send a noop command to flush the buffers
 462    */
 463     protocol_binary_request_noop request= {.bytes= {0}};
 464     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 465     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 466     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 467
 468     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 469     {
 470       memcached_server_write_instance_st instance=
 471         memcached_server_instance_fetch(ptr, x);
 472
 473       if (memcached_server_response_count(instance))
 474       {
 475         if (memcached_io_write(instance, NULL, 0, true) == -1)
 476         {
 477           memcached_server_response_reset(instance);
 478           memcached_io_reset(instance);
 479           fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 480           rc= MEMCACHED_SOME_ERRORS;
 481         }
 482
 483         if (memcached_io_write(instance, request.bytes,
 484                                sizeof(request.bytes), true) == -1)
 485         {
 486           memcached_server_response_reset(instance);
 487           memcached_io_reset(instance);
 488           fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
 489           rc= MEMCACHED_SOME_ERRORS;
 490         }
 491       }
 492     }
 493   }
 494
 495
 496   return rc;
 497 }
 498
 499 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 500                                                   uint32_t* hash,
 501                                                   bool* dead_servers,
 502                                                   const char *const *keys,
 503                                                   const size_t *key_length,
 504                                                   size_t number_of_keys)
 505 {
 506   memcached_return_t rc= MEMCACHED_NOTFOUND;
 507   uint32_t start= 0;
 508   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 509
 510   if (randomize_read)
 511     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 512
 513   /* Loop for each replica */
 514   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 515   {
 516     bool success= true;
 517
 518     for (uint32_t x= 0; x < number_of_keys; ++x)
 519     {
 520       memcached_server_write_instance_st instance;
 521
 522       if (hash[x] == memcached_server_count(ptr))
 523         continue; /* Already successfully sent */
 524
 525       uint32_t server= hash[x] + replica;
 526
 527       /* In case of randomized reads */
 528       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 529         server += start;
 530
 531       while (server >= memcached_server_count(ptr))
 532         server -= memcached_server_count(ptr);
 533
 534       if (dead_servers[server])
 535         continue;
 536
 537       instance= memcached_server_instance_fetch(ptr, server);
 538
 539       if (memcached_server_response_count(instance) == 0)
 540       {
 541         rc= memcached_connect(instance);
 542         if (rc != MEMCACHED_SUCCESS)
 543         {
 544           memcached_io_reset(instance);
 545           dead_servers[server]= true;
 546           success= false;
 547           continue;
 548         }
 549       }
 550
 551       protocol_binary_request_getk request= {
 552         .message.header.request= {
 553           .magic= PROTOCOL_BINARY_REQ,
 554           .opcode= PROTOCOL_BINARY_CMD_GETK,
 555           .keylen= htons((uint16_t)(key_length[x] + ptr->prefix_key_length)),
 556           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 557           .bodylen= htonl((uint32_t)(key_length[x] + ptr->prefix_key_length))
 558         }
 559       };
 560
 561       /*
 562        * We need to disable buffering to actually know that the request was
 563        * successfully sent to the server (so that we should expect a result
 564        * back). It would be nice to do this in buffered mode, but then it
 565        * would be complex to handle all error situations if we got to send
 566        * some of the messages, and then we failed on writing out some others
 567        * and we used the callback interface from memcached_mget_execute so
 568        * that we might have processed some of the responses etc. For now,
 569        * just make sure we work _correctly_
 570      */
 571       struct libmemcached_io_vector_st vector[]=
 572       {
 573         { .length= sizeof(request.bytes), .buffer= request.bytes },
 574         { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 575         { .length= key_length[x], .buffer= keys[x] }
 576       };
 577
 578       if (memcached_io_writev(instance, vector, 3, true) == -1)
 579       {
 580         memcached_io_reset(instance);
 581         dead_servers[server]= true;
 582         success= false;
 583         continue;
 584       }
 585
 586       memcached_server_response_increment(instance);
 587       hash[x]= memcached_server_count(ptr);
 588     }
 589
 590     if (success)
 591       break;
 592   }
 593
 594   return rc;
 595 }
 596
 597 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 598                                              uint32_t master_server_key,
 599                                              bool is_master_key_set,
 600                                              const char * const *keys,
 601                                              const size_t *key_length,
 602                                              size_t number_of_keys,
 603                                              bool mget_mode)
 604 {
 605   memcached_return_t rc;
 606
 607   if (ptr->number_of_replicas == 0)
 608   {
 609     rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
 610                            keys, key_length, number_of_keys, mget_mode);
 611   }
 612   else
 613   {
 614     uint32_t* hash;
 615     bool* dead_servers;
 616
 617     hash= libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 618     dead_servers= libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 619
 620     if (hash == NULL || dead_servers == NULL)
 621     {
 622       libmemcached_free(ptr, hash);
 623       libmemcached_free(ptr, dead_servers);
 624       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 625     }
 626
 627     if (is_master_key_set)
 628     {
 629       for (size_t x= 0; x < number_of_keys; x++)
 630       {
 631         hash[x]= master_server_key;
 632       }
 633     }
 634     else
 635     {
 636       for (size_t x= 0; x < number_of_keys; x++)
 637       {
 638         hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 639       }
 640     }
 641
 642     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 643                                 key_length, number_of_keys);
 644
 645     libmemcached_free(ptr, hash);
 646     libmemcached_free(ptr, dead_servers);
 647
 648     return MEMCACHED_SUCCESS;
 649   }
 650
 651   return rc;
 652 }