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   memcached_return_t rc= MEMCACHED_NOTFOUND;
 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   for (uint32_t x= 0; x < number_of_keys; x++)
 215   {
 216     memcached_server_write_instance_st instance;
 217     uint32_t server_key;
 218
 219     if (is_master_key_set)
 220     {
 221       server_key= master_server_key;
 222     }
 223     else
 224     {
 225       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 226     }
 227
 228     instance= memcached_server_instance_fetch(ptr, server_key);
 229
 230     struct __write_vector_st vector[]=
 231     {
 232       { .length= get_command_length, .buffer= get_command },
 233       { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 234       { .length= key_length[x], .buffer= keys[x] },
 235       { .length= 1, .buffer= " " }
 236     };
 237
 238
 239     if (memcached_server_response_count(instance) == 0)
 240     {
 241       rc= memcached_connect(instance);
 242
 243       if (rc != MEMCACHED_SUCCESS)
 244         continue;
 245
 246       if ((memcached_io_writev(instance, vector, 4, false)) == -1)
 247       {
 248         rc= MEMCACHED_SOME_ERRORS;
 249         continue;
 250       }
 251       WATCHPOINT_ASSERT(instance->cursor_active == 0);
 252       memcached_server_response_increment(instance);
 253       WATCHPOINT_ASSERT(instance->cursor_active == 1);
 254     }
 255     else
 256     {
 257       if ((memcached_io_writev(instance, (vector + 1), 3, false)) == -1)
 258       {
 259         memcached_server_response_reset(instance);
 260         rc= MEMCACHED_SOME_ERRORS;
 261         continue;
 262       }
 263     }
 264   }
 265
 266   /*
 267     Should we muddle on if some servers are dead?
 268   */
 269   for (uint32_t x= 0; x < memcached_server_count(ptr); x++)
 270   {
 271     memcached_server_write_instance_st instance=
 272       memcached_server_instance_fetch(ptr, x);
 273
 274     if (memcached_server_response_count(instance))
 275     {
 276       /* We need to do something about non-connnected hosts in the future */
 277       if ((memcached_io_write(instance, "\r\n", 2, true)) == -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
 349   int flush= number_of_keys == 1;
 350
 351   /*
 352     If a server fails we warn about errors and start all over with sending keys
 353     to the server.
 354   */
 355   for (uint32_t x= 0; x < number_of_keys; ++x)
 356   {
 357     uint32_t server_key;
 358     memcached_server_write_instance_st instance;
 359
 360     if (is_master_key_set)
 361     {
 362       server_key= master_server_key;
 363     }
 364     else
 365     {
 366       server_key= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 367     }
 368
 369     instance= memcached_server_instance_fetch(ptr, server_key);
 370
 371     if (memcached_server_response_count(instance) == 0)
 372     {
 373       rc= memcached_connect(instance);
 374       if (rc != MEMCACHED_SUCCESS)
 375         continue;
 376     }
 377
 378     protocol_binary_request_getk request= {.bytes= {0}};
 379     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 380     if (mget_mode)
 381       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
 382     else
 383       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 384
 385     memcached_return_t vk;
 386     vk= memcached_validate_key_length(key_length[x],
 387                                       ptr->flags.binary_protocol);
 388     unlikely (vk != MEMCACHED_SUCCESS)
 389     {
 390       if (x > 0)
 391       {
 392         memcached_io_reset(instance);
 393       }
 394
 395       return vk;
 396     }
 397
 398     request.message.header.request.keylen= htons((uint16_t)(key_length[x] + ptr->prefix_key_length));
 399     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 400     request.message.header.request.bodylen= htonl((uint32_t)( key_length[x] + ptr->prefix_key_length));
 401
 402     struct __write_vector_st vector[]=
 403     {
 404       { .length= sizeof(request.bytes), .buffer= request.bytes },
 405       { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 406       { .length= key_length[x], .buffer= keys[x] }
 407     };
 408
 409     if (memcached_io_writev(instance, vector, 3, flush) == -1)
 410     {
 411       memcached_server_response_reset(instance);
 412       rc= MEMCACHED_SOME_ERRORS;
 413       continue;
 414     }
 415
 416     /* We just want one pending response per server */
 417     memcached_server_response_reset(instance);
 418     memcached_server_response_increment(instance);
 419     if ((x > 0 && x == ptr->io_key_prefetch) && memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
 420     {
 421       rc= MEMCACHED_SOME_ERRORS;
 422     }
 423   }
 424
 425   if (mget_mode)
 426   {
 427     /*
 428      * Send a noop command to flush the buffers
 429    */
 430     protocol_binary_request_noop request= {.bytes= {0}};
 431     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
 432     request.message.header.request.opcode= PROTOCOL_BINARY_CMD_NOOP;
 433     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
 434
 435     for (uint32_t x= 0; x < memcached_server_count(ptr); ++x)
 436     {
 437       memcached_server_write_instance_st instance=
 438         memcached_server_instance_fetch(ptr, x);
 439
 440       if (memcached_server_response_count(instance))
 441       {
 442         if (memcached_io_write(instance, NULL, 0, true) == -1)
 443         {
 444           memcached_server_response_reset(instance);
 445           memcached_io_reset(instance);
 446           rc= MEMCACHED_SOME_ERRORS;
 447         }
 448
 449         if (memcached_io_write(instance, request.bytes,
 450                                sizeof(request.bytes), true) == -1)
 451         {
 452           memcached_server_response_reset(instance);
 453           memcached_io_reset(instance);
 454           rc= MEMCACHED_SOME_ERRORS;
 455         }
 456       }
 457     }
 458   }
 459
 460
 461   return rc;
 462 }
 463
 464 static memcached_return_t replication_binary_mget(memcached_st *ptr,
 465                                                   uint32_t* hash,
 466                                                   bool* dead_servers,
 467                                                   const char *const *keys,
 468                                                   const size_t *key_length,
 469                                                   size_t number_of_keys)
 470 {
 471   memcached_return_t rc= MEMCACHED_NOTFOUND;
 472   uint32_t start= 0;
 473   uint64_t randomize_read= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
 474
 475   if (randomize_read)
 476     start= (uint32_t)random() % (uint32_t)(ptr->number_of_replicas + 1);
 477
 478   /* Loop for each replica */
 479   for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
 480   {
 481     bool success= true;
 482
 483     for (uint32_t x= 0; x < number_of_keys; ++x)
 484     {
 485       memcached_server_write_instance_st instance;
 486
 487       if (hash[x] == memcached_server_count(ptr))
 488         continue; /* Already successfully sent */
 489
 490       uint32_t server= hash[x] + replica;
 491
 492       /* In case of randomized reads */
 493       if (randomize_read && ((server + start) <= (hash[x] + ptr->number_of_replicas)))
 494         server += start;
 495
 496       while (server >= memcached_server_count(ptr))
 497         server -= memcached_server_count(ptr);
 498
 499       if (dead_servers[server])
 500         continue;
 501
 502       instance= memcached_server_instance_fetch(ptr, server);
 503
 504       if (memcached_server_response_count(instance) == 0)
 505       {
 506         rc= memcached_connect(instance);
 507         if (rc != MEMCACHED_SUCCESS)
 508         {
 509           memcached_io_reset(instance);
 510           dead_servers[server]= true;
 511           success= false;
 512           continue;
 513         }
 514       }
 515
 516       protocol_binary_request_getk request= {
 517         .message.header.request= {
 518           .magic= PROTOCOL_BINARY_REQ,
 519           .opcode= PROTOCOL_BINARY_CMD_GETK,
 520           .keylen= htons((uint16_t)(key_length[x] + ptr->prefix_key_length)),
 521           .datatype= PROTOCOL_BINARY_RAW_BYTES,
 522           .bodylen= htonl((uint32_t)(key_length[x] + ptr->prefix_key_length))
 523         }
 524       };
 525
 526       /*
 527        * We need to disable buffering to actually know that the request was
 528        * successfully sent to the server (so that we should expect a result
 529        * back). It would be nice to do this in buffered mode, but then it
 530        * would be complex to handle all error situations if we got to send
 531        * some of the messages, and then we failed on writing out some others
 532        * and we used the callback interface from memcached_mget_execute so
 533        * that we might have processed some of the responses etc. For now,
 534        * just make sure we work _correctly_
 535      */
 536       struct __write_vector_st vector[]=
 537       {
 538         { .length= sizeof(request.bytes), .buffer= request.bytes },
 539         { .length= ptr->prefix_key_length, .buffer= ptr->prefix_key },
 540         { .length= key_length[x], .buffer= keys[x] }
 541       };
 542
 543       if (memcached_io_writev(instance, vector, 3, true) == -1)
 544       {
 545         memcached_io_reset(instance);
 546         dead_servers[server]= true;
 547         success= false;
 548         continue;
 549       }
 550
 551       memcached_server_response_increment(instance);
 552       hash[x]= memcached_server_count(ptr);
 553     }
 554
 555     if (success)
 556       break;
 557   }
 558
 559   return rc;
 560 }
 561
 562 static memcached_return_t binary_mget_by_key(memcached_st *ptr,
 563                                              uint32_t master_server_key,
 564                                              bool is_master_key_set,
 565                                              const char * const *keys,
 566                                              const size_t *key_length,
 567                                              size_t number_of_keys,
 568                                              bool mget_mode)
 569 {
 570   memcached_return_t rc;
 571
 572   if (ptr->number_of_replicas == 0)
 573   {
 574     rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
 575                            keys, key_length, number_of_keys, mget_mode);
 576   }
 577   else
 578   {
 579     uint32_t* hash;
 580     bool* dead_servers;
 581
 582     hash= libmemcached_malloc(ptr, sizeof(uint32_t) * number_of_keys);
 583     dead_servers= libmemcached_calloc(ptr, memcached_server_count(ptr), sizeof(bool));
 584
 585     if (hash == NULL || dead_servers == NULL)
 586     {
 587       libmemcached_free(ptr, hash);
 588       libmemcached_free(ptr, dead_servers);
 589       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 590     }
 591
 592     if (is_master_key_set)
 593     {
 594       for (size_t x= 0; x < number_of_keys; x++)
 595       {
 596         hash[x]= master_server_key;
 597       }
 598     }
 599     else
 600     {
 601       for (size_t x= 0; x < number_of_keys; x++)
 602       {
 603         hash[x]= memcached_generate_hash_with_redistribution(ptr, keys[x], key_length[x]);
 604       }
 605     }
 606
 607     rc= replication_binary_mget(ptr, hash, dead_servers, keys,
 608                                 key_length, number_of_keys);
 609
 610     libmemcached_free(ptr, hash);
 611     libmemcached_free(ptr, dead_servers);
 612
 613     return MEMCACHED_SUCCESS;
 614   }
 615
 616   return rc;
 617 }