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