git.m6w6.name Git - m6w6/libmemcached/blob - libmemcached/hosts.c

   1 /* LibMemcached
   2  * Copyright (C) 2006-2010 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:
   9  *
  10  */
  11
  12 #include "common.h"
  13 #include <math.h>
  14
  15 /* Protoypes (static) */
  16 static memcached_return_t server_add(memcached_st *ptr, const char *hostname,
  17                                      in_port_t port,
  18                                      uint32_t weight,
  19                                      memcached_connection_t type);
  20 static memcached_return_t update_continuum(memcached_st *ptr);
  21
  22 static int compare_servers(const void *p1, const void *p2)
  23 {
  24   int return_value;
  25   memcached_server_instance_st a= (memcached_server_instance_st)p1;
  26   memcached_server_instance_st b= (memcached_server_instance_st)p2;
  27
  28   return_value= strcmp(a->hostname, b->hostname);
  29
  30   if (return_value == 0)
  31   {
  32     return_value= (int) (a->port - b->port);
  33   }
  34
  35   return return_value;
  36 }
  37
  38 static void sort_hosts(memcached_st *ptr)
  39 {
  40   if (memcached_server_count(ptr))
  41   {
  42     memcached_server_write_instance_st instance;
  43
  44     qsort(memcached_server_list(ptr), memcached_server_count(ptr), sizeof(memcached_server_st), compare_servers);
  45     instance= memcached_server_instance_fetch(ptr, 0);
  46     instance->number_of_hosts= memcached_server_count(ptr);
  47   }
  48 }
  49
  50
  51 memcached_return_t run_distribution(memcached_st *ptr)
  52 {
  53   if (ptr->flags.use_sort_hosts)
  54     sort_hosts(ptr);
  55
  56   switch (ptr->distribution)
  57   {
  58   case MEMCACHED_DISTRIBUTION_CONSISTENT:
  59   case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA:
  60   case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY:
  61     return update_continuum(ptr);
  62   case MEMCACHED_DISTRIBUTION_MODULA:
  63     break;
  64   case MEMCACHED_DISTRIBUTION_RANDOM:
  65     srandom((uint32_t) time(NULL));
  66     break;
  67   case MEMCACHED_DISTRIBUTION_CONSISTENT_MAX:
  68   default:
  69     WATCHPOINT_ASSERT(0); /* We have added a distribution without extending the logic */
  70   }
  71
  72   return MEMCACHED_SUCCESS;
  73 }
  74
  75 static uint32_t ketama_server_hash(const char *key, size_t key_length, uint32_t alignment)
  76 {
  77   unsigned char results[16];
  78
  79   libhashkit_md5_signature((unsigned char*)key, key_length, results);
  80
  81   return ((uint32_t) (results[3 + alignment * 4] & 0xFF) << 24)
  82     | ((uint32_t) (results[2 + alignment * 4] & 0xFF) << 16)
  83     | ((uint32_t) (results[1 + alignment * 4] & 0xFF) << 8)
  84     | (results[0 + alignment * 4] & 0xFF);
  85 }
  86
  87 static int continuum_item_cmp(const void *t1, const void *t2)
  88 {
  89   memcached_continuum_item_st *ct1= (memcached_continuum_item_st *)t1;
  90   memcached_continuum_item_st *ct2= (memcached_continuum_item_st *)t2;
  91
  92   /* Why 153? Hmmm... */
  93   WATCHPOINT_ASSERT(ct1->value != 153);
  94   if (ct1->value == ct2->value)
  95     return 0;
  96   else if (ct1->value > ct2->value)
  97     return 1;
  98   else
  99     return -1;
 100 }
 101
 102 static memcached_return_t update_continuum(memcached_st *ptr)
 103 {
 104   uint32_t host_index;
 105   uint32_t continuum_index= 0;
 106   uint32_t value;
 107   memcached_server_st *list;
 108   uint32_t pointer_index;
 109   uint32_t pointer_counter= 0;
 110   uint32_t pointer_per_server= MEMCACHED_POINTS_PER_SERVER;
 111   uint32_t pointer_per_hash= 1;
 112   uint64_t total_weight= 0;
 113   uint64_t is_ketama_weighted= 0;
 114   uint64_t is_auto_ejecting= 0;
 115   uint32_t points_per_server= 0;
 116   uint32_t live_servers= 0;
 117   struct timeval now;
 118
 119   if (gettimeofday(&now, NULL) != 0)
 120   {
 121     ptr->cached_errno = errno;
 122     return MEMCACHED_ERRNO;
 123   }
 124
 125   list = memcached_server_list(ptr);
 126
 127   /* count live servers (those without a retry delay set) */
 128   is_auto_ejecting= _is_auto_eject_host(ptr);
 129   if (is_auto_ejecting)
 130   {
 131     live_servers= 0;
 132     ptr->next_distribution_rebuild= 0;
 133     for (host_index= 0; host_index < memcached_server_count(ptr); ++host_index)
 134     {
 135       if (list[host_index].next_retry <= now.tv_sec)
 136         live_servers++;
 137       else
 138       {
 139         if (ptr->next_distribution_rebuild == 0 || list[host_index].next_retry < ptr->next_distribution_rebuild)
 140           ptr->next_distribution_rebuild= list[host_index].next_retry;
 141       }
 142     }
 143   }
 144   else
 145   {
 146     live_servers= memcached_server_count(ptr);
 147   }
 148
 149   is_ketama_weighted= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED);
 150   points_per_server= (uint32_t) (is_ketama_weighted ? MEMCACHED_POINTS_PER_SERVER_KETAMA : MEMCACHED_POINTS_PER_SERVER);
 151
 152   if (live_servers == 0)
 153     return MEMCACHED_SUCCESS;
 154
 155   if (live_servers > ptr->continuum_count)
 156   {
 157     memcached_continuum_item_st *new_ptr;
 158
 159     new_ptr= libmemcached_realloc(ptr, ptr->continuum,
 160                                   sizeof(memcached_continuum_item_st) * (live_servers + MEMCACHED_CONTINUUM_ADDITION) * points_per_server);
 161
 162     if (new_ptr == 0)
 163       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 164
 165     ptr->continuum= new_ptr;
 166     ptr->continuum_count= live_servers + MEMCACHED_CONTINUUM_ADDITION;
 167   }
 168
 169   if (is_ketama_weighted)
 170   {
 171     for (host_index = 0; host_index < memcached_server_count(ptr); ++host_index)
 172     {
 173       if (list[host_index].weight == 0)
 174       {
 175         list[host_index].weight = 1;
 176       }
 177       if (! is_auto_ejecting || list[host_index].next_retry <= now.tv_sec)
 178         total_weight += list[host_index].weight;
 179     }
 180   }
 181
 182   for (host_index= 0; host_index < memcached_server_count(ptr); ++host_index)
 183   {
 184     if (is_auto_ejecting && list[host_index].next_retry > now.tv_sec)
 185       continue;
 186
 187     if (is_ketama_weighted)
 188     {
 189         float pct = (float)list[host_index].weight / (float)total_weight;
 190         pointer_per_server= (uint32_t) ((floorf((float) (pct * MEMCACHED_POINTS_PER_SERVER_KETAMA / 4 * (float)live_servers + 0.0000000001))) * 4);
 191         pointer_per_hash= 4;
 192 #ifdef DEBUG
 193         printf("ketama_weighted:%s|%d|%llu|%u\n",
 194                list[host_index].hostname,
 195                list[host_index].port,
 196                (unsigned long long)list[host_index].weight,
 197                pointer_per_server);
 198 #endif
 199     }
 200
 201
 202     if (ptr->distribution == MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY)
 203     {
 204       for (pointer_index= 0;
 205            pointer_index < pointer_per_server / pointer_per_hash;
 206            pointer_index++)
 207       {
 208         char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
 209         size_t sort_host_length;
 210
 211         // Spymemcached ketema key format is: hostname/ip:port-index
 212         // If hostname is not available then: /ip:port-index
 213         sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 214                                             "/%s:%u-%u",
 215                                             list[host_index].hostname,
 216                                             (uint32_t)list[host_index].port,
 217                                             pointer_index);
 218 #ifdef DEBUG
 219         printf("update_continuum: key is %s\n", sort_host);
 220 #endif
 221
 222         WATCHPOINT_ASSERT(sort_host_length);
 223
 224         if (is_ketama_weighted)
 225         {
 226           for (uint32_t x= 0; x < pointer_per_hash; x++)
 227           {
 228              value= ketama_server_hash(sort_host, sort_host_length, x);
 229              ptr->continuum[continuum_index].index= host_index;
 230              ptr->continuum[continuum_index++].value= value;
 231           }
 232         }
 233         else
 234         {
 235           value= hashkit_digest(&ptr->distribution_hashkit, sort_host, sort_host_length);
 236           ptr->continuum[continuum_index].index= host_index;
 237           ptr->continuum[continuum_index++].value= value;
 238         }
 239       }
 240     }
 241     else
 242     {
 243       for (pointer_index= 1;
 244            pointer_index <= pointer_per_server / pointer_per_hash;
 245            pointer_index++)
 246       {
 247         char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
 248         size_t sort_host_length;
 249
 250         if (list[host_index].port == MEMCACHED_DEFAULT_PORT)
 251         {
 252           sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 253                                               "%s-%u",
 254                                               list[host_index].hostname,
 255                                               pointer_index - 1);
 256         }
 257         else
 258         {
 259           sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 260                                               "%s:%u-%u",
 261                                               list[host_index].hostname,
 262                                               (uint32_t)list[host_index].port,
 263                                               pointer_index - 1);
 264         }
 265
 266         WATCHPOINT_ASSERT(sort_host_length);
 267
 268         if (is_ketama_weighted)
 269         {
 270           for (uint32_t x = 0; x < pointer_per_hash; x++)
 271           {
 272              value= ketama_server_hash(sort_host, sort_host_length, x);
 273              ptr->continuum[continuum_index].index= host_index;
 274              ptr->continuum[continuum_index++].value= value;
 275           }
 276         }
 277         else
 278         {
 279           value= hashkit_digest(&ptr->distribution_hashkit, sort_host, sort_host_length);
 280           ptr->continuum[continuum_index].index= host_index;
 281           ptr->continuum[continuum_index++].value= value;
 282         }
 283       }
 284     }
 285
 286     pointer_counter+= pointer_per_server;
 287   }
 288
 289   WATCHPOINT_ASSERT(ptr);
 290   WATCHPOINT_ASSERT(ptr->continuum);
 291   WATCHPOINT_ASSERT(memcached_server_count(ptr) * MEMCACHED_POINTS_PER_SERVER <= MEMCACHED_CONTINUUM_SIZE);
 292   ptr->continuum_points_counter= pointer_counter;
 293   qsort(ptr->continuum, ptr->continuum_points_counter, sizeof(memcached_continuum_item_st), continuum_item_cmp);
 294
 295 #ifdef DEBUG
 296   for (pointer_index= 0; memcached_server_count(ptr) && pointer_index < ((live_servers * MEMCACHED_POINTS_PER_SERVER) - 1); pointer_index++)
 297   {
 298     WATCHPOINT_ASSERT(ptr->continuum[pointer_index].value <= ptr->continuum[pointer_index + 1].value);
 299   }
 300 #endif
 301
 302   return MEMCACHED_SUCCESS;
 303 }
 304
 305
 306 memcached_return_t memcached_server_push(memcached_st *ptr, const memcached_server_list_st list)
 307 {
 308   uint32_t count;
 309   memcached_server_st *new_host_list;
 310
 311   if (! list)
 312     return MEMCACHED_SUCCESS;
 313
 314   count= memcached_server_list_count(list);
 315   new_host_list= libmemcached_realloc(ptr, memcached_server_list(ptr),
 316                                       sizeof(memcached_server_st) * (count + memcached_server_count(ptr)));
 317
 318   if (! new_host_list)
 319     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 320
 321   memcached_server_list_set(ptr, new_host_list);
 322
 323   for (uint32_t x= 0; x < count; x++)
 324   {
 325     memcached_server_write_instance_st instance;
 326
 327     if ((ptr->flags.use_udp && list[x].type != MEMCACHED_CONNECTION_UDP)
 328             || ((list[x].type == MEMCACHED_CONNECTION_UDP)
 329             && ! (ptr->flags.use_udp)) )
 330       return MEMCACHED_INVALID_HOST_PROTOCOL;
 331
 332     WATCHPOINT_ASSERT(list[x].hostname[0] != 0);
 333
 334     instance= memcached_server_instance_fetch(ptr, memcached_server_count(ptr));
 335
 336     /* TODO check return type */
 337     (void)memcached_server_create_with(ptr, instance, list[x].hostname,
 338                                        list[x].port, list[x].weight, list[x].type);
 339     ptr->number_of_hosts++;
 340   }
 341
 342   // Provides backwards compatibility with server list.
 343   {
 344     memcached_server_write_instance_st instance;
 345     instance= memcached_server_instance_fetch(ptr, 0);
 346     instance->number_of_hosts= memcached_server_count(ptr);
 347   }
 348
 349   return run_distribution(ptr);
 350 }
 351
 352 memcached_return_t memcached_server_add_unix_socket(memcached_st *ptr,
 353                                                     const char *filename)
 354 {
 355   return memcached_server_add_unix_socket_with_weight(ptr, filename, 0);
 356 }
 357
 358 memcached_return_t memcached_server_add_unix_socket_with_weight(memcached_st *ptr,
 359                                                                 const char *filename,
 360                                                                 uint32_t weight)
 361 {
 362   if (! filename)
 363     return MEMCACHED_FAILURE;
 364
 365   return server_add(ptr, filename, 0, weight, MEMCACHED_CONNECTION_UNIX_SOCKET);
 366 }
 367
 368 memcached_return_t memcached_server_add_udp(memcached_st *ptr,
 369                                             const char *hostname,
 370                                             in_port_t port)
 371 {
 372   return memcached_server_add_udp_with_weight(ptr, hostname, port, 0);
 373 }
 374
 375 memcached_return_t memcached_server_add_udp_with_weight(memcached_st *ptr,
 376                                                         const char *hostname,
 377                                                         in_port_t port,
 378                                                         uint32_t weight)
 379 {
 380   if (! port)
 381     port= MEMCACHED_DEFAULT_PORT;
 382
 383   if (! hostname)
 384     hostname= "localhost";
 385
 386   return server_add(ptr, hostname, port, weight, MEMCACHED_CONNECTION_UDP);
 387 }
 388
 389 memcached_return_t memcached_server_add(memcached_st *ptr,
 390                                         const char *hostname,
 391                                         in_port_t port)
 392 {
 393   return memcached_server_add_with_weight(ptr, hostname, port, 0);
 394 }
 395
 396 memcached_return_t memcached_server_add_with_weight(memcached_st *ptr,
 397                                                     const char *hostname,
 398                                                     in_port_t port,
 399                                                     uint32_t weight)
 400 {
 401   if (! port)
 402     port= MEMCACHED_DEFAULT_PORT;
 403
 404   if (! hostname)
 405     hostname= "localhost";
 406
 407   return server_add(ptr, hostname, port, weight, MEMCACHED_CONNECTION_TCP);
 408 }
 409
 410 static memcached_return_t server_add(memcached_st *ptr, const char *hostname,
 411                                      in_port_t port,
 412                                      uint32_t weight,
 413                                      memcached_connection_t type)
 414 {
 415   memcached_server_st *new_host_list;
 416   memcached_server_write_instance_st instance;
 417
 418   if ( (ptr->flags.use_udp && type != MEMCACHED_CONNECTION_UDP)
 419       || ( (type == MEMCACHED_CONNECTION_UDP) && (! ptr->flags.use_udp) ) )
 420     return MEMCACHED_INVALID_HOST_PROTOCOL;
 421
 422   new_host_list= libmemcached_realloc(ptr, memcached_server_list(ptr),
 423                                       sizeof(memcached_server_st) * (ptr->number_of_hosts + 1));
 424
 425   if (new_host_list == NULL)
 426     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 427
 428   memcached_server_list_set(ptr, new_host_list);
 429
 430   /* TODO: Check return type */
 431   instance= memcached_server_instance_fetch(ptr, memcached_server_count(ptr));
 432   (void)memcached_server_create_with(ptr, instance, hostname, port, weight, type);
 433   ptr->number_of_hosts++;
 434
 435   instance= memcached_server_instance_fetch(ptr, 0);
 436   memcached_servers_set_count(instance, memcached_server_count(ptr));
 437
 438   return run_distribution(ptr);
 439 }