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   ptr->last_disconnected_server = NULL;
  73
  74   return MEMCACHED_SUCCESS;
  75 }
  76
  77 static uint32_t ketama_server_hash(const char *key, size_t key_length, uint32_t alignment)
  78 {
  79   unsigned char results[16];
  80
  81   libhashkit_md5_signature((unsigned char*)key, key_length, results);
  82
  83   return ((uint32_t) (results[3 + alignment * 4] & 0xFF) << 24)
  84     | ((uint32_t) (results[2 + alignment * 4] & 0xFF) << 16)
  85     | ((uint32_t) (results[1 + alignment * 4] & 0xFF) << 8)
  86     | (results[0 + alignment * 4] & 0xFF);
  87 }
  88
  89 static int continuum_item_cmp(const void *t1, const void *t2)
  90 {
  91   memcached_continuum_item_st *ct1= (memcached_continuum_item_st *)t1;
  92   memcached_continuum_item_st *ct2= (memcached_continuum_item_st *)t2;
  93
  94   /* Why 153? Hmmm... */
  95   WATCHPOINT_ASSERT(ct1->value != 153);
  96   if (ct1->value == ct2->value)
  97     return 0;
  98   else if (ct1->value > ct2->value)
  99     return 1;
 100   else
 101     return -1;
 102 }
 103
 104 static memcached_return_t update_continuum(memcached_st *ptr)
 105 {
 106   uint32_t host_index;
 107   uint32_t continuum_index= 0;
 108   uint32_t value;
 109   memcached_server_st *list;
 110   uint32_t pointer_index;
 111   uint32_t pointer_counter= 0;
 112   uint32_t pointer_per_server= MEMCACHED_POINTS_PER_SERVER;
 113   uint32_t pointer_per_hash= 1;
 114   uint64_t total_weight= 0;
 115   uint64_t is_ketama_weighted= 0;
 116   uint64_t is_auto_ejecting= 0;
 117   uint32_t points_per_server= 0;
 118   uint32_t live_servers= 0;
 119   struct timeval now;
 120
 121   if (gettimeofday(&now, NULL) != 0)
 122   {
 123     ptr->cached_errno = errno;
 124     return MEMCACHED_ERRNO;
 125   }
 126
 127   list = memcached_server_list(ptr);
 128
 129   /* count live servers (those without a retry delay set) */
 130   is_auto_ejecting= _is_auto_eject_host(ptr);
 131   if (is_auto_ejecting)
 132   {
 133     live_servers= 0;
 134     ptr->next_distribution_rebuild= 0;
 135     for (host_index= 0; host_index < memcached_server_count(ptr); ++host_index)
 136     {
 137       if (list[host_index].next_retry <= now.tv_sec)
 138         live_servers++;
 139       else
 140       {
 141         if (ptr->next_distribution_rebuild == 0 || list[host_index].next_retry < ptr->next_distribution_rebuild)
 142           ptr->next_distribution_rebuild= list[host_index].next_retry;
 143       }
 144     }
 145   }
 146   else
 147   {
 148     live_servers= memcached_server_count(ptr);
 149   }
 150
 151   is_ketama_weighted= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED);
 152   points_per_server= (uint32_t) (is_ketama_weighted ? MEMCACHED_POINTS_PER_SERVER_KETAMA : MEMCACHED_POINTS_PER_SERVER);
 153
 154   if (live_servers == 0)
 155     return MEMCACHED_SUCCESS;
 156
 157   if (live_servers > ptr->continuum_count)
 158   {
 159     memcached_continuum_item_st *new_ptr;
 160
 161     new_ptr= libmemcached_realloc(ptr, ptr->continuum,
 162                                   sizeof(memcached_continuum_item_st) * (live_servers + MEMCACHED_CONTINUUM_ADDITION) * points_per_server);
 163
 164     if (new_ptr == 0)
 165       return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 166
 167     ptr->continuum= new_ptr;
 168     ptr->continuum_count= live_servers + MEMCACHED_CONTINUUM_ADDITION;
 169   }
 170
 171   if (is_ketama_weighted)
 172   {
 173     for (host_index = 0; host_index < memcached_server_count(ptr); ++host_index)
 174     {
 175       if (list[host_index].weight == 0)
 176       {
 177         list[host_index].weight = 1;
 178       }
 179       if (! is_auto_ejecting || list[host_index].next_retry <= now.tv_sec)
 180         total_weight += list[host_index].weight;
 181     }
 182   }
 183
 184   for (host_index= 0; host_index < memcached_server_count(ptr); ++host_index)
 185   {
 186     if (is_auto_ejecting && list[host_index].next_retry > now.tv_sec)
 187       continue;
 188
 189     if (is_ketama_weighted)
 190     {
 191         float pct = (float)list[host_index].weight / (float)total_weight;
 192         pointer_per_server= (uint32_t) ((floorf((float) (pct * MEMCACHED_POINTS_PER_SERVER_KETAMA / 4 * (float)live_servers + 0.0000000001))) * 4);
 193         pointer_per_hash= 4;
 194 #ifdef DEBUG
 195         printf("ketama_weighted:%s|%d|%llu|%u\n",
 196                list[host_index].hostname,
 197                list[host_index].port,
 198                (unsigned long long)list[host_index].weight,
 199                pointer_per_server);
 200 #endif
 201     }
 202
 203
 204     if (ptr->distribution == MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY)
 205     {
 206       for (pointer_index= 0;
 207            pointer_index < pointer_per_server / pointer_per_hash;
 208            pointer_index++)
 209       {
 210         char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
 211         size_t sort_host_length;
 212
 213         // Spymemcached ketema key format is: hostname/ip:port-index
 214         // If hostname is not available then: /ip:port-index
 215         sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 216                                             "/%s:%u-%u",
 217                                             list[host_index].hostname,
 218                                             (uint32_t)list[host_index].port,
 219                                             pointer_index);
 220 #ifdef DEBUG
 221         printf("update_continuum: key is %s\n", sort_host);
 222 #endif
 223
 224         WATCHPOINT_ASSERT(sort_host_length);
 225
 226         if (is_ketama_weighted)
 227         {
 228           for (uint32_t x= 0; x < pointer_per_hash; x++)
 229           {
 230              value= ketama_server_hash(sort_host, sort_host_length, x);
 231              ptr->continuum[continuum_index].index= host_index;
 232              ptr->continuum[continuum_index++].value= value;
 233           }
 234         }
 235         else
 236         {
 237           value= hashkit_digest(&ptr->distribution_hashkit, sort_host, sort_host_length);
 238           ptr->continuum[continuum_index].index= host_index;
 239           ptr->continuum[continuum_index++].value= value;
 240         }
 241       }
 242     }
 243     else
 244     {
 245       for (pointer_index= 1;
 246            pointer_index <= pointer_per_server / pointer_per_hash;
 247            pointer_index++)
 248       {
 249         char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
 250         size_t sort_host_length;
 251
 252         if (list[host_index].port == MEMCACHED_DEFAULT_PORT)
 253         {
 254           sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 255                                               "%s-%u",
 256                                               list[host_index].hostname,
 257                                               pointer_index - 1);
 258         }
 259         else
 260         {
 261           sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
 262                                               "%s:%u-%u",
 263                                               list[host_index].hostname,
 264                                               (uint32_t)list[host_index].port,
 265                                               pointer_index - 1);
 266         }
 267
 268         WATCHPOINT_ASSERT(sort_host_length);
 269
 270         if (is_ketama_weighted)
 271         {
 272           for (uint32_t x = 0; x < pointer_per_hash; x++)
 273           {
 274              value= ketama_server_hash(sort_host, sort_host_length, x);
 275              ptr->continuum[continuum_index].index= host_index;
 276              ptr->continuum[continuum_index++].value= value;
 277           }
 278         }
 279         else
 280         {
 281           value= hashkit_digest(&ptr->distribution_hashkit, sort_host, sort_host_length);
 282           ptr->continuum[continuum_index].index= host_index;
 283           ptr->continuum[continuum_index++].value= value;
 284         }
 285       }
 286     }
 287
 288     pointer_counter+= pointer_per_server;
 289   }
 290
 291   WATCHPOINT_ASSERT(ptr);
 292   WATCHPOINT_ASSERT(ptr->continuum);
 293   WATCHPOINT_ASSERT(memcached_server_count(ptr) * MEMCACHED_POINTS_PER_SERVER <= MEMCACHED_CONTINUUM_SIZE);
 294   ptr->continuum_points_counter= pointer_counter;
 295   qsort(ptr->continuum, ptr->continuum_points_counter, sizeof(memcached_continuum_item_st), continuum_item_cmp);
 296
 297 #ifdef DEBUG
 298   for (pointer_index= 0; memcached_server_count(ptr) && pointer_index < ((live_servers * MEMCACHED_POINTS_PER_SERVER) - 1); pointer_index++)
 299   {
 300     WATCHPOINT_ASSERT(ptr->continuum[pointer_index].value <= ptr->continuum[pointer_index + 1].value);
 301   }
 302 #endif
 303
 304   return MEMCACHED_SUCCESS;
 305 }
 306
 307
 308 memcached_return_t memcached_server_push(memcached_st *ptr, const memcached_server_st *list)
 309 {
 310   uint32_t count;
 311   memcached_server_st *new_host_list;
 312
 313   if (! list)
 314     return MEMCACHED_SUCCESS;
 315
 316   count= memcached_server_list_count(list);
 317   new_host_list= libmemcached_realloc(ptr, memcached_server_list(ptr),
 318                                       sizeof(memcached_server_st) * (count + memcached_server_count(ptr)));
 319
 320   if (! new_host_list)
 321     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 322
 323   memcached_server_list_set(ptr, new_host_list);
 324
 325   for (uint32_t x= 0; x < count; x++)
 326   {
 327     memcached_server_write_instance_st instance;
 328
 329     if ((ptr->flags.use_udp && list[x].type != MEMCACHED_CONNECTION_UDP)
 330             || ((list[x].type == MEMCACHED_CONNECTION_UDP)
 331             && ! (ptr->flags.use_udp)) )
 332       return MEMCACHED_INVALID_HOST_PROTOCOL;
 333
 334     WATCHPOINT_ASSERT(list[x].hostname[0] != 0);
 335
 336     instance= memcached_server_instance_fetch(ptr, memcached_server_count(ptr));
 337
 338     /* TODO check return type */
 339     (void)memcached_server_create_with(ptr, instance, list[x].hostname,
 340                                        list[x].port, list[x].weight, list[x].type);
 341     ptr->number_of_hosts++;
 342   }
 343
 344   // Provides backwards compatibility with server list.
 345   {
 346     memcached_server_write_instance_st instance;
 347     instance= memcached_server_instance_fetch(ptr, 0);
 348     instance->number_of_hosts= memcached_server_count(ptr);
 349   }
 350
 351   return run_distribution(ptr);
 352 }
 353
 354 memcached_return_t memcached_server_add_unix_socket(memcached_st *ptr,
 355                                                     const char *filename)
 356 {
 357   return memcached_server_add_unix_socket_with_weight(ptr, filename, 0);
 358 }
 359
 360 memcached_return_t memcached_server_add_unix_socket_with_weight(memcached_st *ptr,
 361                                                                 const char *filename,
 362                                                                 uint32_t weight)
 363 {
 364   if (! filename)
 365     return MEMCACHED_FAILURE;
 366
 367   return server_add(ptr, filename, 0, weight, MEMCACHED_CONNECTION_UNIX_SOCKET);
 368 }
 369
 370 memcached_return_t memcached_server_add_udp(memcached_st *ptr,
 371                                             const char *hostname,
 372                                             in_port_t port)
 373 {
 374   return memcached_server_add_udp_with_weight(ptr, hostname, port, 0);
 375 }
 376
 377 memcached_return_t memcached_server_add_udp_with_weight(memcached_st *ptr,
 378                                                         const char *hostname,
 379                                                         in_port_t port,
 380                                                         uint32_t weight)
 381 {
 382   if (! port)
 383     port= MEMCACHED_DEFAULT_PORT;
 384
 385   if (! hostname)
 386     hostname= "localhost";
 387
 388   return server_add(ptr, hostname, port, weight, MEMCACHED_CONNECTION_UDP);
 389 }
 390
 391 memcached_return_t memcached_server_add(memcached_st *ptr,
 392                                         const char *hostname,
 393                                         in_port_t port)
 394 {
 395   return memcached_server_add_with_weight(ptr, hostname, port, 0);
 396 }
 397
 398 memcached_return_t memcached_server_add_with_weight(memcached_st *ptr,
 399                                                     const char *hostname,
 400                                                     in_port_t port,
 401                                                     uint32_t weight)
 402 {
 403   if (! port)
 404     port= MEMCACHED_DEFAULT_PORT;
 405
 406   if (! hostname)
 407     hostname= "localhost";
 408
 409   return server_add(ptr, hostname, port, weight, MEMCACHED_CONNECTION_TCP);
 410 }
 411
 412 static memcached_return_t server_add(memcached_st *ptr, const char *hostname,
 413                                      in_port_t port,
 414                                      uint32_t weight,
 415                                      memcached_connection_t type)
 416 {
 417   memcached_server_st *new_host_list;
 418   memcached_server_write_instance_st instance;
 419
 420   if ( (ptr->flags.use_udp && type != MEMCACHED_CONNECTION_UDP)
 421       || ( (type == MEMCACHED_CONNECTION_UDP) && (! ptr->flags.use_udp) ) )
 422     return MEMCACHED_INVALID_HOST_PROTOCOL;
 423
 424   new_host_list= libmemcached_realloc(ptr, memcached_server_list(ptr),
 425                                       sizeof(memcached_server_st) * (ptr->number_of_hosts + 1));
 426
 427   if (new_host_list == NULL)
 428     return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
 429
 430   memcached_server_list_set(ptr, new_host_list);
 431
 432   /* TODO: Check return type */
 433   instance= memcached_server_instance_fetch(ptr, memcached_server_count(ptr));
 434   (void)memcached_server_create_with(ptr, instance, hostname, port, weight, type);
 435   ptr->number_of_hosts++;
 436
 437   instance= memcached_server_instance_fetch(ptr, 0);
 438   memcached_servers_set_count(instance, memcached_server_count(ptr));
 439
 440   return run_distribution(ptr);
 441 }